A Comparative Study of the Effect of Commonly Used Pesticides on Cervical Contractions in Pregnant Cows, In Vitro.

Organochlorine insecticides (DDTs), organophosphate insecticides (malathion), carbamate insecticides (carbaryl and thiram), pyrethroid (cypermethrin and fenvalarate) insecticides, and herbicides (glyphosate and atrazine) were selected for this study because they disrupt cervical and myometrial function in the bovine oestrous cycle. However, their potential to affect reproductive success in cattle during pregnancy has not been directly confirmed. The aim of this study was to determine the effects of the investigated pesticides on cervical contractions in pregnant cows. Cervical strips from cows at 4-6 months of gestation were treated with the eight singular pesticides (used at non-toxic, environmental dose) or oestradiol (E2) under two different conditions (37.5 °C for 24 h and 4 °C for 48 h), which were applied to assess pesticide effects under both physiological and prolonged-exposure settings. The strength of the contractions was then measured. The findings of the study demonstrated that both the carbamates and glyphosate increased the force of cervical strip contractions to a greater extent than cypermethrin. In contrast, fenvalerate was observed to induce a state of cervical relaxation, analogous to the effects of E2, while DDT, malathion and atrazine exerted no effect on cervical motor function during the period of pregnancy under investigation. These preliminary findings indicate a potential impact of pesticides on cervical function during pregnancy, but should be interpreted with caution as they are based on isolated tissue at a single concentration. Further in vivo and dose-response studies are needed to confirm their biological and clinical relevance.