Common-source community and industrial exposure to trichloroethylene.

In July 1979, 1,900 gallons of trichloroethylene (TCE) were released into ground and surface water from a pipe manufacturing plant in Montgomery County, Pennsylvania. To evaluate community and occupational exposure to TCE, we conducted environmental and medical surveys. In well water samples obtained in August 1979 within 1 km of the factory, TCE concentrations ranged to 183,000 parts per billion (ppb); EPA's proposed guideline for TCE in drinking water is 5 ppb. Levels of TCE declined with distance from the plant and decreased in the months following the spill. However, lower level TCE contamination was widespread and persistent, suggesting multiple releases. Within the plant, mean time-weighted occupational exposure to TCE of degreaser operators was 205 mg/m3; the recommended time-weighted exposure limit is 135 mg/m3. Mean short-term exposure was 1,084 mg/m3; the recommended short-term limit is 535 mg/m3. Seven of 9 exposed workers reported drowsiness, dizziness, or mental confusion. In exposed workers, mean urinary excretion of TCE metabolites rose from 298 micrograms/L pre-shift to 480 micrograms/L post-shift. On re-evaluation of the factory following improvements in ventilation and work practices, mean time-weighted occupational exposure to TCE had decreased to 84 mg/m3 and short-term exposure to 400 mg/m3; symptom frequency and concentrations of urinary TCE metabolites also were reduced. This episode demonstrates that community and occupational exposure to chemical toxins may share a common origin.