Document mgyZbrzZLooqQLvOQzgp2qnJ

27470 PROPOSED RULES i tlons of the extent of exposures, (4) an inadequate follow-up of annuitant# and (6) incomplete occupational histories on individuals diagnosed as having leuke mia. Infante et al recently reported the results of an ongoing epidemiologic study among workers exposed to benzene dur ing the manufacture of Pliofilm, a proc ess unconfoundcd with mixed solvent ex posures. (SI) Although follow-up U less than 75% completed, the results already demonstrate a statistically significant excess of leukemia in bensene exposed workers as compared with the expecta tions based on the U3. white male popu lation or on a second population em ployed at an industry In the same state over the same period of time. Among benzene expoeed workers, a five-fold excess of total leukemia and a 10-fold excess of myelomonocytic leukemias were demonstrated even under condi tions leading to an underestimate of the true leukemia risk. Those conditions were the treatment and the analyses of Individuals whose vital status was un known--they were assumed to be alive until the last day of the study period. Note was made of the consistency of the types of leukemia in this study popula tion (myelogenous and monocytic) with earlier case reports by Vigilant of work ers who had died from benzene related leukemia in Italy. The wide variety of clinical manifes tations and hematological disorders ob served in humans exposed to benzene, which range from simple anemia and leukopenia to aplastic anemia have been experimentally Induced in animals. However, attempts to demonstrate the development of leukemia in animals ex posed to benzene has met with lees suc cess. To date, a study by Llgnac in 1932 is the only animal study known to OSHA in which leukemia has been observed in animals exposed to benzene. (38) Fiftyfour mice (28 females. 26 males) were given subcutaneous Injections of benzene (0.001 ml In 0.1 ml of olive oil) for 17 to 21 weeks. Nine mice were initially ex cluded following bacteriological exami nation and an additional 12 were lost through atrophy of various organs, es pecially the spleen. Lignac attributed these deaths to the size of the dose of benzene based upon the findings of a preceding experiment. Eight of the re maining 44 mice developed leukemia or Kundrat's lymphosarcoma and died 4 to 11 months after receiving the first injec tion. The absence of concurrent controls makes interpretation of the results diffi cult. and uncertainties as to the strain of the- mice studied has frustrated efforts to independently confirm the findings. More recent studies have failed to pro duce Llgnac's results. Amlel in 1960 uti lized four inbred strains of mice and sub jected them to the same experimental program outlined in Llgnac's study. (39) No leukemic or aplastic hemopathies were observed. More recently, Word ct al. administered benzene sub cutaneously to a species and strain of mice which Is responsive to leukdmogonic agents. (40) Although they observed a slight Increase In the percentage of granulocytic leukemias tn the benzenetreated mice as compared with the con trols. the authors viewed the increase as not statistically significant. Bribe*** msxrwnriow or tax mxsAis The requirements of the emergency temporary atandard are those which 06HA considers essential and feasible to protect employees from the grave danger resulting from benzene exposure until a permanent standard can be pro mulgated tn accordance with sections 8 (b) and <c> of the Act. The following section discusses the significant provi sions of the emergency temporary stand ard for benzene and the necessity for In cluding these provisions in the ET8. A. Scope and application. The emer gency temporary standard applies to all employers and all establishments in which benzene Is present, except for two general groups. The ET8 does not apply to retail automotive service stations. It's estimated that there are presently more than 200,000 such service stations In the country. fUtther, the limited evidence presently available suggests that em ployee exposures during gas dispensing operations are generally below 1 ppm. In light of these facts, and the relatively short duration of the ETS. It has been determined that exclusion of such serv ice stations from the ETS would be ap propriate. Similarly,' the ETS does not cover ex posure to liquids containing benzene In amounts of 1 percent or less by volume, or benzene vapor released by these liq uids. Bensene is a contaminant as well as an additive In a multitude of indus trial substances. OSHA estimates that some 60.000 facilities with over 400,000 employees are engaged In Industrial operations utilizing liquid mixtures con taining 1 percent or less benzene by volume. Also based on the presently available evidence in the Arthur D. Little study the exposure of employee working with these mixture is generally less than 1 ppm on an 8 hour average. In view of the foregoing, the ETS excludes users of these mixtures from its coverage. However, during the proceedings on the proposed permanent standard, it is OSHA's intention to consider the appro priate scope and application of Its per manent standards to protect workers from the leukemia hazard of benzene exposure. Meanwhile, the existing standard in 1 1910.1000 which governs benzene ex posure will continue to apply to retail automotive service stations and to op erations which use liquids containing one percent or less benzene. Thus, these, employers must continue to limit their employees' exposures to benzene to the 10 ppm permissible ex posure limit. 25 ppm limit ceiling and 50 ppm excursion limit of that section. The emergency temporary standard is applicable to "general industry," con struction and maritime. B. Permissible exposure Unit. The standard h is separate permlssnae limits for atr! some exposure and for aye and dermal so posuras. (1) Airborne exposure limits. Con siderable scie atiflo opinion supports the regulatory ptttoy for carcinogens that no safe level exists for any exposed population. I dr example, the National Cancer InsUt ite's Ad Hoo Committer on the Evaluation of Low Levels of En vironmental Chemical Carcinogens (1970) stated No level of u peeure to a chemical carcino gen should b s considered tandooiogiosny Insignificant ! or man. For carcinogenic agents, a "safe level tor man" cannot be es tablished by application et our prseent knowledge. (N< 1,1970, p. 1). Furthermore, NIOHH has stated that, "It Is not possible st the present time to establish an exposure level st which benzene may be regarded to be without danger," a poeitton which it has con sistently taki n with regard to other carcinogens. This reguhtory policy Is consistent with previous OSHA actions to control employee exp wore to carcinogens; sea, eg. the preambles to the carcinogen standards, 29 CFR 1910.1008 at seq. (19 FR $768); th j vinyl chloride standard, 29 CFR 1910.1 )17 (39 FR 35892) and the coke oven emissions standard. 29 CFR 1910.1029 (i PR 48742). Thus, the level of 1 ppm has been ehoeen. not as a "safe" or "no effect" level, but on the basis of OSHA's belief for the reasons set forth in the technic d feasibility and economic Impact study prepared for OSHA by Arthur D. Lit le Co., that 1 ppm is the lowest level that generally can be achieved at th! a time. (2) Ceding i intit. In addition to limit ing 8-hour tine weighted average ex posures to 1 pjm. the emergency stand ard requires that no employee be exposed to beizene in excess of 5 ppm averaged over any 15-minute period. An employee may be exposed to varying concentrations of benzene during the course of the v 'orkday with some periods of exposure ah >ve 1 ppm and correspond ing periods below 1 ppm. OSHA has determined that the .peak excursions permitted unt er file present standard are not apprcprlate in regulating ex posure to bensene--a human leukemia hazard for wlich no safe level can toe determined. For this reason, the 11minute ceiling limit of 5 ppm is estab lished to limil the magnitude of brief excursions whl eh might otherwise occur even where the 8-hour time weighted average was no t Exceeded. (3) Dermal and eye exposure limits. The standard prohibits eye and repeated or prolonged a) In exposure to liquid ben zene. While st idles indicate benzene ta not readily abs >rbed through intact skin, direct contact with liquid benzene can cause blistering and breakage of the skin surface. (46), 47) Under these circum stances, or white the skin is otherwise broken, proloni ed or repeated skin con tact may result in significant absorption of benzene. In idditlon, benzene absorp- FEOERAl REGISTER, VOL 42, NO. 103--FRIDAY, MAY 27, 1977 MCD 000000364