Changes in Cross-Fostered Sprague-Dawley Rat Litters Exposed to Perchlorate

Ammonium perchlorate is used as an oxidizer in rocket fuel. It has become a groundwater contaminant, dissociating to ammonium cation and perchlorate anion. The perchlorate ion competes with iodide for uptake into the thyroid, reducing thyroid hormone production. Pregnant Sprague-Dawley rats were given either untreated or perchlorate (1 mg/kg-day) treated drinking water beginning on gestation day 2. One set of control and exposed dams was sacrificed on gestation day 20. The litters from the second set of control and exposed dams were crossed immediately after parturition and were sacrificed at postnatal day 10. Dam serum and thyroid, pooled fetal sera, and male and female pup sera were collected and analyzed for perchlorate, thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4). Control pups receiving perchlorate through lactation had serum levels at postnatal day 10 of 0.54 μg/ml and 0.56 μg/ml for male and female pups, respectively, whereas exposed fetuses had serum perchlorate lev...