Assessment of chromium toxicity on pregnant mice and their fetal development

Chromium is a naturally occurring element, present in several valence states. Hexavalent chromium compounds [Cr VI] have been known to be more toxic than trivalent [Cr III] compounds. Exposure to chromium could be environmental due to its natural occurrence in rocks and soil as well as due to water, air and soil pollution resulting in high chromium concentrations in plants and food. On the other hand, industrial exposure could also occur as chromium enters into many industries leading to occupational hazards. The aim of the present work was to study the potential developmental toxicity of hexavalent chromium [potassium dichromate] in female mice exposed to chromium during gestation. The study was conducted on one hundred and twenty female mice which were mated with adult males. The day the vaginal plug was seen was considered day 0 of gestation. Mice were divided into four equal groups, each group consisted of thirty mice. Group I[controls], group II [treated with 10 ppm Cr VI], group III [treated with 25 ppm Cr VI], and group IV [treated with 50 ppm Cr VI]. All types of treatment were given via drinking water and started on day 6 through day 15 of gestation [period of organogenesis]. The parameters investigated in this study were maternal and fetal parameters. Maternal parameters included clinical signs of toxicity, food consumption. body weight, as well as absolute and relative organ weights. Fetal parameters included number of implantation sites, number of live and dead fetuses, number of resorptions [early and late], and fetal body weight. Gross external fetal examination, skeletal examination as well as visceral examination were done to detect any fetal malformations. The present study revealed that low concentration [10 ppm] of potassium dichromate [Cr VI] caused few signs of maternal and fetal toxicity while concentrations of 25 ppm and 50 ppm resulted in maternal and fetal toxicity, which was pronounced with the 50 ppm concentration. Maternal toxicity included general signs of toxicity [diminished activity, excessive salivation and hair loss], significant decrease in food consumption, in body weight and in absolute organ weights. Fetal toxicity included significant increase in number of dead fetuses. as well as early and late resorptions; significant decrease in fetal body weight i.e. growth retardation; and significant increase in fetal skeletal malformations in the form of cranial retardation, -absence of sacrum, shortening of long bones and absence of phalanges. No significant gross external fetal or visceral abnormalities were detected in any of the treated groups of mice compared to the control group