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A REVIEW OF STUDIES ON PYRETHROID, CYPERMETHRIN, AND REPRODUCTIVE TOXICITY IN ALBINO MICE

ABSTRACT

The objective of the present study was to find out whether or not sub lethal doses of cypermethrin (CYP), i.e.1.38, 2.76 and 5.52 mg/kg body weight corresponding to 1/476th, 1/238th and 1/119th of LD50 dose of aqueous suspension administered orally, adversely affect gametogenesis, sex steroid secretion, fertility, fertility indices, onset of puberty in progeny and accessory organs of male and female mice and if so whether effects are reversible or not. The work is divided into two chapters. First one deals with male toxicity and second with female toxicity. Three graded doses of CYP as mentioned above, were administered to adult male mice orally through intubation on alternate day for two durations, 6 weeks and12 weeks. There was a dose and duration dependent reduction in i) weight of the body, testes and accessory reproductive organs, ii) serum levels of testosterone, iii) Total counts of epididymal spermatozoa whereas there was an increase in abnormal sperm counts compared to controls. Despite these there was an increase in number of atretic follicles of all categories and weight of the uterus compared to controls. There was a significant delay in onset of puberty and reduction in number of estrous cycles of progeny of medium and high dose CYP treated mice mated with normal males. This is an interesting finding because despite female mice not treated with CYP either during mating or pregnancy period, there was reproductive effect in both male and female offspring. The effects of high dose on different parameters were not reversible within 6 weeks alter withdrawal of the treatment. Following are the novel findings: i) Chronic exposure to very low doses of CYP for long period irreversibly interferes with gametogenic activity via endocrine disruptive action and effects prevail even in progeny, and ii) Fmale mice are more sensitive to reproductive toxic effects of CYP than males.

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