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This study will examine uptake of perchlorate-contaminated irrigation water into plants intended for livestock and/or human consumption and assess factors that might influence uptake. Secondly, these studies will assess health risks to livestock associated with consumption of crops grown using perchlorate-contaminated irrigation water.
Recent advances in analytical capabilities have brought national attention to the widespread distribution of perchlorate. Ammonium perchlorate is a chemical used as an oxidizer in solid propellants, rockets, missiles, fireworks, and some munitions. In many areas of the arid Western U.S., groundwater and surface water supplies that have been contaminated with perchlorate are also used for irrigation of agricultural crops. The major health concern for organisms exposed to perchlorate at high concentrations is interference with normal thyroid function. Concerns have been raised over the potentialfor adverse health effects in populations chronically exposed through drinking water. Limited studies have shown the potential for plant uptake and assimilation into leafy tissues. However, little research has been done to document the effects of chronic low-level perchlorate exposure among humans and livestock that may occur indirectly through ingestion of food items grown with perchlorate-contaminated irrigation water. Thyroid hormones have many roles in vertebrate physiology, including involvement inregulation of embryonic growth and development, and may be affected by perchlorate at low concentrations. Because thyroid hormones play homologous roles in livestock, there exists the potential for disruption of endocrine homeostasis in these species as well.