Teratogenicity study on pyrethrum and rotenone (natural origin) and ronnel in pregnant rats.

Insecticidal formulations in the form of dusts or aerosols containing rotenone from the root of Derris elliptica and pyrethrum from the flower of Chrysanthemum cinerariaefolium are commonly used in homes and gardens. Ronnel (fenchlorphos), a systemic insecticide, is used to control house flies and, upon oral treatment, ectoparasites of cattle. These insecticides are extensively used and their teratologic potential has not been fully investigated. Technical grades of rotenone at 0, 2.5, 5, or 10 mg/kg, pyrethrum at 0, 50, 100, or 150 mg/kg (rotenone and pyrethrum were of natural origin) and ronnel at 0, 400, 600 or 800 mg/kg were tested. Each of these was suspended in corn oil and administered orally in single daily doses on d 6-15 of pregnancy to Wistar rats. The dams were killed on the last day of pregnancy, and all fetuses were evaluated following routine teratologic methods. Rotenone was associated with an increased number of nonpregnant rats and resorptions, at a dose of 10 mg/kg; reductions in maternal body weight gain, fetal weight, and skeletal ossification, together with an increased incidence of extra rib, were found at 5 and 10 mg/kg; but no significant effects were found at 2.5 mg/kg. Increases in the incidence of resorptions in pyrethrum-treated groups and of extra rib in ronnel-treated groups were also observed.