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: 638-21-1; Chemical Formula: C6H5PH2
OSHA had no former requirement for limiting worker exposure to phenylphosphine; NIOSH also has no REL for this substance. The ACGIH has recommended a ceiling limit of 0.05 ppm for this solid. The proposed PEL was a ceiling of 0.05 ppm; NIOSH (Ex. 8-47, Table N1) concurred with the proposed limit, and this limit is established in the final rule.
A 90-day inhalation study conducted by the du Pont Company, in which rats and beagle dogs were exposed to average concentrations of 0.6 ppm or 2.2 ppm phenylphosphine for six hours per day, five days per week, showed that rats exposed to 2.2 ppm had significant hematologic changes and testicular degeneration (E.I. du Pont de Nemours & Co., Inc. 1970, as cited in ACGIH 1986/Ex. 1-3, p. 479). These effects were not noted among rats exposed to 0.6 ppm, but rats exposed at the lower level did show hypersensitivity to sound and touch and mild hyperemia. The dogs tolerated the higher exposure level better than the rats in that some regeneration of testicular damage occurred in dogs during a one-month recovery period. Dogs exposed to 0.6 ppm exhibited intermittent nausea, diarrhea, lacrimation, and hind leg tremor (ACGIH 1986/Ex. 1-3). The ACGIH considered 0.6 ppm to be an NOE level for severe effects in animals and recommended a 0.05-ppm ceiling TLV to provide a tenfold safety margin to protect workers against the changes exhibited by the test animals at the 0.6-ppm level. No comments other than that from NIOSH (Ex. 8-47) were received by OSHA.
OSHA concludes that workers formerly exposed to uncontrolled levels of phenylphosphine were at significant risk of experiencing the nausea, irritation, and CNS effects found to be associated with such exposures in animals. OSHA finds that these effects constitute material health impairments. The Agency concludes that the final rule's ceiling of 0.05 ppm will reduce these significant risks substantially.
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