Some Effects of DDT, Toxaphene and Polychlorinated Biphenyl on Thyroid Function in Bobwhite Quail

Abstract

Bobwhite quail were given technical grade DDT, Toxaphene (Tox), or Polychlorinated Biphenyl (PCB) at 5, 50 or 500 p.p.m. in their feed for 4 months. At monthly intervals groups of quail (usually 10) from each experimental group were tested and compared with control birds. Thyroid, adrenal, liver, and body weights were measured as were the 2-hour thyroidal I131 uptakes. Generally, only the higher dosages were effective in producing changes. DDT: DDT early increased the uptake of I131 by the thyroid and by 4 months the 2-hour uptake had returned toward control levels. The thyroid gland was found to be significantly enlarged after 3 months on treatment and remained enlarged thereafter. DDT produced no consistent effect on body or adrenal weights, but the livers were enlarged after 2 months on high dosage treatment. Toxaphene: Toxaphene stimulated thyroid growth and I131 uptake. In the former case, the effects were statistically significant only at the 4-month period while the total thyroid uptake of I131 was significantly increased at 3 and 4 months on treatment. When expressed as percentage of dose of I131 taken up per mg. of thyroid, the uptake was significantly greater after 2 and 3 months on treatment. Toxaphene in high dose rate significantly decreased body weights at all time periods studied. At all dose levels used, Tox seemed to produce adrenal hypertrophy by 3 months. The effects of this chemical on liver weights was slight or none at all. PCB: PCB seemed to depress thyroid size at low dose levels or early in the experiment and to stimulate growth at higher dose levels or later in the experiment. The enlarged glands of the high PCB group took up more iodide than the controls, but each unit weight of these thyroids took up the same amount of iodide as the controls. On the other hand, the thyroids from birds receiving the lower two doses of PCB took up the same amount of iodide as the controls, but each mg. of thyroid took up less. PCB had no consistent effect on body weight or adrenal weight, but produced a very dramatic increase in liver weight. These results are discussed.