Summary Groundwater safe to drink, no measurable contamination by TCE. General Information What is it? Trichloroethylene (TCE) is an industrial solvent that has entered and persisted in surface and ground water bodies following industrial uses. For example, TCE has been used in dry-cleaning and leaks, spills and waste disposal have led to the chemical entering the environment. Why is it important? This chemical and other related ones have been linked to birth defects (Ruckart et al., 2013; Ruckart et al., 2015), cancers (Rusyn et al., 2014), autoimmune and other diseases (Cooper et al., 2009), and excess mortality (Bove et al., 2014). Exposure to the chemicals can be through inhalation of contaminated air or dust and drinking water. Target or Desired Condition Because TCE does not naturally occur in nature, the desired condition is that concentrations in drinking water or waterbodies is zero. A common proxy for zero concentration is “non-detect”, assuming the detection level is below concentrations considered to be harmful to people or nature. Concentrations at or below the detection limit are given a score of 100. The California standard for maximum contaminant level (MCL) for TCE in groundwater and inland surface water is 5 parts per billion (ppb) and the federal National Toxics Rule for TCE in surface water is 2.7 ppb (SWRCB, 2016). This is therefore the target “undesired condition” and concentrations above the MCL are given a score of 0. Concentrations between the detection limit and the MCL are given a score proportional to the concentration.
