Perchlorate in fish from a contaminated site in east-central Texas.

Perchlorate, a known thyroid endocrine disruptor, contaminates surface waters near military instillations where solid fuel rocket motors are manufactured or assembled. To assess potential perchlorate exposure to fish and the human population which may feed on them, fish were collected around the Naval Weapons Industrial Reserve Plant in McLennan County, TX, and analyzed for the presence of the perchlorate anion. The sampling sites included Lake Waco and Belton Lake, and several streams and rivers within their watersheds. The general tendency was that perchlorate was only found in a few species sampled, and perchlorate was not detected in every individual within these species. When detected in the fish, perchlorate tissue concentrations were greater than that in the water. This may be due to highly variable perchlorate concentrations in the water coupled with individual-level variation in elimination from the body, or to routes of exposure other than water.

Thyroid endocrine disruption in stonerollers and cricket frogs from perchlorate-contaminated streams in east-central Texas.

In October 2001 and March 2002, a field survey of central stonerollers (Campostoma anomalum) from perchlorate-contaminated streams in central Texas was conducted to assess thyroid endocrine disruption. A survey of adult male and female cricket frogs (Acris crepitans) was performed at the same site between 2001 and 2003. Perchlorate is an oxidizer primarily used in solid-fuel rockets, and many sites that processed or used perchlorate are now contaminated. Histological analysis revealed that the fish from contaminated sites had increased thyroid follicular hyperplasia, hypertrophy, and colloid depletion. Multivariate analysis was generally found to be more powerful than univariate analysis. Seasonal differences existed in the degree of thyroidal perturbation were discovered, and fish were generally less sensitive to thyroidal perturbations in March compared to October. Thyroidal histological indicators were also correlated to levels of perchlorate in the fish, water, and periphyton. Periphyton was frequently most strongly correlated to thyroidal indices, suggesting that exposure through the food chain may be of import. In addition, one of the presumed reference sites turned out to be contaminated with perchlorate, and this was reflected by thyroidal biomarkers before perchlorate was detected in the stream water or biota. There was no evidence of colloid depletion or hyperplasia in frogs from any of the sites, although frogs from two sites with greatest mean water perchlorate concentrations exhibited significantly greater follicle cell hypertrophy. Furthermore, there was a significant positive correlation between follicle cell height and mean water perchlorate concentrations for frogs collected from all sites. This is the first known published account of perchlorate-induced thyroid disruption in fish under field situations, only the second known published account for amphibians, and also points out the value of biomarkers for contaminant biomonitoring.