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EFFECTS OF 20 WEEK EXPOSURES IN FEMALE SPRAGUE-DAWLEY (S-D) RATS TO DIBROMOACETIC ACID, A DRINKING WATER DISINFECTANT BY-PRODUCT
Citation:
Murr, A S. AND J M. Goldman. EFFECTS OF 20 WEEK EXPOSURES IN FEMALE SPRAGUE-DAWLEY (S-D) RATS TO DIBROMOACETIC ACID, A DRINKING WATER DISINFECTANT BY-PRODUCT. Presented at Triangle Consortium for Reproductive Biology, RTP, NC, February 07, 2004.
Description:
Effects of 20 week exposures in female Sprague-Dawley (S-D) rats to the drinking water disinfection by-product dibromoacetic acid. A S Murr and J M Goldman, Endocrinol. Br., RTD, NHEERL, ORD, US EPA, Res. Tri. Pk, NC. Sponsor: Audrey Cummings
The drinking water disinfection by-product dibromoacetic acid (DBA) has been shown to adversely affect reproductive function in both male and female rats, albeit at exposure levels well in excess of those normally present in finished water. The present study was designed to explore the reproductive effects in non-pregnant female rats of DBA administered in the drinking water over more extended exposures. Regularly cycling S-D females were provided with 0, 50, 150 or 300 ppm DBA (pH adjusted 5.5 - 6) beginning at 11 wks of age and continued for 20 wks. Estrous cycles were tracked during alternating 2 wk periods throughout the study. In rats continuing to exhibit 4-day cycles, small quantities of tail blood were taken on the day of estrus for estradiol (E2) measurements during the 3rd, 11th and 19th wks of exposure. All animals were killed during wk 20 (diestrous day, 73/4 mo.of age). Organ wts were taken, and serum stored for E2, estrone (E1) and corticosterone assays. Calculated intake for 50, 150 and 300 ppm DBA over the 20 wks averaged 5, 16 and 34 mg/kg body wt, respectively. No treatment-related effects on cyclicity were observed over the course of exposure, and by wk 20 50-60% of rats in each group were still cycling regularly. Serum E2 levels in 4d cycling rats on the 3rd & 11th wks, however, showed an increasing dose-related trend, which was consistent with previous reported changes (Goldman/Murr, Repro. Toxicol., in press). For E1 at sac, all DBA dose groups were significantly elevated over controls. In normally cycling rats at 20 wks, there were no significant changes in ovarian, uterine, pituitary or adrenal wts, although liver showed a dose-related increase. In females that exhibited a persistent vaginal cornification, ovarian wts decreased with dose. The data indicate that while DBA elevated circulating levels of estradiol and estrone, the alteration was without effect on estrous cyclicity in this moderately estrogen-sensitive strain of rat. (This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.)