Previously, OSHA had a limit of 0.5 mg/m3, with a skin notation, for chlorinated camphene. The ACGIH has a TLV-TWA limit of 0.5 mg/m3 and a TLV-STEL of 1 mg/m3 for chlorinated camphene (60 percent), with a skin notation, and these were the limits proposed. The final rule retains the 0.5-mg/m3 8-hour TWA and the skin notation, and adds a 1-mg/m3 STEL for chlorinated camphene, an amber waxy solid with a pleasant, pine-like odor.
Chlorinated camphene has demonstrated a moderately high acute toxicity in animal studies (ACGIH 1986/Ex. 1-3, p. 115). Toxic doses cause varied central nervous system effects, including nausea, muscle spasms, confusion, and convulsions (Hayes 1963/Ex. 1-982). Data indicate that rats and guinea pigs show no significant effects at dietary levels of 800 ppm daily for a six-month period (Alderson Reporting Co., as cited in ACGIH 1986/Ex. 1-3, p. 115). Monkeys tolerate daily feeding at 10 ppm but show toxic symptoms after two weeks' feeding at the 60-ppm level (Sosnierz, Szczurek, Knapek, and Kolodziejczyk 1972/Ex. 1-760). Although chlorinated camphene may accumulate in fatty tissues, it clears quickly when ingestion is terminated (Sosnierz, Szczurek, Knapek, and Kolodziejczyk 1972/Ex. 1-760).
In humans, the acute lethal dose of chlorinated camphene is between 2 and 7 grams, and a dose of 10 mg/kg causes nonfatal convulsions in some exposed individuals. The ACGIH (1986/Ex. 1-3, p. 115) concludes that the acute toxicity of chlorinated camphene is equivalent to that of chlordane, for which the fatal human dose is estimated to be around 6 grams; the ACGIH TLV-TWA for chlordane is 0.5 mg/m3. One study of 25 human volunteers failed to reveal toxic responses to daily 30-minute exposures to 500 mg/m3 for 10 consecutive days, followed by similar exposures for three consecutive days three weeks later (Shelansky 1947, as cited in ACGIH 1986/Ex. 1-3, p. 115). There are no reports of occupational poisonings, and a review of the medical records of employees engaged in the manufacture and handling of chlorinated camphene showed no ill effects in workers exposed for an average of 3.7 years (Frawley 1972, as cited in ACGIH 1986/Ex. 1-3, p. 115).
NIOSH does not concur with OSHA's PELs for this substance; NIOSH believes that chlorinated camphene is a potential occupational carcinogen and should have lower exposure limits (Ex. 8-47, Table N6B; Tr. pp. 3-97, 3-98). No other comments on the health effects of this substance were submitted to the record.
OSHA is retaining the 8-hour TWA PEL of 0.5 mg/m3 TWA and adding a 15-minute STEL of 1.0 mg/m3 for this insecticide. The Agency's skin notation is retained. OSHA concludes that both a TWA and a STEL are required to protect exposed workers against the significant risks of bioaccumulation and neuropathic and systemic effects; the Agency finds that these effects constitute material impairments of health. The STEL ensures that TWA exposures will be maintained under good industrial hygiene control.