TCP was all over the news this summer as information emerged regarding groundwater contamination in Central California following the December 2016 award of $22M to the City of Clovis in a lawsuit against Shell and Dow over TCP contamination in the city’s drinking water wells. On July 18th, the State of California Water Resources Control Board held a meeting to consider adopting proposed regulations for 1,2,3-Trichloropropane (1,2,3-TCP) or a Maximum Contaminant Level (MCL). An MCL establishes a legal threshold limit on the amount of a substance that is allowed in public water systems under the Safe Drinking Water Act. The result of the meeting was the establishment of an MCL at a value of 5 parts per trillion (0.005 micrograms per liter [µg/L]) which will become effective October 1, 2017. Compliance monitoring is set to begin in January of 2018.
Cleanup levels of 1,2,3-TCP in groundwater had previously been established and included a Public Health Goal of 0.005 µg/L, established in 1999, and the Office of Environmental Health Hazard Assessment (OEHHA) risk based public health goal of 0.007 µg/L, established in 2009. Although these goals were developed, they were not considered to be regulatory or enforceable. Recent health concerns related to the exposure of TCP has led to various discussions on establishing a regulatory and enforceable cleanup goal or level.
1,2,3-TCP has been under much debate regarding the health effects associated with exposure to the chemical. 1,2,3-TCP was historically used as a paint and varnish remover, a cleaning and degreasing agent, a cleaning and manufacturing solvent, and was a common component of soil fumigants (nematicide) previously used in agriculture. Test groups recently discovered that the chemical is also present in utilities across the country. 1,2,3-TCP is characteristically mobile in the subsurface, moves to the groundwater aquifer with little adsorption, and is resistant to natural attenuation. It was discovered in extracts of treated groundwater associated with hazardous waste cleanup at a southern California Superfund site in the late 1990s and has been found in up to 574 public supply wells.
The United States Environmental Protection Agency (EPA) concluded that the chemical is likely to be carcinogenic to humans based on studies for which the results included the formation of multiple tumors in animals. However, there is no research showing that the chemical has caused an increase in cancer rates in communities exposed to the chemical. In any case, its toxicity to humans may be high relative to other chlorinated solvents, so even low-level exposure may pose a significant risk to human health.
Treatment technologies to remediate 1,2,3-TCP in groundwater include pump and treat, permeable reactive barriers, in situ chemical oxidation and bioremediation. The most reliable and prevalent remediation method for removing 1,2,3-TCP from groundwater is pump and treat through granular activated carbon (GAC). While this methodology is effective, many municipal water providers have expressed concerns about costs related with treatment, monitoring, and compliance. As such, it is likely that industries suspected of impacting groundwater with 1,2,3-TCP may face legal action for investigation and cost recovery by local water providers.
Another challenge that will be faced with the establishment of the new MCL is by laboratories and their ability to detect the chemical at such low concentrations. Currently the detection limits for 1,2,3-TCP range from 0.02 µg/L to 5.0 µg/L for the most commonly used laboratory methods, which is above the MCL of 0.005 µg/L. The State Water Resources Control Board has recommended the use of three laboratory methods: California Department of Sanitation and Radiation Laboratories (SRL) Method 525M-TCP and Method SRL 525-TCP as well as EPA Method 504.1 for detection of 1,2,3-TCP at concentrations at or below the proposed MCL. It is important to use a laboratory method capable of detecting 1,2,3-TCP at or below the proposed MCL in order to avoid possible false negatives.
If you need further assistance or guidance in assessing environmental risk associated with 1,2,3-TCP or other emerging chemicals, Alta Environmental is here to assist you. If you need expert help with any related site assessments, remediation projects, legal services, and/or other environmental enterprises please do not hesitate to call us at 562-495-5777.