Perchlorate in California's Drinking Water

California is one of only two states that have set enforceable drinking water standards for the chemical perchlorate in drinking water (the other is Massachusetts). Both states acted because there is no federal standard for this contaminant, despite the fact that it has been found in hundreds of drinking water sources at harmful levels across the U.S. While California has shown great leadership in analyzing the dangers of perchlorate and regulating the chemical in drinking water, Clean Water Action and its allies in the environmental community have long contended that its standard of 6 parts per billion (ppb) is not adequately protective of the most vulnerable Californians, namely pregnant women, fetuses, and young developing children. This contention was supported in a reevaluation of the safe level of perchlorate in water released by the California Office of Environmental Health Hazard Assessment (OEHHA) in January 2011. This gives the State the opportunity to establish a more protective standard.

What is perchlorate?

Perchlorate is a chemical primarily used in solid fuel for missiles and rockets. Small amounts of perchlorate are also used in car air bags, military ordinance, fireworks, and fertilizer. At one time it was used as a medication, but serious side effects have resulted in it being used only rarely. While perchlorate is found naturally in the environment, most of it is man-made. Since the 1950s, over 870 million pounds of perchlorate have been manufactured in the United States. As a result of its production, use, and disposal perchlorate is being discovered in soil, drinking water, and irrigation water around the country.

Impacts on California’s Drinking Water

California has the most known drinking water sources contaminated by perchlorate in the country. Almost 300 wells are known to be contaminated at levels over 4 parts per billion, the detection limit used by the State. This is misleading however, since we can in fact detect perchlorate down to 1 or 2 parts per billion and it is expected that there are many hundreds of wells contaminated at lower levels. Furthermore, it does not include contaminated surface water, such as the Colorado River, which serves as a drinking water source for Arizona, Nevada, and much of Southern California, including the city of Los Angeles. While it is unclear how many people this impacts, estimates run from 18 to over 30 million Californians. Impacted areas include, but are not limited to Rancho Cordova near Sacramento (Aerojet); the Llagas Basin of Santa Clara County including parts of Morgan Hill, San Martin, and Gilroy (Olin Corporation); Santa Clarita (Whittiker Bermite), much of the Inland Empire including the city of Rialto (Black and Decker, Goodrich), and the afore mentioned Colorado River (Kerr McGee in Nevada).

Health Effects

Perchlorate at levels currently found in drinking water may cause serious health problems by interfering with the thyroid’s ability to get enough iodide, thus suppressing thyroid hormones critical to growth, development, and metabolism. Because brain development in fetuses and children follows a very specific and time sensitive schedule, even a short period with insufficient iodide and thyroid hormone can result in irreversible problems. These include learning and behavioral disabilities, impaired gait, impaired hearing and vision, mental retardation, and possibly even autism. Studies also indicate that a significant number of women in the U.S. are already iodide deficient and would need to supplement their iodide intake when pregnant. Exposure to perchlorate in their water and food exacerbates such a situation and puts both the woman and her child at risk. Water and food are the most common routes of perchlorate exposure. Perchlorate has been found in some fruits and vegetables irrigated with perchlorate laden water, in dairy products and meat from animals fed with perchlorate contaminated grass or plants, and in human breast milk. Drinking water standards, therefore, need to be particularly stringent when we consider the impacts of food sources on vulnerable populations, as well as the water itself.

Regulatory History: Polluter Interference and Politics

Since perchlorate was first found in drinking water in the 1950’s, the US Air Force, defense contractors, aerospace, and other industries have interfered with government efforts to determine the extent of contamination and to regulate perchlorate. No action to regulate perchlorate at the national level has yet to be taken. In 2011, however, U.S. EPA reversed its original decision not to regulate perchlorate and is slowly moving toward developing a national drinking water standard.

Given the lack of federal regulation, the California legislature passed SB 1822 (Sher), requiring the State to establish a perchlorate drinking water standard by 2004. Sadly, the standard was delayed, thanks to unfounded legal and administrative challenges by the polluter community. In 2007, however, the California Department of Public Health established a standard of 6 ppb.

While Clean Water Action applauded California’s regulation of perchlorate, we opposed the 6 ppb drinking water standard because of scientific evidence demonstrating that any standard higher than 1 ppb would not be adequately health protective of vulnerable populations. In addition, this standard effectively let major polluters in the State off the hook for cleanup since most perchlorate measurements came in just under the 6 ppb level. Subsequent studies on the effects on fetuses and children, as well as the significant numbers of women of child bearing age who are already iodide deficient and exposures through food sources have substantiated this point of view.

Where Are We Now?

California recognizes that scientific knowledge evolves and that it is necessary to revisit decisions on a regular basis. In January 2011, the California Office of Environmental Health Hazard Assessment (OEHAA) released a revised Public Health Goal (PHG) for perchlorate for public comment. A PHG is the level at which, according to current scientific data, no significant public health threat exists. Under state law, drinking water standards are to be established as close to the PHG as is economically and technologically feasible.

It has become a regular tactic on the part of industry interests to stall progress by simply questioning the validity of the science on which it is based, without much validity. It was no surprise therefore that during the public comment period to revise the perchlorate PHG, the Perchlorate Study Group and the Partnership for Sound Science in Environmental Policy –both front groups for industry polluters -- jointly requested an external scientific peer review of the draft PHG document. In November 2011, OEHHA posted the completed peer reviews on their website and is currently in the process of responding to them and making any revisions to their analysis they deem appropriate.

What does this mean to the public?

A more stringent perchlorate PHG in California will have a number of important implications for public health, most notably, it will:

  • Provide a tool for Clean Water Action and its allies to advocate that the California Department of Public Health reevaluate the enforceable drinking water standard and establish one that will better protect the public and hold polluters responsible, and
  • Inform national efforts to regulate perchlorate.

A revised PHG of 1 ppb will provide clear scientific evidence needed for U.S. EPA to establish a national standard of 1 ppb in order to ensure that our most vulnerable populations are protected.