CAMPHOR (SYNTHETIC)

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: 76-22-2; Chemical Formula: C₁₀H₁₆O

In the NPRM (53 FR 21029), OSHA inadvertently indicated that its current limit for synthetic camphor is 2 ppm as an 8-hour TWA; however, the limit previously listed in 29 CFR 1910.1000, Table Z-1 (which is shown on Table Z-1-A of this final rule) was 2 mg/m³, or approximately 0.3 ppm. The ACGIH TLVs for camphor are a 2-ppm (12 mg/m³) TWA with a 3 ppm (18 mg/m³) STEL. This misrepresentation of the Agency’s existing limit made the ACGIH limits appear more protective by comparison, and thus OSHA erroneously proposed to revise the PEL upward, an action that would constitute a relaxing of the current 2 mg/m³ TWA PEL. Consequently, OSHA has reconsidered its discussion of the evidence on synthetic camphor. In the final rule, OSHA is retaining its 2 mg/m³ (0.3 ppm) TWA PEL; NIOSH’s comments (Ex. 8-47) on the proposal support this decision. Synthetic camphor is a colorless or white crystalline substance with an aromatic odor.

Synthetic camphor is known to cause severe injuries in animals exposed for prolonged periods by inhalation to a level of 6 mg/m³. Exposure may cause convulsions, congestion, changes in the gastrointestinal tract, and damage to the kidneys and brain (Flury and Zernik 1931b/Ex. 1-996). Animal bioassays showed that camphor was not carcinogenic in rats injected subcutaneously; however, when the cancer promoter, croton oil, was concurrently applied to the skin of mice, 2 of 110 treated mice developed carcinomas (Graffi, Vlamynck, Hoffman, and Schultz 1953/Ex. 1-903).

In humans, there are reports of industrial exposure to camphor that resulted in coma, dyspnea, and headache; one fatality from inhalation of the vapor has been noted (Flury and Zernik 1931b/Ex. 1-996).

The basis for ACGIH adopting the 2-ppm TLV-TWA and 3 ppm TLV-STEL is a report by Gronka, Bobkoski, Tomchick, and Rakow (1969/Ex. 1-1043), which evaluated airborne exposures and the health status of six employees in a synthetic-camphor-processing plant. The authors reported that exposure for up to 10 months did not produce eye or nasal irritation if concentrations of camphor were maintained at or below 2 ppm. The investigators recommended that the former TLV of 2 mg/m³ be revised to 2 ppm (12 mg/m³).

The health status of the six employees was determined before the plant installed local ventilation and improved handling procedures; at that time, camphor concentrations ranged from 24 to 43 mg/m³. Four of the six employees examined showed inflammation of the nose and throat, and one reported having occasional numbness in the fingers. After process improvements were installed, only two of the employees were still working in the camphor-processing area; the remaining four had been away from direct contact with camphor.

OSHA concludes that the results of this study provide an inadequate basis for increasing the 2 mg/m³ PEL to 12 mg/m³ (2 ppm). The small number of employees examined by Gronka et al. (1969/Ex. 1-1043) and the lack of comprehensive medical examinations after exposures declined to 2 ppm provide no assurance that long-term exposure to 2 ppm is not associated with adverse health effects. In addition, the animal study conducted by Flury and Zernik (1931b/Ex. 1-996) demonstrated severe effects in animals exposed for prolonged periods to a level one-half that found in the plant studied by Gronka et al. (1969/Ex. 1-1043). Therefore, OSHA concludes that establishing the 2-ppm (12 mg/m³) limit is unwarranted, and the Agency is retaining its 2 mg/m³ (0.3 ppm) limit for synthetic camphor in the final rule. No comments, other than those made by NIOSH, were submitted to the record.