Posted by: tommtn | March 6, 2015

California Adopts New Public Health Goal for Perchlorate

Tom Bloomfield, The Gallagher Law Group PC
On February 27, 2015, California revised its Public Health Goal (“PHG”) from 6 parts per billion (“ppb”) down to 1 ppb for perchlorate in drinking water. For now, the primary state drinking water standard (Maximum Contaminant Level or “MCL”) for perchlorate remains unchanged at 6 ppb. As stated by the California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (“OEHHA”):

“The update considers recent toxicological and epidemiological literature providing new information on exposures to and possible effects of perchlorate, focuses on infants as a susceptible population, and, pursuant to California Health and Safety Code Section 116365.2, incorporates updated drinking water ingestion rates for infants. These considerations have resulted in a decrease of the perchlorate PHG from 6 ppb to 1 ppb.”

Additional information about the new PHG, including technical support documents, public comment and responses and a fact sheet, can be found here.

The PHG is not a regulatory standard that must be achieved by water purveyors but it does have the potential to affect the primary drinking water standard for perchlorate. The Health and Safety Code requires the Department of Public Health to review the primary drinking water standard, or MCL, every five years and amend the standard if:

(1) Changes in technology or treatment techniques that permit a materially greater protection of public health or attainment of the public health goal.
(2) New scientific evidence that indicates that the substance may present a materially different risk to public health than was previously determined.

California Health and Safety Code, section 116365(g).

The PHG is one factor in setting the MCL, but it does not dictate the level. State law also requires the agency to consider technical and economic feasibility. The code requires the following:

Each primary drinking water standard adopted by the department shall be set at a level as close as feasible to the corresponding public health goal placing primary emphasis on the protection of public health, and that, to the extent technologically and economically feasible, meets all of the following:

(1) With respect to acutely toxic substances, avoids any known or anticipated adverse affects on public health with an adequate margin of safety, and
(2) With respect to carcinogens, or any substances that may cause chronic disease, avoids any significant risk to public health.

California Health and Safety Code, section 116365(a).

In practice, most MCLs are set at higher concentrations (e.g. less stringent) than the PHG. Specifically, of the 87 drinking water contaminants with MCLs and PHGs, 54 have an MCL greater than the PHG. Some are significantly higher. For instance, arsenic has a PHG of 0.004 ppb and an MCL of 10 ppb. Cadmium has a PHG of 0.04 ppb and an MCL of 5 ppb.

If the state elects to lower the MCL for perchlorate, that more stringent standard has the potential to increase costs to water purveyors and water users. For example, while there are some industrial sources of perchlorate due to weapons manufacturing, fireworks manufacturing and other industrial activities, perchlorate also exists in groundwater due to farming and natural sources. In Southern California citrus orchards, Chilean nitrate fertilizer was in wide use this last century. Naturally occurring perchlorate can also exist and is well documented in semi-arid regions. Both of these non-industrial sources can produce perchlorate in groundwater at concentrations greater than 1 ppb.

For further questions on this development, please contact Tom Bloomfield at

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