| Threshold of Trichloroethylene Contamination in Maternal Drinking Waters Affecting Fetal Heart Development in the Rat Paula D. Johnson,1 Stanley J. Goldberg,2 Mary Z. Mays,3 and Brenda V. Dawson4 1University Animal Care, 2Pediatric Cardiology, 3Research Office, and 4Department of Internal Medicine, University of Arizona, Tucson, Arizona, USA Abstract
Halogenated hydrocarbons such as trichloroethylene (TCE) are among the most common water supply contaminants in the United States and abroad. Epidemiologic studies have found an association but not a cause-and-effect relation between halogenated hydrocarbon contamination and increased incidence of congenital cardiac malformations or other defective birth outcomes. Avian and rat studies demonstrated statistically significant increases in the number of congenital cardiac malformations in those treated with high doses of TCE, either via intrauterine pump or in maternal drinking water, compared with controls. This study attempts to determine if there is a threshold dose exposure to TCE above which the developing heart is more likely to be affected. Sprague-Dawley rats were randomly placed in test groups and exposed to various concentrations of TCE (2.5 ppb, 250 ppb, 1.5 ppm, 1,100 ppm) in drinking water or distilled water (control group) throughout pregnancy. The percentage of abnormal hearts in the treated groups ranged from 0 to 10.48%, with controls having 2.1% abnormal hearts, and the number of litters with fetuses with abnormal hearts ranged from 0 to 66.7%, and the control percentage was 16.4%. The data from this study indicate not only that there is a statistically significant probability overall of a dose response to increasing levels of TCE exposure, but also that this trend begins to manifest at relatively low levels of exposure (i.e., < 250 ppb) . Maternal rats exposed to more than this level of TCE during pregnancy showed an associated increased incidence of cardiac malformations in their developing rat fetuses. Key words: cardiac malformations, cardiac teratogenicity, environmental contaminants, halogenated hydrocarbon, heart defects, heart development, TCE, trichloroethylene. Environ Health Perspect 111:289-292 (2003) . Address correspondence to P.D. Johnson, University of Arizona, UAC, PO Box 210101, 1127 E. Lowell, Tucson, AZ 85721 USA. Telephone: (520) 621-3483. Fax: (520) 621-8833. E-mail: pdj@peds.arizona.edu Statistics were performed by M.Z.M. grant P42 ES04940 from the National Institute of Environmental Health Sciences (NIEHS) , the NIH, and the Southwest Environmental Health Sciences Center at The University of Arizona supported the project described in this article. Received 26 July 2001 ; accepted 26 July 2002. An erratum was published in Environ Health Perspect 113: A18(2005) .
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