The effects of low dosages of trichloroethylene on chick development

This study reports the effects of low dosages of trichloroethylene (TCE) (1-25 mumol/egg) on chick development when embryos were exposed directly to TCE on days 1 and 2 and examined at day 14 of embryogenesis. The results indicate that in terms of embryotoxicity, growth defects and morphological anomalies, the treated embryos differed significantly from the controls. The low doses of TCE tested produced 50% mortalities. Survivors in all instances exhibited these developmental defects: evisceration; subcutaneous edema; light pigmentation of the epidermis; beak malformations; club foot and patchy feathering. The incidence of these malformations varied depending on the day of exposure to TCE except for embryos treated with 1 mumol. Irrespective of the day of injection or concentration, the highest proportion of malformations were those of light pigmentation and edema. Neither controls (uninjected embryos, O) nor sham controls (mineral oil injected embryos OMO) exhibited any malformations. Differences in measurements of crown-rump (CR), leg, wing, toe and beak lengths between treated embryos and controls were significant at the P less than 0.05 level of confidence. However, there was no significant difference between the weights of livers of treated embryos and controls nor was any pathology noted for the livers. The embryotoxicity of TCE is described by comparing the average percentage of deaths caused by all concentrations of TCE injected on both days 1 and 2 of embryogenesis. For TCE injected embryos this average was 2.5 times higher than the average for sham controls and 6 times higher than for uninjected controls.