Document oD6B99e80K8VQMe6KG4bRQLag

38--Industrial Toxicology 1194 TABLE 38-E THRESHOLD LIMIT VALUES FOR CHEMICAL SUBSTANCES IN WORKROOM AIR, 1973 (Continued) NOTICE OF INTENDED CHANGES (Cont'd) vironmental conditions have not been suf ficiently defined to assign a TLV (lb) la Human Carcinogens--Substances rec ognized as occupational carcinogens with an assigned TLV Asbestos, all forms, 5 fibers/cc > 5pm in length bis (Chloromethyl) ether, 1 ppb Chromates, certain insoluble forms, lCMVg/m3 Coal tar pitch volatiles 200/*g/m8 Nickel carbonyl, 1 ppb lb Human Carctnogens -- Substances known to be potent occupational car cinogens without an assigned TLV. 4-Aminodiphenyl (p-Xenylamine) Benzidine and its salts beta-Naphthylamine 4-Nitrodiphenyl For the substances m lb, no exposure or contact by any route, respiratory, skin or oral, as detected by the most sensitive methods, shall be permitted "No ex posure or contact" means hermitizing the process or operation by the best practica ble engineering methods, and protecting the worker by proper equipment that will insure virtually no contact or entry of the carcinogen by any route 2 Experimental Carcinogens-- Industrial substances found to be of high potency m inducing tumors under experimental conditions in animals Beryllium Chloromethyl methyl ether 3, 3'-Dich!orobenzidine Dimethyl sulfate Ethylenimine 4, 4'-Methylene bis (2-chloroanilme) N-Nitrosodimethylamine beta-Propiolactone For the above compounds, worker ex posure by alt routes should be reduced to a minimum in light of the warning of the potency of these substances to induce tumors in animals "Reduced to a mini mum" means extraordinary care shall be taken both in manufacture and in handling so that worker exposure by all routes is kept below the limit of sensitivity of the analytic method of determining the ex posure concentration Appendix B B1 Polytetrofluoroethylene0 decomposition products. Thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxy gen Because these products decom pose in part by hydrolysis m alkaline solution, they can be quantitatively determined in air as fluoride to pro vide an index of exposure No TLV is recommended pending determina- Trade names Algoflon, Fluon, Halon, Teflon, Tetran tion of the toxicity of the products, but air concentrations should be kept below the limit of sensitivity of the analytic method B2 Caroline and/or petroleum dietiUatee. The composition of these materials vanes greatly and thus a single TLV for all types of these matenals is no longer applicable In general, the aromatic hydrocarbon content will de termine what TLV applies Conse quently the content of benzene, other aromatics and additives should be de termined to arnve at the appropriate TLV (Elkins, et al AIHA J 24 99, 1963) Appendix C B 1 THRESHOLD LIMIT VALUES FOR MIXTURES When two or more hazardous sub stances are present, their combined effect, rather than that of either individually, should be given primary consideration In the absence of information to the con trary, the effects of the different hazards should be considered as additive That is, if the sum of the following fractions. exceeds unity, then the threshold limit of the mixture should be considered as being exceeded C, indicates the observed at mospheric concentration, and Ti the cor responding threshold limit (See Example 1A a and 1A c )