[Ethyl benzimidazole carbamate: teratogenic effect and presence in the milk of cows after administration of thiophanate].

After oral administration of 40 mg/kg of thiophanate to dairy cows, the active metabolite, ethyl-1H-benzimidazol-2-yl carbamate (EBC) reached a maximal concentration of 0.44 microgram/ml during the first milking and was eliminated by the mammary gland after 60 h. BCE is teratogenic in rats at doses of over 6.8 mg/kg while thiophanate at doses of up to 148 mg/kg is not. These results indicate that thiophanate treatment for dairy cattle may be questionable.