Document oexV529VkQe262LpwmMnD4gOr

ASBESTOS AND SILICA DUST Regulations and Exposure in Srywall Cperotions Harrison B. Rhodes Technology Manager and Blair L. Ingalls Supervisor, Special Projects Union Carbide Corporation Metals Division Niagara Falls, New York Introduction This two-part article is intended to acquaint drywall contractors with the current and proposed reg ulations governing the use of prod ucts containing asbestos and crystalline silica. The concluding article in the next issue will present data on the exposure to airborne asbestos and crystalline silica (quartz) during the sanding of tape joint com pound. A total of seven industrial locations were tested. Exposures to asbestos during the wet-out of dry-mix compounds and during cleanup will also be shown BACKGROUND AND CURRENT STATUSOSHA ASBESTOS REGULATIONS The Williams-Steiger Occupa tional Safety and Health Act was passed in 1970 with the stated ob jective of assuring, insofar as feasible, every American worker a safe and healthy workplace. Under the provisions of this act, the Sec retary of Labor issued an emer gency temporary standard for exposure to asbestos dust on De cember 7, 1971. After extensive public hearings, a permanent standard, effective July 7, 1972, was promulgated. The asbestos standard and the methods used by OSHA to develop it were immediately subjected to a massive legal attack by the Indus trial Union Department, AFl-CIO. In addition to the law suit, OSHA was under continued pressure from other labor groups, public interest groups, and spurred on by the news media to make revisions. It was also recognized that this was the first health standard written. As such, there were parts that were vague, parts that were impractical to enforce, and parts that were overly restrictive without a cor responding benefit in protection for the worker. During1973, OSHA decided that the asbestos standard should be altered. The initial concept was to replace it with a series of manda tory work practices that would minimize the admittedly cumber some monitoring requirements. The asbestos industry was asked to submit proposed work practices and a technical committee was formed under the auspices of the Asbestos Information Association/ North America. This committee consisted of representatives from about a dozen asbestos producers and large manufacturers of asbes tos-containing products. Commu nication was also maintained with trade associations that used asbes tos or its products. A draft work practice for joint taping was drawn up and submitted to the CDC1 for comment. The technical committee drafted several broad work practices re lating to the handling of asbestos. It soon became evident that a large number of specific work practices would be needed to cover the wide range of industrial situations where asbestos or asbestos-containing products were used The commit tee also examined and recom mended changes in the portions of the regulations that were vague or overly restrictive. The IUD decision was an nounced in mid 1974 by the United States Court of Appeals for the Dis trict of Columbia. The court gener ally upheld the OSHA position in the matter and noted that, al though the Congress had poorly defined the procedures to be used to set such standards, OSHA had used proper methods to collect and evaluate the conflicting evi dence presented. The judgments made to arrive at the standard were within the discretion granted to OSHA; and, more particularly, the court said that it was correct and proper to consider economic fac tors. Two points were remanded for further consideration; those re lating to record retention and the time allowed for compliance. After the court decision, OSHa materially altered their position on the revision of the asbestos regu lations. Under heavy pressure to issue health regulations for other substances, a decision was made to amend the asbestos regulations only to the extent needed to clarify ambiguities. No changes were to be proposed in the allowableexposure levels. Many of the suggestions for clarifying language made by the AIA/NA Technical Committee were understood to have been ac cepted. The redrafting of the regulation along these lines was apparently completed in late 1974 and the re sults were submitted for review to various governmental departments as required by law and policy Dur ing 1975 key personnel changes occurred at policy making levels in both OSHA and NIOSH. At some point, apparently quite recently, the decision was made to drop the amendment concept and reopen the entire asbestos and health con troversy. This information became 6 public when the proposed changes were published in the Federal Register on October 9,1975. The asbestos standard that was promulgated on June 7, T972 and which is still in effect can be di vided i ntoseven main categories: I.Sets the maximum allowable airborne asbestos concentra tions in the workplace at a ceiling level of 10 fibers/cc longer than 5 micrometers and at a time-weighted average (TWA) for an 8-hour shift of 5 fibers/cc longer than 5 micro meters. The TWA drops to 2 fibers/cc longer than 5 micro meters in july 1976. 2. Defines the acceptable proce dures to meet these standards 3 Defines where personal pro tective equipment may be used and specifies the types available. 4. Specifies monitoring require ments and the procedures to be used. 5. Specifies requirements for caution signs, caution labels, and housekeepingprocedures. 6. Requires medical examina tions for all employees "ex posed to asbestos." 7. Sets requirements for keeping of medical and monitoring records. The standard was written in lan guage that fits conventional fixed manufacturing locations. It pre sents some very real problems, however, when applied to the con struction industry where the job site and the work force are transi ent. The areas of particular diffi culty to drywafl contractors are those dealing with monitoring and medical examinations. The AIA/ NA Technical Committee recom mended a cutoff level below which medical examinations were not re quired. It was also proposed that monitoring could be dropped where monitoring experience had demonstrated the levels to be con sistently below the cutoff or where the asbestos had been properly modified by a bonding agent to prevent excessive dust. The revised standard proposed on October 9, 1975 follows the same general pattern but differs in the following critical points: 1.The allowable exposure level is reduced to 5 fibers/cc long er than 5 micrometers ceiling and 0.5 fiber/cc longer than 5 micrometers time-weighted average (TWA). 2. Monitoring and record keep ing requirements are increased substantially although a pro vision to discontinue moni toring under certain cir cumstances is included. 3. There is no cutoff level on the medical examination require ment. OSHA has reviewed the recent medical literature on asbestos and has proposed regulations based on a very strict interpretation thereof. They have not assessed the eco nomic (inflationary) impact of the proposed regulations but have stated their intention to do so or certify that there is no impact be fore public hearings are started. The burden of proof has been placed on industry to demonstrate thatthese regulations are overly re strictive. There is no question that if they are promulgated as pro posed, they will place a very heavy burden on asbestos producers and users. Appropriate responses will be submitted bv various segments of the asbestos industry and other interested parties. OSHA has stated in the Federal Register that the construction in dustry will not be covered by the newly proposed regulations. They will continue to operate under the present regulations until a new vertical standard for that industry is developed. This should not lead to a raise sense of security, how ever, because the same medical conclusions on allowable exposure levels are applicable regardless of the industry where they occur. Al so, the OSHA health regulations are rapidly moving towards a fixed format that will embody all of the same basic concepts regardless of the substance being regulated. It should be noted that the develop ment of an asbestos standard for the construction industry is in prog ress and recommendations have been submitted to OSHA by the Advisory Committee for the Con struction Industry. PROPOSED OSHA REGULATIONS -- CRYSTALLINE SILICA Asbestos products do not consti tute the only potential health haz ard for the drywall industry. Tape joint muds contain crystalline silica which has long been recog nized as the cause of a disabling lung disease called silicosis. The National Institute for Occupa tional Safety and Health (NIOSH) has prepared a Criteria Document relating to occupational exposure to crystalline silica and submitted it to OSHA on November 11,1974. A proposed silica regulation has been drafted by OSHA and was to have been published during Sep tember 1975. The pressure on OSHA to prepare other regulations has delayed this publication but it will undoubtedly appear in a few months. NIOSH recommended an allow able maximum exposure level to airborne crystalline silica of 50 micrograms per cubic meter of air (50pg/M3). Medical examinations, extensive monitoring, record keep ing, signs, warning labels, and oth er provisions similar to the asbestos regulations were also recom mended. An action level of one half the allowable exposure limit was also defined as a cutoff point below which the regulations would not apply. 7 OSHA REGULATIONS- INERT OR NUISANCE DUST Table G-3 of Section 1-910.93 of the OSHA regulations as revised on June 7, 1972 lists the maximum allowable airborne concentrations of inert or nuisance dust as 5 milli grams/cubic meter (mg/M3) in the respirable fraction and 15 mg/M3 in the total dust. If a dust is below the allowable levels for asbestos and silica but above that for nui sance dust, the regulations have been violated This regulation has been les> widely publicized than those for asbestos and silica but has been in effect for a number of years. It must also be considered when job-site dust conditions are examined. COMPOSITION OF TAPE JOINT COMPOUNDS Tape joint mud, either dry in bags or already mixed in five-gallon containers, is a well-known ma terial at the job site. Few appli cators realize, however, what goes into a mud and how carefully the ingredients must be balanced to give the critical blend of properties necessary to make the mud work properly during application and after it has dried. The ingredients in a typical ready-mix tape joint compound are listed below: COMPOSITION OF TYPICAL READY-MIX TJC Ingredient Water Limestone Percent by Weight Wet Dry Basis Basis 31 -- 41 60 Mica (and Clay) Binder Asbestos Miscellaneous 16 7 3 2 100 23 10 4 3 100 Looking at the dry basis, which represents the condition when the mud is cured, it can be seen that the principle ingredient is lime stone. This is the bulk filler that keeps the cost of the product down. It does not impart any hand ling properties to the wet mud. The next largest ingredient is finely-ground mica which is in the form of tiny flat plates These tend to form a loose structure in the wet mud and have an important bear ing on how the mud flows when trowelled and how it shrinks when it dries. The other mineral ingredient is asbestos. It is present at a level of 3-5% and performs the function of controlling shrinkage and crack ing when the mud dries. It is also very important to trowelling prop erties which allow the mud to form easily in thick sections and permits feathering of the wet edge. The most critical function of asbestos in most muds is to provide freezethaw stability. Muds which do not contain asbestos will generally be unusable after they have been frozen The binder in ready-mix is usu ally vinyl acetate, while casein, starch, or a similar "glue" is used in the dry mixes. It cures to hold the compound rigid and firmly at tached to the wall. The miscellaneous ingredients include such items as additives, fungicides, surfactants, cellulosic thickeners, and proprietary mate rials. These are important ingredi ents but will not overcome the effects of an improperly balanced blend of ma\or components. A compounder who wishes to formulate a mud without asbestos will have to replace it with a ma terial that will impart similar prop erties. The mica can be increased or some other fiber-like material, such as certain clays, may also be used. Additional cellulosic thick ener to give the necessary viscosity is also likely to be required. This has a tendency to make the vis cosity unstable, i.e., correct at the plant when manufactured but either too high or too low when the mud arrives at the job site. The reformulation problem be comes much more complicated when silica is considered. Four dif ferent limestones commonly used in the manufacture of TJC have been analyzed for crystalline sili ca content and found to range from 0.3 to 2%. Similarly, three different micas had silica contents of 2, 5, and 9%. While asbestos is usually free of crystalline silica, clays often contain substantial quantities. By proper selection of ingredi ents, it is possible to produce a mud with a silica content as low as 0.3%. Unless the low silica ingredients are readily available mud costs will increase. Since silica appears everywhere in nature, it is unlikely that a tape joint mud can be pre pared without detectable levels. If the proposed regulations are promulgated, workplace monitor ing can be extensive and a con siderable financial burden can be imposed on contractors. Eleven commercially available muds were found to contain from 0.3 to 2.5% of crystalline silica which is consistent with the silica content of the raw materials. Very few mud suppliers appear to be aware of the potential silica prob lem. It is well known that the major tape-joint compounders have had extensive research programs under way for the past several years to develop asbestos-free muds that work as well as those with asbes tos. So far, the programs have had limited success. The muds devel oped are more expensive and gen erally do not perform as well. The formulations now in use evolved to their present high-performance level over many years and it is, ob viously, difficult to replace the key functional ingredient. {Continued on page 30) 8 (Confirmed from page 3) associations and other special in terest groups do it...so, why can't we do it? Much has been said about in volvement and participation How ever, we cannot too often repeat that, if we are to solve the prob lems facing us in these turbulent times, we must all work together to understand the nature of our age and the world in which we live. Many of the problems affecting our Industry todav stem from very ba sic roots. We have created a society founded on science and tech nology, yet have not found a mean ingful place for many of the younger generation nor success fully employed the abilities of a large part of the older generation. We are in a crisis over values and aims of our culture; our efforts have been centered on materialism and striving for world leadership, rather than concentrating on values and the full development of human resources in our homes and in our own communities. As surely as day follows night, it is an in escapable fact that we are all af fected by the events of our times. There is no longer a place to run and hide, and we cannot afford to accept complacency or trust in the security of our own backyards. We must take responsibility for more than our own concerns so that each person may have the opportunity to develop his own potential for good and thereby strengthen the entire nation. We must, in short, be motivated toward involvement. You ask what CDCI will do for you? It will do what you ask of it and demand of it, for you as a member do indeed have a voice. The association has now been in existence some 20 years and is recognized as the spokesman of the Drywall Industry, both by gov ernment and those within the In dustry. So let's all get involved... let's not be like a shot from a 16 ga. shotgun, but let s be a cannon ball, moving through the halls of Congress and showing that our In dustry is a unified group from one end of the nation to the other and spanning the seas. For, if you don't get involved, the new laws and regulations, the growing lack of concern for quality, the steadily de creasing productivity rate and the escalating prices will eventually put your Industry--and you--out of the market. And sooner than you may think, one morning you will awake to find another product in its stead. Not reasonable, you say? Then, isn't it reasonable that you, who have made a living from this great Industry, should con tribute to the well-being of that Industry and stand shoulder-toshoulder with confidence, 6,000strong across the nation and throughout the world, to assure that the Drywall Industry does en dure and will continue to make this world a better place in which to live, work and play? -------- Howard R. Leederman Editor (Continued from page 8 ) ASBESTOS EXPOSURE IN THE TAPE JOINT INDUSTRY The tape joint industry had their attention drawn forcibly to the as bestos standard in the Spring of 1974. A group at Mt. Sinai Hospital, led by Dr. Selikoff, announced the results of a study of 59 tapers who were members of Local Union 1974, Drywall Tapers and Pointers of Greater New York. The fiber counts found during sanding were generally very high and one long time worker in the industry had a clearly recognizable case of lung fibrosis. The same data were trans mitted to NIOSH who issued an alert to the industry. At the time of this publicity, a major supplier of asbestos and oth er products to tape joint compound manufacturers had collected dust count samples during sanding at two locations in Florida. In con trast to the New York City results, the fiber levels found were low and well within the regulations. A pos sible reason for the difference can be found in the application and sanding conditions, i.e., hand-tool applied and heavily sanded in New York City compared with Ames tools and light sanding in Florida. The question of different work practices was pursued further with various contractors It was found that the amount of sanding done varied widely, even within a geo graphical area, ft depended on the way the mud was applied, i.e., Ames vs. hand tools, the skill of the operator running the mud, the type of finishing coat to be applied to the wall, the size and quality of the job, i.e., custom or "mass production," the amount of venti lation, and the personal preference of the contractor. In addition to these mechanical factors, different mud formulations appeared to vary widely in their tendency to gener ate dust when sanded. In general sanding was minimized to reduce costs. It was obvious that more infor mation from other parts of the country w'as needed to better de fine the levels of asbestos exposure to be expected. With the assistance of the CDCI and the excellent co operation of various individual contractors, field tests have now been run in New York, Texas, Michigan, and Minnesota. The New York, Michigan, and Minnesota sites were carefully selected to cov er as wide a range as possible in the "intensity" of the sanding op eration. Conditions varied from one man sanding lightly to three men sanding heavily in the same apartment. The New York tests al so provide information on hand tool application. In addition to as bestos tests, air samples were collected at several of the locations to check the airborne concentra tion of crystalline silica (quartz) in the respirable fraction of the dust. The results of these tests will be presented in the January-February Issue. 30 PL.AINTTIIFFF'S EXHIBIT GP-206 INTERDEPARTMENTAL COMMUNICATION DATE: March 1, 197% TO: *See Below LOCATION: FROM: M. F. Fink location; Tigard SUBJECT: AIRBORNE SUBSTANCES - DUSTS, MISTS t ETC *T0: Mr, K. W. Brown - Acmw^ Mr. J. D. Rauch - Akron Mr. J. S. Jorgensen - Blue Rapids Mr. C. G. Terry - Brunswick Mr. E. H. Allen - Buchanan Mr. 0. B. Covington, Jr. - Fort Dodge Mr. R. W. Nielsen - Grand Rapids Mr. C. R. Coats - Lovell Mr. C. F. Hummel - Sigurd Mr. M. S. Jorgensen - Wilmington Mr. J. E. Becker - Delair Mr. E. M. Rigby - Pryor Mr. M. A. Palmowski - Chicago Mr. R. V. Favero - Marietta Mr. H. W. Scharf - Milford cc: Mr. G. E. Wilson - Portland Mr. E. B. Hollingsworth - Wilmington Mr. T. W. Richards - Tigard Mr. C. W. Lehnert - Tigard Mr. J. W. Hart - Wilmington Mr. K. L. Gipson - Portland Mr. J. R. Hurd - Portland Mr. H. W. Peele - Wilmington Mr. J. DiLorenzo - Portland After months of controversy the Threshhold Limit Values recommended by Governmental Industrial Hygienists has been approved and accepted by Federal and a majority of State agencies responsible for enforcement of industrial hygiene regulations. One exception is the State of New York. They have proposed their own standards which have been reviewed and will be adopted very soon. This will create a hardship unless^ an agreement is negotiated between the State and OSHA. New York State Department of Labor and U. S. Bureau of Mines do have an agreement, however, this agreement does not extend past the calcining or when heat is applied to the rock. The plant will be exposed to two separate agencies, one State and the other Federal. At Buchanan, the U. S. Bureau of Mines has no jurisdiction, the entire operation will be subject to two agencies. OSHA regulations specifies that unless an accord is reached with state agencies or the state plan is approved Airborne Substances 2 March 1, 1974 by OSHA the federal regulations must be adopted. When an accord is reached and approval given, the agency having the most stringent regulations shall prevail. This condition may change but as of this date we doubt if any action has been taken by the state or OSHA. Fortunately the standards include gypsum dust in the nuisance category and allowable limit is 50 MPPCF (Million Particles Per Cubic Foot). At times the readings may specify million particles per cubic meter. This can be obtained by using the . conversion factor namely: MPPCF X 35.3 equals MPPCM We will refer to Threshhold Limit Value or Permissable as TLV. You will note that gypsum TLV is 50 MPPCF when the free silica is less than 1#. This should not be confused with combined silica. Free silica (alpha quartz) will be considerably lower than the silicate content. Gypsum may carry 25 to 35$ combined silica but very rarely exceeds 2$ free silica. Rock determinations were made in all of our domestic mining operations, the alpha quartz content averaged 0.89$ to approximately 2.00$. When the free silica is less than 1$ the permissable allowable is 50 MPPCF. When it exceeds 1$ the following conversion factor is used: TLV divided by $ alpha quartz + 10. If a reading of 35 MPPCF is obtained and the free content is 3$, the permissable value would be 30 divided by 3$ + 10 or 13. The hygienists recommend that when the alpha quartz is 1$ the allowable should not exceed 30 MPPCF. Based on 3$ free silica this would result in an allowable of 23.1 MPPCF. Roof drilling samples taken in the Akron mine were analyzed and free silica determinations averaged between 3.9$ to an occasional 5.1$ in the high range. Most recent sampling indicated that TLV should not exceed 19.0 MPPCF. It must be understood that dust particles larger than 10 microns are not considered injurious, i.e., in the nuisance dust varieties. Also 10 microns is not visible to the naked eye. We could have an excessive count although the air may appear clear of dust. Free silica particles remain suspended in the air con siderably longer than other dusts due to size and weight. As a rule dust counts are averaged out to the time exposure or length of the shift. This is acceptable when an employee works Airborne Substances -3 - March 1, 1974 on different jobs during the shift and dust exposure may fluctuate. Note paragraph, "Nuisance Particulates" Page A. A spot test may be taken during the first hour of the shift and a low count will be obtained. Samples taken during the latter part of the shift resulted in free silica 3 and 4 times the previous tests. Samples analyzed of settled dust exceeded 5.00$, however, samples taken by the driller's position were less than 1.00$. This example was more pronounced in the milling operations. Airborne samples averaged from 4.8 to 8.1 MPPCF, free silica determination 0.89$. Settled dust samples, taken from window sills, ledges, etc. resulted in concentrations of 11.90$ alpha quartz. L This condition is pointed out to emphasize the need for good housekeeping in all areas. Fortunately the dusts in the mining operations contain moisture reducing the odds of having dust disturbed and blown about the working areas. When the air seems to contain heavy concentrations of dust, a check of the operations shall be made to seal off any leaks. In addition dust masks must be worn until the condition is corrected. The MSA 8000 series has been approved by the U. S. Bureau of Mines and OSHA for non toxic dusts. This mask is preferable to others as they can be discarded at the end of the shift compared to an expensive and time consuming hygiene program when the more elaborate respirators or masks are used. Cost of the MSA 8000 series is less than 20 cents purchased in quantity lots. They are approved for all nuisance dusts, mica, asbestos and limestone. The MSA 8500 is standard in the Tigard Lab. This may seem lengthy and somewhat technical but we want to stress the importance of good housekeeping and enforcement of respiratory protection. Perlite TLV permissable 30 MPPCF. Here again the free silica is a factor. Dust masks shall be worn when exposed to perlite dusts, unloading cars, expanding and adding to mixes. Based on tests by U. S. Bureau of Mines, free silica contents of perlite averaged 3 to 4$. Combined silica averaged 72.00, 73.00 and 74.00$. Perlite, because it is a volcanic glass having a chemical composition similar to the volcanic ash and obsidion should be considered potentially capable of producing adverse reactions in lung tissue. Further studies are being made to determine the physiological effects on the respiratory system. It has been proven that there is an increase in the silica content and alpha quartz during the expanding process. A dust mask program shall be enforced. Mica TLV has been lowered from 50 to 20 MPPCF. This TLV carries a conversion factor when the free silica exceeds 1$. When purchasing mica a request should be made to the supplier for Airborne Substances -4- March 1, 1974 an analysis of the product especially the percentage of free silica. We believe that the grades of mica used in our plants do not exceed 1?. The dust mask program is a must when handling the product. Talc, non fibrous or non asbestos form. 20 TLV. Talc (fibrous) Cristobalite and Tremolite use. Asbestos TLV based on length of fibers. Asbestos. At the present time TLV 8 hour time weighted average airborne concentrations of asbestos fibers to which any employee may be exposed shall not exceed five fibers longer than five micrometers per cubic centimeter of air as determined by the method prescribed and approved by OSHA and NIOSH. The TLV is subject to change on 1/1/1976. Two fibers or less per cubic centimeter of air based on five micrometers. Based on recent surveys we are in compliance at all operations, however, a lot of static has developed at Akron. We do believe that this is the result of the lack of cooperation between OSHA and the state. Attached is an outline of safety practices for asbestos fibers. In addition a copy of the approved and adopted Threshhold Limit Values is attached. Review the charts and if you wish to have more information regarding any of the substances please advise. Although the value reductions may seem drastic, the greater part of the problem can be eliminated by education, enforcement of respiratory equipment, personal hygiene and cooperation with the rules. The employer is responsible for rule enforcement. Special attention must be given to housekeeping, especially in the asbestos operations. All spillage shall be immediately cleaned up. Bags of asbestos in storage shall be covered and finally dust masks must be worn. To repeat the earlier statement, the one-day use MSA masks have been approved by OSHA to prevent breathing asbestos dust. MFF:jg Attachments IV SAFETY PRACTICES FOR ASBESTOS FIBERS The following recommendations for asbestos handling have been adapted from the safety practices instituted by JohnsManvile: 1. In all stages of handling -- packaging, transporting, unloading, storing and in-plant moving -- asbestos fiber bags should be handled carefully and in such a manner as to prevent the generation of dust. 2. Unitized loads should be lifted intact to and from holds of ships, and off and on land transport by fork lift trucks or other suitable handling equipment. 3. Care should be taken to avoid puncturing the asbestos fiber bags during unloading from ships, railroad cars, trucks or other modes of transportation. No hooks or other sharp instruments should be used. Loose fiber accumulated during transit should be picked up by vacuum cleaner before unloading. 4. Damaged bags should be immediately repaired, resealed or put into suitably closed receptacles. Any spillage of asbestos fiber should be picked up either by vacuum equipment or after thoroughly wetting, by sweeping, and should be deposited in suitable closed receptacles. 16 5. For storage, fiber bags should be stacked and moved with care to avoid breakage, protected from puncture by moving vehicles and, if possible, should be isolated from traffic in the warehouse and covered to prevent dust generation. To prevent deterioration of stored bags, the principle of first-in, first-out should be followed. 6. Maximum possible enclosure and fully effective dust control hoods should be^ provided at all stages of in-plant handling where dust is unavoidably created, such as at bag opening, fiber dumping and bag disposal operations. Loose fiber should be cleaned from work areas as described in 4, above, to prevent dust regeneration. 7. The wearing of respiratory protective equipment approved by the U.S. Bureau of Mining for protection against asbestos dust should be required at all stages of asbestos fiber handling where quantities of dust are generated which cannot be kept within the Threshhold Limit Value by dust control equipment or other methods. 8. Waste materials, such as collected dust and empty fiber bags, should be placed in special closed re ceptacles and disposed of in such a way as to prevent the release of dust. Methods applicable uner 6 and 7 above, should be used during these operations. 17 9 . All dust from exhaust systems should be collected and safely disposed of. It should not be released into the outside air. Particular attention should be paid to the protection of the employees whose job it is to dispose of the collected dust. 10. Storage piles of bags of asbestos shall be covered with a non-clinging cover or tarp. Plastic is recommended. All spillage shall be vacuum cleaned to prevent so called fugitive fiber release. 18 i nreshold Limit Values for iD73 Adopted at the 35th Annual Meeting of the American Conference of Governmental Industrial Hygienists Boston, Massachusetts, May 21-25, 1973. Threshold limit value* refer In airborne concentrations of substances amt represent conditions under which it is believed that nearly ail workers may he repeatedly exposed day after day without adverse effect. Because of wide varia tion in individual susceptibility, however, a small percentape of workers may experience discomfort from some sub stances at concentrations at or below the threshold limit, A smaller percentage may be affected more seriously by aggra vation of a pre-existing condition or by development of an occupational illness. Simple tests arc now available (J, Occup. Med. 9: 537, 1967; Ann. N.Y. Acad. Sci,, 151, Art. 2: 968, 1968) that may be used to detect those individuals hypcrsusccptiblc to a variety of industrial chemicals (respiratory irritants, hemolytic chemicals, organic isocyanates, carbon disulfide). These tests may be used to screen out by appropriate job placement the hyperreactive worker and thus in effect im prove this "coverage" of the TLVs. Threshold limit values refer to time-weighted concentra tions for a 7 or 8-hour workday and 40-hour workweek. They should be used ns guides in the control of health hazards and should not be used as fine lines between safe and dangerous concentrations. (Exceptions arc the sub stances listed in Appendices B and F and those substances designated with a "C" or Ceiling value, Appendix D) Time-weighted averages permit excursions above the limit provided they arc compensated by equivalent excur sions below the limit during the workday. In some instances it may be permissible to calculate the average concentration for a workweek rather than for a workday. The degree of permissible excursion is related to the magnitude of the threshold limit value of a particular substance as given in Appendix D. The relationship between threshold limit and permissible excursion is a rule of thumb and in certain eases may not apply. The amount by which threshold limits may be exceeded for snort periods without injury to health depends upon a number of factors such as the nature of the contaminant, whether very high concentrations - even for short periods - produce acute poisoning, whether the ef fects arc cumulative, the frequency with which high con centrations occur, and the duration of such periods. All factors must be taken into consideration in arriving at deci sion as to whether a hazardous condition exists. Thrcsnold limits arc based on the best available informa tion from industrial experience, from experimental human and animal studies, and, when possible, from a combination d: :nc three. The basis on which the values arc established nay differ from substance to substance; protection against mpairmeni of health may oc a guiding factor for some, vhcrcas reasonable freedom from irritation, narcosis, nuiance or other forms of stress may form the basis for thcrs. The amount and nature o: the information available for stablrsh.ng a TLV varies from substance to substance, concquentiy, the precision of the estimated TLV is also sub let to variation and the latest Documentation should be onsutted in order to assess the extent of the data available Dr a given substance. The committee holds to the opinion that limits based on hyscal irritation should be considered no less binding than lose based on physical impairment. There is increasing evitnce that physical irritation may initiate, promote or ac`ierate physical impairment through Interaction with other temical or biologic agents. In aplte of the fact that terioui Injury k not believed tely ai a result of expome to the threshold limit eoncen- tralions, the best practice is to maintain cnn< 'miration*. of all atmospheric contaminants as low as r prach t. These limit* arc intended for use in the pro nee of indus trial hygiene and should he interpreted and applied only by a person trained in this discipline. They arc not intended ' for use, or for modification for use, (I) as a relative index of hazard or toxicity, (2) in the evaluation of air pollution nuisances, (3) in estimating the toxic potential of continu ous, uninterrupted exposures, (4) as proof nr drproof of an existing disease or physical condition, or (5) for adoption by countries whose working conditions differ from those in the United States of America and where substances and processes differ. Ceiling vs Time-Weighted Average J.imits. Although the time-weighted average concentration provide* the most sat isfactory, practical way of monitoring airborne agents for compliance with the limits, there arc certain substances for which it is inappropriate. In the latter group arc substances which arc predominantly fast acting and whose threshold limit is more appropriately based on this particular re sponse. Substances with this type of response arc best con trolled by a ceiling "C" limit that should not be exceeded. It is implicit in these definitions that the manner of sam pling to determine compliance with the limits for each group must differ; a single brief sample, that is applicable to a "C" limit, is not appropriate to the time-weighted limit; here, a sufficient number of samples arc needed to permit a time-weighted average concentration throughout a com plete cycle of operations or throughout the work shift. . Whereas the ceiling limit places a definite boundary which concentrations should not be permuted to exceed, the time-weighted average limit requires an explicit limit to the excursions that arc permissible above the listed values. The magnitude of these excursions may be pegged to the magnitude of the threshold limit by an appropriate factor shown in Appendix D. It should be noted that the same factors arc used by the Committee in making a judgment whether to include or exclude a substance tor a "C" listing. "Skin" Notation. Listed substances followed by the des ignation "Skin'* refer to the potential contribution to the overall exposure by the cutaneous route including mucous membranes and eye, cither by airborne, or more par ticularly, by direct contact with the substance. Vehicles can alter skin absorption. This attention-calling designation is intended to suggest appropriate measures for the prevention of cutaneous absorption so that the threshoki limit s not invalidated. Mixtures. Special consideration shouirf be give.*, also the application of the TLVs in assessing the health hazards which may be associated with exposure to mixture* of two or more substances. A brief discussion of basic ,\*risuifr- tions involved in developing threshold kmii yah..-, fo; mix tures, and methods for their development, am pi. hod In specific examples arc given in Appendix C. Nuisance Particulates. In contrast to fibrogvnic dusis which cause scar tissue to be formed in lungs when inhaled in excessive amounts, so-called "nuisance" dusts have a long history of little adverse effect on lungs and do not produce significant organic disease or toxic effect when exposures arc kept under reasonable control. The nuisance dusts have also been called (biologically) "inert" dusts, but the latter term is inappropriate to the extent that there is no dust which does not evoke some cellular response in the lung when inhaled li\sufficient amount. However, the lung-tissue reaction caused by Inhalation of nuisance dusts has the A AvfMt ItrJ/OCCUFATIONAI MAZAftOS 11 Ml<. u m i h.u.u U nsiics: l)Thc architecture of (he air ti'm.nns inl.it I. 2) Collar.cn (near tissue) is not formal to n significant extent. 3) The tissue reaction it potentially rcvmihlc. Fxivxsivc coitccntratinnx of nuisance dusts in the work room ntr may seriously reduce visibility (iron oxide), may muse unpleasant deposits in the eyes, ears and nasal pas sages (Port la ml Cement dust), or cause injury to (he skin or mucous membranes by chemical or mechanical action per sc or by the rigorous skin cleansing procedures necessary for their removal. v A threshold limit of 10itig/m3, or 30 inppcf, of total dust < \rr quart? is recommended for substances in these categories and for which no specific threshold limits have been assigned. This limit, for a normal workday, docs not apply to brief exposures at higher concentrations. Neither does t( apply to those substances which may cause physiol ogic impairment at lower concentrations hut for which a threshold limit has not yet been adopted. Some nuisance particulates arc given in Appendix F. Simple Asphyxiants - "Inert" Gases or Vapors. A lumber of gases and vapors, when present in high concern rations in air, act primarily as simple asphyxiants without if her significant physiologic effects. A TLV may not be ccommcndcJ for each simple asphyxiant because the limit- ng factor is the available oxygen. The minimal oxygen con- ent should he 18 percent by volume under normal atmo- phcnc pressure (equivalent to a partial pressure, p02 of 35 mm Ifg). Atmospheres deficient in do not provide dequate warning and most simple asphyxiants arc odorless, everat simple asphyxiants present an explosion hazard, .ccount should be taken of this factor in limiting the con ' centration of the asphyxiant. Specific ex.-rmpb . tr- li fed m Appendix |;. Physical factors. It is recognized that such pl y k ,-d fac tors as heat, ultraviolet and ionizing radiation, humidify, abnormal pressure (altitude) and the like ru iy pi w .vJric'l stress on the body so that the effects from exp".re at a threshold limit may be altered. Mo t of tlx < mp - . act adversely to increase the toxic response of a .nlr f me Al though most threshold limits have built-in safety Intor, to guard against adverse effects to moderate deviation*, from normal environments, the safety factors of most substances arc not of such a magnitude as to lake care of grov, devia tions. l**or example, continuous work at temperatures about 90l: for overtime extending the workweek more than 25% might he considered gross deviations. In such instances judgment must be exercised in the proper adju*.ments of the threshold limit values. "Notice of Intent." At the beginning of each ; var, pro posed actions of the Committee for the forthcoming year arc issued in the form of a "Notice of Intended Changes." This Notice provides not only an opportunity for comment, but solicits suggestions of substances to be added to the list. The suggestions should be accompanied by substantiating evidence. The list of Intended Changes follows the Adopted Values in the TLV booklet. Legal Status. By publication in the Federal Register (Vol 36, No. 105, May 29, 1971) the Threshold Limit Values arc now official federal standards for industrial air. Reprint Permission. This publication may be reprinted provided that written permission is obtained from the Secretary-Treasurer of the Conference and that it be pub lished in its entirety. . ADOPTED VALUES Substance ppmfl^ mp/M3*' Abate _ 10 Acetaldehyde Aeonc acid too ISO 10 25 Acetic anhydride Acetone s 1,000 20 2,400 Acetonitrile 2-Acct vl.-irmnofluorene -- Skin, 40 70, -- A1 . Acetylene F -- Acetylene dichloride, at# 1, 2* Dichlnroethylene -- Acctvlene ietrahromlde Acrolcm Acrylamide -- Skin ;i , i ^ o.i > _ 14 0.25 0.) A.Tvlonitriic - Skin AUrin - Skin AIM alcohol - Skin Allvl c llnrulo - '20 2 1 45 0.25 3 c Ali> 1 plyridyl ether (AGE) Ally! rrnryi disulfide AJundt:m (Al 0 ) 4-ArmnouipUvnyi - Skin 2-Anunneth;,nol. see Ethanoiarr.llie <> _ ,_ . - . E.. A1* _ 2-Aimnopyndinc O.S 2 Ammom; Ammonium chloride, fume 25 IS -- iO Ammonium tuifamaie (Ammttl) a-Ar.iyi acciati.- - .' 10 too 52S *ec- Arryl acetate 125 650 Amlmc - Skin Amsioine (o, p-isomers) - Skin S 19 -- 0.5 Antimony & compounds (as Sb) ANTU (alpha naphthyl thiourea) . ' Alton ., Arsenic & compounds (as Aa) ,1 -- F '-- 1 O.S 0.3 _ O.S Arsine 1 0.01 Asphalt (petroleum) fumes * . -- Annphos methyl - Skin 1_ . Barium (soluble compounds) ' 1-- . 0.2 5 0.2 O.S Benzene (benzol) - Skin Benzidine - Skin p-Benroqulnone, Qulnone Benzoyl peroxide Benzyl chloride Beryllium > 25 ,-- i . 1 <a > i 5 5 0.602 OCCU9A'*Ul HA*AftOS/Aewf 19?) (In Alphabetic Order) Substance VV' ' ppnfJ ng/M-*9j Biphenyl, see Diphenyl Bismuth tclluridc 4 D^muth tcllunde (se-doped) Boron oxide ` Boron tribromide C Boron trinuoride Bromine Bromine pentafluoride Dromoform - Skin Butadiene (1, 3-butadiene) 4 Butane Butancthiol, see Butyl mercaptan 2-Butanonc * 2-Butoxy ethanol (Butyl CeDoeohre) -- Skin Butyl acetate (n-butyl acetate) scc-Uulyl acetate tcrt-Butyl acetate Butyl alcohol scc-Butyl alcohol tort-linty 1 alcohol C Butylaimno - Skin C tcrt-Hutyl chromate ( CrOj) -- Skm n-Butyi giycidy! ether (BGE) Butyl mcrcaptar. P-icrt-Butyltolucne Caumium (Metal dust and sohtbie aalUy **C Cadmium oxide fume (at Cd) Calcium carbonate Calcium arsenate , Calcium oxide . Camphor (Synthetic) Carbaryl (SevinB) Carbon black . 1 ., Carbon dioxide ., Carbon disulfide - Skin ' Carbon monoxide Carbon tetrachloride -- Skin Cellulose (paper fiber) ' Chlordana - Skin Chlorinated cemphene - Skin Chlorinated diphenyl oxide _ -- I 1 0.1 0.1 O.S 1,000 soo 200 50 ISO 200 200 100 *50 :oo 5 -- 50 0.;* it -- -- 2 5,000 20 50 10 -- -- -- -- _ 10 5. 10 10 3 0.7 , 0.7 5 2.200 1,200 - 590 240 710 950 950 >00 iOO .5 0.1 270 i 60 oTs E 1 5 :: 5 3.5 *9,000 60 55 65 E O.S O.S O.S 0 Suhxtsnr* Cldnrinr .1 3 Chlorine dioxide 0.1 0.3 C Chlorine trifhmrldr ' 0.1 0.4 C CMoroavetaldrhrdc 13 ^ 9L -- Chlornacrtophrnnnr (phoiiacvlchlorlde) 0.08 , 0.3 Chlorohenrrnc (mnimrhlofohentent) . 7$ 350 o-CliInrohm/yliilrnf mnlnnonltrlle (OCHM) - Skin Chlor nhfomnmrlhflnr J Oiloro l, .VhutndHm e 0.01/' 0.4 900 / 1,080 CMoroprrne - --- -- Chlorodiphcnvl (4J7J- Chlorine) -- Ski* -- I Chlorodlphenyl ($4^ Chlorine) - SkJlI 1 -Chlorn, 2. 3- epoxy-propane, eee Fpiehlorhydrin -- o.s -- 2-Chl(*ti*clhannl, see Ethylene rhlorohvdrln --` -- Cbloroothylrnc. ucc Vinyl chloride -- - Chloroform (trichtoromethane) 25 120 l-Chloro- l-nitropropane Chloropicrin 20 0.1 too 0.7 Chloroprcnc (2-chloro-|, 3-botadlene) ' - Skin . 21 Chromic acid nnd chromates (as CrOg) -- . 90 0.1 Chromium, sol. chromic, chromoM salts ax Cr. ' Metal A insol. nails _ AU .0.3 (i.o) `4 Coal dint (bituminous} (Respirable dust fraction <5% quartz) (If !> 5^ qunrtl ttM . respirable mass formulas) * '. . , _ * 2 Coal tar pitch volatiles (ben rone soluble fraction) anthracene. BaP, phcnanthreM, acridine, chrysene, pyrene) Cobalt, metal fume 4 dust Copper fume Dusts and Mists . Corundum (A 1 jOj) Cotton Dust (raw) Crat:' herbicide i* , . A14 -- '-- -- - - 0.2 0.1 0.1 1 E ( 1) 10 Crcso! (ail isomer*) -- Skin 5 22 Crotonaldehyde 26 Cumene -- Skin Cyanide (as CN) -- Skin Cyanopen 50 245 --5 10 -- Cyclohexane 300 1,050 Cvdohcxanol so 200 Cyclohexanone SO 200 Cyclohcxcne 300 1,01 s Cydopentadicnc 2,4-D DDT DDVP, sec Dichlorvos ' 75 .-- '-- -- 200 10 1 - Dccaborane - Skin Demeton'' -- Skin Diacctonc alcohol (4-Hydroxy* : 0.05 1 . '. * 0.3 0.1 4-methyl- 2-pcntanone) - 'so 240 1, 2-Diamtnocthane, see Ethylcncdiamine _ __ _ Diarmnn - Skin 0.1 Diaromethanc 0J 0.4 Dihirane 0.1 0.1 * !. 2-Dii'romocthane (ethylene dihromidc) - Skin Dibrom^ 20 145 --3 * 2-N Dihutylan.inoethenol -- Skin Dthu;yl phosphate Dioutylphthalaic 2 14 i --s C Dicriloraectylcne 0.1 0.4 C o-Dicn lor ooen zero SO 300 p-Dienioronen/enc Dichi.irohcn/tdine -- S*in 7S 450 - A1* DichiorodiDuoromctnane 1,000 4,950 1, 3-Dkhloro-5, S-Dimethyl hydMtMR -` 0.2 4 \, 1 -Dichlorocthane ' 200 820 1, 2-Dchlorocthanc , . so 200 1. 2-Dichloroethylene 200 , 790 A Dichlorocthyl ether - Skin 5 30 Dichioromethane, see Methylene' , * chloride . --. -- Dichloromonofluoromethene . 1,000 4,200 C 1, l-Dichloro-l-nltroethane - ' 10 * 0 1, J-Dichlofopropane, see fropytenedtehtoride v- (> -- / -- Dlchlorotetianuoroethane x Dlchlorrot (DDVF) - Skin . 1,000 7,000 -- ' 1 Dlektrtn - Skin ' *. - ,, 0.28 . Sulr.tnncn ppm-^ mg/M'N DiclhylaiuuuDielliylaminn ethanol - Skin 7'< 10 Ihclhylrm* trtamine -- Skin Dirlhylrllu-r, sec Ethyl ether l)>nimrodihroniomc thane C l)rly idyl nllirr (l)GI ) 1 - 100 o.s Diliydriixyhcnrenc, are IlydrOQUlaon* 4 Dlisolnifyl krtonc 25 Diho|ropylamine - Skin DimrthoxyvnHhnnc, see Methylal S - Dimethyl acetamide - Skin 10 Dimrfhyltiminc ( 41 )lmct li yla minoa xohen r.cnc 1 Dlmrlhylaminnhciizcnc, see Xytldene 10 -- -- Dimethylanlllnc (N-dlmethylenRine) - Skin Dlmcthylhcnxcne, see Xylene s _ Dimethyl 1,2-dlhromo- 2*dlchloroettiyf phosphate, sec Dlllrom Dime t hylformamidc -- Skin 10 2, 6-Dimcthylhcplanone, ace Diisohutyl ketone - t, l-Dimcthylhydrarine -- Skill Dimcthylphlhalate 0.5 -- Dimcthylsulfate - Skin Dinitrobcnzcnc (ell isomers) -- Skin . Dinitro-o-cresol -- Skin Dinitrotoluene -- Skin Dioxanc (l)icthylene dioxide) -- Skin (1 ) -- -- -- . 100 Diphenyl 0.2 Diphenyl amine Dlphcnylmethane diisocyenste (tee -- Methylene hisphenyl isocyanate (MDI) -- Dipropylene glycol methyl ether . - Skin 4 Diquat 100 -- . Di-sec. octyl phthalate (DE2* cthylhcxylphthalate Emery Emiosnlfan (Thiodan*) -- Skin Endrin - Skin ` -- -- -- Epichlorhydrin -- Skin ErN - Skin 5 - 1, 2-r.poxypropane, see Propylcneoxidc 2, 3-Epoxy-i-proptnol, see Glycidol Ethane F Ethancthioi, see Ethylmercapten - Etlmnolaminc 4 2-Ethoxyethanol -- Skin 2-Ethoxycthylacetate (CeUoeolve acetate) - Skin Ethyl acetate Ethyl acrylate -- Skin Ethyl alcohol (ethanol) 3 too 100 400 25 1,000 F.thyiominc 10 Ethyl sec-amyl ketone (S~methyl*3heptanone) Ethyl benzene Ethyl bromide Ethyl butyl ketone (3-Heptanon*) Ethyl chloride 25 too 200 50 1,000 Ethyl ether F.thyl t'nrmrite Ethyl .ncrcaptan Etliyt silicate 400 100 O.t. 100 Ethylene Ethylene cuic.runydrin -- Skin ? 5 Ethy.cncuiamine SO Ethylene dibrnmide. see 1, 2-Dioromoethane - Ethylene otcr.toridc, see l, 2-Dichlorocthanc - C Ethylene piycol jjmtraie tnd/oc Nitroglycerin - Skin , A. 0.2tf/ , Ethylene glycol monomethyl 4th#f , ' acetate (Methyl celloeobre acetate) -- Skin 4 Ethylene glycol, particulate 4 Ethylene glycol, vapor Ethylene imlne -- Skin Ethylene oxide 25 - too O.S* so Ethylidine chloride, tea 1 1 Dlchtoroethane N-Ethylmorpholine -- Skin Ferbem Ferrovanadtum dnat - 20 - - , Fhaorlde (aa F) - 75 50 4 860 2.8 1 50 20 35 s A* - 25 - 30 1 5 (5) 1 0.2 1.5 360 I 10 - 600 0.5 5 E 0.1 0.1 19 O.S -- 6 370 540 1.400 1 00 1.900 18 130 435 390 230 2.600 2,200 300 use 16 25 -- - - 120 10 260 1 90 94 10 1 2.5 C ' A***! 1978/OCCUPATIONAL HAZARDS IS .-.hIi- ;men ppni' 1 lo.'fiiu 1 1<<< >rM tnc lil nrnmethene 1 orrn ihlgliyile l oimic acid rmfnt.il -- Skin Furfur's 1 alcohol (osnhil r tivrin Miinm tryahyilrlde (Germane) C.l i'-N. fibrous'' ik dust t;hviin mist (dvcidni (2. t l poxy-t-propanol) Ctvcol monocthyl ether, aaa ? 1 thoxycthanol Graphite (Synthetic) (hithinn *, see Atinphosmethyt Gypsum 1 lafninm Helium lli'pfithtor -- Skin Hepbrne (n-hcplane) Mcx.udiliKocthanc -- Skin 1 Ifs.u Idoroiinphihalene - Skin Mix.iflimfoaci'tonc 1 iw.un* (n-hcxanc) 2-lh-sanonc Hrv-ne (Methyl isobutyl kOtOM) mt I li xy] acetate Mvdr.i/inc - Skin 11\ ilmpcn Hydrogen bromide 11 \drorrn chloride llvdror.en cyanide -- Skill 11 > .iro ten fluoride Hydrogen peroxide ' ,. Hydrogen sdcn.de hydrogen sulfide 1 ivdrot, u.nonc * 1 l<ooo 1 5 5 (50) 0.2 SO --. --' -- -- -- F -- 500 I - 0.1 500 100 100 so 1 F 3 5 10 3 1 0.05 10 -- j 5.000 3 9 20 nooi 0.0 E E ISO - E -- 1E 0.5 - 0.5 2,000 10 0.2 0.2 1,800 410 410 200 1.2 - 10 7 11 a 1.4 0.2 IS 3 indent Indium ana compounds, M Ift Iodine Iron oxide iumc Iton pcntacarhonyl f.. . Iron xilt^. soluble, as Fa hoamyl acetate Isoamyl alcohol Isobutyl acetate Isobutyl alcohol Isophor one - 10 - 0.1 -- 0.01 - 100 . 100 150 ' 100 - 45 0.1 1 10 0.0S 1 525 360 700 300 - Isopropyl acetate 250 950 Isopropyl alcohol Isorropylamlne Isopropylcther Isopropyl glyctdyl ether (IGE) Kaolin Ketone Lc.iJ. inorganic compounds fumes & dusts Le.id arsenate 400 s 250 SO -- 0.1 980 12 1,050 240 E 0.9 0.1S O.IS Limestone Lindane Lithium hydride E 0.5 0.025 L. P.G. (Liquefied petroleum fit) Magnesite Magnesium oxide fume Mnuthion -- Skin M. dcic anhydride Ni^n^new and compounds, i| 5 Marbic Mercury (Alkyl compounds) - Skin, C.01 Mercury (All forms except alkyl) 'o.oi Mrsitvl oxide 25 loo Mclhanc Mctn.incthiol, see Methyl marcapun F - Met. ( xvc.do; - 10 I-i.'i ii.o\yctb:.noi - Skin ',vV\VMc:(pw!y,*_), Methyl acetate Methyl acetylene (propyne) Methyl acctylene-propsdient miltore (MA IT) Methyl acrylate - Skin ' Met hylncryloniirile - Skin Mcthyhi (dlmcthoxymethsna) ' Methyl alcohol (methanol) Melhylxmine Methyl amyl alcohol, in Methyl . 35 200 1,000 1,000 JO .1 1,000 200 10 ttO bio 1,650 1,800 35 3 2,100 260 12 Isobutyl carblnol Methyl 2<yanoacrytete Methyl Itoemyl ketone 21 100 475 . . 1 Sulutnnen ppm-^1 Methyl (n-amyl) kt tone (Mlipiannne) 100 463 Methyl bromide -- Skin IS 40 Mrlhyl butyl ketone, tea 2-llrx.inonc -- --, Methyl cellmoive - Skin sea * } Mrllmx yethanol -- Methyl cctlosidve acetata -- Skin, aaa ! lltylrnr elycol monomethy1 / her nrvl.-f- --t - }' -yl fi 1 00 210 f vl chloroform i'0 1,900 f vlcyilc.nexane 500 2.000 T vie yilnhcxnnol 30 2 1$ . thylcyrlohcianone - ' so 2 50 r tcyclopcntndirnyt " -rse 1 arhtmyl (ns Mn) ' ' * .1 drmrtnn -- Skln 0.1 0.2 -- 0.5 1 \ 1 ethyl ketone (Ml K' r 2-Butanone - Mi I' %' formate too 250 Mr II vl iodide -- Skin 5 28 Methyl ixnhuty! carblnol -- Skin 25 100 Methyl isohntyl ketone, see Hcaona - * Methyl isocymutc -- Skin Methyl mercaptan Methyl methacrylate Methyl parathion -- Skin 0.02 0.5 too -- O.05 1 410 0.2 Methyl propyl ketone, see 2*Pentanone -- - C Methyl silicate 5 .50 C a Methyl styrene 100 480 C Methylene hisphcnyl isocyanate (MD1) 0.02 0.2 Mctliylenc chloride (dlchloromethane) (sno) (lf740) Molybdenum (soluble compounds) % 5 (insoluble compounds) - 10 Monomethyl anlllna -- Skin 29 C Monomethy! hydrasina -- Skin 0.2 0.35 Morpholine - Skin 20 70 . Naphtha (coal tar) 100 400 Naphthalene 0Nephthy)amine 10 - > Neon Nickel carbonyl F 0.001 <(Ald)0.007 Substance Nickel, metal and soluble compounds (as Ni) Nicotine - Skin Nitric acid Nitric oxide ' p-Nilroanilinc - Skin Nitrobenzene - Skin p-Nitrochiorobcntene -- Sldn 4-Nitrodiphcnyl A.`methane Ndrogen C Nitrogen dioxide Nitrogen trifluoride Nitroglycerin - Skin Nifromcthanc i*N.:.v: propane 2-i'-s:roproi N-Nitrosodi lamina (dimethv i'-^' 'oamina) -- Skin Nitfwr.-ducnc - Skin Nitrr`;;chlnrnmethana,uoa C'hloropicrin Nitrous oxide Cctschloronaphthalanu -- Skin Ocir.nc Gii mist, particulate . , Oil mist, vapor Osmium tetroxide Oxalic arid Oxygen difluorida Oianr Paraquat -- Skin Parathion - Skin Perlite Pentaborane Pentachloronaphthalana - Skin , Pentachlorophenol - Skin Pcntaerythrltol Pentane 2'Pentanone Parchloroct h ylena Perehloromefhyt mercaptan Perehloty! fluoride ppm*^ m - 2 25 1 1 - 100 I 5 10 0.2 100 25 25 i 0.5 5 30 6 5 A1* 310 9 29 -> 250 90 90 - A' S 30 F - 400 - 0.1 ,900 , 'V - o.OM -; 0.05 0.1 0.1 0.2 - 0.5 - 0.. , - mppcf 50 0.005 0.01 - 0.5 - 0.5 - 500 3,500 300 700 too >370 o.s 0.6 3 14 D Sllilvt.liVIt IVindmni t >t^ till.tics, (naphtha) >n* _ 1*hrni1 Skin T Phynvlem- diamine - Skin I'lu nt 1 cther I'ln tn 1 rthrr-Diphcnvl mixture fHpQ) Hu m Irthylrnr, see Styrene s -- i i, 19 0.1 7 7 l'tu n\l givcidvl ether (PGE) I'linu I1\ ilmrinr -- Skin . C riirn\lp>nphine 1 licn.Mhn/inf - Skin . * rhi'vdtm (Mcvinphnx*) -- Skin . riio^cv nc (carbonyl chloride) t'hoxpbmr '* . ritixphnric arid < * .. ' I'hotphortts (vellow) rhotphi'inn pnttarhlnrlde rhi'<|'horiu (vnlaMilfida Phosphorus trichloride Phih.ihc anhydride Fierik a*id - Skin Po.u* (M'lvaiyM, Jdndandlone) Plavli-r of Paris I'htmimi (SohiMe Sells) aa Ft Pol \ v idorohiphenylt, see ip s 0.01 _ ' 0.1 0.2 -- 0.1 2 _ '- 60 22 1 0.21 'S ' 0.1 : o.4 0.4 1 0.1 1 I 2 12 0.1 0.2 E 0.002 CMprodiphrnyJt -- ., __ Pol* trtrnnuoroethyient decomposition products - B1 Tr^iMnc 3 Propiol.vtonc F __ A* Prop ircvl alconol -- Skin 1 n*Propv| acetate rropyl alcohol n-P'-pv| nitrate Prop*lone dichloride (1, 2- 200 200 25 , 840 soo no Pirhtoroprnpane) * lYopyirnc glycol monomethyl ether Prop* lent imine -- Skin Prop* lone oxide Prop* nc, see Methylacetylene Pyrct hrum Pvndinc 75 100 2 100 .- _ i s ,. 250 260 5 240 5 IS Qumonc . 0.1 0.4 RPX - Skin 1.5 Rhodium, Metal fume and dusts(as Rh) Soluble salts Konncl 0.1 -- 0.001 _ 10 9 Rosin Core Solder, pyrolysis produete (a< formaldehyde) Roicnone (commercial) Roug: . _ - 0.1 5 E Selenium compounds (as Se) -. 0.2 Selenium hexafluoride * 0,02 0.4 Silicon Silicon carbide Silver, metal and soluble compounds j- 10 E 0.01 Sodium fluoroscetate (1060) - Skftu 9 Sodium hydroxide Starch !1 'k '' -- 0.0 S 2 E Stihin.' 0.! 0.2 Sluildarci solvent Strychnine Styrene (Monomer) (Fhanytathylsna) 200 _ too 1,1 SO 0.12 420 2 Suhtiii^ns (Proteolytle aniymao n-* 100% pure crystalHnu . iT/ymC; oncrosc 0.0002 --E Sulfur Jio Aide 5 12 sulfur hexafluoride Sulfuric ,,cm &000 -- 6,000 i Sulfur monocmoriat Sulfur pcnfafluoride Sulfur tetrafiuoride 1 0.022. 0.1 6 0.22 0.4 Sulfury! fiuoriae S 20 Systox, see Demeton* 2, , 5 7 Tantalum _ 10 5 TEDP-Skin Tenon decomposition products Tellurium 11 * _ . 0,2 B1 0.1 Tellurium hexafluoride TEPP - Skin Terphenyls 1,1, l, 2-Tetractdor<v2, ' , '' .` 0.02 _. 1; i ** 0.2 0.02 9; i 2-dlfluoroethane fi, 1, 2. 2-Tetrachioeo-l, 2-dlflworoethene It l 2, 2-TtncMoretlhaM - 9kto . ' ' . 200 . . 200 11 '' 4,170 4,1 to! ` 21 : Stilnlaitr.a Tctraclilornrlliylcne, eee IVrcldon .ethylene Teirachlnroiticthane, see Carbon Iclracltloridi- Trlrachlornn.iphlhalcne -- Skin - Tetraethyl lead (as l*h) - Skin - Telr.iliyclrnfurnn . Tclr.imrlliyl lead (as Ph) - Skin 200 -- Tetramcthyl surcinnnltrllc - Skin 0.2 Tctranilromethanc 1 Tctryl (2, 4, 6-lrtnitrophenyf* mrihylnitramine) - Skin -- Thallium (soluble compounds) --Skin (as Tl) Tliirain* _ Tin (inorganic compounds, except Soil and SnOl) aa Sn _ Tin (organic compounds) - SUn (as Sn) Tin oxide Titanium dioxide _ -- Toluene 100 Toincnc-2,4-diixocyanate 0.02 o-Toluilic s Toxaphcne, see Chlorinated camphcoe . ' - Tributyl phmphale -- 1, I, l-Tnchlornctbana,aee Methyl chloroform _ 1, t, 2-Trichioroethanc -- Skin 10 Trichloroethylene Trichioromrthane, see Chloroform , 100 - Trichloronaphthalcne -- Skin -- 1, 2. 3-Trichlnropropane so 1,1, 2-Trichloro 1, 2, 2-trifluoroethanc 1,000 Tricthyhminc 25 Trifluoromonobromomathana ,000 Trimethyt benzene 25 2, 4, 6-Trinitrophenol, tea Picric acid 2, 4, 6 TrinitrophcnylmathyinKramina, sec Tctryl Trinitrotoluene -- Skin \ . .. x -- Trinrthocrcsyl phosphate - -- Triphcnyl phosphate -- Tungsten A compounds, as W Soluble _ Insoluble - Turpentine 100 Uranium (natural) solubls 4 InsoluMa compounds, as U _ Vanadium (VgOg), as V Dust lumc _ - Vinyl acetate 10 Vinyl benzene, see Styrena - Vinyl bromide 250 Vinyl chloride Vinyicyanide, aee Acrylonitrile 200 -- Vinyl toluene Warfarin 100 - Wood dust (nonallar|enic) - Xylene (xylol) too Xylidtno -- Skin a Yttrium Zinc chloride fume -- -- Zinc oxide fume -- Zirconium compounds (as Zr) - 0.100^ 5,0 AJ 0.120*' 2 6 1.2 0.1 5 2 0.1 i: E 375 0.14 22 5 _ 45 535 5 300 7,600 too 4,, 0C 120 _ _ 1.5 0.1 3 1 S 560 0.2 0.5 0.02 30 - 1,100 770 460 0.1 5 435 9 i . NOTES Capital letters refer to appended 1972 Addition See notice of intended changes ** 1973 Addition a) Parts of vapgr or gas per million parts 01 contaminated dir by volume at 25 C and 760 mm. Hg. pressure. b) Approximate milligrams of substance per cuoic meter of air. d) An atmospheric concentration of not more than 0.02 ppm, or personal protection may be necessary to avoid headache. e) <5-7pm in diameter. f) As sampled by method that does not collect vapor. g) According to analytically determined composition. h) For control of general room afc, biologic monitoring Is essential for peraonnel control. Radtotctivtfy: For permissible concentrations of radioisotopes ir. Ir, # U.S. Deportment of Commerce, National Bureau of Stan* dardi Handbook *9, "Maximum Farmlaalble Body Burdins and e l\ riui'Mhli' Cooerntf.-ititMt* of Itadmituelidr* in Air ami In k' Mit Cm (>iipnfl'iul I xposwc," June 5*. Also, ate U.S. IVlMrlmml of I'ommrrn', Nilinnal llttrrau of Standard*, Hand* K>oW 5. `TrrtiiluiWr Dnc from Internal Srnirm of Ionizing Kadi* Minn," September 14. 1*M, and addendum of April IS, 1958. A rerurt. Rule Radiation Protection Criteria, published by (be Nation* il Committee on Radiation Protection, revise* and utndrrnlzea tha fpBicpl of tbe NCRT standard* of 1934, 1957 and 1951; obtainable is NOtr Rrpt. No. 39, P.O. Don 4117, Waablnfton, D.C. 30001. MINERAL DUSTS obtlance Ntp.p.e.f.0 IILICA Cfbtoballte, QryitalMiie Amorphous, Including netwftl dlatoinaeeout earth aart* Uae one-half tha value calculated from tha count or meat formulae for quartz. 20 TLV In n^pcf: i \ % quartz + |0 TLV for rc*pirable duet !* mg/m`\ to mr/m3kf % Kcspirahlc quart* 4 2* lea. (used idymite .iCATES (K. j % quartz) TLV for "total dost,* respirable and nonrespirable: 30 mx/m3 quarts 3 Use quarts formulae, Uae ona-half tha value calculated from formulae for quarts. * Asbestos, alt types Mica Perlite Portland Cement Soap*tone Tale (non-asbestiform) Talc (fibrous) use asbestos limit Trcmolitc (see Talc, fibrous) Graphite (natural) 20 30 30 20 20 -- -- 15 iee Notice of Intended Changes for Mineral Dusts. J1SANCE PARTICULATES t Appendix E) 30 m.p.p.c.f. or 10 rng/m3 of total dust <Tl% quart* tha "Adapted" list. Documentation Is available for each of thec Ubituncr*. Substance mg/M1^ flnyrnn _ a Caprolactam (2-OxohaxaqethrtenJmtne) Dust -- Vapor Carhnfiiran -- Shin Carbon tetrahromide Cesium hydroxide t'alrcliol ChlorodifturKomcthane 5 - 0.1 -- *1 1,000 4 bivChlnromethyl ether .-- 4 Chlnr<melhyl ether ('hlompyrifo* (Dursben*) -- Bkhl -- -- 4 o-C'hlorotoliicne o-Cblornst yrene Clopidol (Coplrn*) 2(lil>ro-6-(tricltloromethyl) 30 30 -- pyridine (N-,Serve*) Crufomatc (Ituclene*) -- - 4 Cotton dust, raw -- 4 Cyclolicxylamine Oicycloprntndicnyl Iron Diethyl phthalate 10 - -- 3,5-Diiutrrvo.toluamlde (Eoslane) - 4 Dimethyl sulfate -- Skin 4 Dioxanc -- Skin 4 Disyston -- Skin ' . -- so -- 4 Efhylidcnc norbornene Porntamide 0.2 -- Furfuryl alcohol * s 4 Hcxachlorocyclopcntsdicne .0.01 Isophoronc >V 10 4 Manganese cyclopentadienyl trtearHon y| (as Mn) -- Skin --. 4-4'-Mcthylene bis (2*chloroanlllna) - Skin 0.02 4C Methylene bis (4*cycJohexy)efie isocyanate) 0.01 4 Methylene chloride (DichloroflMthane) Mcthylcthyl ketone peroxide ^ Mineral wool Tiber 1 ' '' 230 C 0.2 -- 4 Phorate (Thimet) -- Skin -- Picioram (Tordon*) - Potassium hydroxide - 4 Silicon tetrahydride (Silane) Tricyclohexyl tin hydroxide o.s (Pliclrsn*) Vinylidene chloride -- 10 4 Zinc stearate -- 0.5 1 25 0.03 1.4 2 4.5 1.300 a; Atb 0.2 -- 383 10 . 10 05 .2m'. 40 10 s 5 A2 0.1 0.6 20 20 0.1 55 0.B A2 0.11 390 1.5 E 0.05 10 C2 0.7 5 40 E NOTES inversion factors >pcf X 35.3 * million particle* per cubic meter = particles per c-c. Millions of particles per cubic foot of sir, based on impinger samples counted by light-field technic*. The percentage of quartz in the formula is the amount deter* mined from airborne umples, except in those instances In which other methods have been shown to be applicable. Both concentration and percent quarts for tha application of this limit arc to be determined flrom tha fraction gaming a alia* selector with tha follou4A0 characteristics: Aerooynamic Diameter (Jim) (unit density sphere) <2 2.5 3.5 5.0 iC , % passing selector 90 75 50 25 . 0 containing <J% quartz; if quartz content > 1%, use formulae for quarts. NOTICE OF INTENDED CHANGES (for 1973) These substances, with their corresponding values, comprise se for which either a limit has been proposed for tha first time, Tor which a change in the ''Adopted" listing has bean proposed, both cases, the proposed limits should be considered trial limits t wilt remain In tbe listing for t period of at least two years. !f, tt two years no avtdanca comas to light that questIons the appro* ittfiees of the values herein', tha valuta MB be rteontldered for a) Part* of vapor or gas per million parts of contaminated air by volume at 25C and 760 mm. Hg. pressure. b) Approximate milligrams of particulate per cubic meter of air. m) Lint free dust a* measured by the verticaLelutriator, cotton-dust sampler described in the Transactions of the National Conference on Cotton Dust. J.R. Lynch, pg. 33, May 20, 1970. Capital letters refer to Appendices. 4 1972 Revision or Addition * 1973 Revision or Addition CHANGES IN ADOPTED VALUES TENTATIVE LISTINGS All changes that are recommended are based or. ^ocui.ientec, evidence which bavtOable from the chairman. Substance Cadmium oxioe fumv Carbon dioxide bisChloroethyl ether Copper fume Iron Oxide fume Paraffin wax fume Sodium hydroxide Froni To 0.2 .:./n3 C D.05 m:/m- Doci .iciUition to permit T1A o: 2.',000 ppm provided cer.nir. sti; dated me dieit criteria are .vu . C 15 ppm 5 pp.T. # 0.1 mg/m5 0.2 mg/m* 10 mg/m3 1 mg/m3 2 mg/m3 5 mg/m5 2 mg/m3 C 2 mg/ms NOTICE OF INTENDED CHANGES MINERAL DUSTS Sqpatsnoa TLV Aibeetoc (Altypto) I F 5 fiberIn length") A**  n ll.'iir _ Pl* I!*' respirable mass formula for i|ii.vt/. Use respirable mass formula few quartz. i determined hy the membrane filter method il 400*450 X Rgnlfie.itlnn (4 mm <h)rrflvr) phase contract llumlnatloit. mccntrAttnns S fihmfml Hut not to exceed 10, may be rmlttcd for IS-mlmiit perloth reck hour up to Art Uaw My. 3 Itevnlon m Addition NOTICE OF INTENDED CHANGES APPENDIX A f . ' 1 Carcinogens i Committer lists below those Mihxtimrrt in industrial use that coven carcinogenic in man nr have induced cancer In animate experimental conditions. Present listing of those substances genie for man fakes two forms, those for which a TLV has "irrwJ (la), and those for which environmental conditions M hern sufficiently defined to assign a TLV (lb). mm Carcinogens - Substances known to be occupational tnnprns with an assigned TLV: Asbestos, 5 flberafec^S/im In th. certain insoluble chromates, 0.1 mg/ni3;Coal ter pitch itilcs. :oo pph; Nickel carbonyt, | ppb. , mm Carcinogens - Subttances known to be occupational innpens without an assigned TLV: miMmhphonyl .'uhne & its salts 'hlorometltyl ether womethyl ether Naphthyhminc trojjplienyt ] I , 1 \c sulvsi.incci in I o, no exposure or contact by any route, >ry. skm or oral.as detected by the most sensitive methods, permitted. "No exposure contact** meanshermitizing the nr operation by the best practicable engineering methods, u-ctme the worker by proper equipment that will insure no contact or entry of the earelnogen by any route. hmrntai Carcinogens -Industrialsubataneaa foundto be nch potency in inducing tumor* under experimental inons III animals: , ' ; . 'tyiaciinofUiorenc hclilorobcnzidioc >clhytaminoazobenzene t hy I sulfate cninune icthjlcnc bis (2-Chloroanlllne) rosodinicrbylamine 'ropiolactone I , f . : above, worker exposure by all routes should be reduced imum in light of the warning of the potency of these & to induce tumors in animals. "Reduced to a minimum** traordinary care shall be taken both In manufacture and in so that worker exposure by all routes It kept to an ? minimum. I APPENDIX B 'Trafluoroctnyicnc* Decomposition products. Thermal lpoviiton of the fluorocarbon chain in air leads to the :;on of oxidi/cd pr:iuuc.s containing carbon, fluorine and n. liLjausc ihcw proouc:s decompose in part by hydro. -.Ualine solution, they can be quantitatively determined ,c. fluoride io provide an index of exposure. No TLV rr.cndeo pending ocicemination of the toxicity of the but r.ir conccn,rations should be minimal. >ii and/or Petroleum Distillates. The composition of these ais vanes jrcaily :.nd thus a single TLV for all types of naunan is /.c* Jonjv: applicable, in general, the aromatic aroon content win determine what TLV applies. Conse* i the content of benzene, other aromatics and additives be determined to arrive at the appropriate TLV (EUttat, I.H.A.J. U- 99. 1963). . nea: Algoflort, FJuon, Halon, Teflon, Tetran ' . ' .. APPENDIX C HOLD LIMIT VALUES FOR MIXTURES 'o or more hazardous substances are present, their com* t, rather than that of either Individually, should be given nslderatlon. tn the absence of information to the con* iffacls of the different hazards should be consider*d as set la. If the turn of tha foliowin3 fractions, exceeds unity, then the threshold limit of (he minor' shr.ni'l he considered as heinr exceeded, fj indicates the Mtvrvrrl atm', ^ le concentration, anil T| the cnrrrsp'indiHtt threshold limit (' -r Example I A *, and lA.c.). Exception* to the shove rule may be made when there is r""d reason to believe that the chief effects of the different harmful substance* ars not In fact additive, but Independent as when purely local effects on different organs of thr body .ire produced hy the various components of the mixture. In such cases the threshold limit ordinarily Is exceeded only when at least one member of the aeries Itself has a value exceeding unity (See Example t A c.). Antagonistic action or potentiation may occur with some combi nations of atmospheric contaminants. Such e.v :,t prrvni rrm-i be determined individually. Potentiating or -.tntaponi'.or t ,,k .->t necessarily harmful by themselves. Potentiating eff- us or i.-xpo'ure to such agents by routes other than that of inhalation is at <> po > Ible, c.g. imbibed alcohol and inhaled narcotic ftnchloroct ykri'.). Potentiation is characteristically exhibited at hiyh concentrations, less probably at low. When a given operation or process characteristically emus num ber of harmful dusts, fumes, vapors or gases, it will frc'ii.or.n* 1 c only feasible to attempt to evaluate the hazard by mcasurtnvvi! or a single substance. In such eases, the threshold limit used for tmj substance should be reduced by a suitable factor, the magnitude of which will depend on the number, toxicity and relative quantity of the other contaminants ordinarily present. Examples of processes which are typically associated witn two or more harmful atmospheric contaminants are welding, automobile repair, Nesting, painting, lacquering, certain foundry operations, diesel exhausts, etc. (Example 2 in iA.a.). THRESHOLD LIMIT VALUES FOR MIXTURES EXAMPLES General ease, where air is analyzed for each component: t, Additive effects. (Note: It Is essential that the atmosphere be analyzed both qualitatively and quantitatively for each component present, in order to evaluate compliance or ooneompiitnce with this calculated TLV.) Cy Cj Example No, I! Air contains 5 ppm of carbon tetrachloride (TLV = 10 ppm) 20 ppm of ethylene dichloride (TLV * 50 ppm) and 10 ppm of ethylene dibromide (TLV * 25 ppm) Atmospheric concentration of mixture * 5 20 10 = 35 ppm of mixture S 20 10 2S 20 20 j0+ SO* 25 * 50 Threshold Limit is exceeded. Furthermore, the TLV of this mixture may be calculated by reducing . Che total fraction to l.OU.c. 35 j TLV of mixture - -21 ppm Example No. 2: Air contains 200 ppm of hcxar.c (TLV ~ 500 ppm/ 100 ppm of methylene ch,orii.c (TLV - s>00 ppm) wno 20 ppm of perehlorocthyicnc 'TLV * iGG ppm) Atmospheric concentration of mix.ure * 200 j 100 * 20 * 320 ppm of mixiu.ir 200 >00 20 300-* 100*100 -00 500 * 500 *100 ' 500 = 500 ' ^ Threshold Limit is not exceeded. The TLV of this mixture 320 0,8 s 400 ppm lAb* Special case when the source of contaminant is a liquid mix ' lure and the atmospheric composition is assumed to be simi lar to that of the original material; e.g. on a time weighted average exposure basis, alt of the liquid (solvenl) mixture eventually evaporate*. Additive effectt (approximate solution) I, The percent composition (by weight) of the liquid mix , ture la known, the TLVe of the constituent* must be JU* ted In mg/m*. . i, I', r ft, 4 ,.i/t,,it, , iiih/iH.ihh' uith this ft, V, field Avtiphttg imtnimcnts aluml,/ hr calibrated, tn ihr lahtaeatory, * for rrspontr to this specific qiumffMrtw and qualitative mpnr mixture, amt atm to fractional concentrations of this mlstury, r.tt.,1/2 the 77. V; tftO the TL V; 2 X the 71*7/0 X the TLV: etc.) LV f mltivn - I temple No. I: Liquid mhrnl rnntilM (by weight) $0% hptM (TLV * 1000 mg/m*K30% methylene chloride (TLV a 1140 mg/w3) 10% irelikirM(liyliM (TLV * 070 mg/m*) LV of mixture 0< 0.3 0,1 * 2000 * 1740* *?0 1 >0025 .00017 .0003 * .00072* I J90 mg/m3 this mixture: $0% or 69$ mg/m3 Is heptane, 30%Or 417 mg/m* h methylene chloride end 20% or 171 %/>* % perchlorocthylcne ese values can be converted to ppm si follow k, >ttne - 2000 mg/m3 = $00 ppm I mg/m3 0.25 ppm 69$ mg/m3 * 174 ppm > :hylen* chloride 1740 mp/m3 * 500 ppm I mp/m3 * 0.287 ppm 417 mg/m3 * 119 ppm :hioroe(hyiene 670 mg/m3 * 100 ppm I mg/m3 * 0.1$ ppm 27R mp/m3 42 ppm TLV of this mixture = 174 119 42 * 33$ ppm. L Independent effects. Air contains 0.1S mg/m3 of lead (TLV,0.2) end 0.7 mg/m* of sulfuric acid (TLV.j), 0.1$ 0.7 0.20s 0,7$; | 0.7 Threshold limit is not exceeded. General Exact Solution for Mixtures of N CompMMrta With Additive Effects and Different Vapor he----as. (1) C, Cj ... c* *7; ' By the Law of Partial Pressures, 1C, = *P|, ar.d oy Rnojit'a Law. rp; = Fi*1i6 Comh.nc (3) sob (4) to obtain *C; =..FlP;. CoiTioinir.^: ; 1), (2,1) and (5), we obtain f.P: .'7P20 UP* 1 and solving for 7. ,)T-F>pb*r>C,,T r--' r,P, i pi* 1*1 z()T rrrrr ieL t- / T -- ThrnlmM l.iimf in ppm. C - V|vr rmicciitr;itiin mi ppm. p -- Vapor pressure of i iinipiin'-tii in viluliitn. p -- VsjMir prc'.siire of pure component. F -- Mol fraction of component in solution, a - A constant of proportionality. Subscripts I, 2,... ft relate the above quantities to compo* nents I, 2,... n, respectively. Subscript I refers to an arbitrary component from 1 to n. Absence of subscript relates the quantity to the mixture. 1B.b* Solution tn be applied when there Is a reservoir of the solvent mixture whose composition does not change appreciably by evaporation*' Bxoet Arithmetic Solution of Specific Mixture Solvent Triehloro* cthylene(l) MoL wt. 131.4 Density TLV P\ 25*C Mr.l fr.11 *!.: m h.iir.md- hair solution by volume 1.46 g/ml too 73mm Hg 0.527 Methylchloro form (2) 133.42 1.33 c/ml 350 125mm Hg 0.473 FjP, *(0.527) (73)* 38.2 Fj pj= (0.473)(I25)* 59.2 38.2 $9.2 (97.4) (350) TLV *38.2 -$9.2 * * 100 * 350 (97.4) (350) --mu-- 177 TLV 177 ppm (Note difference in TLV when account is taken of vapor pressure and mol fraction In comparison with the pbova sample where euch account is not taken.) 1. A mixture of one part of (I) purthioa (TLV, 0.1) and two parts of (2) EFN (TLV, 0.3). Cm * 3C, -Tm *-"L7^I* 0.21 mg/m,3 1C TLV for Mixtures of Mineral Dusts. For mixtures of biologically active mineral dusts the general I formula for mixtures may be used. For a mixture containing 80% talc and 20% quarts, the TLV ' for 100% of the mixture is given by: TLV -Q.d \\T~ * 3.4 mppcf 2C *2.5 Essentially the same result will be obtained if the tir.u: of the more (most) toxie component is used provided the effects are additive, in the above example the limit for 20% quarts is 10 mppcf. . ror another mixture of 25% quarts, 25% morphou siiici and $0% talc: TLV * 0 35 0)as 0,5 * 7.3 mppcf 2.5 * 20 * 20 The limit for 25% quartz approximates 8 mppcf. APPENDIX D PERMISSIBLE EXCURSIONS FOR TIMEWEIGHTED AVERAGE (TWA) LIMITS The Excursion TLV Factor In the Table automatically defines the magnitude of the permissible excursion above the limit for those uhetancto not given a "CM designation; La. tha TWA limits. Exam* pU's in the Table show Ihul nitrobenzene, (hr TI.V fu which h I ppnt, nhnuM never he allowed In rivrnl .1 ppm. Similarly, carbon tetrachloride, TLV |0 ppm, should never he allowed to exceed 20 ppm. fly contrast, those substances with "CH designation are not subject to the excursion factor and must be kept below the TLV. These limiting excursions are to be considered lo provide a "ruleof-thumb" guidance for Hsied substances generally, and may not provide the most appropriate excuralon for a particular substance. Efforts art being made to develop such specific excursions, when Indicated to be elgnlftcantly different from that focommended bp the present excursion factors* Substance TLV Excursion factor . Max. Cone Permitted for short time Nitro benzene Carbon tetra chloride o-Oirhlorobenzene Acetone Boron Trifluoride Dutytamlne Styrene monomer 1 ... 10 SO 1000 Cl CS CI00 9 2 1.5 1.35 ~ - 9 20 75 1350 J 5 100 For all substances: Excursion TLV >0-1 (ppm or mg/m3), Factor * 3 TLV >1-10 " *2 TLV >10-100 " TLV >100-1000" M *1.5 " *1.25 BASIS FOR ASSIGNING LIMITING "C" VALUES By definition in the Preface, a listed value bearing a "C" designation refers to a "ceiling** value that should not be exceeded; all values should fluctuate below the listed value. This, in effect, makes the **CH designation a maximal allowable concentration (MAC). In general, the bases for assigning or not assigning a "C" value rest on whether excursions of concentration above a proposed limit for period* up to IS minutes mty result In ) Intolerable Irritation, b) chronic, or Irreversible tissue change, or c) narcoels of sufficient degree to Increase accident pronaneaa, Impair self reaeua or materially reduce work efficiency. APPENDIX E Soroo Nubanco PvtkulitM qj Alundum (Al303) Calcium carbonate Cellulose (paper fiber) Portland Cement Corundum (AijOj) Emery Class, flbrousr^ or duet Glycerin Mist Graphite (synthetic) Gypsum Vegetable oil misu (except castor, cashew nut, or similar Irritant oils) Kaolin Limestone Magnesite Marble Pentaerythritoi Plaster of Paris Rouge , Silicon Carbide Starch Sucrose Tin Oxide Titanium Dioxide q) When toxic impurities art not pressm, .g. quarts <1% r) < S-7JMI In diameter I APPENDIX F Some Simple Asphyxiant* - "Inert" Gases and Vapors^ Acetylene Argon Butane Ethane Ethylene Hydrogen Methane Neon . Nitrogen Nitrous Oxide ) As defined under simple asphyxiants, in preface.