MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KIN-1116-959849) Evaluating developmental effects of three xenobiotic chemicals on Xenopus laevis.

Kumsher King, M¹, Dickson, K¹, La Point, T¹, Venables, B¹, Waller, W¹, Irizarry, E¹, ¹ University of North Texas, Denton, Texas, USA

ABSTRACT- The Frog Embryo Teratogenesis Assay – Xenopus (FETAX) is useful for screening the developmental toxicity potential of pure chemicals and complex mixtures. In this study, FETAX was used to assess the teratogenic potential of two anti–microbial agents and one herbicide. Triclosan (2,4,4′–trichloro–2′–hydroxydiphenyl ether) is a broad-spectrum anti–microbial agent found in a variety of personal care products including soaps, detergents, cosmetics, pharmaceuticals, plastics and fabrics. In a survey by the U.S. Geological Survey, triclosan was one of the most frequently detected compounds in U.S. streams, with a median concentration of 0.14 g/L. Triclocarban (3,4,4–Trichlorocarbanilide) or TCC is used in North America as an anti–microbial and preservative in bar and liquid soaps and body washes. The TCC Consortium reported that TCC concentrations ranged from <0.074 g/L to 0.228 g/L in U.S. streams. Atrazine [6–chloro–N–ethyl–N′–(1–methylethyl)–1,3,5–triazine–2.4–diamine] is an herbicide used extensively throughout the United States to control weeds in corn fields. Environmental concentrations of atrazine vary with season and location, but are typically measured in the tenths of a part per billion range. At environmentally relevant concentrations, none of the three xenobiotics tested induced teratogenic effects using FETAX. Triclosan was tested in concentrations ranging from 0.007 g/L to 100 g/L. TCC was tested at concentrations ranging from 12.5 g/L to 50.0 g/L. For both anti–microbials, mortality and malformation rates did not differ significantly from controls at any concentration. Future studies with triclosan and TCC will be performed to estimate their LC50 and EC50 in the FETAX model. Atrazine was tested at concentrations ranging from 0.0003 mg/L to 30 mg/L. We estimated an LC50 of 12.8 mg/L and an EC50 of 4.6 mg/L. Although these values are similar to recently reported results, we intend to confirm these initial LC50 and EC50 estimates.

Key words: FETAX, triclosan, triclocarban, atrazine