Chromium-6 and Our Drinking Water … How Safe?

Facts about chromium-6 existing in drinking water can be hard to swallow. We may live on the opposite coast from Hinkley, California, the city of focus in the 2000 movie “Erin Brockovich,” yet the carcinogenic contaminant that infiltrated the drinking water there knows no borders. The movie shed a national spotlight on the issue of hexavalent chromium, also known as chromium-6, and the health risks associated with the metal classified as an unregulated contaminant.

In a posting on the Environmental Working Group’s (EWG) website written by senior scientist David Andrews and managing editor Bill Walker, the authors state that a new EWG analysis of federal data from nationwide drinking water tests shows that “the compound contaminates water supplies for more than 200 million Americans in all 50 states yet federal regulations are stalled by a chemical industry challenge that could mean no national regulation of a chemical state scientists in California and elsewhere say causes cancer when ingested at even extraordinarily low levels.”

According to the EWG report, chromium-6 in the Washington Suburban Sanitary Commission system averaged 0.111 ppb (parts per billion). The EWG report is based on data collected by the Environmental Protection Agency (EPA) from 2013 to 2015, part of that agency’s current work to assess levels of chromium-6 in drinking water.

The Maryland Department of the Environment (MDE) and EPA websites explain that chromium is “an odorless and tasteless metallic element found naturally in rocks, plants, soil, volcanic dust and animals. The most common forms of chromium that occur in natural waters in the environment are trivalent chromium (chromium-3) and hexavalent chromium (chromium-6). Chromium-3 is an essential human dietary element and is found in many vegetables, fruits, meats, grains and yeast. Chromium-6 occurs naturally in the environment from the erosion of natural chromium deposits and industrial processes can also produce it. There are demonstrated instances of chromium being released to the environment by leakage, poor storage or inadequate industrial waste disposal practices.”

Chromium-6 is currently regulated under the EPA’s Safe Drinking Water Act (SWDA) only as a component of “total chromium.” According to the 2012 EPA article, “Chromium in Drinking Water,” the EPA’s drinking standard for total chromium is 0.1 milligrams per liter or 100 ppb. The current standard is based on potential adverse dermatological effects over many years, such as allergic dermatitis.

California is the only state to establish a maximum contaminant level (MCL) for chromium-6; in 2014, this was set at 10 ppb. However, previously in 2011 the California Office of Environmental Health Hazard Assessment had established a public health goal for chromium-6 at .02 ppb.

On Oct. 5, 2016, after reviewing information published by WSSC regarding testing and levels of chromium-6 in area drinking water, Montgomery County councilmembers Roger Berliner and Marc Elrich sent a letter to WSSC requesting further information due to the compound’s link to lung cancer, liver damage, and reproductive and developmental problems as documented in the cases in Hinkley.

“We appreciate that WSSC is voluntarily testing for hexavalent chromium and publishing the information.  We are also `pleased that the averages are well below California’s MCL. However, we note that virtually none of the levels were .02 ppb (parts per billion) or below, the PHG (Public Health Goals) set by California scientists,” noted Berliner and Elrich.

The councilmembers also questioned WSSC’s report that “the only treatment technologies known to effectively remove hexavalent chromium are reverse osmosis and anion exchange, both of which are prohibitively expensive.” They requested more details about the costs involved and inquired about a treatment called ‘blending’ to dilute the water and reduce the contaminant load.

WSSC’s General Manager Carla A. Reid responded in an Oct. 20, 2016 letter, “Blending drinking water from more than one source is a strategy utilized in very limited circumstances for certain contaminants where an alternative supply of high quality water is available for mixing with lower quality water. WSSC has only two sources for our drinking water supply, Potomac and Patuxent, both of which contain similar amounts of chromium. Therefore, blending is not a viable option for WSSC to reduce levels of hexavalent chromium.” Reid added that reverse osmosis is energy and greenhouse gas intensive and may cause unintended adverse consequences, including increased lead and copper corrosion.

Regarding WSSC’s claim of “prohibitive” costs for treatment, Reid explained, “With the tremendous financial constraints most utilities are already facing with failing infrastructure, it is highly questionable whether these additional costs are justifiable given their limited presumed benefit and also the potential household sources of hexavalent chromium (e.g., plumbing fixtures).” WSSC’s website states that some “household plumbing fixtures with chrome plating or stainless steel components may also release hexavalent chromium in the water.”

Reid referenced a 2013 report by the Water Research Foundation (WRF), “Hexavalent Chromium: Cost Implications of a Potential MCL,” in which WRF estimated that “if hexavalent chromium is regulated at a MCL of 1 ppb, the projected cost of water treatment, to the level of l ppb, would be $1.3 billion for initial capital expenditures, and $400 million for annual operating costs for a utility serving 1.8 million customers. These figures are more than half of our current six-year total CIP of $1.9 billion and FY17 total operating budget of $736 million, and would correspond to a rate increase of approximately 68%.”

EWG’s Andrews and Walker point to a “tug-of-war between scientists and advocates who want regulations based strictly on the chemical’s health hazards and industry, political and economic interests who want more relaxed rules based on the cost and feasibility of cleanup.” They further state, “If the industry challenge prevails, it will also extend the EPA’s record, since the 1996 landmark amendments to the SDWA, of failing to use its authority to set a national tap water safety standard for any previously unregulated chemical.”

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