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A.L. Reeder,¹ G.L. Foley,³ D.K. Nichols,⁵ L.G. Hansen,⁴ B. Wikoff,⁴ S. Faeh,⁴ J. Eisold,⁴ M.B. Wheeler,¹ R. Warner,² J.E. Murphy,⁴ and V.R. Beasley⁴

¹Departments of Animal Sciences and ²Natural Resources and Environmental Sciences, College of Agricultural, Consumer, and Environmental Sciences and ³Veterinary Pathobiology and ⁴Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
⁵Department of Pathology, National Zoological Park, Washington, DC 20008 USA

Abstract

Cricket frogs (Acris crepitans) from several different sites in Illinois were collected to assess the effects of environmental contamination on the prevalence of intersex gonads. Of 341 frogs collected in 1993, 1994, and 1995, 2.7% were intersex individuals. There was no statistically significant relationship between the chemical compounds detected and cricket frog intersexuality. However, there was an association approaching significance (p = 0.07) between the detection of atrazine and intersex individuals. A comparison of reference sites with sites that had point polychlorinated biphenyl (PCB) and polychlorinated dibenzofuran (PCDF) contamination revealed a significant relationship between sex-ratio reversal and contamination with PCBs and PCDFs. The sex ratio of juvenile frogs studied from three sites with PCB and PCDF point contamination favored males over females, which was the opposite of the sex ratio in control ponds (p = 0.0007) . The statistically significant correlation between organochlorine contamination and sex-ratio reversal suggests PCBs and PCDFs can influence cricket frog sexual differentiation. The current study suggests that in cricket frogs, sex ratios and the prevalence of intersex gonads are altered by environmental contamination. Key words: Acris crepitans, amphibian, contaminants, endocrine disrupters, intersexuality, polychlorinated biphenyls, polychlorinated dibenzofurans. Environ Health Perspect 106:261-266 (1998) . [Online 2 April 1998]

http://ehpnet1.niehs.nih.gov/docs/1998/106p261-266reeder/ abstract.html

Address correspondence to V.R. Beasley, Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois, 2001 S. Lincoln Avenue, Urbana, IL 61801-6199 USA.

We are grateful to Laura Hungerford for help with the statistical analysis and indebted to Lauren Brown for his continuing input. We thank the Midwest Society of Toxicology and the John G. Shedd Aquarium for partial funding of this study.

Received 22 July 1997 ; accepted 6 January 1998.