Document Yr7X8Q5gEYYG4ovwgr4qoaDgV

VRD 0002348897 CanTox Inc Consultants in Toxicology Health and Environmental Sciences A August 13, 1993 RECEIVED HE I 6/993 THE CHLORINE INSTITUTE. INC. Mr. Arthur E. Dungan Vice President, Health and Environment The Chlorine Institute, Inc. 2001 L. Street, N.W., Suite 506 Washington, D C. USA 20036 Dear Mr. Dungan: Enclosed is the first draft of the Plain Language Document that summarizes, in lay terms, the findings of the Critical Review. Dr. Munro is circulating this draft to members of the Expert Panel for their input. Dr. Nestmann is forwarding a copy of the draft to Brad Lienhart at CMA. We look forward to comments from the Technical Committee. Yours sincerely, CanTox Inc. for; Robert F. Willes, Ph.D. Principal Enel. cc: Dr. R. Smerko CALGARY OFFICE 2723 37 Atnu*N.E., Suite 206 Calgary. Alberta. Canada T1Y 5R9 Telephone: (403) 291-4646 Facsimile: 4403) 2S0-344S HEAD OFFICE 2233 Argentia Road. Suite 308 Mississauga, Ontario, Canada L5N 2X7 Telephone: (416) 342-2900 Facsimile: (416) 542-1011 HALIFAX OFFICE 12 LaurenlUn Drive Halifax. Nova Scolia. Canada B3M 3C3 Telephone/Facumile: (9021 443-1200 868 8110*000 oyA CanTox Inc. Consultants in Toxicology Health and Environmental Sciences PLAIN LANGUAGE DOCUMENT 4 Prepared for: The Chlorine Institute, Inc. 2001 L St., N.W., Suite 506 Washington, DC 20036 August 13, 1993 CALGARY OFFICE 2723 37 Avenue N.E., Suite 206 Calgary, Alberta, Canada T1Y SR8 Telephone: (403) 291-4646 Facsimile: (4031 250-344S HEAD OFFICE 2233 Argentia Road, Suite 308 Mississauga, Ontario, Canada L5N 2X7 Telephone: 4416) 542-2900 Facsimile: (416) 542-1011 HALIFAX OFFICE 12 Laurentian Orive Halifax, Nova Scotia, Canada t3M 3G3 Telephone/Facsimile: (902) 443-1200 TABLE OF CONTENTS CanTox INTRODUCTION KEY FINDINGS FOR EACH PRODUCT CATEGORY I CHLORINE Sources of Chlorine Cause-Effect Relationship Evaluation of the Potential for Adverse Effects from Chlorine Recommendations n POLYCHLORINATED BIPHENYLS (PCBs) Sources of'PGBs. Physical and Chemical Properties of PCBs and Fate in the Environment The Cause-Effect Relationship Evaluation of the Potential for Adverse Effects from PCBs Recommendations X i : : in VINYL CHLORIDE AND POLYVINYL CHLORIDE Sources of Vinyl Chloride and Polyvinyl Chloride The Cause-Effect Relationship :: < Evaluation of the Potential for Adverse Effects from Vinyl Chloride and PVC \VJ Recommendations -JH IV CHLORINE DISINFECTION OF DRINKING WATER AND WASTE WATER Production of Chlorinated Chemicals Througfcjp&infection with Chlorine The Cause-Effect Relationship Evaluation of the Potential for Adverse Effects from Cfhlorinated Chemicals Produced During Disinfection with Chlorine^ Evaluation of Alternative Methods of Water Disinfection^ Recommendations V INCINERATION OF CHLORINATED MATERIALS Production of Chlorinated Chemicals Through Incineration The Cause-Effect Relationship Evaluation of the Potential for Adverse Effects from Chlorinated Chemicals Produced During Incineration Recommendations VI WOOD PULP BLEACHING Production of Chlorinated Chemicals Through Wood Pulp Bleaching The Cause-Effect Relationship Recommendations 1 7 7 7 8 8 8 9 9 9 10 11 12 13 13 13 14 14 15 15 15 20 20 20 22 4 VRD 000 204 8899 VRD 9002048 900 CanTox VH CHLORINATED ORGANIC SOLVENTS Sources of Chlorinated Organic Solvents The Cause-Effect Relationship Evaluation of the Potential for Adverse Effects from Chlorinated Organic Solvents Recommendations vm THE USE OF CHLORINE IN THE DEVELOPMENT PESTICIDES Recommendations OF CONCLUSIONS 22 22 23 24 25 25 26 26 A \ VRD 0001048991 INTRODUCTION CanTox A Since ancient times, humans have used chemicals as tools in the quest for improved quality of life. Originally, useful chemicals were obtained as natural extracts, but with the understanding of chemistry came the ability to synthesize specific chemicals for particular applications. Many of these specifically produced chemicals contain chlorine molecules as part of their chemical makeup. A chlorinated organic chemical is made up of atoms of carbon and hydrogen and chlorine. In addition to being synthesized for specific applications, chlorinated organic chemicals originate from natural souses and are also by-products or end-products resulting from various human activities includiiigpulp and paper production, incineration, manufacture of numerous consumer products and disinfection of drinking water. Chlorine-containing chemicals are used in the production of numerous consumer goods including pharmaceuticals, food additives, crop 4 protection agents, sunscreens, cosmetics? plastics, adhesives, paints, varnish, antifreeze, spandex and soft drink syrup, to name just a few^In addition, some alternative processes and chemicals may be less environmentally friendly, or the potential hazards have not been sufficiently well studied compared to those based on chlorine'chemistry. As the production of chemicals, including chlorinated organic chemicals, has increased to support the growing demands of society, so too have scientific knowledge and societal concern about the possible effects of chemicals released into the environment. Active field and laboratory research into the biological effects of specific chemfcaUNhas suggested an association between releases of large quantities of certain chemicals, reSotog in increases in their concentrations in the environment, and adverse effects on wildlife, ^^chlorinated chemicals for which these associations have been observed represent a small subsd^8fctf|e entire universe of chlorinated chemicals. This small group of chlorinated chemicals has jMpfcjies that result in their ability to accumulate in the tissues of organisms as they are passed fromwe&to predator up the food chain (a process known as bioaccumulation). The combinat^^pf their bioaccumuiative properties and the quantities released into the environment results^J^reat enough concentrations in animals at the top of food chains that adverse effects may occur. Numerous other chlorinated organic chemicals, that do not have these structurally and functionally bioaccumuiative properties, do not result in such effects in the environment. These 1 VRD 0001048902 CanTox observations show that the mere presence of chlorine on a molecule does not cause it to have adverse effects in the environment. While there have been allegations that the bioaccumulative chlorinated chemicals can cause adverse effects at very small concentrations (parts per trillion and parts per billion in the environment), a detailed comprehensive review of the existing scientific evidence regarding the potential of these and other chlorinated chemicals to affect the environment or human health has not previously been undertaken. This study was conducted in order to produce an interpretive evaluation of the potential adverse effects of chlorinated chemicals on human health and the environment. This was achieved through the application of sound scientific principle^to the assessment of the vast amount of data existing on these chemicals. , 4 There are several thousand chlorinated organic chemicals, rendering it impossible to evaluate each one of them thoroughly, withfcrthe scope and time frame of this work. However, many have been studied in great detail througji|fsting of animals in the laboratory, studying humans and wildlife exposed to chemicals in the environment, and measuring their concentrations in different media of the environment (e.g., ak^ Wafer, soil, sediments, animals). Since it was not practical nor feasible to assess the potential adverse effects of all chlorinated chemicals on human health and the environment, it was necessary to select a group of chemicals that could be studied. This selection process considered those chemicals which have been identified by different agencies as concerns due to potential adverse efffecti^In addition, consideration was given to the availability and completeness of information da-. to base an assessment, Finally, consideration was given to usefulness of the chemical as example from which various scientific principles could be assessed for application ixfth^jNievelopment of new chemicals and products that would not be harmful to human health or tW^avironment. The chemicals were chosen to include representatives of the major classes of chfoiiteted organic chemicals that could serve as surrogates for those not studied in detail. In idanuying the chemicals, the various types of product categories, in which chlorine is employed|^ere considered. The chemicals of greatest concern were selected from a list of 93 chlorinated chemicals identified by various agencies as potential concerns to the environment, including human health (Table 1). By considering total quantities of use and the potential for the 2 VRD 0002846993 4 CanTox chemical to produce harmful effects, 46 chlorinated chemicals were selected for detailed evaluation in the eight product categories (Table 2). The eight product categories cover a wide spectrum of chlorine chemistry used by society and are as follows: i) molecular chlorine, ii) polychlorinated biphenyls (PCBs), iii) vinyl chloride/polyvinyl chloride (VCM/PVQ, iv) chlorine disinfection of drinking water and waste water, v) incineratioELjOf chlorinated materials, vi) wood pulpbteaching, vii) chlorinated orgpic solvents and viii) the use of chlorine m the development of pesticides. For the first seven product categories, thecpossible harmful effects were evaluated, from past and v present uses of the chlorinated chemicals included in each product category, and predictions of future safe use patterns were made. In the caise^of pesticides, the role of chlorine in pesticide activity was assessed, and the need to assess each Chemical individually was discussed, based on its potential to cause hazardous effects relative to-iti potential benefits. 3 APPROACH TO THE SCIENTIFIC EVALUATION OF DATA CanTox In order to evaluate the potential for a specific chemical to cause adverse effects on human health or the environment, the following questions must be addressed: is there opportunity for exposure of humans or the environment to the chemical? can the chemical interact with biological systems in a manner consistent with known biological principles? is there a scientificjpasis for concluding that specific adverse effects are associated with exposure to the cffemical? is the degree of exposure sufficiently high to be likely to cause adverse effects? If the available information is s the potential for adverse effect lswer these questions, then it is possible to evaluate nvironmental concentrations of specific chemicals. In attempting to answer these questions fobe^representative chlorinated organic chemicals chosen for the current study, a rigorous scientifidSpproach was taken to the interpretation of the published information. The amounts and types of^information available varied among the different chlorinated chemicals, with most falling into the following categories: studies of concentrations of specific chemicals in air, water, soil, sediment and biological tissues. VRD 00020 4 8905 CanTox In evaluating the available studies in these various categories, the scientific strengths and weaknesses of the supporting information were assessed, as it affected the validity of the conclusions. After reviewing numerous studies on each of the representative chlorinated organic chemicals, conclusions regarding the potential for each of them to cause adverse effects were made based on the overall weight-of-evidence. One of the most important outcomes of this type of weight-of-evidence analysis is the establishment of sound cause-effect relationships. The mere presence of a chemical in the environment in association with a particular adverse effect does not necessarily mean the observed effect was caused by that chemical. In assessing the plausibility of possible carae-effect relationships between chemicals and adverse health effects, the following consideratfiM# were made: A does the adverse effect bOcur more frequently in populations of humans and/or animals known to be exposed to tl&eftemical? is the adverse effect more severe in humans and/or animals exposed to higher concentrations? has the adverse effect been reported toi& associated with exposure to the chemical by different investigators, in different placesf a| different times? does the adverse effect occur only after exposure to the chemical has begun? does the adverse effect disappear or become less severe when the chemical is removed or concentrations are lowered? %r is the chemical likely to be able to cause the observed effect according to known biological principles? have similar chemicals been associated with the adverse effect? Once having established the plausibility of a cause-effect relationship, the rell^pship between the dose and the magnitude of the effect was examined. The purpose of this erapbrtion was to determine the highest dose of a chemical that could be tolerated by humans o^a^ldlife without causing adverse effects. As the earliest toxicologists knew, it is the dose that miles the poison, with the most innocuous chemicals (such as water) capable of causing adverse effects when consumed in excessive quantities, and the most hazardous chemicals (such as cyanide) having no adverse effects when consumed in very small amounts. This determination of a no 5 YRD 9002048906 CanTox effect or "safe" dose for each chemical is usually based on the results of controlled studies in laboratory animals, in which low, medium and high doses were given every day for life. This type of study, where the doses are known and only one chemical is given, provides a reliable means of determining the safe dose for an animal (usually rats or mice). The "safe" dose for humans was calculated either by the application of safety factors to the safe dose observed for animals in laboratory studies (i.e., by dividing the safe dose for an animal by factors of 10, 100 or 1000, depending on the type of study, species tested, and severity ami type of effect caused at higher doses in animals), or by the use of theoretical dose-response models. 4 To evaluate the potential far adverse effects to occur from concentrations of chemicals in the %\ environment, the exposures expected as a result of environmental concentrations are either estimated using exposure modeler measured directly in tissues of exposed populations. If the estimated exposures (doses) are low|han the "safe" dose, then no adverse health effects might be expected. If the exposures exceeded the "safe" dose, there is the potential for adverse health effects. This type of assessment was conducted for all the representative chemicals in each product category, based on their rates dfplease and measured concentrations in the v'' " ' environment. In order to put the environmental concentrations of chlorinated organic chemicals associated with the product categories into perspective^ the sources of such chemicals produced through natural processes, independent of human activities, also were evaluated. To summarize, the following steps were taken in the assess each product category: the selected chemicals in Determination of sources and amounts of the selected chlorinat the environment from human activities and natural processes. released to Estimation of typical exposures to various organisms, including' information on concentrations of the chemicals in air, water, soil and other'* media. , using ninenfal Assessment of the potential of the chemicals to cause harmful effects, and the uiM >f this information to determine safe levels of exposure for each chemical. 6 VRO 900204 8997 CanTox Assessment of the degree of concern or risk from the use of the chemical by comparing the exposures from environmental media against the upper exposure limit of the chemicals. KEY FINDINGS FOR EACH PRODUCT CATEGORY I CHLORINE Sources of Chlorine Sources of chlorine re uman activities include the following: the manufacture of olastand adhesives; the manufacture of chlorinated oEganic chemicals; the manufacture of drugs; ?V ' the manufacture of various household gbOdfe. including deodorants, cleaners and bleaches; use of chlorine for drinking and waste water disinfection. A The Environmental Protection Agency's Toxics Release Inventory estimated the total quantities V; of chlorine released into the environment by human activities & United States to be between 35 and 36 million pounds per year over the period 1987-1990. iff, is approximately one tenth or less, of the annual production of chlorine from natural sources.\Cldprine released into the environment rapidly reacts with water or water vapors to produce hyom^ioiic acid (HC1). Natural sources of chlorine include: volcanic eruptions; the break-down of sea salt by ultra-violet light from the sun (known as Volcanic eruptions have been estimated to contribute from 0.4 to 11 million tons ofchlorine/year (800 million to 22 billion pounds) on a global basis. The production of chlorine in the 7 8068*01000 (MM CanTox atmosphere by the photolysis of sea salt is believed, by Swedish scientists, to result in the deposit about 1 to 23 pounds of chlorine per hectare of land each year on a global basis. Cause-Effect Relationship The potential for harmful effects to the environment from chlorine is associated with the corrosivity of hydrochloric acid produced by the reaction of chlorine with water in the environment or in the respiratory tissues of air breathing organisms. Evidence from studies with laboratory animals and from accidental human exposures have shown that sufficiently high concentrations of chlorilejas or hydrochloric acid can cause irritation to tissues at the site of contact with effects becomiri&^bss severe at lower doses. At sufficiently low concentrations of hydrochloric acid no adverse effects occur. Evaluation of the Potential for Adversp Effects from Chlorine The conclusion of the interpretive review ofth^ available information on chlorine is that, with ' '"5. the exception of spills related to transportation and use, and large accidental releases from point sources, the concentrations of chlorine in the environment over the past two decades have been below those expected to cause unwanted or harmful effects on human health or the environment. Recommendations Continued efforts are required to make sure that spills and accidentsfh^release chlorine to the environment are minimized and those that occur are controlled as quSwO] possible. The current trends in the adoption of best-available-technologies for systems thai of chlorine to the environment must continue, to ensure that potential harmfu snt the release from the uses of chlorine are prevented in the future. 4 8 VRD 000204 8 9 0 n POLYCHLORINATED BIPHENYLS (PCBs) CanTox Sources of PCBs Historically, the largest use of PCBs was in the electrical industry, because their superior heat absorbing capacity and electrical insulating properties provided greater safety (e.g., reduced fires and explosions) compared to alternative materials. PCBs are no longer manufactured, but are still in use in some closed systems. Until recently it was believed that there were no known natural sources of PCBs; however, PCBs, not related to any human activities, were identified in ash from the 1980 voleajpq, eruption of Mt. St. Helens in Washington state, indicating their formation from natural procegies independent of human activities. The quantities of PCBs released to the environment frora.volcanic eruptions are unknown. Physical and Chemical Properties of PCBs and Fate In the Environment The term PCBs denotes a family of 209 chemicals with chlorine attached at various places on the molecule. Depending on the position and ampuat of chlorine, the different PCBs exhibit a wide range of physical and chemical properties. For example, the ability of the different PCBs to dissolve in water ranges over 5.5 million-fold and the potential for vapors to form in the air ranges 100,000-fold among the different PCBs. The ability^fdifferent PCBs to be stored in the '00- body fat of animals ranges over 10,000-fold, and becomes increasing amounts of chlorine on the molecule. Since the behavior of chemicals in the ^jyisgnment is determined by their physical and chemical properties, the differences in propertie^^the various PCBs are reflected in their distribution, disappearance and movements in the enviTmmcnt. Generally, as the amount of chlorine contained in PCBs increases, their disappearance Swliqgjadation in the environment becomes slower. Some forms of PCBs are stored in the fat of org^S^s following exposure. These PCBs are subsequently passed to predators and stored in the fat of ^^redator. Since elimination from biological tissues is very slow for some of these PClNj^heir concentrations stored in fat gradually increase in organisms if their rate of exposure exceeds their rate of elimination. This leads to the potential for adverse effects especially in predators at the top of food chains, such as fish-eating birds and mammals. 9 a im a z M B nya CanTox The combination of unrestricted use and of physical properties, which favor long range atmospheric transport, bioaccumulation and slow breakdown of PCBs has resulted in their widespread distribution in the environment, including remote areas such as the Arctic and Antarctic. Due to their widespread occurrence, PCBs are found at low concentrations in tissues, (such as fat, liver, blood and breast milk) of people with no known occupational or unique environmental exposures. Concentrations of PCBs in various aquatic wildlife (e.g,, fish and fish-eating birds) are generally greater than those reported for humans, primarily because of the characteristics of aquatic food chains and the less varied diets of aquatic wildlife (i.e., almost The Cause-Effect Relations!^* Laboratory studies on animals have indicated that PCBs have the potential to cause adverse effects on reproduction and that extreme^doses of some PCBs can increase the incidence of liver cancer in rats. These effects have been shown to be dose-related (i. e., they become less severe and less prevalent at lower exposures). There Is good evidence indicating that sufficiently low exposures to PCBs do not cause adverse effects.,,, Certain adverse effects, such as eggshell thinning in some species of Great Lakes fish-eating birds and crossed bills in cormorants, increased in prevalenceijpd severity as the concentrations of PCBs and several other chemicals in the environment , and have declined as concentrations have declined. This consequent decline in environrtrestti concentrations of PCBs % '% and the recovery of bird populations is consistent with a cause-effect relationship between PCBs suggesting tnat loss or naoitat caused Dy increasing urbanization and tauity industrial practices occurring at the same time that concentrations of PCBs and other chemicals were increasing. also played a role in the population declines observed in certain wildlife species during this time 10 VRD 000204 891 1 CanTox A period. Because of the existence of these other influences on the reproductive health of wildlife it is not possible to attribute the observed adverse effects in fish-eating birds solely to PCBs, although the weight of evidence suggests that they have likely played a role in the observed effects. Evaluation of the Potential for Adverse Effects from PCBs The conclusion of the assessment of PCBs is that environmental releases between their initial introduction in the 1920s .until cessation of manufacturing in the 1970s, were not appropriate based on what is now kn&gjk about their behavior in the environment and the possible harmful effects they may produce whefrexposures are too great. These possible harmful effects of PCBs alone are difficult to determine'in the field, because wildlife are exposed at the same time to mixtures of many different chemicals^ However, laboratory studies demonstrate that PCBs could interfere with reproduction of wildlife ia tfie environment. The greatest concerns are for wildlife species at the top of aquatic food chains (e.g., fish-eating birds and mammals). The information now available, on the properties of PCBs and oAfbe possible harmful effects that can result from chemicals with such properties if exposures ageJgreat enough, shows that these types of chemicals should not be used in ways that allow their direct release into the environment. V% Following controls over the use of PCBs in 1972, and banning of their production in 1978, the quantities of PCBs released into the environment were reduda$if^Dv uring the 1970s and early 1980s, substantial decreases were observed in the concentrations bfPCBs in the environment and in organisms, including humans and aquatic wildlife. Changesproduction and use practices of several other chlorinated chemicals {e.g., DDT, hexachldf^p^ne, mirex) also occurred during this same time period. Since the mid-1980s, the concentnTMn^?f PCBs in the environment have been decreasing more slowly compared to the decreases sedh^p the 1970s immediately following the restrictions in their use. A major factor responsible fc|0|g slower rates of decrease of environmental concentrations appears to be the continued releasesw^Bs from old electrical equipment still in service, from various PCBs storage facilities, and from landfill sites. In addition, PCBs already in the environment are being transported around the earth, primarily in the atmosphere. This transportation process continues to deposit PCBs into 11 716 81*0 7000 OilA* CanTox water bodies, where they can be accumulated by various organisms. Therefore, future rates of decreases in concentrations of PCBs in the environment are expected to remain slow relative to those observed historically. Based on current knowledge about dose-response relationships for the possible harmful effects of PCBs, mostly from laboratory studies, and from studies of human populations historically exposed to PCBs in the workplace, no harmful effects would occur from exposures of humans to current environmental concentrations of PCBs. However, there is a greater likelihood for harmful effects on certaiiwwildlife than humans, due to dietary habits and position in the food chains. This greater possibility for harmful effects from PCBs is particularly pronounced in * y'n, species that eat almost exclusively fish and other aquatic organisms. Concern about possible harmful effects in such species fSfinderstandably great in regions of the environment where the concentrations of PCBs, together wrtft cther chemicals, are markedly elevated (e.g., various "hot spots"). With the exception of these localized "hot spots", caused by historical point-source releases of chemicals, any adverse effects on the environment expected from current environmental concentrations of PCBs should be minor. Although PCBs were once considered to be resistant to natural biological breakdown, there is now considerable laboratory and field evidence to the contrary, although their breakdown fare varies significantly depending on the numbers and positions of chlorine on the PCBs. As the environmental concentrations of PCBs and other bioaccumulative chemicals continue to decline, throjjfgh restrictions on environmental release rates, through natural, physical and biological degrifedfcdion processes, and through % '4 continued burial via sedimentation, the degree of harmful effect^kN^calized "hot spots" will continue to decline. ^^ Recommendations Chemicals having physical and chemical properties similar to those ofcertain PCBs,|vji|ch result in their accumulation in the environment, should not be used in ways that lead^^beir uncontrolled release into the environment. The knowledge that these types of chemicals can be widely distributed throughout the world and will degrade slowly, should govern the design and 12 CanTox use of new chemicals so that the situation that occurred with PCBs and other bioaccumulative chemicals is not repeated. m VINYL CHLORIDE AND POLYVINYL CHLORIDE Sources of Vinyl Chloride and Polyvinyl Chloride Vinyl chloride and polyvinyl chloride are products of the plastics industry. Vinyl chloride, as it is, is not used in conmercial products, but is the starting product for the production of polyvinyl chloride (PVQ^PVC (called polymers) is made by linking a large number of vinyl chloride units together to forrof# long chain of linked molecules. PVC is a solid material with great stability in the environment Its most recognized use is in PVC pipe, used in many drainage and plumbing appticatiofcSk^Under good manufacturing procedures, the residual concentration of vinyl chloride in moderitpVC products is below the lower limit of analytical detection limits. Vinyl chloride can be released to the atmosphere &js a vapor, and it rapidly degrades by reactions with ultraviolet light. It does not accumulate through fbod chains and ultimately is completely broken down by biological systems. Vinyl chloride molecules are reactive and readily join together in the presence of oxygen, sunlight or heat to forin Stable PVC. No information was available on the air concentrations of vinyl c locations remote from \ production/manufacturing facilities. However, based on the conceti s reported near such facilities and the rapid rate at which it is destroyed in ambient air, itrations in air in remote locations would be expected to be very small, and not even m with current techniques. The Cause-Effect Relationship Laboratory studies using animals have demonstrated that high dose, long-term exposure to vinyl chloride can result in the development of liver cancer. In addition, exposures of humans to 13 3cs0 S ea VRD 000204 8914 A CanTox unacceptably high concentrations of vinyl chloride in some workplaces prior to the 1970s are believed to have resulted in increases in an unusual liver cancer (called angiosarcoma) in workers. Intermediate break-down products formed during the degradation of vinyl chloride are reactive and bind to genetic material (DNA) in cells. The reactions of these reactive intermediates with DNA are believed to be responsible for the cancer-producing activity of vinyl chloride. Through changes in technology, the air concentrations of vinyl chloride in workplaces in the 1980s were reduced about^l0,000- to 100,000-fold compared to the pre-1970 values. Lower concentrations in the workplace, combined with protective equipment used by workers, virtually eliminated risks of liver cancel from occupational exposures associated with the use of vinyl chloride. Evaluation of the Potential for Adverse Effects from Vinyl Chloride and PVC No harmful effects to human health or the general environment occur from PVC itself. The major concern regarding PVC is the possible exposure of workers to PVC dust arising from the use of PVC materials in manufacturing processes, anfpossible products (e.g., vinyl chloride monomer) arising during its production. Through modifications in the manufacturing processes, the concentrations in the workplace have been reduced to nearanalytical detection limits (about 5 parts per billion) and are not associated with adverse effectf'ptiNhumans or the environment. Recommendations The use of production and manufacturing technologies that eliminate releaSei tfyinyl chloride to the environment should continue, thereby preventing air concentrations of vii u chloride from exceeding current undetectable values and ensuring that no harmful effects on hui ealth or the environment would occur. Continued care is required to ensure that spills and a^^^ntal releases of vinyl chloride are minimized, and if accidents occur, that the resulting releases are controlled to prevent harmful effects to human health or the environment. 14 168*07000 fl t CanTox IV CHLORINE DISINFECTION OF DRINKING WATER AND WASTE WATER Production of Chlorinated Chemicals Through Disinfection with Chlorine Chlorine is used in the disinfection of drinking and waste water in order to prevent the spread of waterborne diseases such as typhoid and cholera, diseases which used to claim the lives of millions of people in Western society prior to the development of water treatment techniques. Several chlorinated chemicals are produced as unwanted by-products of the chlorine disinfection process, and low concentrations of these remain in the finished water. Everyone consuming chlorine-disinfected tap wa^ris exposed to low concentrations of these chemicals. These are not uniquely man-made chemicifeMost are also produced in significant amounts through natural processes, and exposure to huifiini and the environment would occur to some degree even if they were not found in treated drinking and waste water. In addition, improvements in the techniques of disinfection of drinking- water with chlorine can substantially reduce the concentrations of these unwanted by-products in the finished water. `'y'-J, K-. The Cause-Effect Relationship % The most significant chlorinated chemicals found in water disinfected with chlorine were evaluated in terms of their potential for causing adverse effects. For all these chemicals, substantial amounts of information were available ailowing^asacterizarion of the types of effects they could cause and of the doses required to cause the e >ses were determined for each of the chemicals that would be expected to result in no of adverse effects on humans or the environment. Evaluation of the Potential for Adverse Effects from Chlorinated Ch During Disinfection with Chlorine Produced The majority of the chlorinated chemicals studied in drinking water are present in tap water at concentrations far less than the concentration at which adverse effects would be expected. Two types of chlorinated organic chemicals (chlorinated ketones and nitrogen compounds) could not 15 VRD 0002048916 CanTox be rigorously evaluated due to inadequacies in the toxicological data base; however, the very low concentrations (parts per billion) of these were considered not likely to be associated with adverse health effects. Two types of inorganic chemicals (chlorite and chlorate) have been detected in some drinking water samples at concentrations exceeding those recommended as allowable. This exceedance of the allowable concentration in some cases may not be significant in terms of potential adverse health effects, because of the highly conservative procedures followed in establishing the recommended maximum concentrations. Overall it can be concluded that disinfection of drinking water using chlorine results in the production of a safe water supply. A The concentrations of chlophaled organic chemicals in rivers, lakes or streams receiving waste water disinfected with chlorine^were below those that would be associated with adverse health effects on aquatic organisms, ^m0/'-s. ome cases the concentrations of one type of chemical ,4&r. (chlorinated phenols) exceeded surface water guidelines in the effluent, prior to entry into the receiving water. These occurrences wereprimarily historical and surface water quality guidelines were not exceeded once the effluent was diluted into the receiving water. Another group of chlorinated chemicals (chlorinated dioxins and furans) can occur at concentrations in waste waters (primarily from sewage treatment plants) that are high enough to warrant some concern. This concern stems from the potential for these compounds to bioaccumulate through the aquatic food chain. The chlorinated phenols and chlorinated dioxins and furans may have been present in the raw water prior to treatment and may not have been produced as a result of chlorination, and so no conclusion regarding the effect of chlorination potential for them to cause adverse effects can be made. Overall the weight-of-evidence indicates that chlorine disinfection of would not be associated with adverse effects on humans or the environme: and waste water Evaluation of Alternative Methods of Water Disinfection There are a number of other processes which can be used in the disinfection of drinking water and waste water, each of which was evaluated for suitability in terms of the following criteria: 16 U6BBBZBBB fla t CanTox production of chemicals at concentrations not associated with adverse effects the availability of information on the types and quantities of various by-products from alternative water disinfection processes, and of information required to assess their potential harmful effects ability to effectively destroy bacteria, viruses and parasites in water retention of disinfection capability throughout the water distribution and storage system improve the taste, smell, clarity and color of the water after treatment Disinfection using chlonpiNneets all these criteria, while the other methods of disinfection meet only some of them. In m^st^cases, the available information required to assess alternative " %% disinfection technologies is incomplete, particularly regarding the identification and quantification of by-products. A major deficiency Jji the use of ultraviolet light for water disinfection is the yv-.K'. . lack of residual disinfection capacity outside the water treatment plant. The overall conclusion from the current assessment is that disinfection of drinking water and waste water by chlorination remains the method^,choice. Recommendations The scientific basis for the establishment of the maxsnum allowable concentration of chlorite and chlorate should be more rigorously defined. s* `-y. The maximum concentration of chlorate and chlorite in finished drinking water should be reduced, through adjustments and refinements of the disuttfep&on process. Continued vigilance needs to be employed in the control of the process to ensure that the concentrations of chlorinated phenols water guidelines. water treatment exceed surface The source of chlorinated dioxins and furans in treated waste waters established, and a detailed risk assessment, incorporating analysis of the a< chain, needs to be conducted to ensure that concentrations are below those cause environmental concerns. 17 VRD 0002849916 INCINERATION OF CHLORINATED MATERIALS CanTox Production of Chlorinated Chemicals Through Incineration Chlorinated chemicals can be emitted from incinerators as a result of incomplete burning of materials fed into the incinerator, or through chemical reactions occurring in the incinerator stack. Numerous chlorinated chemicals have been detected in emissions from incinerator stacks. Most of these are not uniquely man-made chemicals but are also produced in significant amounts through natural processes*, particularly those involving high temperatures such as volcanic eruptions and forest fire&^jluman and environmental exposure to these chlorinated chemicals would occur even if incineratibn technologies were not used, and the available information demonstrates that insignificant ns of such chemicals arise from a properly operated, best- Jfr. available-technology incinerator. The Cause-Effect Relationship The most significant chlorinated chemicals found in incinerator emissions were evaluated in terms of their potential for causing adverse effects: For most of these chemicals a substantial amouat of information was available to allow characterization of the possible effects they may cause and the doses required to cause the effects. For eadvoithe chemicals, upper dose limits were developed that would not be expected to result in the OcaUrrence of adverse effects on %. % i humans or the environment. .V&a Evaluation of the Potential for Adverse Effects from During Incineration Produced The potential for adverse effects from chlorinated chemicals produced through inci^ejyon was evaluated through the assessment of an actual facility employing the best available tea|p^>gy. 4 18 The steps taken in conducting this analysis included the following: CanTox prediction of concentrations of representative chemicals in air, water, soil and wildlife resulting from the incinerator emissions; prediction of exposure to humans and wildlife resulting from these environmental concentrations; comparison of expected exposure from the incinerator emissions with the maximum safe exposure limits for each chemical. The predicted exposure^^hlorinated organic chemicals from the case study incinerator were substantially lower than trf^naximum safe exposures, indicating that no adverse effects on human health or the environment would be expected. In addition, the predicted exposures to the chemicals were substantially (o^irs^pf magnitude) less than those associated with exposures from ambient background sources, independent of the incinerator. Although the amounts of chemicals emitted from an incinerator arifdependent on a number of factors related to the design and operating conditions of the facility, the case study facility is considered representative of a * *2. modem day incinerator employing best availabie technology. Emission rates of chlorinated chemicals from any such facility would be very low, and not associated with any adverse effects. Recommendations //%. Outdated incinerator facilities should be upgraded or replaced tonsure that the best available technology is being employed. New facilities should be constructed Isi% only the best available technology in order to ensure minimal concentrations of chemicals i|^^ssions. Operating incinerators should be monitored to ensure they are operating properly. 19 016 8 *87808 llm vi WOOD PULP BLEACHING CanTox Production of Chlorinated Chemicals Through Wood Pulp Bleaching In order to manufacture high quality white paper, the wood pulp must be bleached. Historically, the only method of bleaching pulp was to use gaseous chlorine. This resulted in the formation of a number of chlorinated organic chemicals as the chlorine reacted with other chemicals used in the process and with chemicals from the wood itself. Most of these chemicals are not uniquely man-made chemicals, andmany are produced in significant amounts through natural processes independent of wood pulf^production. All the classes of chlorinated organic chemicals produced from pulp bleaching are represented by naturally occurring chemicals. Therefore, low concentrations of chemicals that^are the same as or similar to those produced by pulp mills if would be encountered by orgaiusnss^the environment, even if chlorine was not used in the pulping process. w Improvements in wood pulp bleaching technology and the development of new processes have led to the ability to whiten wood pulp using forms ofChlorine other than gaseous chlorine. These modern processes result in the production of very low. level chlorinated organic chemicals. The Cause-Effect Relationship % <5 Biological effects of pulp mill effluents can be evaluated in two toxicity testing of effluent in the form that it is discharged from tftfe mill; evaluation of toxicity of individual chemicals present in mill efflu Effluents from pulp mills using molecular chlorine are generally toxic to fish si in tanks containing undiluted effluent. Since there are numerous chlorinated and non chemicals present in the effluent, it is not possible to determine from this type of stud^fv rich particular chemical or mixture of chemicals is responsible for the toxicity of the effluent. 20 U 6 8 H Z 0 0 0 fliflf CanTox In field studies, adverse effects have been observed in fish downstream from some pulp mills. Recent studies have indicated that once the mills stop using chlorine in the bleaching process, some adverse effects on the fish continue to be observed. This suggests that non-chlorinated chemicals, and/or the disruption of habitat are at least partially responsible for the observed effects. Effluents from pulp mills using the best available technology are not lethal to fish, and in fact fish can survive without evidence of adverse effects when exposed for four days to undiluted effluents from such mills. Individual chlorinated chemicals representative of the major classes of these chemicals were evaluated in order to whether any particular chemicals were present at high enough concentrations to cause adversft&fects (i.e., growth and reproduction effects) in fish downstream from pulp mills. Potential advise effects on human health were evaluated on the basis of consumption of fish living downstream from pulp mills. This evaluation was based on mills using chlorine bleach or gaseous chlorin^ita the bleaching process, since very small amounts of chlorinated chemicals are produced by mills using modem methods. For most of the representative chemicals, concentrations measured in rivers downstream of pulp mills are below those that could be associated with adverse effects. For two classes of chemicals insufficient data were available to allow a rigorous assessment to be conducted (chlorinated fatty and resin acids and chlorinated ketones). i r%- There was only one group of chemicals for which concentrations ii ve cause for concern (chlorinated dioxins and furans). The concern regarding the chlorii xins and furans stems from the facts that they can cause adverse effects on reproduction and tf ,ey bioaccumulate in the aquatic food chain. Since the potential effects of these chemicals v site and mill specific, the assessment was based on a specific case study. Concentrationw^^chlorinated dioxins and furans in fish were measured downstream from a mill that used gaseou|c!|orine as the bleaching agent. This mill is remotely located, and fish living downstream are from migrating by a dam on the river. These characteristics minimized the potential influences of factors unrelated to the pulp mill. The concentrations of chlorinated dioxins and furans in fish caught downstream were below those that would be associated with adverse effects in fish, 21 VRD 0O1B4 89 22 CanTox although consumption of the fish by fish-eating mammals and birds such as otters and osprey could possibly result in accumulation in these species of enough chemical to adversely affect reproduction. Consumption of these fish by humans would not be expected to result in the accumulation of enough chemical to cause adverse effects. A In pulp mills not using gaseous chlorine for whitening pulp, chlorinated dioxins and furans cannot be detected in effluent. If it is assumed that concentrations of these chemical do exist at concentrations at the detection limit (10 parts per quadrillion), the resulting concentration in fish would not be expected to^esult in adverse effects in any species, including predators high on the food chain such as ottepand osprey. Similarly, no adverse effects would be expected from .w-Ai. the other chlorinated cl in the effluent from mills employing alternative methods for whitening pulp. Recommendations m- Pulp mills should use best available technologyTor producing and bleaching wood pulp so as to avoid the use of chlorine bleach or gaseous chlorine and thereby reduce or eliminate the discharge of chlorinated organic chemicals, particularly chlorinated dioxins and furans, to the aquatic environment. Research efforts should continue to focus on elucidating the factors or non-chlorinated chemical(s) responsible for the effects obiprVed in fish populations near pulp mills. *? VH CHLORINATED ORGANIC SOLVENTS Sources of Chlorinated Organic Solvents Chlorinated organic solvents are used in a wide range of production and mfhU&ctunng processes. Chlorinated organic solvents are generally small molecules that are derivatiy^^low molecular weight hydrocarbons. These chemicals include compounds such as chloroform, carbon tetrachloride, dichloromethane (methylene chloride), dichloroethane, and di-, tri-, and tetrachloroethylene. Chlorobenzenes are also widely used as solvents in the chemical industry. 22 CanTox During use, chlorinated solvents would be released into the workplace and the local environment surrounding production and manufacturing facilities. The implementation of more stringent effluent and emission criteria and improvements in operating technologies, based on a general improvement in the scientific understanding of the behavior and potential effects of chemicals on the environment, have resulted in decreased total quantities of chlorinated organic solvents released to the environment in the past decade. However, some environmental releases from these point sources still remain, even though they have become fewer with time and are within recommended limits. The chemicals from these point-source releases continue to disperse into the environment and contribute to the general ambient concentrations of these chemicals. Most of the chlorinated orgamb^emicals used as solvents are also released into the environment as by-products of a number ofotigf human activities (e.g., chlorine disinfection of drinking water, products of incomplete combustii(PICs), chlorine bleaching of paper pulp), and as products of a number of natural processes independent of human activities. 4C3 CCDO <s <S cu The Cause-Effect Relationship fy - The most significant chlorinated chemicals wfaidh are used as solvents, such as carbon tetrachloride, chloroform, the chloroethylenes and ttu$ chlorobenzenes, were evaluated with respect to their potential for causing adverse effects. For all these chemicals, substantial amounts of information were available. As a result, a detailed characterization of the types of K.<*Sy effects caused and of the doses required to cause the effects tfas|eompleted for each chemical. Doses were determined for each of the chemicals that would^ta^^xpected to result in no occurrence of adverse effects on humans or the environment. As a rule, the chlorinated solvents are of a relatively low order of toxicit the liver and kidney generally being the main organs affected in humans and/or animals recenirij^Jiigh doses. Some of the chlorinated organic chemicals have been reported to induce tumors ^^toratory studies using animals, albeit through mechanisms which may be related to the extrem<^p the doses tested or to the specific physiology of the test animals. As a result, for some of the chlorinated organic solvents, the observation of tumors in certain animal studies is not likely to be relevant to degrees of exposure experienced by humans from the environment. 23 VRD 0092048924 CanTox Evaluation of the Potential for Adverse Effects from Chlorinated Organic Solvents A The evaluation of the potential adverse effects of chlorinated solvents on human health and the environment was based on exposures to ambient concentrations of the chemicals. It is not possible to conduct a general assessment of potential adverse effects that may be associated with point source releases because such assessments would be specific to the site, workers and processes involved. With the exception of certain low molecular weight chlorinated chemicals such as chloroform and carbon tetrachlorid^^fman and environmental exposures to chlorinated organic solvents from general ambient sourCe%!rouid be substantially below exposure limits considered to be '':sy protective of human health andffiie environment. In the case of chloroform and carbon f tetrachloride, exposures to the average ambient environmental concentrations would be substantially below the exposure limig*- considered protective of human health and the environment. However, at the maximum ambient environmental concentrations reported historically at certain locations in specific urbaiitenters, the recommended exposure limits would be exceeded by a small margin. This does not mean that adverse health effects would be associated with exposures to the maximum ambient environmental concentration since there are substantial margins of safety between the exposure limits and exposures that could produce observable adverse health effects. *, ' The releases of solvents produced by human usage to the envirori^M^. particularly chloroform vi and carbon tetrachloride, have decreased over time, with increased us&g<|^a closed, non-emissive systems. In the case of chloroform, historical data on drinking water Castrations indicated that the procedures used for the disinfection of water supplies with chloilfcl^pe resulting in elevated levels of chloroform in the Finished water; however data from sy^edp^nsing best- available-technologies for the disinfection of drinking water using chlorine |fe|onstrate substantially lower concentrations of chloroform in the finished water {e. g., apprc^hing^jp-fold lower concentrations). Therefore, the contributions of human activities to the concentrations of chlorinated organic solvents in the environment will continue to decline in the future with the 24 s z t im B B t Jh CanTox increased use of improved technology. These declines would be coincident with decreasing human exposures and decreasing potential for the induction of adverse effects. Recommendations Efforts should continue to be directed toward reducing environmental releases of chlorinated organic solvents through the implementation of improved technologies (e.g., closed-systems, non-emissive procedures). Occupational exposures should continue to be monitored and best available technologies should be employed to continue to reduce human and environmental exposures to chlorinateao^anic solvents. Vm THE USE OF CHLOK2$E IN THE DEVELOPMENT OF PESTICIDES Many pesticides contain chlorine and madydo not. The biological activity of pesticides does not correlate with the presence or absence of chlorine on the molecule. Non-chlorinated pesticides can be more toxic than chlorinated pesticides. Many pesticides are produced naturally by plants, and some of these contain chlorine, indicating that chlorinated pesticide were produced in nature before the advent of synthetic pesticides. Non-chlofmated pesticides produced by plants can induce at lower doses the same adverse effects than certain of the more publicized synthetic chlorinated organic pesticides. %- While evaluating the potential for a pesticide to cause adverse effi&aon non-target organisms, the potential benefits associated with the use of the chemical must be c^Jrpidered. The chlorinated pesticide DDT provides a good example of a case in which the benefit^lfW been ignored and the reasons for its widespread use forgotten in the wake of concern ov^riatential adverse reproductive effects in birds. DDT is highly effective against disease-carrylip^ insects, is significantly less likely to cause poisoning in humans or other mammals than alternative chemicals, and is cheap and easy to produce. At the time of its most widespread use, the 1940s and 1950s, scientists, industry and end-users were unaware of its potential to bioaccumulate through the food chain. It is estimated that the death from malaria of over one billion humans and countless wild animals are prevented each year due to the World Health 25 CanTox Organization's mosquito control program using DDT, which still operates in many tropical countries. The use of DDT in Europe immediately after the second world war is believed to have prevented the deaths from disease of as many people as died from the war itself. It is easy to understand how DDT came into favor and widespread use, when the benefits were known and the potential for adverse effects on the environment was not clearly understood. Presently, DDT and other similar pesticides that bioaccumulate and have been associated with adverse effects on reproduction on fish eating birds, are banned from use in most countries, except in those threatened with malaria outbreaks. The knowledge that certain* structures of chemicals result in undesirable properties, such as % toxicity to non-target organisn&or bioaccumulation potential, has led to the ability to specifically design pesticides which do not fiavethese faults. New pesticides are more specific in their action against pests and may be rapidly degraded in the environment. Some contain chlorine and some do not. Some are made using chlorine iathe production process without containing chlorine in the final product. Because of their specificity and potency against target pests, the amounts used tend to be much smaller, thus reducing the already low risk of adverse environmental impacts. 3a0 *2 <a Recommendations The evaluation of the potential for pesticides to cause adverse effects should continue to incorporate an assessment of the potential benefits as well as tftemks associated with their use, as is now the approach of regulatory agencies in most countries. IflLspevaluation should be based on scientific data, not on whether or not a pesticide contains chldrine^ The development of highly specific pesticides, that are rapidly broken down in the environnnfiilfiwid need to be used only in small quantities should be encouraged. CONCLUSIONS Chlorinated chemicals are produced by natural processes and are ubiquitous in the environment. This provides evidence that organisms and ecosystems have evolved means of surviving in the presence of low concentrations of these types of chemicals. It is therefore expected that low 26 VRD 0002048927 CanTox concentrations of similar chemicals produced by human activities would not cause adverse effects. The results of the current study support this contention and indicate, with the exception of a few bioaccumulative chemicals present at excessive concentrations in localized areas, that chlorinated chemicals do not pose a threat to humans or the environment. * Those chlorinated chemicals that have been associated with adverse effects in the environment are all from one subset of the universe of chlorinated chemicals, those that have the ability to bioaccumulate through the food chains because of slow rate of excretion and breakdown in biological systems. Thesejypes of chemicals have been banned, or their use has been severely restricted, resulting in noticeable decreases in their concentrations in the environment over the years. The concentrations of^tiese chemicals will continue to decline albeit slowly, and the recovery of affected species, alrisSy well underway, is expected to continue. Attention should also be directed toward the significance,of habitat loss in the slow recovery of some species. Known "hot-spots", where the concentrations of these chemicals are substantially elevated compared to the general environment, require continued attention to reduce release rates from point sources to the environment and to investigatepossible remediation procedures if warranted. In addition, the knowledge gained on the properties and characteristics of chemicals that have been implicated in various environmental and human health problems must be used in the design and development of new products and processes to avoid a rbkxxurrence of such problems in the future. Other chlorinated chemicals, which do not bioaccumulate through fbo^hains and are readily degraded in the environment, have not been associated with adverse eff&tiSM concentrations at which they are found in the environment. Continued improvements in technologies (e.g., the use of closed systems and non-emissive technologies) using and generating chlornS^.chemicals, and increased vigilance in the prevention of spills and accidental releases of these c^^^als will ensure further reductions in the future in the already low risks to humans and the env^pj|\pient from chlorinated organic chemicals. 27 Table 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL OROUP Chemical Drinking Water PRODUCT CATEGORY Watte Water Solvents Incineration Chlorinated Alkanes (Continued) Chlorinated Athene* Dibromochloropropane 1.2-Dichloropropane 1 ,2-Dibromo-3-chloro-propane Dichloroechylene 1,1 Dichloroethylene 1.2-Dichloroethylene (Cit) l-2FDich)oroethyleae (Trana) Trichloroethylene Tatnchloroethylane ] ,3-Dichloropropene (Cia) Pentachioropropane V'- Pulp & Paper PVC/VCM PCBs PVC (monomer) C anTox 29 Z6mma*aHA Table 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL OROUP Chemical Drinking Water PRODUCT CATEGORY Wane Water Solvenla Incineration Chlorinated Inorganics Chlorinated Alkanes HC1 Chlorate Chlorite Dichloromethene Chloroform Carbon Tetrachloride Chloromalhane Bromodichloromethaoe Chlorodibromomethane TrichJorodihydroxyelhen* v" Pulp & Paper PVC/VCM PCBa C anTo x 28 616 8 H1000 OH A* XOJLNV3 Table 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP __________ Chemical Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Chlorinated Phenols, Catechols, Gnaiacets 2-Chlorophenol 2,4-Dicblorophenol 2,6-Dichloropheool 2.4.5-TrichIorophenol 2.4.6-Trichlorophenol 2.3.4.5-Tetrschlorophenol 2.3.4.6-Tetnchlorophenol PenUchlorophenol Tetrichlorophenol Dichlorocatcchol Tetrachlorocatechol Trichlorocatechol 3,4,5-Trichlorocatechol ,< 4,5-Djcblorogui||el: ' Dichlorosuettfipl (otBer isomers) > Pulp & Paper PVC/VCM PCBs C anTo x hlonxUhydroconiferyl Alcohol Chlorovanillin TrichlorovanillyUlcohol Trichloroecetosyringone 31 l6*HZ06ft Table 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP Chemical Drinking Water PRODUCT CATEGORY Waale Water Solvent* Incineration Dichloro-3,4-dihydroxypropiophenone Chlorinated Nitrogenous Compounds Dichloroecetonitrite Nitrochloroform Chlorinated Aldehydes Tricbloroethanal Chloropropenal Chloromethoxydibenzaldehyde Chloralhydrate Chlorinated PCDDs, PCDFs 2.3.7.8- T4CDD 1.2.3.7.8- P.CDD 1.2.3.4.7.8- H.CDD 1,2,3,4,8,9-H<CDD & Pulp St Paper PVC/VCM PCBa C anTo x 32 Z68HZ0B^ QNA VRD 0002048933 Table 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP Chemical Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Chlorinated PCDDs, PCDF* (Continued) PCBs Chlorinated Fatty Acids Chlorinated Resin Acids Chlorinated Amines 1,2,3,6,7,8-H^CDF 2,3.4.6,7,8-HiCDF 1,2,3,4,6,7,B-H?CDF 1,2,3,4,7,8,9-H7CDF 0,CDF PCBs Dichlorostearic Acid Chlorodehydroabietic acid Dichlorodehydroebietic acid 3,3'*Dichlorobenzidine Pulp & Paper PVC/VCM PCBi C anTo x 33 VRD 000 204 8 9 34 Table 2 Representative Priority Chemicals Assessed in Stand-Alone Documents CHEMICAL GROUP Chlorinated Inorganics Cl, CIO, HCI Chlorate Chlorite Chlorinated Alkanes' Chloroform Carbon Tetrachloride Dichloromethane 1.1-Dichloroethine 1.2-Dichloroethane Dichloromethane 1,1,1 -Trichloroelhane Chlorinated Alkenes* Trichloroethylene Chlorine Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Pulp & Paper N\ vv` . 4,v.-' :\..i.-.. M &.> v<*' V PVC/VCM PCBs C anTox 34 i VRD 009 20 4 8 9 35 Table 2 Representative Priority Chemicals Assessed in Stand-Alone Documents CHEMICAL GROUP Chemical Chlorine Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Chlorinated Ketones* TriehIorotcelone Ttnchloroacetone 1, l-Dichloropropanone 1,1, t-Trichloropropanone Dichlorocyclopentene-I ,2dione 3-Chloro-4-|dichIoromethyl]5-hydroxy-2(5H)-fur*none Chlorinated Benzenes* Hexecblorobenzene Dichlorobenzene 1.4-Dichlorobenzene 1.4-dichlorobenzene i ,2,4-Trichlorobenzene Chlorinated Phenols, Catechols, Guaiacols* Penlachlorophenol 2,4,6-Triehlorophenol $ 2.4-Dichtorophent^#* 5 H\\ ' Chlorocs Pulp & Paper PVC/VCM Chlorinated Nitrojji pounds' Dichloroecetonitrile Nitiochloroform 35 PCBs C anTox VRD 0092048936 Table 2 Representative Priority Chemicals Assessed in Stand-Alone Documents CHEMICAL GROUP Chemical Chlorine Chlorinated Aldehydes* Trichloroethana1 ChJoralhydrata PCDDs/PCDFsPCBs* Chlorinated Fatty Adds* Dichlorostearic acid Chlorinated Resin Acids* Chlorodehydroabietic acid Dichlorodehydroabietic acid Chlorinated Sulfooes and Thiophenes 1,1 -DichlorodimathyIwlfone Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Pulp & Paper a a ' a a a * Environmental effects to be discussed for the group of chlorinated chemicals in the preliminary list (see Table 1-1). k Human and mammalian toxicity data to be discussedfor the chemical group. * 2,3.7,8- substituted dioxin and furan isomers. f 73 ^v\\\ x PVC/VCM a PCBs a C anTo x 36 A VRD 0002048937 FAX TO: COMPANY: FAX: 0 of pages: FROM: COMPANY: FAX: PHONE: DATE: SUBJECT: Dr. Robert Willes CanTox, Inc. 416-542-1011 2 (including this page) Dave Penney Vista Chemical Company 512-331-2387 512-331-2468 July 26, 1993 Plain Language Document Dear Dr. Willes: Attached are my comments on the plain language document. If you have any question, please do not hesitate to call me. Sincerely, Dave Penney CC: Mr. Art Dungan, The Chlorine Institute VRD 0002048938 CanTox A harmful effects from the uses of chlorine gas are avoided in the future. The supporting evidence for these conclusions regarding possible harmful effects of chlorine are presented in detail in the product category document entitled "Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Chlorine" (Chlorine Institute, 1993b). 267 268 269 270 271 6.0 VINYL CHLORIDE (VCM) AND POLYVINYLCHLORIDE (PVC) 272 Polyvinylchloride is a made by linking a large number of VCM units together to form a polymer (a molecular chain). P^GJs,:a solid material with great stability in the environment. One of the historical concerns about tf&presence of non-polymerized VCM in PVC products has been largely addressed by modifiedf'manufacturing and production techniques. Under good manufacturing procedures, the residral concentration of VCM in modem PVC products is below % laLlli o5*-. analytical detection limits (about 1 part peri million). 'f 273 274 275 276 277 278 Vinyl chloride monomer (VCM) is released ifrthe atmosphere as a vapor. It is reactive, and 279 readily joins together (polymerizes) in the presencejof oxygen, sunlight or heat to form PVC. 280 Vinyl chloride monomer rapidly degrades in the environment by reactions with ultraviolet light 281 It does not accumulate through food chains, and ultimately is degraded to carbon dioxide and 282 _________ % water by biological systems. Intermediate^]formed during the K*\ -- 283 of VCM are reactive, and bind to genetic material in cells. ^Tlie reactions of these reactive 284 V. K: v intermediates are believed to be responsible for the cancer-producmg,activity of VCM. 285 The conclusion of the assessment of PVC afe that no harmful effects Shuman health or the 286 general environment occur from PVC itself, Tifhie maawjor concern is the jjoosifcte-^ 287 exposure of workers to PVC dusts arising from the use of PVC materials uf manufacturing 288 processes, and possible products arising during its production. fa 289 Prior to the 1970s, the air concentrations of VCM were too great in some workplaces vriiere it was produced or used to manufacturing (in the range of 100 to 1000 parts per million). Exposures to such air concentrations of VCM are believed to have caused increases in liver 290 291 292 n VRD 0082048939 CanTox A cancer in workers. Through changes in technology, the air concentrations of VCM in workplaces in the 1980s were reduced about 10,000- to 100,000-fold compared to the pre-1970 values. These lesser air concentrations of VCM in the workplace, combined with protective equipment used by workers, virtually eliminate risks of liver cancer from occupational exposures. 293 294 295 296 No information was available on the air concentrations of VCM at locations remote from production/manufacturing facilities. However, based on the concentrations reported near such facilities and the rapid rate at which VCM is destroyed in ambient air, the air concentrations of VCM in remote locations would be expected to be very small, and not measurable with current techniques. Based on predictions from the amounts of VCM exposure required to increase liver 297 298 299 300 301 cancer in workers, and the use'of this information to predict cancer rates that could occur at the vary small air concentrations of-V@M in remote locations (assumed to be equal to the limits of analytical measurement of about 5 parts per billion), no measurable harmful effects to the health of the general public would be expected .to occur from VCM in the general environment. 302 303 304 305 The use of production and manufacturing technologies that eliminate releases to the environment will ensure that air concentrations of VCM remain at current undetectable values, and that no harmful effects on human health or the environment^wquld be expected from VCM. Continued care is required to ensure that spills and accidental releases of VCM are minimized, and, if accidents occur, the resulting releases of VCM are controlled to ensure that no harmful effects ,J:<y to human health or the environment occur. The supporting evidence for these conclusions are V- V, presented in the product category document entitled "Interpretive;: Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health ^and the Environment - Polyvinylchloride and Vinyl Chloride Monomer (Chlorine Institute, 1993c). 306 307 308 309 310 311 312 313 314 7.0 POLYCHLORINATED BIPHENYLS (PCBs) 315 Historically, the largest use of PCBs was in the electrical industry, where they woe used because their greater heat absorbing capacity and electrical insulating properties provided greater safety compared to alternative materials. Until recently it was believed that there were no 316 317 318 12 CanTox CD known natural sources of PCBs; however, PCBs, not related to any human activities, were identified in ash from the 1980 volcanic eruption of Mt. St. Helens in Washington state. 319 S 320 * ec Commercial PCBs are mixtures of chlorinated biphenyls (two phenol units joined together) with 321 varying percentages of chlorine by weight. For example, the PCBs mixtures denoted as Aroclor 322 1242, 1254 and 1260 are 42%, 54% and 60% chlorine by weight, respectively. Chemically, 323 the term PCBs denotes a family of 209 chemicals with chlorine added in different positions on 324 the biphenyl unit. Depending on the position and amount of chlorine, the different PCBs exhibit 325 a wide range of physical and chemical properties. For example, water solubilities range over 326 5.5 million-fold, vapor pressures over 100,000-fold, both decreasing with increasing amounts 327 of chlorine on the PCBs molecule. Their lipid solubilities range over 10,000-fold, and increase 328 with the amount of chlorine on tfte|PCBs. Since the behavior of chemicals in the environment 329 is determined by their physical andisfremical properties, the differences in properties of the 330 various PCBs are reflected in their distribution, destruction and movements in the environment. 331 Generally, as the amount of chlorine contained in PCBs increases, their destruction in the 332 environment is slower, resulting in increased environmental persistence of the PCBs with greater 333 amounts of chlorine. v| 334 PCBs can be destroyed by ultra-violet light in the atmosphere and at water surfaces, and the speed of this destruction increases as the amount of chlorine "bn the molecule increases. The speed of destruction by bacteria, fungi and animals, on the other.hand, is slower for the PCBs with greater amounts of chlorine. The position of the chlorine'"bn . the PCBs molecules also affects their speed of destruction, particularly by biological systems; P^Bs with so-called coplanar structures are destroyed much more slowly than the non-planar congeners; consequently the co-planar PCBs are present at greater concentrations than non-planar PCBs'in animals at the top of food chains (for example, polar bears, seals and certain fish-eating birds);.**. y-y 335 336 337 338 339 340 341 342 The combination of unrestricted use and the physical and chemical properties of PC^BySyh'save resulted in their widespread distribution in the environment, including remote areas suchTas the arctic and antarctic. Due to their widespread occurrence, PCBs are found in human tissues, such as fat, liver, blood and breast milk, of people with no known occupational or unique 343 344 345 346 13 VRD 000 204 8941 CanTox A environmental exposures. The concentrations of PCBs in various aquatic wildlife (e.g., fish and fish-eating birds) are generally greater than those reported for humans, primarily because of the biomagnification of PCBs in aquatic food chains, and the resulting higher exposures of aquatic wildlife compared to humans. 347 348 349 3S0 The conclusions of the assessment of PCBs are that their uses, from initial introduction in the 1920s until the 1970s, were not appropriate based on what is now known about their behavior in the environment and the harmful effects they can possibly produce when exposures are too great. These possible harmful effects of PCBs alone are difficult to determined because wildlife are exposed at the same%meto mixtures of many different chemicals. However, laboratory studies demonstrate the PCBs%ould interfer with reproduction of wildlife in the environment. The greatest concerns are for wildlife species at the top of the food chain (e.g., fish-eating birds and mammals). The information riow^available on the properties of PCBs and the possible harmful effects that can result from chemicals with such properties if exposures are great enough, shows that these types of chemicals should not be used in ways that allowed their direct releases into the environment. iy%'% % 351 352 353 354 355 356 357 358 359 360 361 Following controls over the use of PCBs in 1972, and banning of their production in 1978, the quantities of PCBs released into the environment was reduced. During the 1970s and early 1980s, substantial decreases were observed in the concentrations of PCBs in the environment, and in organisms, including humans and aquatic wildlife. Changes in the production and use practices of several other chlorinated chemicals (e.g., DDT, hiex&chlorobenzene, mirex) also occurred during this same time period. Since these changes in environmental concentrations of PCBs and several other chlorinated organic chemicals with similar^properties to PCBs, recoveries of the reproduction of some fish-eating bird populations have been observed, although the recovery process is still incomplete. ^ f\ ''..s'}'- Since the mid-1908s, the concentrations of PCBs in the environment are decreasing mbr^Jslowly ' y/ compared to the decreases seen in the 1970s immediately following the restrictions in thdlr use. A major factor responsible for the slower rates of decrease of environmental concentrations appears to be the continued releases of PCBs from old electrical equipment still in service, and 362 363 364 365 366 367 368 369 370 371 372 373 374 14 VRD 0002848942 CanTox A from various PCBs storage facilities. In addition, PCBs already in the environment are being transported, primarily in the atmosphere, around the earth. This transportation process continues to deposit PCBs into water bodies, where they can be accumulated by various organisms. Therefore, future rates of decreases in current concentrations of PCBs in the environment are expected to be slow relative to those observed historically. 375 376 377 37S 379 Based on what is known, mostly from laboratory studies, about dose-response relationships for 380 the possible harmful effects of PCBs, and from studies of human populations historically exposed 381 to PCBs in their workplaces, no harmful effects should occur from exposures of humans to 382 current environmental concentrations to PCBs. However, there is a greater potential for harmful 383 effects on wildlife than humanl^particularly for those species at higher levels of the food chain 384 because of the potential for great^exposures. This greater possibility for harmful effects from 385 PCBs is particularly pronounced irt^^cies with diets that are virtually 100% fish and other 386 water-dwelling organisms. The concern^ about possible harmful effects in such species is 387 particularly great in regions of the environment where the concentrations of PCBs, together with 388 other chemicals, are markedly elevated (e.g.; various "hot spots"). However, except in such 389 regions of localized "hot spots" caused by historical point-source releases of chemicals, any 390 adverse effects on the environment expected from current environmental concentrations of PCBs 391 should be minor. If PCBs are responsible for the harmful effects reported in wildlife in the "hot 392 spots", the degree of the harmful effects should continue to decrease in the future as the 393 environmental concentrations of PCBs continue to decline through natural physical and biological 394 degradation processes, and continued burial through sedimentations. 395 Nonetheless, the lessons learned oa_why the chemical, physical and biological properties of PCBs made their historical uses unacceptable, provides a great deal of infbtfmation that can be applied in the evaluation and judgement of current and future uses of otheriCKbmicals. The message from these lessons is to avoid the release into the environment of chemicals with such undesirable chemical, physical and biological properties. The supporting evidence for these conclusions regarding possible harmful effects of PCBs are presented in detail in the product category document entitled "Interpretive Review of the Potential Adverse Effects of Chlorinated 396 397 398 399 400 401 402 15 VRD 0002048943 A CanTox Organic Chemicals on Human Health and the Environment - Polychlorinated Biphenyls" 403 (Chlorine Institute, 1993d). 404 8.0 REFERENCES 405 Chlorine Institute. 1993a. Interpretive Review of the Potential Adverse Effects on Human Health and the Environment from Chlorinated Organic Chemicals - Introduction and Methods -. Chlorine Institute, ???T?, Washington, DC. 406 407 408 Chlorine Institute. 1993&i,ilnterpretive Review of the Potential Adverse Effects on Human Health and the Environment ijpom Chlorinated Organic Chemicals - Chlorine -. Chlorine Institute, ?????, Washington, DBfJr .-4-1%. 409 410 411 Chlorine Institute. 1993c. InterpretiveJteview of the Potential Adverse Effects on Human Health and the Environment from Chlorinated Organic Chemicals - Polyvinyl Chloride and Vinyl Chloride Monomer Chlorine Institute, ?????^Washington,' DC. v. >' Chlorine Institute. 1993d. Interpretive Review of the Potential Adverse Effects on Human Health and the Environment from Chlorinated Organic Chemicals - Polychlorinated Biphenyls (PCBs) -. Chlorine Institute, ????, Washington, DC. T ^ 412 413 414 415 416 417 Chlorine Institute. 1993e. Interpretive Review of the PotentiakAdyerse Effects on Human Health and the Environment from Chlorinated Organic ChemicalsV Chlorinated Pesticides Chlorine Institute, ?????, Washington, DC. i\ 418 419 420 Chlorine Institute. 1993f. Interpretive Review of the Potential Adverse Effects; on Human Health and the Environment from Chlorinated Organic Chemicals - Disinfection Drinking Water and Waste Waters with Chlorine -. Chlorine Institute, ?????, Washington, DC^jf 421 422 423 16 VRD 0002048944 4 CanTox Chlorine Institute. 1993g. Interpretive Review of the Potential Adverse Effects on Human Health and the Environment from Chlorinated Organic Chemicals - Bleaching Wood Pulp with Chlorine Chlorine Institute, ?????, Washington, DC. 424 42S 426 Chlorine Institute. 1993h. Interpretive Review of the Potential Adverse Effects on Human Health and the Environment from Chlorinated Organic Chemicals - Incineration of Chlorinated Materials Chlorine Institute, ?????, Washington, DC. 427 428 429 Chlorine Institute. 1993i. Interpretive Review of the Potential Adverse Effects on Human Health and the Environment fforhiOhlorinated Organic Chemicals - Chlorinated Solvents -. Chlorine M\_ Institute, ?????, Washington', 430 431 432 Z \> % `-vf 17 VRD 000204 8 9 4 5 jyw-21r'93,13i54 ID:THE UINYL INSTITUTE TEL NO:201 890-7029 184 P01 * "T)kWt f-tnneu July 2lr 1993 FAX toi FROM: Meredith scheck M. M. Marshall Jvu^\ I spoke with a Dr. Kastman at CanTox regarding limits of detection of vinyl chloride in air and polymer used for the CanTox documents. According to Dr. Nestraan, Cantox used 0.5 ppm in air and 10-20 ppb in polymer. The reason Fred Xrause's and my comments were not incorporated was that Art Dungan has relied on Dave Penny's review on behalf of the Vinyl institute. According to Jim Isner, Ceon R&D, the detection limit Is 5 ppb in air and 1-5 ppb in polymer. Please insure that this i&6ua is resolved. Thanks cc: Bob Burnett - VI W. F. Patient 7. E. Krause MSMEMO.MMM VRD 8002048946 CanTox A cancer in workers. Through changes in technology, the air concentrations of VCM in workplaces in the 1980s were reduced about 10,000- to 100,000-fold compared to the pre-1970 values. These lesser air concentrations of VCM in the workplace, combined with protective equipment used by workers, virtually eliminate risks of liver cancer from occupational exposures. 293 294 295 296 No information was available on the air concentrations of VCM at locations remote from production/manufacturing facilities. However, based on the concentrations reported near such facilities and the rapid rate at which VCM is destroyed in ambient air, the air concentrations of VCM in remote locations ywould be expected to be very small, and not measurable with current techniques. Based on predictions from the amounts of VCM exposure required to increase liver cancer in workers, and the uiseW this information to predict cancer rates that could occur at the vary small air concentrations of'VGM in remote locations (assumed to be equal to the limits of analytical measurement of about 5 parts'per billion), no measurable harmful effects to the health of the general public would be expected occur from VCM in the general environment. 297 298 299 300 301 302 303 304 305 The use of production and manufacturing technologies that eliminate releases to the environment will ensure that air concentrations of VCM remain at current undetectable values, and that no harmful effects on human health or the environment^would be expected from VCM. Continued care is required to ensure that spills and accidental releases of VCM are minimized, and, if accidents occur, the resulting releases of VCM are controlled to ensure that no harmful effects to human health or the environment occur. The supporting evident^ for these conclusions are presented in the product category document entitled "Interpretive. Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment Polyvinylchloride and Vinyl Chloride Monomer (Chlorine Institute, 1993c). 306 307 308 309 310 311 312 313 314 7.0 POLYCHLORINATED BIPHENYLS (PCBs) 315 Historically, the largest use of PCBs was in the electrical industry, where they wet# used because their greater heat absorbing capacity and electrical insulating properties provided greater safety compared to alternative materials. Until recently it was believed that there were no 316 317 318 12 < VRD 0002048947 CanTox harmful effects from the uses of chlorine gas are avoided in the future. The supporting evidence for these conclusions regarding possible harmful effects of chlorine are presented in detail in the product category document entitled "Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Chlorine" (Chlorine Institute, 1993b). 267 268 269 270 271 6.0 VINYL CHLORIDE (VCM) AND POLYVINYLCHLORIDE (PVQ 272 Polyvinylchloride is a made by linking a large number of VCM units together to form a polymer 273 i0/ v'-f (a molecular chain). PVGJS a solid material with great stability in the environment. One of 274 the historical concerns about tne presence of non-polymenzed VCM in PVC products has been 275 largely addressed by modified' manufacturing and production techniques. Under good 276 manufacturing procedures, the resided^concentration of VCM in modem PVC products is below 277 analytical detection limits (about 1 part per million). 278 Vinyl chloride monomer (VCM) is released 'to^the atmosphere as a vapor. It is reactive, and readily joins together (polymerizes) in the presencelpf oxygen, sunlight or heat to form PVC. Vinyl chloride monomer rapidly degrades in the environment by reactions with ultraviolet light. It does not accumulate through food chains, and ultimately is degraded to carbon dioxide and water by biological systems. Intermediate bron.li riw*ivrt prorii^ts formed during the degradation of VCM are reactive, and bind to genetic material in cells. < The reactions of these reactive intermediates are believed to be responsible for the cancer-producmg activity of VCM. 279 280 281 282 283 284 285 The conclusion of the assessment of PVC that no harmful effects to^human health or thp . 286 general environment occur from PVC itself. Th? major^oncem regarding?"^ is the ^oss*if4a*co-J}' 287 exposure of workers to PVC dusts arising from the use of PVC materials nfeManufacturing 288 processes, and possible products arising during its production. 289 Prior to the 1970s, the air concentrations of VCM were too great in some workplaces vfiiere it was produced or used to manufacturing (in the range of 100 to 1000 parts per million). Exposures to such air concentrations of VCM are believed to have caused increases in liver 290 291 292 11 OOZl-O* irohi :J|iiu!ij,.iu<>Mdi|4i 3VS8 eprurj >.[035 ton r)i|TH janq tm|u*jnri 11 3DUJO XVJJ1VH ''L, ;Qi ni' HOL-etS (9tM :I!^!53PJ 0063-ZtS (9IK :auOL|d3|aj. IXZ Nfl pptup^ Oijfjuo 'F8nps5issjw 80C U"S pPoa puu3jv ZIZZ 331330 OV3H *~h Cj--^cj -9 ji "s \( 'H'A-,ry onj^ 7-/o ^ + eM to rj^fS a<^n ^ \\c. >|^^-r >-ov Cffl-I)1;; not' I f fit- duoij.: ; 0bS 11 -i*,Ki,3 90i'"S 'ts"wv:! tr.r 3 3H10 18V01V0 pua S30U3IDS IBJU9U1U0I1AU3 JU9pIS9JJ 90IA a`Md `sswM *pqh ZijSJp ^>zpQ dui xoiireo `Xpjaouis sjnoA a '-rated ^ Wj ,, dlnd JO uoireraupuj `siuaAps `sapppssd aisu^/rai^M. Supjuua uo uoissnosip b spnpui / t / jou ssop jusuinDop snjj, juaumooa atenSuiri urei<j aip jo yEJp pmui ire pssopus puy ssBsjd Vc.^ ,, ~AC ' :wv -resa *3w *3iauiSNr 3NIH01H3 ='-L. ~'tS NJ i-Sy mj V'A-^r^ ^ y^i c ~~oi4iT _______ "3 ii t* ^--19 H-o ^ 900Z 3a `uoiSutqsBM 90S aims "M'N *1S T 100Z duj 9jnjysui 9upop3 sqjireSuna `3 Jniyiy 661 `M ounr sssuaps |FjuaaJUOJjAU3 pup qj|pan A8o|OOuoi ui sjupiinsuo^ 'DIM | X01NV3 VRD 0002948948 xNajMODoa aovnoNrv'i Os <S cs CoSc XOJNV3 VRD 0002048950 PLAIN LANGUAGE DOCUMENT Table of Contents CanTox A Page 1.0 INTRODUCTION 1 2.0 SELECTION OPOSEMICALS FOR ASSESSMENT g-r 3.0 BASIC SCIENTIFIC MANCIPLES FOR THE ASSESSMENT OF THE SELECTED CHEMICALS^. ^ * 4.0 SOURCES OF CHLORINATED ORGANIC CHEMICALS %, 5.0 CHLORINE 4 4 7 9 6.0 VINYL CHLORIDE (VCM) AND POLYVINYLCHLORIDE (PVC) n 7.0 POLYCHLORINATED BIPHENYLS (PCBs) 8.0 REFERENCES *v ^ .. 12 16 VRD 0602048951 1.0 INTRODUCTION CanTox A 1 During the past 10 to 20 years, people have become aware that concentrations and numbers of chemicals in the environment have increased and in some areas the concentrations have been sufficient to cause adverse effects in wildlife. Recent attention has been directed toward chlorinated chemicals, since the most infamous of the chemicals studied (i.e., PCBs, DDT) contain chlorine. Although actions have been taken to limit the release of chemicals such as PCBs and DDT into the environment, several years are required before their concentrations will fall to acceptably low concentrations. For example, polychlorinated biphenyls (PCBs), (discussed in detail laterf^vere found to persist in and spread throughout the environment. Because of their physical, chemical and biological properties, and the way m which they were used, PCBs accumulated in animals at the top of ecosystem food chains (e.g., fish-eating birds and mammals) and, in some cases,^exposures were sufficient to cause harmful effects in these animals. When the harmful effects of PQBiin the environment became known, the use of PCBs was restricted to closed systems (in 1972) and the production of PCBs was stopped in 1978. They still are found, however, in older electrioal^equipment \hat has not yet been taken out of service. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 The above information on chemicals like PCBs, has raised concerns that all chlorinated chemicals may behave in similar ways to PCBs. However, &e now know that this is not the case. Each chemical possess a unique set of characteristics that can be used to predict how it behaves in the environment and interacts with biological systems:.-: In addition, chlorine and chlorinated chemicals are widely used by modem society without^known substitutes, or for which the toxic effects of the substitute have not been fully elucidatedti^ Thus ensuring that harmful environmental effects will not occur cannot be achieved by eliminating.the production and use of chlorinated chemicals. Further, many chlorinated chemicals are used 'td manufacture products that have clear benefits to society. For example, chlorinated chemicals afe essential to the manufacture of plastics (e.g., polyvinylchloride), paper products, drugs fo^feating diseases, and disinfectants in hospitals and the home. Chlorine is one of the chemicals (ifsed in the manufacture of some pesticides that are important in the control of disease-bearing insects and insects and weeds that can reduce agricultural production. Chlorine itself is used as a 17 18 19 20 21 22 23 24 25 26 27 28 29 1