The Colorado River below Lake Mead, which supplies drinking water for approximately 20,000,000 people, is contaminated by ammonium perchlorate. We identified populations who were exposed and unexposed to perchlorate-contaminated drinking water and compared median newborn thyroid-stimulating hormone (TSH) levels after adjusting for age in days at measurement and for race/ethnicity. Median newborn TSH levels in a city whose drinking water supply was 100% perchlorate-contaminated water from the Colorado River below Lake Mead were significantly higher than those in a city totally supplied with non–perchlorate-contaminated drinking water, even after adjusting for factors known or suspected to elevate newborn TSH levels. This ecological study demonstrates a statistically significant association between perchlorate exposure and newborn TSH levels. It suggests that even low-level perchlorate contamination of drinking water may be associated with adverse health effects in neonates and highlights the need for both further study and control of human low-level perchlorate exposure.
From the Office of Epidemiology and Statistics, Bureau of Public Health Statistics (Dr Brechner) and the Office of Environmental Health, Bureau of Epidemiology and Disease Control (Dr Humble), Arizona Department of Health Services, Phoenix; Hillsdale College, Hillsdale, Michigan (Mr Parkhurst); and the Department of Biostatistics (Dr Brown) and Departments of Internal Medicine and Epidemiology (Dr Herman), University of Michigan, Ann Arbor.
Address correspondence to: Dr Ross J. Brechner, 2700 N. 3rd Street, Suite 4075, Phoenix, AZ 85004; e-mail firstname.lastname@example.org.