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VRD 0002048841 A CHEMICAL MANUFACTURERS ASSOCIATION August 17> 1993 To: Chlorine CoordinatingCouncil Science and HealthWork Group CMA/CCC Matrix Team From: Clyde Greenert Subject: Cantox Study "Plain Language Document" Draft Attached is the August 13 draft of this summary of "The Interpretative Review of Potential Adverse Effects of Chlorinated Organics on Human Health and the Environment." Your review and comments would be appreciated. Also, i'll buy lunch for the best alternate title suggested for this summary - "Plain Language Documents," does not do much for mef cc: Elizabeth Festa Watson Robert Romano 2501 M Street, NW. Washington. OC 20037 202-887-1100 Panafax 202-887-1237 Telex 89617 (CMA WSH) VRD 0082648842 AUG 13 '93 09*50flM CfiHTOX INC CanTox Inc. ComirftAfit* in TcsckofcfY HaaHh and Environmanul Sdanct* PLAIN LANGUAGE DOCUMENT P.2 A Prepared for Hie Chlorine Institute, Inc. 2001 L St, N.W., Suite 506 Washington, DC 20036 August 13, 1993 CAlCAtV OFFICE 373) 37 Avotm N.l* t>t* 304 Cilgary, AtbarU, CVUM T1Y SM TdtphoM! HD) 291*4446 Facrimite (WI 3)0*3445 HUD OFFICE 2223 ArgaMia Road, Suita 309 Mlaiiouuga, Ontario,, Canada UN 2X7 Tataphona: 1419) S43-34O0 Faolmila; (416) 342*1011 HALIFAX OFFICE it lainwlw Oiiw Malta. Nava leaiU. Canada DM 30 TftoptoM/FirtJmM*: (M2) 443-1200 AUG 13 '93 09s 50AM CflKTOX INC TABLE OF CONTENTS P.3 CanTox INTRODUCTION KEY FINDINGS FOR EACH PRODUCT CATEGORY CHLORINE Sources of Chlorine Cause-Effect Relationship Evaluation of the Potential for Advene Effects from Chlorine Recommendations n PQLYO^IgftNATBD BIPHENYLS (PCBs) Sources ofTOB* Physical andT3&nical Properties of PCBs and Fate In the Environment The Cause-Effecfe^glationship Evaluation of the^j&teouial for Adverse Effects from PCBs Recommendations <*5^ VINYL CHLORIDE AN^OLYVINYL CHLORIDB m Sources of Vinyl Chloride and Polyvinyl Chloride The Cause-Effect Relationship^^ Evaluation of the Potential for Amese Effects from Vinyl Chloride and PVC Recommendations ^ IV CHLORINE DISINFECTION OF D G WATER. AND WASTE WATER Production of Chlorinated Chemicals Thzou tion with Chlorine The Cause-Effect Relationship Evaluation of the Potential for Adverse Effects fro Chemicals Produced During Disinfection with Chlo Evaluation of Alternative Methods of Water Disinfect! Recommendations 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 7 7 8 8 8 9 9 9 10 11 12 13 13 13 14 14 15 20 20 20 22 |*VRD 0002048844 AUG 13 '93 09:51AM CANTOX INC P.4 CAftfOX vn CHLORINATED ORGANIC SOLVENTS Sources of Chlorinated Organic Solvents The Cause-Effect Relationship Evaluation of the Potential for Advene Effects from Chlorinated Organic Solvents Recommendations vm THB USB OF CHLORINE IN THE DEVELOPMENT OF PESTICIDES Recommendations 22 22 23 24 23 25 26 CONCLUSIONS 26 ft VRD 0602848845 ftUG 13 '93 09:51PM CPNTOX INC INTRODUCTION P.5 CanTox Since ancient times, humans have used chemicals as tools in the quest for improved quality of life. Originally, useful chemicals wen obtained as natural extracts, but with tbe 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 axe also by-products or end-products resulting from various human activities indudmj&JijJp and paper production, incineration, manufacture of numerous consumer products and dismraSion of drinking water. Chlorine-containing chemicals are used in the production of numerous 5t$S8amcr goods including pharmaceuticals, food additives, crop protection agents, sunscreens, cosmSfi^y plastics, adhesives, palms, varnish, antifreeze, spandex and soft drink syrup, to name just a few^Biaddition, 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 chlorinecwanistiy. As the production of chemicals, including chloriifgjd 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 ^Environment. Active field and laboratory research into the biological effects of specific cherrffta&bas suggested an association between releases of large quantities of certain chemicals, rc&frfcu in increases in their concentrations in the environment, and adverse effects on wildllfe/T^chlorinated chemicals for which these associations have been observed represent a small subrarofethe entire universe of chlorinated chemicals. This small group of chlorinated chemicals has pMputies that result in their ability to accumulate in the tissues of organisms as they are passed from^^to predator up tbe food chain (a process known as bioaccumulation). The combiaati^^pf their bioaccumul&tive properties and the quantities released Into tbe environment results^^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 bioaccumulative properties, do not result in such effects in the environment. These 1 VRD 0002048846 AUG 13 *93 09J52ft1 CAKTOX INC P.6 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 bloaccumulatlve chlorinated chemicals can cause advene effects at very small concentrations (pans 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. There are several thousand chfiSSpatod organic chemicals, rendering it impossible to evaluate each one of them thoroughly, withfmjke scope and time frame of this work. However, many have been studied in great detail througjJfegUng 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., air|*w0br, soil, sediments, animals). Since it was not practical nor feasible to assess the potential ajQj^e effects of all chlorinated chemicals on human health and the environment, It was necessai^j&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 advene cffigtjl In addition, consideration was given to the availability and completeness of information to base an assessment. Finally, consideration was given to usefulness of the chemical as rgpneral example from which various scientific principles could be assessed for application inSthg^development of new chemicals and products that would not be harmful to human health or ti^jopyironment. The chemicals were chosen to include representatives of the major classes of dummied organic chemicals that could serve as surrogates for those not studied in detail. In id^fjtSjj^ing the chemicals, the various types of product categories, in which chlorine is employdt^yere 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 l). By considering total quantities of use and the potential for the 2 VRO 0002046847 AUG 13 '93 09J 52PM CANTOX INC P.7 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, U) polychlorinated biphenyls (PCBa), Hi) vinyl chloride/polyvinyl chloride (VCM/FVC), iv) chlorine disinfection of drinking water and waste water, v) mclncratiorkof chlorinated materials, vi) wood pu^&aching, vii) chlorinated wMc solvents and viii) the use of chlorfi$|3t the development of pesticides. For the first seven product categories, impossible harmful effects were evaluated, from past and present uses of the chlorinated chemicals included in each product category, and predictions of future safe use patterns were made. In the ^afjNef pesticides, the role of chlorine in pesticide activity was assessed, and the need to assess ea^jjfaemical individually was discussed, based on its potential to cause hazardous effects relative potential benefits. 3 m m Z B B B QUA AUG 13 '93 09!53AM CAMTOX INC APPROACH TO THE SCIENTIFIC EVALUATION OF DATA P.8 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 humam or the environment to the chemical? can the chemical interact with biological systems in a manner consistent with known biological principles? is there a sdentifl^basls for concluding that specific adverse effects are associated with exposure to the tfSmical? Is the degree of exposure sufficiently high to be likely to cause adverse effects? If the available information is su to answer these questions, then it is possible to evaluate the potential for advene effects caused ^environmental concentrations of specific chemicals. In attempting to answer these questions fo^^representatlve chlorinated organic chemicals chosen for the current study, a rigorous sclentifi^Sjjjjj^ro&ch was taken to the interpretation of the published information. The amounts and types a^^ormation available varied among the different chlorinated chemicals, with most falling intffthe following categories: laboratory studies using individual cells, isolated ce organisms exposed to known concentrations of a ponents or specialized test ical; laboratory studies using animals exposed to known conceo under controlled conditions for time periods ranging from day; of a single chemical heir lifetime; field studies to assess possible adverse effects in animals by com; or without known exposures to mixtures of chemicals (known as studies): ulations with idemiological studies to assess possible adverse effects in humans by comparing populai ith or without exposures to mixtures of chemicals (known as epidemiological studie studies of concentrations ofspecific chemicals in air, water, soil, sediment and biological tissues. A 4 PLtG 13 '93 09:53PM CmTOX INC P.9 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 advene effects were made based on the overall welght-of-evidence. One of the most important outcomes of this type of weight-of-evidence analysis is the establishment of sound cause-effect relationships. Hie 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 cause-effect relationships between chemicals and adverse health effects, the following considerable wore made: does the adverse effect known to be exposed to more frequently in populations of humans and/or animals cal? is the adverse effect more concentrations? in humans and/or animals exposed to higher has the adverse effect been reported associated with exposure to the chemical by different investigators, In different place^^ different times? does the adverse effect occur only after ex; to the chemical has begun? does the adverse effect disappear or become less seatfe when the chemical is removed or concentrations are lowered? xJ is the chemical likely to be able to cause the obsernj^ffect according to known biological principles? * have similar chemicals been associated with the adverse eff< Once having established the plausibility of a cause-effect relationship, the rell between the dose and the magnitude of the effect was examined. The puipose of this exits ion was to determine the highest dose of a chemical that could be tolerated by humaiu flildtife without causing adverse effects. As the earliest toxicologists knew, it is the dose that m&Es 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 ao adverse effects when consumed in very small amounts* This determination of a no- 5 VRD 0801048849 A  VRD 8002948850 PUG 13 ' 93 092 54PM CflNTOX INC P.10 CanTox effect or "safe* dose for each chemical is usually based an the results of controlled studies in Uboratoiy animals, in which low, medium and high doses were given every day for life. This type of study, where the doses axe 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 (l.c., 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 and type of effect caused at higher doses in animals), or by the use of theoretical dose-response models. To evaluate the poteatuH&Adverse effects to occur from concentrations of chemicals in the environment, the exposurefjppected as a result of environmental concentrations are either estimated using exposure modeS^fc measured directly in tissues of exposed populations. If the estimated exposures (doses) are kntfSQhu the "safe" dose, then no adverse health effects might be expected. If the exposures exceeded^feCsafe" 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 OT^raease and measured concentrations in the environment. In order to put the environmental ^initiations of chlorinated organic chemicals associated with the product categories into perspectf^lhe sources of such chemicals produced through natural processes, independent of human activities, also were evaluated. o. To summarize, the following steps were taken in the assessdKtf^f the selected chemicals in each product category: Determination of sources and amounts of the selected chloric* the environment from human activities and natural processes. s released to Estimation of typical exposures to various organisms, including information on concentrations of the chemicals in air, water, soil and media. using ental Assessment of the potential of the chemicals to cause harmful effects, and the usamr this information to determine safe leveb of exposure for each chemical. 6 VRD 000204 8851 AUG 13 ' 93 09{55AM CAMTOX INC 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 luman activities include the following: the manufacture of piastiSp&nd adhesives; the manufacture Of cMorinaie<r^|&nic chemicals; the manufacture of drugs; the manufacture ofvarious household including deodorants, cleaners and bleaches; use of chlorine for drinking and waste waWrjiijinfection. The Environmental Protection Agency's Toxics Release Iqg^ftjpry estimated the total quantities of chlorine released Into the environment by human acdvitie?i$hft United States to be between 35 and 36 million pounds per year over the period 1987-1990. approximately one tenth or leas, of the annual production of chlorine from natural sources\&torine released into the environment rapidly reacts with water or water vapors to produce hyafflpftloric acid (HC1). Natural sources of chlorine include: volcanic eruptions; the break-down of sea salt by ultra-violet light from the sun (known as photo! Volcanic eruptions have been estimated to contribute from 0.4 to 11 million tons ofchlorine/year (800 million to 22 billion pounds) oq a global basis. The production of chlorine in the 7 VRD 8902848852 AUG 13 '93 09!55PM CPNTOX INC P.12 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 hannAil effects to the environment from chlorine la 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 chlorufeggavor hydrochloric add can cause Irritation to tissues at the site of contact with effects becomffigjjfes severe at lower doses. At sufficiently low concentrations of hydrochloric acid no adverse occur. Evaluation of the Potential for Advegj^gffects from Chlorine The conclusion of the interpretive review of^&Tfcvailable information on chlorine is that, with the exception of spills related to transportation a& Ac, and large accidental releases from point sources, the concentrations of chlorine in the envirftUMnt 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 accidentflhmjreleasc chlorine to the environment are minimized and those that occur are controlled as qdftSKiWas possible. The current trends in the adoption of best-available-technologies for systems thau^invent the release of chlorine to the environment must continue, to ensure that potential hamftAwfeeis from the uses of chlorine are prevented in the future. 8 AUG 13 '93 03* 55PM CPNTOX INC H POLYCHLORINATED BIPHENYLS (PCBs) P.13 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 PCBstJmwever, PCBs, not related to any human activities, were identified in ash from the 1980 vofcjiaeruption of ML SL Helens in Washington state* indicating their formation from natural prooafes independent of human activities. The quantities of PCBs released to the environment frdfl^blcanic eruptions are unknown. Physical and Chemical Properties of and Fate in the Environment The term PCBs denotes a family of 209 chd89f3h with chlorine attached at various places on the molecule. Depending on the position and of chlorine, the different PCBs exhibit a wide range of physical and chemical properties. Fdn&^mple, 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 abilit$pftlfferent PCBs to be stared in the body fat of animals ranges over 10,000-fbld, and becomes increasing amounts of chlorine on the molecule. Since the behavior of chemicals in thexbatonment is determined by their physical and chemical properties, the differences in propeitiw^Jthe various PCBs are reflected in their distribution, disappearance and movements in the envWlpMt. Generally, as the amount of chlorine contained In PCBs increases, their disappearance ot&taradation in the environment becomes slower. Some forms of PCBs are stored in the fat of orgajtgns following exposure. These PCBs are subsequently passed to predators and stored in the fat of ^e^redator. Since elimination from biological tissues is very slow for some of these PCg^foeir 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 VRD 0002048853 PUG 13 'S3 09:56flM CPNTOX INC P.14 CanTox The combination of unrestricted use and of physical properties, which favor tong range atmospheric transport, bioaccumulation and slow breakdown of PCBs has resulted in their widespread distribution in the environment, including remote areas such aa 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 repotted for humans, primarily because of the characteristics of aquatic food chains and the less varied diets of aquatic wildlife (i.e,, almost ail fish) compared to hui The Cause-Effect Relatlo Laboratory studies on animals hadg^pdicated that PCBs have the potential to cause adverse effects on reproduction and that extremities of some PCBs can increase the incidence of liver cancer in rats. These effects have been shown jp be dose-related (t.e., they become less severe and less prevalent at lower exposures). ThereySpod evidence indicating that sufficiently low exposures to PCBs do not cause advene effeetA. J- Certain adverse effects, such as eggshell thinning in some species of Great Lakes fish-eating birds and crossed bills in cormorants, increased in prevaletl^^nd severity as the concentrations of PCBs and several other chemicals in the environment f&Jtisgsed, and have declined as concentrations have declined. This consequent decline in eavironmwtal concentrations of PCBs and the recovery of bird populations is consistent with a cause-effecftb^onship between PCBs and reproductive effects in fish-eating birds. It must be noted, howerergsthat several other chlorinated and non-chloriiuued chemicals were also present in these birds, M fell controls over the release of these chemicals occurred during the same time period as the usedk&PCBs were regulated. Therefore, it Is not possible, based on the Held data available, to ijje^rate the possible cause-effect relationships of such a mixture of chemicals. In addition, there is^^Jpnce suggesting that loss of habitat caused by increasing urbanization and faulty 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 aa cs css r-o css VRD 0002848856 RUG 13 '93 09:57PM CANTOX INC P.16 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 ceitakbyildlife than humans, due to dietary habits and position In the food chains. This greater pastf^ity for harmful effects from PCBs is particularly pronounced in species that eat almost excEShfely fish and other aquatic organisms. Concern about possible harmful effects in such species^^^derstandably great in regions of the environment where the concentrations of PCBs, together wffft^iher chemicals, are markedly elevated {e.g,t various "hot spots"). With the exception of these Jg^tiized "hot spots", caused by historical point-source releases of chemicals, any adverse effects on the environment expected from current environmental concentrations of PCBs shoularapSaimor. Although PCBs were once considered to be resistant to natural biological breakdown. Hheib is now considerable laboratory and field evidence to the contrary, although their breakdowtffefe 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, Suough restrictions on environmental release rates, through natural, physical and biological degfadM processes, and through continued burial via sedimentation, the degree of harmful effedSr localized "hot spots" will continue to decline. Recommendations Chemicals having physical and chemical properties similar to those ofcertain PCBs,|vfijph result in their accumulation in the environment, should not be used in ways that lead#flMheir uncontrolled release Into the environment. The knowledge that these types of chemlcalscan be widely distributed throughout the world and will degrade slowly, should govern the design and 12 * VRD 0082048857 AUG 13 '93 10500PM CflNTOX INC P.17 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 commercial products, but is the starting product for the production of polyvinyl chloride (FVQfcjrVC (called polymers) Is made by linking a large number of vinyl chloride units together to fonjfel long chain of linked molecules. FVC is a solid material with great stability in the eavironrifl^ Its most recognized use is in PVC pipe, used In many drainage and plumbing appUcatidd^Under good manufacturing procedures, the residual concentration of vinyl chloride in mod^^VC products is below the lower limit of analytical detection limits. Vinyl chloride can be released to the atmosphereVyvapor. and it rapidly degrades by reactions with ultraviolet light. It does not accumulate tbroufifrood 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 foffOtable PVC. No information was available on the air concentrations of vinyl chMri kat locations remote from production/manufacturing facilities. However, based on the conccn tqg$ns reported near such facilities and the rapid rate at which it is destroyed in ambient air, (rations 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 AUG 13 '93 10501AM CAffTOX INC P.18 CanTox unacceptably high concentrations of vinyl chloride in some workplaces prior to the 1970a are believed to have resulted In increases in an unusual Uver cancer (called angiosarcoma) in workers. Intermediate break-down products formed during the degradation of vinyl chloride are reactive and bind to genetic material (DNA) hi cells. The reactions of these reactive intermediates with DNA are believed to be responsible for the cancer-producing activity ofvinyl chloride. Through changes In technology, the air concentrations of vinyl chloride in workplaces in the 1980s were reduced abouLlO.OOO- to 100,000-fold compared to the pre-1970 values. Lower concentrations in the wongpee, combined with protective equipment used by workers, virtually eliminated risks of liver caEapfrom occupational exposures associated with the use of vinyl chloride. Evaluation of the Potential for Advecp^ffects from Vinyl Chloride and PVC No harmful effects to human health or the environment occur from PVC itself. The major concern regarding PVC is the possible exifegjjre of workers to PVC dust arising from the use of PVC materials in manufacturing processes,ImEEpossible 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 fiqjg^uialytical detection limits (about S parts per billion) and are not associated with adverse cffect^^^umans or the environment. Recommendations The use of production and manufacturing technologies that eliminate rdeasw ofvinyl chloride to the environment should continue, thereby preventing air concentrations of Ymggjchloride from exceeding current undetectable values and ensuring that no harmful effects on hun^ur^ealth or the environment would occur. Continued care is required to ensure that spills and ajd&lental 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 VRD 0002048859 AUG 13 '93 10:03*1 CflNTOX INC P.19 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 concentations of these remain in the finished water. Everyone consuming chlorine-disinfected tap wkJs exposed to low concentrations of these chemicals. These are not uniquely man-made chemidumftost are also produced in significant amounts through natural processes, and exposure to and the environment would occur to some degree even If they were not found In treated drifting and waste water. In addition, improvements in the techniques of disinfection of drinldqj^ater with chlorine can substantially reduce the concentrations of these unwanted by-products in the finished water. The Cause*Effect Relationship The roost significant chlorinated chemicals found in water disinfected with chlorine were evaluated in terms of their potential for causing adverj^^fects. For all these chemicals, substantial amounts of information were available aUowing^Sfacterization of the types of effects they could cause and of the doses required to cause the effects*. Doses were determined for each of the chemicals that would be expected to result in no o< on humans or the environment. ghee of adverse effects Evaluation of the Potential for Adverse Effects from Chlorinated Chi 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 IS ?RD 0002048860 AUG 13 '93 10! 02PM CPNTOX INC P.20 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 ofdrinking water using chlorine results in theproduction of a safe water supply. The concentrations of cmqshated organic chemicals in rivers, lakes or streams receiving waste water disinfected with chlon^mere below those that would be associated with adverse health effects on aquatic. organums.`w^some cases the concentrations of one type of chemical (chlorinated phenols) exceeded suri^^water guidelines In the effluent, prior to entry into die receiving water. These occurrences wcr^fynarily 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 urtvfurans) can occur at concentrations in waste waters (primarily from sewage treatment plants)are high enough to warrant some concern. This concern stems from the potential for there com^^fels to bioaccumulate through the aquatic food chain. The chlorinated phenols and chlorinated dioxins and Allans may have been present in the raw water prior to treatment and may not have beeiw&uced as a result of chlorination, and so no conclusion regarding the effect of chlorination offf^tpotential for them to cause adverse effects can be made. Overall the weight-of-evidecce indicates that chlorine disinfection of dftfiging and waste water would not be associated with adverse effects on humans or the enviroiunefcc 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 VRO 0002048861 AUG 13 '93 10! 03AM CflNTOX INC 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 harmftii 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 chloria9taeets all these criteria, while the other methods of disinfection meet only some of them. In ntut&ases, the available information required to assess alternative disinfection technologies is indpmpjpto, particularly regarding the identification and quantification of by-products. A major deffciwpyifl the use of ultraviolet light for water disinfection is the lack of residual disinfection capadtyoutaide the water treatment plant. The overall conclusion from the current assggment is that disinfection of drinking water and waste water by chlorination remains the methOMclioice. Recommendations The scientific basis for the establishment of the chlorite and chlorate should be mote rigorously deft allowable concentration of The maximum concentration of chlorate and chlorite in finfiSfy drinking water should be reduced, through adjustments and refinements of the disfiifggtion process. Continued vigilance needs to be employed in the control of the water treatment process to ensure (hat the concentrations of chlorinated phenols dJwlofaexceed surface water guidelines. The source of chlorinated dioxins and fhrans In treated waste waters Reals to be established, and a detailed risk assessment, Incorporating analysis of the ac{($& food chain, needs to be conducted to ensure that concentrations are below those tSi&fcxild cause environmental concerns. A 17 AUG 13 '93 105 04PM CflNTOX INC INCINERATION OF CHLORINATED MATERIALS P.22 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 firS^Kuman and environmental exposure to these chlorinated chemicals would occur even If Incin&raBn technologies were not used, and the available Information demonstrates that insignificant afflictions of such chemicals arise from a properly operated, best- available-technology incinerator. The Cause-Effect Relationship The most significant chlorinated chemicals fouiflA incinerator emissions were evaluated in terms of their potential for causing adverse effectiTfim most of these chemicals a substantial amount of information was available to allow characterization of the possible effects they may cause and the doses required to cause the effects. For cad^^Lhe chemicals, upper dose limits were developed that would not be expected to result in the l^ijfi^ence of adverse effects on humans or the environment. Evaluation of the Potential for Adverse Effects from Chiorina During Incineration hemicals Produced Is The potential for adverse effects from chlorinated chemicals produced through incinenfcion was evaluated through the assessment of an actual facility employing the best available tearaolpgy. 18 TVRD 9002048863 AUG 13 '93 105 04AM CAKTOX INC The steps taken in conducting this analysis included the following: P.23 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 exposuresjffahlorinated organic chemicals from the case study incinerator were substantially lower than ufistaaximum safe exposures, indicating that no advene effects on human health or the environment would be expected. In addition, the predicted exposures to the chemicals were substantially (ormyof magnitude) less than those associated with exposures from ambient background sourceajmo^ndent of the incinerator. Although the amounts of chemicals emitted from an incinerator a^TOpendent on a number of factors related to the design and operating conditions of the facility, the caw, study facility is considered representative of a modem day incinerator employing best avaUamg^echnology. Emission rates of chlorinated chemicals from any such facility would be very lamad not associated with any adverse effects. Recommendations Outdated incinerator facilities should be upgraded or replaced ^qsure that the best available technology is being employed. New facilities should be constructedffi^g only the best available technology In order to ensure minimal concentrations of chemicals^^^lsslons. Operating incinerators should be monitored to ensure they are operating properly. * 19 M um uBB oaf AUG 13 '93 10505PM CPTfTOX INC VI WOOD PULP BLEACHING P.24 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 & 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, an^many are produced in significant amounts through natural processes independent of wood puipwductian. All the classes ofchlorinated organic chemicals produced from pulp bleaching are rebffesented by naturally occurring chemicals. Therefore, low concentrations of chemicals thSSjpfe the same as or similar to those produced by pulp mills would be encountered by organiso^^fefcthe environment, even if chlorine was not used in the pulping process. A Improvements in wood pulp bleaching technorerfrand the development of new processes have led to the ability to whiten wood pulp using formlg&hlorine other than gaseous chlorine. These modern processes result in the production of very loS2jevel chlorinated organic chemicals. The Cause-Effect Relationship Biological effects of pulp mill effluents can be evaluated in two toxicity testing of effluent in the form that it is discharged fro evaluation of toxicity of individual chemicals present in mill efflueJul Effluents from pulp mills using molecular chlorine are generally toxic to fish {flap din tanks containing undiluted effluent. Since there are numerous ehinrimteri and non-f chemicals present in the effluent, it is not possible to determine from this type of stud^which particular chemical or mixture of chemicals is responsible for the toxicity of the effluent. 20 J18H B ZB 0B QUA* AUG 13 '93 10:061 CflNTOX INC P.25 CanTox In field studies, advene effects have been observed in fish downstream from some pulp mills. Recent studies have indicated that once the milk 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 advene effects when exposed for four days to undiluted effluents from such mills. Individual chlorinated c representative of the major classes of these chemicals were evaluated in order to de whether any particular chemicals were present at high enough concentrations to cause adve; (/.., growth and reproduction effects) in fish downstream from pulp mills. Potential ads^ effects on human health were evaluated on the basis of consumption of fish living downstf^^fc- from pulp mills. This evaluation was based on mills using chlorine bleach or gaseous chlori^^the bleaching process, since very small amounts of chlorinated chemicals are produced by millsj^ng modem methods. For most of the representative chemicals, ooncet^j^ms measured in riven downstream ofpulp mills are below those that could be associated with dl^9fae 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). There was only one group of chemicals for which concentrations Ititater gave cause for concern (chlorinated dioxins and furans). The concent regarding the chlorinawSjijtoxins and fUrans stems from the facts that they can cause adverse effects on reproduction and matijliey bioaccumulate in the aquatic food chain. Since the potential effects of these chemicals af&SvMv site and mill specific, the assessment was based on a specific case study. Concentratioftalpf^chlorinated dioxins and furans in fish were measured downstream from a mill that used gaseoufcn|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 minimwh the potential 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 advene effects in fish, 21 9988 HZ000 AHA* AUG i3 '93 10S07AM CPNTOX INC P. 26 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. In pulp "dW* not using gaseous chlorine for whitening pulp, chlorinated dioxins and fhrans 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 tojssult in adverse effects in any species, including predators high on the food chain such as mtg&gd osprey. Similarly, no adverse effects would be expected from the other chlorinated chemfcwln the effluent from mills employing alternative methods for whitening pulp. Recommendations A Pulp mills should use best available technolofj^fbr producing and bleaching wood pulp so as to avoid the use of chlorine bleach or gaseous Offline and thereby reduce or eliminate the discharge of chlorinated organic chemicals, p&rticUllfj^ chlorinated dioxins and fUrans, to the aquatic environment Research efforts should continue to focus on elucidating the factors or non-chlorinatfid chemical(s) responsible for the effects o in fish populations near pulp mills. vn CHLORINATED ORGANIC SOLVENTS Sources of Chlorinated Organic Solvents Chlorinated organic solvents are used in a wide range of production and m|nu|acturing processes. Chlorinated organic solvents are generally small molecules that are derivativ^f^tow molecular weight hydrocarbons. These chemicals include compounds such as chloroform, carbon tetrachloride, dichloromcthanc (methylene chloride), dichloroethane, and dl-, tri-, and tetrachioroethylene. Chlorobenzenes are also widely used as solvents in the chemical industry. 22 flUG 13 '93 10:08(41 CANTOX INC P.27 CanTox During use, chlorinated solvents would be released into the workplace and the local environment surrounding production and manufacturing facilities. Hie 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 orgaiub^qnicals usod as solvents are also released into the environment as by-products of a number of oftp human activities (e.g., chlorine disinfection of drinking water, products of incomplete combu&3^(PICs), chlorine bleaching of paper pulp), and as products of a number of natural processes ifftf^tendent of human activities. The Cause-Effect Relationship * The most significant chlorinated chemicals are used as solvents, such as carbon tetrachloride, chloroform, the chlorocthylenes and^^fc 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 characterization of the types of effects caused and of the doses required to cause the effects masompleted for each chemical. Doses were determined for each of the chemicals that woulMw*icDected 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 toxicity^wim the liver and kidney generally being the main organs affected in humans and/or animals recewSwugh doses. Some of the chlorinated organic chemicals have been reported to induce tumors jQjjpor&tory studies using animals, albeit through mechanisms which may be related to the extrcm$g the doses tested or to the specific physiology of the test animals. As a result, for someof 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 $ 9 m a t0 0 0 (ft a AUG 13 '93 10:09AM CANTOX INC P.28 CanTox Evaluation of the Potential for Adverse Effects from Chlorinated Organic Solvents 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 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 tetrachloride^Mgan and environmental exposures to chlorinated organic solvents from general ambient sourceawould be substantially below exposure limits considered to be protective of human health aiffitphe environment. In the case of chloroform and carbon tetrachloride, exposures to the S^Sj^sge ambient environmental concentrations would be substantially below the exposure lim^Kponsidexed protective of human health and the environment. However, at the maximum ambient environmental concentrations reported historically at certain locations in specific urb^^hters, the recommended exposure limits would be exceeded by a small margin. This does ni^jjjiean that advene health effects would be associated with exposures to the maximum ambient et^tonmental concentration since there are substantial margins of safety between the exposure limits and exposures that could produce observable adverse health effects. T* The releases of solvents produced by human usage to the enviro particularly chloroform and carbon tetrachloride, have decreased over time, with increased closed, non-emi&slve systems. In the case of chloroform, historical data on drinking water dOl^Qi^Btions indicated that the procedures used for the disinfection of water supplies with chiorih& wore resulting is elevated levels of chloroform in the finished water; however data from sy&eJjriWiaing bestavailable-technologies for the disinfection of drinking water using chlorine Remonstrate substantially lower concentrations of chloroform in the finished water (e. g,, approachintf^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 6 98 8HZ000 aai^ AUG 13 '93 105 10PM CPMTOX INC P.29 CanTox increased use of improved technology. These 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-emlssive procedures). Occupational exposures should continue to be monitored and best available technologies should be employed to continue to reduce human and environmental exposures to chlariaate^OBuic solvents. Vm THE USE OF CHLOlfl^ IN TOE DEVELOPMENT OF PESTICIDES Many pesticides contain chlorine and mgjjhdo not. The biological activity ofpesticides does not correlate with the presence or absence of chlorine on the molecule. Non-chlorinated pesticides can be more toxic than chlorinated pesticides^Sbiy pesticides are produced naturally by plants, and some of these contain chlorine, indicating thuffiorinated pesticide were produced in nature before the advent of synthetic pesticides. Non-chmn&ted 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 efrcbj*on non-target organisms, the potential benefits associated with the use of the chemical must beronsidered. The chlorinated pesticide DDT provides a good example of a case in which the benefi&1$|ye^een ignored and the reasons for its widespread use forgotten in the wake of concern oVbepotential adverse reproductive effects in binds. DDT is highly effective against disease-camawfe. insects. is significantly less likely to cause poisoning in humans or other mammals thaCagernative chemicals, and is cheap and easy to produce. At the time of Its most widespread use, dimp 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 0188*01000 ONA* AUG 13 '93 10: HAM CANTOX INC P.30 CanTox Organization's mosquito control program using DDT, which still operates in many tropical countries. The use of DDT in Europe immediately alter 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 ceraiipstructures of chemicals result in undesirable properties, such as toxicity to non-target oiganxlag&r bioaccumulation potential, has led to the ability to specifically design pesticides which do not Iffl^these faults. New pesticides are more specific in their action against pests and may be rapidly de^^ed in the environment. Some contain chlorine and some do not. Some are made using chlorine production process without containing chlorine in the final product. Because of their specificity ami potency against target pests, the amounts used tend to be much smaller, thus reducing the afferar low risk of adverse environmental impacts. Recommendations The evaluation of the potential for pesticides to cause^|d|ers effects should continue to incorporate an assessment of the potential benefits as well as tfratisks associated with their use, as is now the approach of regulatory agencies In most countries. TflEm^aluation should be based on scientific data, not on whether or not a pesticide contains tiu&ftiup- The development of highly specific pesticides, that are rapidly broken down in the envirom^hmand need to be used only in small quantities should be encouraged. Ni '* 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 u m a z a ja AUG 13 '93 10:11AM CANTOX INC P.31 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 advene 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 excredoo and breakdown in biological systems. Theaejjypea of chemicals have been banned, or their use has been severely restricted, resulting in nagrablo decreases in their concentrations in the environment over the years. The concentrations onpsso chemicals will continue to decline albeit slowly, and the recovery of affected species, alflSfly well underway, is expected to continue. Attention should also be directed toward the signiftOT^of habitat loss in the slow recovery of some species. A Known "hot-spots", where the concentrations of these chemicals are substantially elevated compared to the general environment, requif^Wnued attention to reduce release rates from point sources to the environment and to invcstigafcrasiblc remediation procedures if warranted. In addition, the knowledge gained on the propertieOwl 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^r^occurrence of such problems m the ftiture. Other chlorinated chemicals, which do not bioaccumulate through Ito&shains and are readily degraded in the environment, have not been associated with advene concentrations at which they are found In the environment. Continued improvements in techn6l&|j^(c.g,, the use of closed systems and non-emlssive technologies) using and generating chloraiu&xhcmicah, and increased vigilance in the prevention of spills and accidental releases of these tijjemfcals will ensure further reductions in the future in the already low risks to humans and the emMuient from chlorinated organic chemicals. 27 AUG 13 *93 1 0 :1 2 m CANTOX INC VRD 8002048871 Table I Preliminary List of Chemicals of Concent Per Product Category CHEMICAL OlOUP Cfcexzaca! Drtofcia* VMtf PRODUCT CATEGORY Waat* WUr Sotveota PiKCw>chloopfop Mp * PVC/VCM PCb P-32 29 <SJ CD r- os oo I CM o {'I XOLNV3 If *d ONI XOINdO wyei:0T es ei snw XOJ.NV3 p'd ONI XOiNW WtJT:0T 6. T SfW AUG 13 '9 3 105 13AM CANTOX INC VRD 0002848875 Table t Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP __________ Gmicil ChlHtattirkHb,CRKklilG^b 2-CUonptMnol 2,4-DkMarofhcaoi 2^-Mknfhaul 2,4,5-T(k]itoK)fi>oJ 2,-L^Tndtlarapivenol 2,3,4>T^ckloropbeul 2,3.4>TMn(ihkw3pbMd I*Ti<irfctnfhtnnl TtcUm|Am4 DfcklmMKM TtliwhlaHinlrflwl SdiiEai WMr PBODUCT CATEGORY VmU V4k Sotwft hflwriiw ___ _ __ _______ _____ Pidp * pvcrvcM PCBa P.35 Trirtr*~mr nmjiinf'iM 31 n > X m XO]NV3 y 96`d 3NI XOINfcO WWT:0T 6 T STlb AUG 13 *93 1 0 :15AM CANTOX INC VRB 0002048877 Tabic 1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL CROUP Chwniftl DrWdqg HtODUCT CATEGORY WMta Vttr SdMdi InfiwTttipa rci* FCDDs, rCDFs JA3.4.7.HLCDF 24,4,6,7,1-H*CDF 1.24,4t6.74-H,CDF I,24.4.7.I4-H,CDF O.CDF CMoriute4 Fifty Ao* CIliifiilflKMkAoii Clli iilfl liiiiM a PVOVCM PC** TOTAL NO. CHEMKAj^-. >'u* If * n 54 20 It n > I X 3 33 70 o <9 < Table 2 Representative Priority Chemicals Assessed in Stand-Alone Documents XOLNVO ee-d ONI XOINbD WbST:0T 6, T STW AUG 13 '9 3 1 0 :16AM CANTOX INC VRD 0002048879 Table 2 Representative Priority Cliemicals Assessed in Stand-Alone Documents CHEMICAL GROUP Ckfokal CUmw fllnfiralif Tifria* TikUametMt TawUBMfaw 1.1-DkMonpnyiaoM 1.1.1-TrichktfOfrapMeae PieMwoeydnfnNwa-l^l- 4oae l-Oi*cro-4-|dicfalc meiaSyH$-bjrfKNir-2(SH)- CMariaateJ Bauaf Wj ntODOCT CATEGORY Waite Water SafwWt rvcmii KBfe OMmM NkrocMarolom 35 n > X TJ 8 VRD 0001048680 Table 2 Representative Priority Chemicals Assessed in Stand-Alone Documents CHEMICAL CROW OwaMcal rfcln^irf AUtfcyttes** _________________________________PRODUCT CATEGORY CUtrioe Drialnt Water Wde Water SeiiMti Ttkfcfareertie--I CMufJ^JUa ICDMKIlfr rev^ Cfchr^itol Fatly Adda* Piehloroeteem acid CkkwAaydioili hr ecad DtcMoan I rl^m.liirdr add t.t it*-*---1e-^ * Environmental effects to be ijuiMwi for the {roup of * Human and manamajac toxicity data to be * 2,3,7,b- auhadtnled iliaxm nd funs iaaoen. & clwrifib in the prelinnwy fiat (see Tfcfalo 1-1). Cir rvovcM 36 n > Z. 8 *u h AUG 13 '9 3 1 0 :ISAM CANTOX INC 1888*07003 QUA A Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Vinyl Chloride (VCM) and Polyvinyl Chloride (PVC) Report of an Expert Panel May 26. 1993 VRD 0902048882 Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment Vinyl Chloride (VCM) and Polyvinyl Chloride (PVQ - Report of an Expert Panel1 A Expert Panel Members E. Delzell, S.D. The University of Alabama at Birmingham Department of Epidemiology School of Public Health Birmingham, Alabama John Giesy, Ph.D. Department of Fisheries & Wildlife Michigan State University East Lansing, Michigan J.Ztoull, Ph.D., M.D. Environmental & Occupational Health Center University of Kansas Medical Center Kansas City, Kansas D. Mackay, Ph.D. Department of Chemical Engineering & Applied Chemistry University of Toronto Toronto, Ontario I.C. Munro, Ph.D., F.R.C.Path, Chairman CanTox Inc. Mississauga, Ontario G. M. Williams, M.D. American Health Foundation Valhalla, New York 1 This report was prepared, under the direction of the Expert Panel, by CanTox Inc. with supervision by Robert F. Willes, Ph.D. The Expert Panel provided direction in the preparation of the documents and critical scientific interpretation of the issues addressed in each product category document. The documents provide an interpretive review of the significance of observed past, present, and predicted future environmental concentrations of chlorinated organic chemicals to human health and the environment. VRD 0002048883 A Members of the Expert Panel and Area of Their Expertise Dr. Elizabeth Delzell, Ph.D., is Professor of Epidemiology, School of Public Health, University of Alabama, Birmingham. Dr. Delzell is an expert in the field of epidemiology and has provided critical review and analysis of the interpretation of the epidemiological and ca$e studies of the chemicals included in the product category documents. Dr. John Doull, Ph.D., M.D., is Professor of Pharmacology and Toxicology, and Director, Center for Environmental and Occupational Health, University of Kansas Medical Center. Dr. Doull is an expert in human toxicology, and provided critical review and analysis in the areas of mammalian toxicology, metabolism and carcinogenicity of the chemicals included in the product category documents. Dr. John Giesy, Ph.D., is Distinguished Professor of Fisheries and Wildlife, Michigan State University in East Lansing. Dr. Giesy is an expert in aquatic toxicology, and provided critical review and analysis in the areas of aquatic and wildlife toxicology and the interpretation of natural and anthropogenic sources, environmental concentrations and environmental fate of the chemicals included in the product category documents. Dr. Donald Mackay, Ph.D., is Professor, Department of Chemical Engineering and Applied Chemistry, and Chairman, Environmental Engineering Program, University of Toronto. Dr. Mackay is an expert in the environmental fate of organic chemicals, and provided critical review and analysis in the area of environmental chemistry and fate, and sources and environmental concentrations of the chemicals included in the product category documents. Dr. Ian Munro, Ph.D., is President, CanTox Inc. and an expert on toxicology and health safety and highly experienced in dealing with complex regulatory issues related to product safety. Dr. Munro provided critical review and analysis of the major components considered in the safety assessment of the chlorinated chemicals and in the area of regulatory toxicology. Dr. Gary Williams, M.D., is Director of the American Health Foundation, Valhalla, NY, and a Research Professor, Department of Pathology, New York Medical College, Valhalla, NY. Dr. Williams is an expert on chemical carcinogenicity/mutagenicity, and provided input into the critical area of biochemical aspects of toxicity and carcinogenicity of the chemicals included in the product category documents. A VRD 0002048884 Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Vinyl Chloride (VCM) and Polyvinyl Chloride (PVC) - Table of Contents Page PREFACE i EXECUTIVE SUMMARY xiii CHAPTER 1 INTRODUCTION 1.1 Introduction 1-1 CHAPTER 2 PROPERTIES, SOURCES AND ENVIRONMENTAL FATE OF VINYL CHLORIDE AND POLYVINYLCHLORIDE 2.1 Sources and Environmental Fate 2.1.1 Anthropogenic Sources 2.1.2 Natural Sources 2.2 Environmental Fate 2.2.1 Physical-chemical Properties 2.2.2 Environmental Fate 2.3 Vinyl Chloride Regulations 2.3.1 Regulations of VCM in Air 2.3.1.1 Concentrations of VCM in Emissions and Ambient Air 2.3.1.2 Regulations of VCM in Water 2.3.1.3 Soil 2-1 2-1 2-3 2-3 2-3 2-4 2-6 2-6 2-6 2-7 2-7 CHAPTER 3 POTENTIAL ENVIRONMENTAL HAZARDS AND HEALTH SIGNIFICANCE OF ENVIRONMENTAL CONCENTRATIONS OF VCM 3.1 Introduction 3.2 Environmental Concentrations 3.2.1 VCM Concentrations Associated With Production/Manufacturing Facilities 3.2.2 VCM Concentrations Remote from Production and Manufacturing Facilities 3.3 Hazard Assessment 3.3.1 Polyvinyl Chloride 3.3.1.1 Bioavailability, Metabolic Conversion (Pharmacokinetics), and Bioaccumulation 3.3.1.2 Mammalian Toxicology (Laboratory Animal and Biochemical Studies) 3.3.1.3 Epidemiology Studies 3-1 3-1 3-1 3-3 3-3 3-3 3-3 3-3 3-4 VRD 0802048885 A 3.3.1.4 Exposure Limits 3.3.2 Vinyl Chloride 3-4 3-5 3.3.2.1 Bioavailability, Metabolic Conversion(Pharmacokinetics), and Bioaccumulation 3-5 3.3.2.2 Mammalian Toxicology (Laboratory Animal and Biochemical Studies) 3-6 3.3.2.3 Mechanisms of Toxicity 3-8 3.3.2.4 Epidemiology Studies 3-8 3.3.2.5 Exposure Limits 3-12 3.4 Aquadc Wildlife Hazard Assessment 3-13 3.4.1 Lab Studies 3-13 3.5 Terrestrial Wildlife Hazard Assessment 3-13 3.6 Other Environmental Effects 3-13 3.7 Significance of Environmental Concentrations 3-13 CHAPTER 4 REFERENCES 4.1 References 4-1 98 88 HZ0B0 QHA Table 1-1 Table 1-2 Table 2-1 Table 2-2 Table 3-1 Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Vinyl Chloride (VCM) and Polyvinyl Chloride (PVQ - List of Tables and Figures Preliminary List of Chemicals of Concern Per Product Category Representative Priority Chemicals Assessed in Stand-Alone Documents Physical/Chemical Properties Physical/Chemical Properties of Vinyl Chloride Cancer Risk Estimates for Near-Plant Air Concentrations of VCM Page iv x 2-3 2-6 3-16 Figure 2-1 Level I Fugacity Modeling 2-6 VRO 0002048887 PREFACE A Over the past two to three decades, concerns about chlorinated chemicals have increased and there are divergent opinions regarding how society should react to the use of these chemicals. Sound scientific information has historically been the driving force behind the identification of concerns regarding the adverse effects of chemicals in the workplace and environment. Similarly, future actions governing the production and use of chemicals by society should also be based on the best possible scientific evaluation of the consequences of their uses with respect to maintaining a viable balance between environmental quality and providing clear benefits to society. Such scientific evaluation requires an understanding of i) the potential for chlorinated organic chemicals to produce adverse effects on the ecosystem, including humans, ii) the contributions of both anthropogenic (/.., related to human activities) and natural (independent of human activities) sources of chlorinated chemicals to total concentrations versus the environment, ill) the environmental fate of the chemicals that determine the distribution and losses from the environment, and iv) the determination of the degree of anthropogenic activities that could be sustained without exceeding the assimilative capacities of the environment and the occurrence of adverse effects. In an effort to assist continued progress in the application of sound scientific principles to the assessment of the potential adverse effects of chlorinated chemicals, a series of documents have been prepared, under the direction of an expert panel, that provide a detailed review and interpretive evaluation of the scientific information available on the historical, current and future status of chlorinated chemicals in the environment. The objective of this interpretive review was to provide an overview perspective on the potential adverse effects on the environment of chlorine and chlorinated organic chemicals for eight categories of products that involve specific chlorinated organic chemicals. The product categories identified included: chlorine, polychlorinated biphenyls, vinyl chloride/polyvinyl chloride, chlorinated organic solvents, chlorine disinfection of drinking water/waste water, incineration of chlorinated materials, bleaching wood pulp for production of paper, and the use of chlorine in the development of pesticides. For each of the first seven product categories, an interpretive review of the potential effects on human health and the environment of representative chlorinated chemicals of potential concern has been prepared. For the eighth product category, pesticides, a slightly different approach was adopted which addressed the issue of risk/benefit analysis as applied to the use of chlorine in the development of pesticides. Copies of all documents are available from the Chlorine Institute The protocol followed in preparation of the seven product category documents has been outlined below. A preliminary list of chlorinated chemicals of the greatest concern and of the most relevance to each of the product categories was developed based on published quantitative analytical and hazard data. A total of 93 chlorinated chemicals were identified and were grouped by chemical class (i.e., chlorinated inorganics, chlorinated alkanes, chlorinated alkenes) (see Table 1-1). It was beyond the scope and intention of the interpretive review to conduct a detailed assessment of the environmental and health effects of all 93 chlorinated chemicals. The i VRD 0002048888 A use (i.echlorine disinfection) as well as alternatives were examined and considered in the final conclusions regarding the human health and environmental effect of each product category, where information on alternatives were available. in Table 1-1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP Chemical Drinking Water PRODUCT CATEGORY WuU Water Solventa Incineration CUoriaaltd Alhenw (Continued) Chlorinated ASmn 1 ,2*Dtchlofopropaae 1,2-Dibro<no-3-cbk>n>^>ropane Dichloroelhylene 1,1 -Dkhloroethykne l,2-Dichlorocihyleoc(Cie) I-2,Dichloroelhylcne(Trana) Trichloroethylene Tetrachloroelhykoe 1,3-Dichloropropcne (Ci) Peouchlocopropene PenUchlorabutadiene Heuchlorobutadiene Hex*cblorocyclopemedicoe HcMchlorohexslriene *- Vinyl Chloride PVC Chlorinated Acids Polyvinyl Chloride Monockloroecetk Acid Trichloroacetic Acid Pulp A Paper PVOVCM PCBa (monomer) 6898P02000 OKA Table 1-1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP Chemical Drinking Water PRODUCT CATEGORY Waite Water Solvents Incineration Chlorinated rbcoob, Catecbob, Gualacob 2'Chlorophcnoi 2.4-Oichlofophcool 2.6-Dtditorophcnoi 2,4,3-Trichlorophenol 2.4,6*Trichlofophciwl 2(2l4rS~TctnchlorophenoI 2.3.4.6-TelnchIorophenof Pentnchlorophenol Telmchlorophcnol Dichlorocatechol Tetrachlorocaiechol Trichloroeatechol 3,4>S-Trichlorocalecho| 4.5-Dkhlorofuaiacol Dichtorofualacol (other iaomcra) Tclncbloroftiaiacol Trichkwofuaiacola Trichtorodihydrocooifcryl AkofeoJ CMofovenilfin Trichlorwooilljrlaloohol Triehloroecetoeyrinfone Dichlow>-3.4 dihydioKyproplopfceooM Pulp A Paper PVC/VCM PCBa 06m0Z080 OM Table 1-1 Preliminary List of Chemicals of Concern Per Product Category CHEMICAL GROUP Chemical Drinking Water PRODUCT CATEGORY Wane Water Solvents Incineration Chlorinated PCDOa. PCDFl (Continued) PCBi Chlorinated Fatty Acids Chlorinated Resin Adds Chlorinated Aminas Chlorinated Ethers Chlorinated SulToocs and Thiophenes TOTAL NO. CHEMICALS l,24,4,t,7,l-HlCDF 1,2,3,4,7,1,9-HjCDF 0,CDF 1 PCBi Dichloroitearic Acid CMorodehydroabietic acid Dicblorodehydroabktic acid 3.3 '-EKchlorobenridioe 4,4*fnethylene*bii-(2-chlo(oaiiiline) 8is(2-chloroethyl)ether CUotD-2-thiophcoic Acid Chlotothiopbenedicathoxylic Acid 1, l-OichlorodiOKthylauirone 93 12 49 44 - 37 Pulp A Paper 34 pvcrvcM 20 PCBe IS I 6 8 8 MZ000 Table 1-2 Representative Priority Chemicals Assessed in Stand-Alone Documents CHEMICAL CROUP ------------------------------------------------------------------- Chankal Chlorine Chlorinated Ke(oo* TrtehlorottctoiM Tetrachloroocttooc 1,1'DicKloropropeoone 1.1.1 -Trichloropropenoos DichlorocyclopcnUne-l ,2- dioiw 3*Chloco-4-|dicMoromeihyll> 5-bydn>xy-2(5H}-ftirenon Chlorinated Bemenes* HeuchlorobcozcM Dtchlorobcozcm 1.4-Dkhloroheazene 1.4-4ichlofoheozene 1.2.4- Trichlorobcnzaa* Chlorinated Phenols, Catecbob, Gualacols* PenuchloropKcnol 2,4,6-Trkhloropheool 2.4-Dichloropbcnol ChlorocalecbotP CbloroguaiecolP Chlorinated Nitrogenous Cowpounds' DtcKloroacctonhrila NkrodUotofono Drinking Water PRODUCT CATEGORY Waste Water Solvents Incineration Pulp* Paper rvc/vcM pcbs I6HHi000 GUA VRD 0002048892 A VINYL CHLORIDE MONOMER (VCM) AND POLYVINYL CHLORIDE (PCV) EXECUTIVE SUMMARY This document focuses on the interpretation of the potential adverse effects of vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) on human health and the environment. Potential secondary effects related to pyrolysis products from VCM and PVC are addressed in the Product Category document entitled "Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment - Incineration of Chlorinated Chemicals The assessment of the potential adverse effects of VCM and PVC has been based on the application of the dose-response principles that govern the actions of chemicals on biological systems as outlined in a document entitled "Interpretive Review of the Potential Adverse Effects of Chlorinated Organic Chemicals on Human Health and the Environment Introduction and Methods The overall conclusions of the interpretive review of the available information on VCM and PVC are: i) No potential adverse effects to public health or the general environment would occur from PVC. The primary concern regarding PVC relates to occupational exposures to PVC dusts arising from the use of PVC materials in manufacturing processes. ii) Historical (pre-1970s) concentrations of VCM in work environments of production/manufacturing facilities were excessive (in the range of 100 to 1000 ppm), and resulted in increased risks of liver angiosarcoma in workers. iii) Although no data were identified on the concentrations of VCM in air at locations remote from production/manufacturing facilities, based on the concentrations reported near such facilities and the rapid rate of disappearance half-life of VCM in ambient air, the concentrations of VCM in air in remote locations would be expected to be infinitesimal. iv) Following an in-depth, detailed review of the available epidemiological information on VCM, Sir Richard Doll (1988) concluded that "according to any reasonable criterion, the hazard to the general public (if there is any at all) must be negligible" from VCM exposures at locations remote from VCM production/manufacturing facilities. This conclusion is in agreement with the prediction that the concentrations of VCM in air in remote locations would be infinitesimal, and substantially less than current analytical detection limits (< 5 ppb). v) With the exception of spills related to transportation and use, and accidental releases from point sources, the predicted risks to populations assumed to be constantly exposed to the detection limit for concentrations of VCM in air (< 5 ppb as reported in the mid1980s within a few hundred meters of production/manufacturing facilities), would be in the range of one per million to one per 10 million. vi) The implementation of non-emissive technologies would be expected to diminish the already undetectable concentrations of VCM in air near production/manufacturing facilities, and thereby further diminish the already infinitesimal, and unmeasurable VRD 8002048893 potential risk to human health and the general environment. However, continued product stewardship is required to ensure spills and accidental releases are controlled to prevent the future occurrence of adverse effects to human health or the environment. The supporting evidence for this conclusion is based on an assessment of sources, environmental fate, hazard potential and environmental concentrations of PVC and VCM. Physical/Chemical Properties and Environmental Fate PVC is a polymer of VCM, and is a very stable, solid material that is relatively inert chemically, environmentally and biologically. PVC does not depolymerize or degrade under natural environmental conditions. One of the historical concerns of the presence of nonpolymerized VCM in PVC products has been largely addressed by modified manufacturing and production techniques. Under good manufacturing procedures, the residual concentration of VCM in modem PVC products is below analytical detection limits. VCM (also referred to as chloroethene, chloroethylene or monochloroethylene) is a molecule of two carbon atoms joined by an unsaturated bond and containing three hydrogen atoms and one chlorine atom. VCM has a high vapor pressure and is slightly soluble in water, consequently volatilization into the atmosphere is the major transport process in the environment. VCM is reactive, and readily polymerizes in the presence of oxygen, sunlight or heat to form PVC. VCM rapidly degrades in the troposphere via photochemical oxidation. As indicated by the low log K, of 1.38, VCM does not adsorb to organic carbon of soils/sediments or accumulate in biological tissues. Certain strains of microorganisms (e.g., Mycobacterium) can use VCM as a carbon and energy source under aerobic conditions. Biological degradation of VCM to CO* can occur under both aerobic and anaerobic conditions. Hazard Potential of VCM As with other chemicals, the potential for adverse effects of VCM depends on the concentrations that occur in target tissues within the body where adverse effects develop. These tissue concentrations depend on the bioavailability of the chemical from various environmental media through different routes of exposure. At room temperature, VCM is a gas. As such, inhalation is the most significant route of exposure in the environment and in occupational settings. VCM is readily and rapidly absorbed by the lung and readily metabolized to the reactive epoxide intermediate, chloroethylene oxide, which can rearrange spontaneously to chloroacetaldehyde, then undergo further metabolism. VCM does not accumulate in tissues. VCM is not a potent acute toxic agent, and acute lethality is not observed until air concentrations reach 113,000 to 230,000 ppm (294 to 595 g/m3). At these high exposures VCM acts as a narcotic or anaesthetic agent. In addition, at acutely toxic doses, tissue damage to lung, liver and kidneys has been observed. Following repeated, non-lethal exposures, the principal target organ for VCM is the liver. VCM was not found to be teratogenic in a number of laboratory studies on mammals. VRD 0002048894 A Evidence for the carcinogenicity of VCM in animals is conclusive based on positive data from numerous laboratory studies on animals. Both IARC and the U.S. EPA have concluded that there is sufficient evidence for VCM carcinogenicity in humans based upon the epidemiological data on workers exposed to high concentrations between the 1940s and late 1960s. VCM exposure has been associated with the development of a specific cancer (angiosarcoma) of the liver. There is disagreement in the reported literature regarding the potential for VCM to produce other types of cancer; however, there of some evidence for such concerns among persons with extreme exposures such as those that occurred historically in occupational settings. The results of in vitro mutagenicity studies and observations of chromosomal aberrations in peripheral blood lymphocytes in workers indicate a DNA-reactive mechanism for the mutagenicity/carcinogenicity of VCM. VCM has also been shown to be activated, via P450 enzyme systems, to a reactive epoxide intermediate that is believed to result in alkylation of DNA. Sources and Environmental Concentrations The majority of VCM is produced for use in the production of vinyl chloride homopolymer and copolymer resins. VCM is also used to a lesser extent as a component in the synthesis of methyl chloroform and as a co-monomer with vinylidene chloride to produce resins. A former use of VCM was as a propellant in aerosol cans and as a refrigerant. PVC resins manufactured from VCM are used in the manufacture of a variety of industrial and commercial products ranging from building materials to household and medical items. Undefined quantities of VCM can be produced from biotic and abiotic transformation of chlorinated solvents such as 1,1,1-trichloroethaneand 1,1-dichloroethane. 1,1,1-Trichloroethane and 1,1-dichloroethane both have a number of anthropogenic and natural sources. The natural sources of these VCM precursors suggest that there may be sources of VCM produced by natural processes independent of human activities, although such sources have not been unequivocally identified to date. The primary source of VCM in the environment is from emissions and effluents from VCM and PVC production and manufacturing facilities. Such releases rapidly volatilize into the atmosphere. Since 1979, VCM emissions from production facilities have been regulated in both Canada and the United States. Prior to 1975, it was estimated that PVC plants released 22.7 million kg of PVC and 110 million kg/year of VCM into the environment in the United States. Implementation of regulatory standards have substantially reduced total environmental releases of VCM and PVC, and currently the major sources are from accidental releases and spills. The concentrations of VCM in air are greatest near industrial facilities involved in its production and use in various manufacturing processes. Average concentrations of VCM in air in the late1970s were 44 jtg/ms near production facilities for Houston, Texas, and 10 to 40 pg/m3 near facilities in England. Air concentrations near production facilities were generally below analytical detection limits (< 13 *ig/m3 or 5 ppb) by the mid-1980s. In the work environment, air concentrations of VCM have decreased over the years with the reduction of emissions through improved operating technologies. Workplace concentrations in the Netherlands decreased from approximately 1000 ppm in 1945-1955 to 5 ppm after 1975 (Barnes, 1980), and data from the late 1980s to the present indicate workplace air concentrations generally <0.1 ssm e m a an* ppm with occasional values near 1 ppm in specific production/handling areas. Since production and manufacturing facilities are major sources of VCM, decreases in workplace concentrations would be expected to coincide with decreases in environmental releases. This relationship is supported by the declining environmental concentrations of VCM reported near production and manufacturing facilities observed between the 1970s and early 1980s. Potential Significance of Environmental Concentrations of VCM The available information on the physical/chemical properties, environmental fate characteristics and sources of VCM indicate that the major environmental concerns for VCM come from exposures of production and manufacturing workers and possibly populations living near such facilities. There would be little opportunity for exposures, and therefore risks of adverse effects, to the general public, or aquatic and terrestrial wildlife from VCM at locations distant from production and manufacturing facilities. As outlined above, the air concentrations near such facilities (within a few hundred meters) were historically in the range of 10 - 40 ppb in the mid1970s, and had decreased to values below detection limits (< 13 pig/m3 or 5 ppb) by the mid1980s. Based on current concentrations of VCM in air in the work environment (generally in the range of 0.1 to 0.2 ppm), the concentrations near facilities would be expected to be substantially less than analytical detection limits at the present time, and in the future. The characterization of the potential health risks that could result from exposures to such concentrations of VCM in air requires the comparison of resulting levels of exposure against a cancer potency estimate. The U.S. EPA has, over the years, proposed cancer potency slope values for VCM of 0.0174, 0.0295 and 2.3 (mg/kg body weight per day)'1, based on lung and liver tumors, respectively, following inhalation exposure to up to 30,000 ppm VCM and oral exposure to 0-17 mg/kg body weight/day (5 days/week) in laboratory rats. These cancer potency slopes translate into RsD (Risk Specific Dose) values of 0.575, 0.339 and 0.00435 /ig/kg body weight/day at a lifetime risk of one per 100,000, a range of 132-fold, based on available laboratory information and the EPA risk assessment approach. Cancer potency factors estimated from epidemiological studies of workers exposed to VCM in the 1940s, 1950s and 1960s, range from 0.00024 to 0.000024 (mg/kg body weight/day)1. These estimates assume exposures to 100 to 1000 ppm VCM resulted in a mortality incidence due to liver cancer of 2 per 100. The cancer potency estimates derived from the epidemiological data would translate into RsD values of approximately 42 to 420 jtg/kg body weight/day at a lifetime risk of one per 100,000. These exposure limits are starkly different from the greatest potency value proposed by EPA, and indicate that VCM is less potent by some 9500- to 95000-fold. Such large differences in estimates of cancer potency, using different data and approaches, result in equivalent differences in the risk estimates, and therefore, in the interpretation of the potential significance of the environmental concentrations of VCM near production/manufacturing facilities. Risk estimates based on the EPA values range from approximately 15 to 7700 per 100,000 for the air concentrations of VCM near production facilities in the mid-1970s, and from 7.4 to 980 per 100,000 for the mid-1980s air concentrations of VCM near production facilities. Risk estimates based on the epidemiological data range from 0.08 to 0.2 per 100,000 for the mid1970s air concentrations, and from 0.01 to 0.1 for the mid-1980s air concentrations. VRD 0002048896 A Based on a critical evaluation of the available epidemiological evidence available from workers exposed to VCM between the early 1940s and the 1960s, Doll (1988) concluded that potential risks from VCM to the "general public (if there is any at all) must be negligible". This conclusion is in agreement with the risk assessment summarized above using cancer potency estimates based on epidemiological data. Based on the environmental fate of VCM, the potential health risks to the general public in regions remote from VCM production and manufacturing facilities would be even more negligible, and certainly unmeasurable using conventional epidemiological study approaches. The maintenance of procedures for non-emissive uses of VCM and strict attention to operations to avoid accidental releases are needed to ensure that the current status of no adverse effects on human health and the environment is maintained. In the future, improved production and manufacturing control technologies and attention to accident prevention, in keeping with policies of progressive product stewardship, will continue to reduce emissions of VCM from production and manufacturing facilities, thereby further reducing the already negligible and unmeasurable risks predicted from current environmental concentrations of VCM near production and manufacturing facilities.