Perchlorate Exposure in Imperial Valley Residents Consuming Regionally Grown Produce

Perchlorate is a component of rocket fuel that has contaminated the lower Colorado River, a major source of water in Southern California. We characterized exposure to perchlorate and several other analytes in an underserved population consuming regional produce in the Imperial Valley, CA, near the U.S./Mexico border. Volunteers (n=31) provided samples of produce, drinking water, and a 24-hour urine sample. Participants were almost all Hispanic, mean age = 41 years, and 65% female (none was pregnant). Average perchlorate dose was 0.112 µg/kg/day (geometric mean; range: 0.02-0.51 µg/kg/day). Perchlorate was not detected in most drinking water samples, with all samples below state regulatory limits. Produce perchlorate levels were generally below 10 ppb, with the exceptions of nopales (one sample at 1398 ppb) and quelites (Mexican greens - two samples exceeding 1700 ppb). Perchlorate levels in produce and number of dairy servings from questionnaire data were associated in a linear fashion with perchlorate dose. The mean perchlorate dose was on average 69% higher than that of the U.S. reference population as measured in the National Health and Nutrition Examination Survey. Although no participants exceeded the U.S. Environmental Protection Agency's reference dose of 0.70 µg/kg/day, three individuals exceeded the California benchmark dose (0.37 µg/kg/day). While this investigation involved a small number of subjects, the higher than average perchlorate exposure may raise issues of environmental justice and concern among women of reproductive age.