OSHA formerly had no permissible exposure limit for endosulfan. The ACGIH has a TLV-TWA of 0.1 mg/m3, with a skin notation. The proposed PEL was 0.1 mg/m3 as an 8-hour TWA, with a skin notation; NIOSH (Ex. 8-47, Table N1) concurs. The final rule establishes an 8-hour TWA PEL for endosulfan of 0.1 mg/m3, with a skin notation. Technical endosulfan is a tan, semi-waxy solid mixture; it may have a slight odor similar to that of sulfur dioxide.
The insecticide, endosulfan, is similar in its acute oral toxicity to the related insecticides aldrin and dieldrin (TLV-TWAs of 0.25 mg/m3), except that it is slightly more toxic than these substances in female laboratory animals. In rats, the oral LD(50) for endosulfan is 43 mg/kg for males and 18 mg/kg for females (Farm Chemicals Handbook 1974/Ex. 1-1147a). The dermal LD(50)s in male and female rats are 130 mg/kg and 74 mg/kg, respectively (Farm Chemicals Handbook 1974/Ex. 1147a). The respiratory LC(50) for male rats is 50 mg/kg for 4 hours of exposure (Association of American Pesticide Control Officials, Inc. 1969, as cited in ACGIH 1986/Ex. 1-3, p. 230).
In laboratory tests of chronic exposure, rats tolerated oral doses of up to 3.2 mg/kg/day for 3 months without injury (Gaines 1975, as cited in ACGIH 1986/Ex. 1-3, p. 230), and dogs tolerated doses up to 0.75 mg/kg for 1 year (Ely, MacFarlane, Galen, and Hines 1967/Ex. 1-414). A 2-year dietary level of 10 ppm (approximately 0.5 mg/kg/day) in rats was associated with a statistically insignificant decline in female survival rates and caused a reduction in testis weights in males. At 5.0 mg/kg/day, histopathologic findings showed renal tubular damage and some hydropic changes in rat livers (Czech 1958, as cited in ACGIH 1986/Ex. 1-3, p. 230).
Inhalation of endosulfan dust by humans has been associated with slight nausea, confusion, excitement, flushing, and dry mouth (State of California: Department of Industrial Relations/Ex. 1-8). Nine employees who had been working with 50-percent water-wettable endosulfan powder for only a few days had convulsions (Association of American Pesticide Control Officials, Inc. 1969, as cited in ACGIH 1986/Ex. 1-3, p. 230). With the exception of NIOSH's comments, no evidence on endosulfan was submitted to the record.
OSHA concludes that exposure to endosulfan poses a significant risk of systemic poisoning and renal and testicular damage, and the Agency therefore is establishing a PEL of 0.1 mg/m3 TWA for endosulfan, with a skin notation; these effects constitute a material impairment of health within the meaning of the Act. OSHA finds that this limit will substantially reduce the significant risk associated with exposure to this substance at the levels formerly permitted by the absence of an OSHA limit.