Reversibility of the toxicological changes induced by photomirex and mirex

Atsdr Evaluation of Health Effects of Chemicals

“…Ultrastructural analyses of thyroids from rats treated for 28 days showed dilation of the rough endoplasmic reticulum at 0.25 mg/kg/day and increased columnar cells with irregularly shaped lysosomal bodies, dilation of cisternae, and increased vacuolization at 2.5 mg/kg/day (Singh et al, 1982(Singh et al, , 1985. Similar effects were observed following dietary exposure to 0.25 mg/kg/day for 148 days (Chu et al, 1981a) and for 28 days (Chu et al, 1981b). A similar study found comparable effects after 21 months in both sexes of rats dosed at 0.07 mg/kg/day (Chu et al, 1981c).…”

“…Studies in rats indicate that mirex is toxic to the thyroid (Chu et al, 1981a,b;Singh et al, 1982Singh et al, , 1985NTP, 1990). Doses of 0.25 mg/kg/day for 28 days resulted in a reversible reduction in colloid, a thickening of follicular epithelium, and angular collapse of the follicles, but had no effect on serum levels of T3 or T4 (Chu et al, 1980b(Chu et al, , 1981a. Ultrastructural analyses of thyroids from rats treated for 28 days showed dilation of the rough endoplasmic reticulum at 0.25 mg/kg/day and increased columnar cells with irregularly shaped lysosomal bodies, dilation of cisternae, and increased vacuolization at 2.5 mg/kg/day (Singh et al, 1982(Singh et al, , 1985.…”

“…The adaptive effects observed are those generally produced by halogenated hydrocarbons; these include increase in liver weight or size (Gaines and Kimbrough, 1970;Mehendale et al, 1973;Abston and Yarbrough, 1976;Davison et al, 1976;Chadwick et al, 1977;Fulfs et al, 1977;Villeneuve et al, 1977;Robinson and Yarbrough, 1978a,c;Warren et al, 1978;Hewitt et al, 1979;Larson et al, 1979a;Pittz et al, 1979;Chu et al, 1980bChu et al, , 1981aMehendale, 1981b;Robacker et al, 1981;Yarbrough et al, 1981Yarbrough et al, , 1984Yarbrough et al, , 1986aYarbrough et al, ,b, 1992Ritchie and Ho, 1982;Chambers and Trevethan, 1983;Ervin and Yarbrough, 1983;Fujimori et al, 1983;Williams and Yarbrough, 1983;Curtis and Hoyt, 1984;Karl and Yarbrough, 1984;Jovanovich et al, 1987;Plaa et al, 1987;Purushotham et al, 1988;Wilson and Yarbrough, 1988;Elgin et al, 1990;Teo and Vore, 1991;Thottassery and Yarbrough, 1991 ). Other effects observed include hepatocellular hypertrophy (Gaines and Kimbrough, 1970;Davison et al, 1976;Fulfs et al, 1977;Ulland et al, 1977a;Yarbrough et al, 1981), cytopla...…”

“…In contrast, females given 1.8-2.8 mg/kg/day for two generations produced a decreased number of litters (Gaines and Kimbrough, 1970). Administration of 0.25 mg/kg/day to male and female rats for 91 days prior to mating and then through lactation resulted in a decreased mating and litter size (Chu et al, 1981a). Male and female mice at 0.65 mg/kg/day for 30 days prior to mating, and then for an additional 90 days, experienced reduced fecundity and had reduced litter size and number of offspring (Ware and Good, 1967); however, only one dosage level was tested.…”

Evaluation of mirex, photomirex and chlordecone in the terrestrial aquatic laboratory model ecosystem.

“…Although no specific human health hazards have been attributed to photomirex, this is more probably a function of the close geographic correspondence between mirex and photomirex pollution, and of the general difficulty of assessing the effects of low level pollutants, than of the innocuous nature of photomirex (31)(32)(33)(34). Since the worst environmental pollution by photomirex occurs as a consequence of the manufacture of mirex rather than during the use of mirex as a pesticide, the proposed substitution of ferriamicide for mirex in order to facilitate photodegradation (10) will not effectively diminish photomirex contamination.…”