CYCLONITE

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: 121-82-4; Chemical Formula: C₃H₆N₆O₆

OSHA has not previously had a permissible exposure limit for cyclonite. The Agency proposed an 8-hour TWA of 1.5 mg/m³, a STEL of 3 mg/m³, and a skin notation, and NIOSH (Ex. 8-47, Table N1) concurred with the selection of these PELs. The ACGIH has an 8-hour TWA limit of 1.5 mg/m³ for this substance. In the final rule, OSHA is establishing a 1.5-mg/m³ 8-hour TWA PEL for cyclonite, with a skin notation;the Agency has decided not to establish a STEL for this substance (see Section VI.C.17 for a discussion of OSHA’s rationale in regard to STELs). Cyclonite exists in the form of orthorhombic crystals.

Cyclonite, an explosive and a rat poison, has not been shown in animal studies to be acutely toxic. In industry, reports of poisonings as a result of occupational exposures to cyclonite were widespread as late as 1962 (Kaplan, Berghout, and Peczenik 1965/Ex. 1-338). Exposure causes central nervous system effects, including nausea, vomiting, convulsions, and unconsciousness. These clinical signs result from repeated gastrointestinal and respiratory exposures and from skin absorption (Sunderman et al. 1944, as cited in ACGIH 1986/Ex. 1-3,p. 162; von Oettingen, Donahue, Yagoda et al. 1949/Ex. 1-398). In an epidemiological study, Hathaway and Buck (1977/Ex. 1-418) reported that 8-hour TWA exposures ranging up to 1.57 mg/m³ and averaging 0.28 mg/m³ caused no identifiable abnormalities attributable to cyclonite exposure. The American Industrial Hygiene Association (Ex. 8-16) urged OSHA to drop the STEL for this substance.

OSHA is establishing an 8-hour TWA limit of 1.5 mg/m³ TWA and a skin notation for cyclonite. The Agency concludes that establishing these limits for this previously unregulated chemical will protect workers from the significant risk of neuropathic effects, which constitute material health impairments that are associated with inhalation or percutaneous exposure to cyclonite.