OSHA had no previous limit for diethyl phthalate. The proposed rule contained an 8-hour TWA exposure limit for this substance of 5mg/m3, and this limit is adopted in the final rule. NIOSH (Ex. 8-47,Table N1) supported the Agency's determination. The ACGIH has a TLV-TWA of 5 mg/m3 for this stable, colorless, odorless, oily liquid with a bitter taste.
Diethyl phthalate exposure may cause polyneuritis and disturbance in vestibular function. By most routes of administration, thissubstance has low acute toxicity in laboratory animals. Oral LD(50) valuesin the rat range between 9.5 and 31 g/kg (Shibko and Blumenthal 1973/Ex.1-934); the intraperitoneal LD(50) for the rat is 5.08 ml/kg (Singh,Lawrence, and Autian 1972/Ex. 1-436) and, for the mouse, 2.8 g/kg (Calley,Autian, and Guess 1966/Ex. 1-890). Chronic feeding studies lasting six ormore weeks resulted in no-effect levels of 2.5 g/kg/day for the rat and 1.25 g/kg/day for the dog, with no specific lesions attributable to diethyl phthalate and no unusual incidence of tumors (Shibko and Blumenthal 1973/Ex. 1-934).
A study of workers exposed to a mixture of diethyl phthalate, dibutyl phthalate, and di-2-ethyl hexyl phthalate vapors in air at concentrations of 8 to 53 mg/m3 resulted in findings of no phthalates in the blood (before or after the exposure) and no peripheral polyneuritis (Raleigh, personal communication, as cited in ACGIH1986/Ex. 1-3, p. 200). Fassett (1963a, as cited in ACGIH 1986/Ex. 1-3, p.200) reported transient nasal and throat irritation produced by exposure to the heated vapors of diethyl phthalate, but no cumulative effects have been noted. A Russian study of workers (employed for between 0.5 and 19 years) who were exposed to several phthalate plasticizers (e.g.,butyl phthalate, the higher aryl phthalates, dioctyl phthalate, and benzyl butyl phthalate), as well as to sebacates, adipates, andtri-o-cresyl phosphate at concentrations ranging from 1.7 to 66 mg/m3 reported that there were complaints of pain, numbness, and spasms in the upper and lower extremities. These complaints were related to the duration of exposure and usually began after the sixth or seventh year of employment (Milkov, Aldyreva, Popova et al. 1973/Ex. 1-646). These investigators reported polyneuritis in 32 percent of the 47 persons examined for this health effect; of 81 persons evaluated for vestibular dysfunction, 78 percent showed depression of vestibular receptors (Milkov, Aldyreva, Popova et al. 1973/Ex. 1-646).
OSHA is establishing an 8-hour TWA PEL of 5 mg/m3 for diethyl phthalate. The Agency concludes that this limit will protect workers against the significant risks of polyneuritis and vestibular dysfunction, which constitute material health impairments that are potentially associated with occupational exposure to this substance at levels above the new PEL.