OSHA's former limit for picric acid was 0.1 mg/m3 as an 8-hour TWA, with a skin notation. The Agency proposed to retain the 0.1 mg/m3 TWA limit and skin notation and to add a 15-minute STEL of 0.3 mg/m3 for this substance. NIOSH (Ex. 8-47, Table N1) concurred with the proposal. In the final rule, the Agency has retained the 8-hour TWA of 0.1 mg/m3 and a skin notation, but has determined that the evidence is insufficient to establish the 15-minute short-term exposure limit of 0.3 mg/m3 proposed by the Agency for this substance.
Picric acid occurs as colorless to pale yellow, odorless, intensely bitter crystals. Picric acid and its salts are toxic by ingestion, skin contact, or inhalation, and these substances also have skin-sensitization potential (Schwartz 1944/ Ex. 1-367). Available reports concerning human exposures describe edema, papules, vesicles, and desquamations of the face, mouth, and nose (Sunderman, Weidman, and Batson 1945/ Ex. 1-383). The symptoms of systemic poisoning following skin absorption include headache, vertigo, vomiting, nausea, diarrhea, and skin and conjunctival discoloration, as well as discoloration of urine and albuminuria; high-dose exposures caused destruction of erythrocytes and produced gastroenteritis, hemorrhagic nephritis, and acute hepatitis (Sunderman, Weidman, and Batson 1945/Ex. 1-383). Occupational exposure to ammonium picrate dust at concentrations of 0.0088 to 0.1947 mg/m3 caused dermatitis only in those workers who were least exposed; the ACGIH believes that this suggests that desensitization or adaptation occurs with repeated exposure (ACGIH 1986/Ex. 1-3, p. 490). Except for the concurrence of NIOSH (Ex. 8-47, Table N1), no comments related to picric acid were submitted to the record. Since the time of OSHA's proposal, the ACGIH has decided to delete its TLV-STEL for picric acid (Threshold Limit Values and Biological Exposure Indices for 1988-1989, ACGIH 1988b). OSHA has re-examined the evidence described above and has determined that the 0.1 mg/m3TWA limit alone is sufficient to protect employees from the significant risk of contact dermatitis associated with exposure to picric acid (OSHA's general policies for establishing short-term limits are described in Section VI.C.17). Therefore, OSHA is not including a STEL for picric acid in the final rule.
In the final rule, OSHA is retaining an 8-hour TWA of 0.1 mg/m3 and a skin notation for picric acid. The Agency concludes that these limits will protect workers against the dermatitis and sensitization associated with occupational exposures to picric acid. OSHA finds that both dermatitis and sensitization are material impairments of health.