Reproductive toxicity in female mice of dioxin-contaminated soils from a 2,4,5-trichlorophenoxyacetic acid manufacturing site

Reproduction in female C57B/6 mice treated with contaminated soils from a 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) manufacturing site and a metal scrap yard in Newark, New Jersey was studied. Soils contained a wide variety of contaminants, including halogenated dibenzodioxins and dibenzofurans, benzene, alkylbenzenes, chlorobenzenes, polyaromatic hydrocarbons, phenolics, phenoxy acids and other compounds. Acute and reproductive toxicity (primarily fewer live pups born and fewer pups surviving until weaning) was observed from the manufacturing site soil (soil A; with 2,050 μg 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD)/kg soil and 18 mg total dibenzodioxins and dibenzofurans/kg soil); the scrap yard soil (soil B; with 230 (μg 2,3,7,8-TCDD/kg soil) had no observable effect. Soil recontaminated with 2,3,7,8-TCDD, or 2,3,7,8-TCDD in corn oil interfered with estrus cycling and completely prevented reproduction. If 2,3,7,8-TCDD treatment was terminated, estrus cycling resumed within four weeks, but reproduction was still unsuccessful for these mice. The results suggest that 1) the manufacturing site soil (soil A) is toxic but the signs of toxicity cannot be solely attributed to the 2,3,7,8-TCDD content; 2) even though the bioavailability of 2,3,7,8-TCDD from this soil is low (Umbreitet al. 1986), other reproductive toxins are bioavailable or the low doses of 2,3,7,8-TCDD that are bioavailable may be sufficient to be reproductive toxins; 3) 2,3,7,8-TCDD blocks estrus in mice and (as previously reported) interferes with reproduction; and 4) after cessation of dosing, thein situ concentrations of 2,3,7,8-TCDD that block estrus are decreased below an effective level within four weeks.