Trichloroethylene (TCE), a chlorinated organic compound which used to be employed as a solvent and degreasing agent in a wide range of industrial activities, is one of the most often detected volatile organic chemicals in groundwater in the U.S. There is evidence that exposure to TCE might be associated with developing excess cancer and birth defects, among other diseases. Among all other water uses, the safety of watering garden vegetables with TCE-contaminated water is a recurrent concern. The scarcity of scientific data on the topic makes this question a challenge to health professionals. This presentation demonstrates how we approached this issue for a community where the maximum concentration of TCE detected in a close-by monitoring well at a given time was 65 µg/L.
METHODS:
We performed a semi-quantitative risk assessment, which ultimately allowed us to make sound public health recommendations about watering garden vegetables with this well water. We based our risk assessment on the results and experimental conditions of peer-reviewed studies by Schnabel et al. (1997), Topp et al. (1986) and Burken and Schnoor (1998), who investigated TCE uptake by a variety of plants from water. We estimated the TCE concentration in the vegetables based on the contaminant water concentration and its octanol-water partition coefficient. The estimated TCE concentration in vegetables combined with appropriate assumptions on vegetable consumption and handling, allowed us to calculate the risk to develop cancer and non-cancer diseases associated with the ingestion of these vegetables.
RESULTS:
In this evaluation, both cancer and non-cancer risks were evaluated and the assessment was most likely based on an overestimated intake value. Our analysis showed that watering garden vegetables with water containing 65 µg TCE/L did not present any appreciable risk to human health. Depending on the evaluation method, we also determined that potential health risks might start appearing at TCE water concentrations >500 µg TCE/L or >170 µg TCE/L depending on the method used. In both cases, the concentration to which our subject population was exposed was well below any potentially problematic TCE level.
CONCLUSIONS:
There is no appreciable human health risk from consuming garden vegetables grown with well water contaminated with TCE at a concentration of 65 µg/L. However, we do recommend that vegetables be washed thoroughly before consumption as a prudent public health practice.