Newsletter >> Winter 2018 >> 1,2,3-TCP

1,2,3-Trichloropropane: Another emerging issue for drinking water

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bosco ramirez

President, Eurofins Eaton Analytical

1,2,3-TCP is a fungicide/nematocide and chlorinated solvent component that has been found in numerous locations around the country.

It has been regulated in Hawaii for a number of years (current MCL 0.6 ug/L with a possibility of significant reduction in the future) and has been the subject of lawsuits in California (CA) for nearly 10 years, as drinking water suppliers have been concerned about its persistence.  CA has a public health goal (PHG) for 1,2,3-TCP of 0.7 ng/L.  1,2,3-TCP was included in USEPA’s third round of the Unregulated Contaminant Monitoring Rule (UCMR) and was found in more than 1.4% of public water supplies at levels exceeding the reference dose, but the EPA analytical method used for UCMR 3 only had a sensitivity of 30 ng/L, so all detects were automatically above the reference level.

Starting in 2001, the State of California began monitoring for 1,2,3-TCP as part of its own UCMR and determined that it was present in many groundwater sources in California, impacting nearly 100 public water supplies in the state. California has had a GC/MS purge-and-trap method in place for accurate measurements at this level since 2002.

In 2017, CA established an MCL of 5 ng/L (5 ppt) in drinking water, effective in 2018. This regulation will require numerous water supplies in CA to monitor their sources for 1,2,3-TCP and if it is found above the MCL, install treatment.

The most effective treatment technique for removal of 1,2,3-TCP is granular activated carbon (GAC).  Results of EPA UCMR 3 monitoring are also prompting utilities in other parts of the country (e.g. Pennsylvania) to evaluate the need for treatment.

With this in mind, Eurofins Eaton Analytical developed a proprietary purge-and-trap GC/MS technique capable of accurate and precise measurements at the 0.5 ng/L level (10X lower than the CA MCL) to assist utilities and their consultants with treatment evaluations.  This method is now being used to evaluate GAC breakthrough and help optimize treatment plans.