NEUROBEHAVIORAL EFFECTS OF EXPOSURE TO TRICHLOROETHYLENE THROUGH A MUNICIPAL WATER SUPPLY

Abstract

Objective We studied a population-based sample of 143 residents of a Colorado community whose municipal water supply had been contaminated with trichloroethylene (TCE) and related solvents from adjacent hazardous waste sites. A hydraulic simulation model was used in conjunction with a geographic information system to estimate residential water supply exposures to TCE. Approximately 80 percent of the participants had potential TCE exposure exceeding the Maximum Contaminant Level (5 ppb) and 14 percent had potential exposure exceeding 15 ppb. Methods The Neurobehavioral Core Test Battery and tests of visual contrast sensitivity were administered approximately 6 years following peak concentrations of TCE in the municipal drinking water system. Multivariate analysis of variance adjusted for age, gender, and education was used to compare mean test scores of residents classified by GIS modeling into four exposure groups (< 5 >5–10 >10–15 >15 ppb). Results Estimated TCE exposure >15ppb was associated with lower performance on the Digit Symbol contrast sensitivity C and contrast sensitivity D tests. Mean scores for confusion, depression, and tension were also higher in the high exposure group compared to referents. When the data were stratified by alcohol consumption, there was strong evidence of effect modification. The effects were restricted to drinkers and were substantially stronger among persons concurrently consuming alcohol. Conclusion This study adds to the evidence that long-term exposure to very low concentrations of TCE and chemically related compounds is associated with neurobehavioral deficits in humans. The interaction between TCE and alcohol has important implications for occupationally exposed individuals