Cardiac teratogenicity of trichloroethylene metabolites.
OBJECTIVE
The hypothesis of this study was that metabolites of trichloroethylene (TCE), dichloroethylene (DCE) and related compounds were responsible for fetal cardiac teratogenic effects seen when TCE or DCE is consumed by pregnant rats during organogenesis. Identification of teratogenic metabolites would allow more accurate assessment of environmental contaminants and public health risks from contaminated water or possibly municipal water supplies which, when chlorinated, may produce these potentially dangerous chemicals.


BACKGROUND
Human epidemiologic studies and previous teratogenic studies using chick embryos and fetal rats have shown an increased incidence of congenital cardiac lesions in animals exposed to TCE and DCE.


METHODS
Metabolites and compounds studied in drinking water exposure included: trichloroacetic acid (TCAA), monochloroacetic acid (MCAA), trichloroethanol (TCEth), carboxy methylcystine (CMC), trichloroacetaldehyde (TCAld), dichloroacetaldehyde (DCAld), and dichlorovinyl cystine (DCVC). Compounds were administered to pregnant rats during fetal heart development.


RESULTS
Fetuses of rats receiving 2,730 ppm TCAA in drinking water were the only group that demonstrated a significant increase in cardiac defects (10.53%) compared with controls (2.15%) on a per fetus basis (p = 0.0001, Fischer's exact test), and a per litter basis (p = 0.0004, Wilcoxon and p = 0.0015, exact permutation tests). Trichloroacetic acid also demonstrated an increased number of implantation and resorption sites (p < 0.05) over controls. Other maternal and fetal variables showed no statistically significant differences between treated and untreated groups.


CONCLUSIONS
Of the metabolites tested, only TCAA appeared to be a specific cardiac teratogen in the fetus when imbibed by the maternal rat.
Johnson
P D
PD
Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona, Tucson, USA. pdj@peds.arizona.edu
Dawson
B V
BV
Goldberg
S J
SJ
D000014:Abnormalities, Drug-Induced / Q000209:etiology*; D000079:Acetaldehyde / Q000009:adverse effects / Q000031:analogs & derivatives; D000085:Acetates / Q000009:adverse effects; D000818:Animals; D002697:Chloral Hydrate / Q000009:adverse effects / Q000031:analogs & derivatives; D003553:Cystine / Q000009:adverse effects / Q000031:analogs & derivatives; D004000:Dichloroethylenes / Q000009:adverse effects*; D005314:Embryonic and Fetal Development / Q000187:drug effects; D004785:Environmental Pollutants / Q000009:adverse effects; D005023:Ethylene Chlorohydrin / Q000009:adverse effects / Q000031:analogs & derivatives; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000196:embryology; D006330:Heart Defects, Congenital / Q000139:chemically induced* / Q000196:embryology; D006801:Humans; D018811:Maternal Exposure; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013723:Teratogens; D014238:Trichloroacetic Acid / Q000009:adverse effects; D014241:Trichloroethylene / Q000009:adverse effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000009:adverse effects; D014881:Water Supply
D000085:Acetates; D004000:Dichloroethylenes; D004785:Environmental Pollutants; D013723:Teratogens; D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; D002697:Chloral Hydrate; D003553:Cystine; C006972:chloroacetic acid; D014238:Trichloroacetic Acid; D005023:Ethylene Chlorohydrin; C015798:dichloroacetaldehyde; C005849:2,2,2-trichloroethanol; C021100:trichloroacetaldehyde; D000079:Acetaldehyde