Document 3QjN5Q0JnLEnp0QKZE63Ypbyy

27 Ifi'i PROPOSED RULES j report show* a UU*Ucally algnlncant inc. Mse In the rlk for devdojrtn* myelgg>1.0111 leukemia ftmong worker* expoeed to Lcu-ene. W* hope thle new information will lio of assistance to you In reaching 4 dedoum on the most appropriate regulator/ action. In his letter of April 15. 1977. trans mitting the report on the Goodyear Plio film plant, the Director of NIOSH again urged that an emergency standard be issued. REASONS FOR ISSUANCE OF AN * EMERGENCY "safe level fix man* cannot be established by appUcatloa of our present knowledge. (NOT. IST70, p. 1) And NIOSH has taken the position that in regqlrtlng i^gfteqr^causlng sub stances " * it Is hot possible at pres ent to determine s safe exposure level for carcinogens." (Rev. Arsenlo Crit. Doc. 1975.) Since leukemia is a form of cancef and exposures generally below 25 ppni have' already Induced leukemia, it is not cur rently possible to determine whether a octane aromatics. The two industries are responsible for 94 percent of the total OB. production at benzene. Recovery through cataly 4o reiormaiiom including the benzene foi med from the nydrodealkylation of toluene, accounts for almost 80 percent of ti e total quantity produced. Recovery of o >al-derived benzene, pri marily as a by-product of the coking process In steel mills, w&* once the major source of benuene. Today, however, it accounts for only 6 percent of the total 0.8. productior. TEMPORARY STANDARD safe level- of exposure exists for worker The product on of benzene is rapidly nie Assistant Secretary finds that ex posure to benzene poses a grave danger to humans. Specifically, human exposure to benzene can induce chromosomal aberra tions. bone marrow damage and destruc tion, and other blood dyscraslas. More over. the accumulated studies strongly support the conclusion that benzene causes leukemia in humans. The data collected by NIOSH and made available during the past few weeks show that workers exposed to benzene in an Ohio Pliofilm plant have contracted leukemia at a rate at least five times the rate ex pected in the general population. Because of the conservative statistical approach to> evaluating these preliminary data, final results of this study will certainly show that the Increased risk of develop ing leukemia from exposure to benzene is even greater than five times the nor mal incidence of this disease. This new evidence has been interpreted by NIOSH, and is found by OSHA, to conclusively establish that benzene causes leukemia in humans. This conclusion is supported by the substantial body of clinical and epidemiological evidence previously vail- epldemlologlcal evidence previously available which suggested the same cas ual relationship between benzene ex posure and leukemia. In view of the new evidence the relationship can no longer populations exposed to benzene. There fore, the Assistant Secretary has deter mined that exposure must be reduced to the lowest feasible level. Furthermore, during the period of time for faormal rtflemaktag, workers would continue to be exposed to levels higher than those that maybe achieved by this ET8.` In conclusion, the Assistant Secretary determines that exposure of employees to a cancer-causing substance in the workplace environment is a "grave dan ger" within the meaning of section 6(c) (1) (A) of the Act The proposition that cancer, and substances that cause can cer. pose a grave danger to man does not need lengthy discussion. The nature of a cancer hazard differs from other types of toxicity. Employees exposed to carcin ogens risk incurable, irreversible and, in most cases, fatal consequences. These consequences may be Irreversibly set in time. No symptomatic evidence of the development of the cancer may be ap parent to the employee during a long latency period. A single exposure episode may be sufficient to cause cancer. These factors, which establish the grave danger posed by exposure to carcinogens, also lead Inexorably to the conclusion that It Is' necessary to provide immediate pro. tectlon for employees through the issu ance of an emergency temporary stand be subject to serious question. ard, within the meaning of section 6(c) expanding with approximately li billion pounds produced in 1976. Only eleven other chemical) and only one other hy drocarbon (etliylene) are produced In greater tonnage in the DH. Approxi mately 86 perci nt of this benzene is used chieflly as an tr termedlate in the produc tion of other organic chemicals, includ ing styrene, phenol, and cyclohexane. The remaining amount is used primarily in the manufai tur* of detergents, pesti cides, solvents ind paint removers. Ben zene is also present as a component of motor fuels, averaging less than 2 per cent In gasoline. The first ma lor industrial use of ben zene. however, was as a solvent' in the rubber industry just preceding Work! War I. During World War Z, benzene .' production was stimulated greatly by the demand for and resulting production of toluene in the t lanufaoture of explosive*. The large qua itities of benzene which were -produced resulted in its more wide spread use as a starting point for the manufacture cf various organic com pounds. This situation led to greatly in creased uses oi benzene as a solvqpi In the artificial leather, rubber goods, and rotogravure Industries, and as a start ing material in organic synthesis. Industries and processes currently using benzene include the chemical, printing, litho graph, rubber - cements, rubber fabricating, paint, varnish, stain The Assistant Secretary concludes, (l).(B) of the Act. removers, adhesives, and petroleum in based on a review of the latest NIOSH The existing 10 ppm standard, adopted dustries. Benzene is also used extensively study and recommendations together from the ,-NSI national consensus in chemical lab kratories as a solvent apit with the epidemiological and clinical standard, was based largely on benzene's as a reactant hi numerous chemical ap studies and other scientific data, that general toxicity rather than on the leu plication*. Wlure benzene Is produced benzene exposure subjects workers to the risk of contracting leukemia, a malig kemia hazard and. therefore, does not. within the meaning of section 6(b)(8) and used tn lars e amounts, it is generally used In enclosed systems, although ex nant and irreversible disease. The best of the Act, provide the protection now posures can occ ur during liquid transfer available scientific evidence indicates shown to be necessary. The Assistant operations, fror l equipment leakage and that no safe level for exposure to a. car cinogen, Including benzene, can be es Secretary finds that this emergency tem carryover loeaes, and In maintenance op porary standard better effectuates the erations. tablished or assumed to exist. OSHA has purposes of the Act than the National considered this question of a safe level consensus standard. in previous rulemaking proceedings (see preambles to carcinogen standards (39 BACKGROUND AND DISCUSSION Or EARLIZR PR 3753). vinyl chloride standard (39 PR DATS 35392). and coke oven emissions stand Benzene (C6H6) is a clear, odorless, ard (11 PR 43713)) and has relied on non-corrosive, highly flammable liquid that considerable body of scientific opin with a strong, rather pleasant odor. Ben ion holding that, when dealing with a . zene's low boiling point and high vapor carcinogen, no safe level exists given population. For example, for the any Na- ' pressure cause under ordinary it to evaporate rapidly atmospherio conditions, tlonal Cancer Institute's Ad Hoc Com giving off vapors nearly three times mittee on the Evaluation of Low levels heavier than air. A. Toxic effect). Benzene has been rec ognized as a toxic substance capable of causing acute r chronic effects since 1900. Xnhalatloii is the primary route of entry'of benzens in the worker. Benzene diffuses rapidly through the lungs and Is quickly absorbed into the blood. The rate of absorption is greatest during the first five minutes ami thereafter declines sig nificantly. Bens me saturation of the cir culating blood i say reach as high as 70- 80 percent of tie air content of benzole within the first 30 minutes. Relatively of Environmental Chemical Carcinogens Benzene is produced primarily by the complete satura Jon of the blood may not (1970) states: petrochemical ana petroleum ruticing in be attained for two to three days. No level of exposure to a chemical carcin dustries by the process ciilod catalytic Though the available literature sug ogen should he eonetdered Soxiootogloftlly In- reformation, . which converts certain gests that beam le is not readily absorbed tigniflcaat. for ono. ^or earcinogente agents. lower octane hydrocarbons into higher through the biman skin, appreciable FEDERAL REGISTER, VOL 42, NO. 103--FRIDAY, MAY 27, 1977 MCD 000000360