Comparative inhalation toxicity of technical chlordane in rats and monkeys.

Technical chlordane (1,2,4,5,6,7,8,8-octachloro-3a,4,7,7-tetrahydro-4,7-methanoinda ne) is used extensively for control of certain wood-boring insects. The present study was conducted to evaluate the inhalation toxicity of technical chlordane in rats and monkeys. Range-finding (28-d) and subchronic (90-d) inhalation studies with Wistar rats, and subchronic (90-d) inhalation studies with cynomolgus monkeys were conducted. In the range-finding study in rats, the threshold of toxicity for technical chlordane was approximately 5.8 micrograms/l. Among the observations made during the course of the 90-d study, in which technical chlordane was administered by inhalation to rats and monkeys at concentrations close to 0.1, 1.0, and 10 micrograms/l, the most significant were associated with alterations in the liver and were confined to rats only. However, in the rat, the effects on the liver were largely reversible during 90 d following cessation of administration of technical chlordane. The no-effect level of chlordane inhalation in rats appears to be between 0.1 and 1.0 microgram/l, while in monkeys the no-effect level is in excess of 10 micrograms/l. This study demonstrated that the monkey, a species closely related to humans, can tolerate relatively high chlordane concentrations without any adverse effects.