You are here:
The Effects of Simazine, a Chlorotriazine Herbicide, on Female Pubertal Development
Citation:
Zorrilla, L. M., E. K. GIBSON, AND T. E. STOKER. The Effects of Simazine, a Chlorotriazine Herbicide, on Female Pubertal Development. Presented at Society of Toxicology 49th Annual meeting, Salt Lake City, UT, March 07 - 11, 2010.
Impact/Purpose:
Therefore, the current study examines the effects of simazine on pubertal development and estrous cyclicity in the female rat using the U.S. EPA's Endocrine Disrupter Screening Program (EDSP) Female Pubertal (Tier 1) protocol (21 day dosing period
Description:
Several chlorotriazine herbicides, such as atrazine and its metabolites, have been shown to target the neuroendocrine regulation of male and female reproductive development. Simazine is a pre-emergence herbicide used to control broad-leaf weeds and annual grasses on citrus, nuts and com crops. It is the second most commonly detected pesticide in surface and ground waters in the U.S., Europe, and Australia. Simazine is structurally related to, and shares metabolites with, atrazine; however, no studies have evaluated the effects of simazine on pubertal development in the female rat. Therefore, the current study examines the effects of simazine on pubertal development and estrous cyclicity in the female rat using the U.S. EPA's Endocrine Disrupter Screening Program (EDSP) Female Pubertal (Tier 1) protocol (21 day dosing period). In the first block, Wistar rats were gavaged with 0, 12.5, 25, 50, or 100 mg/kg of simazine from postnatal day (PND) 22 to 42. In a second block, the dosing period was extended to the first day of estrus following PND 62 and an additional group (200 mg/kg) was included. Vaginal opening was delayed at 25 mg/kg and higher and the day of first estrous was significantly delayed at 100 mg/kg and above. However, no treatment effect on the number of estrous cycles was observed. Serum prolactin (PRL) levels were decreased following simazine exposure at 50 mg/kg and higher. These data demonstrate that simazine delays the onset of puberty in the female rat and decreases serum PRL similar to other chlorotriazines. Extension of the dosing period enables monitoring of chemical effects on estrous cyclicity, which can provide critical information on the effects ofreproductive competence. This abstract does not necessarily reflect US. EPA