Effect Of Exposure To TBBPA Or/and Cd On Thyroid Hormone In Peripubertal Rats

Flame retardant industry began in the nineteen eighties in our country, and then, it showed a steady development trend. In recent years, the consumption of the flame retardant has risen sharply and the increasing of relevant products results in the high-speed rise of the demand of tetrabromobisphenol-A（TBBPA）. With the increasing of Electronic wastes containing TBBPA, great importance has been attached on the pollution of TBBPA to the environment and the effect on human health. TBBPA, chemical structure with thyroid hormones, which can interfere with the normal functions of the thyroid gland by different ways. In addition, TBBPA and Cd are both endocrine disruptors and often coexist in the form of compound pollution in water environment.In this study, using TBBPA and Cd as subjects, the single and combined subchronic exposed experiment on adolescence SD rats are established. Through the oral exposure experiment of TBBPA and CdCl₂, the growth and development situation and thyroid disruption effect of rats are analyzed. The study is not only beneficial to the comprehensive evaluation on toxicity of TBBPA and Cd, also provides the theory basis for the health risks about combined pollution of brominated flame retardants and heavy metals. It has practical value and scientific significance for assessing the potential health risks of similar combined pollution in river basin.The results showed that:（1） After oral exposure of TBBPA, there is a downturn in the serum T4 level of female rats and the TSH level of male rats drop significantly. TBBPA may exist gender differences and disrupt the steady state of thyroid hormone, but there is no obvious dose effect relationship.（2） After oral exposure of TBBPA, middle and high dose group of rats have a certain degree of follicular epithelial hyperplasia and follicular area are decreased, but there is no significant difference in thyroid follicular colloid area of different dose groups. TBBPA have weak toxicity on thyroid organization morphology.（3） Single CdCl₂ exposure and combined exposure of TBBPA and CdCl₂ can both make female rats thin and may lead to the toxicity of liver and kidney. Compared with single CdCl₂ exposure, combined exposure is more likely to cause the toxicity of kidney.（4） Single CdCl₂ exposure and combined exposure did not cause the obvious changes in thyroid hormone of adolescence female rats, but the TSH level of high combined dose group has a tendency to rise which may cause significant change of TSH level with exposure time increased. The weight of thyroid, thyroid follicular structure and colloid area did not change obviously, therefore in this study TBBPA and Cd did not show obvious combined effect of thyroid disruption.