OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
CAS: 95-49-8; Chemical Formula: C7H7Cl
Formerly, OSHA had no limit for o-chlorotoluene. The Agency proposed an 8-hour TWA of 50 ppm (consistent with the ACGIH’s TLV-TWA) and a 75-ppm STEL for this substance, a colorless liquid. NIOSH(Ex. 8-47, Table N1) supported this proposal. In the final rule, OSHA is establishing a 50-ppm 8-hour TWA for o-chlorotoluene. The Agency has decided not to establish a STEL (see Section VI.C.17 for a discussion of OSHA’s rationale in regard to STELs for this rulemaking).
The oral LD(50) in rats for o-chlorotoluene is greater than 1600 mg/kg. When the undiluted material was administered orally in doses ranging from 50 to 100 mg/kg, the animals experienced weakness and vasodilation at the higher dose levels, but all survived and were gaining weight two weeks later (ACGIH 1986/Ex. 1-3, p. 137). When the undiluted liquid was applied to the skin of guinea pigs in doses of 1 ml or10 ml/kg for 24 hours, moderately severe skin irritation occurred at both dose levels. The guinea pigs lost weight over the two-week period following application, indicating percutaneous absorption of this substance; however, no dermal LD(50) has been established for o-chlorotoluene. One drop of undiluted material in the eyes of rabbits produced a delayed erythema of the conjunctiva, although this effect cleared after 14 days (Ely 1971, as cited in ACGIH 1986/Ex. 1-3, p.137). Rats exposed to an atmosphere of 21 mg/L (or about 4000 ppm) for six hours exhibited loss of coordination within 1.5 hours, prostration at 1.75 hours, and tremors at 2 hours. At 14,000 ppm, rats showed loss of coordination, vasodilation, labored respiration, narcosis, and eye tearing. Rats exposed at 4000 and 14,000 ppm survived. At 175,000 ppm, one of three rats died (Ely 1971, as cited in ACGIH 1986/Ex. 1-3,p. 137). In another study, mice, rats, and guinea pigs were exposed to o-chlorotoluene at a concentration of about 4400 ppm. Mice showed gasping and convulsions within 30 minutes, and guinea pigs and rats exhibited gasping, hyperpnea, ataxia, and convulsions in 45 minutes. All animals were comatose within 60 minutes, and, except for two guinea pigs that continued to survive at 14 days, all of the animals died (Hazleton Laboratories, Inc. 1966, as cited in ACGIH 1986/Ex. 1-3, p. 137).
In rabbits, the 24-hour patch test resulted in moderate skin irritation; albino rabbits displayed conjunctival irritation from a single instillation of 0.1 ml of undiluted o-chlorotoluene, but no corneal damage was observed seven days later (Hazleton Laboratories, Inc. 1966, as cited in ACGIH 1986/Ex. 1-3, p. 137).
Data concerning human exposures are lacking; no cases of dermatitis or poisoning have been reported as a result of occupational exposure. Personal communications from several occupational health experts have recommended limits for o-chlorotoluene ranging from 25 to 200 ppm TWA (Hopton 1962, Mastromatteo 1971, Elkins 1972, Torkelson 1972, all as cited in ACGIH 1986/Ex. 1-3, p. 137). These limits were recommended on the basis of analogy with similar compounds, such as the chlorinated benzenes. OSHA received comments on o-chlorotoluene from NIOSH (Ex. 8-47, Table N1), the du Pont Company (Ex. 3-660), and the American Industrial Hygiene Association (Ex. 8-16). du Pont and the AIHA stated that OSHA should not adopt limits (short-term, ceiling, or skin notations) for substances for which the ACGIH has dropped or is on record as intending to drop such limits (Exs. 8-16 and 3-660). OSHA agrees with this view in many cases (see Sections VI.C.17 and VI.C.18 for discussions of OSHA’s policy on STELs and skin notations in this rulemaking).
OSHA is establishing an 8-hour TWA PEL of 50 ppm for o-chlorotoluene. The Agency concludes that this limit will protect workers from the significant risks of eye and skin irritation and systemic poisoning, all material impairments of health that may occur following exposure to this substance at levels above the new PEL.