Erin Brockovich is back in the news for the groundwater contaminant that made her famous, chromium-6 (hexavalent chromium). She became a celebrity after she and chromium-6 were the subject of a 2000 movie, starring Julia Roberts. Since then, chromium-6, has been on the radar of many water quality scientists.
The reason for her latest celebrity appearance has little to do with chromium-6 and more to do with the “Erin Brockovich Effect.” If she shows up, the media and the public will take notice. It is a successful diversion from the real story.
What’s the Real Story
The real story is that California’s State Water Resources Control Board was hasty in enacting chromium-6 standards 3 years ago. California became the first state in the nation to issue a drinking water standard for chromium-6, setting a maximum concentration of 10 parts per billion (ppb).
This week, a Sacramento judge ruled that the standard adopted three years ago, was invalid because of economic feasibility. In other words, treating water to remove chromium-6 below 10 ppb is very costly. As you can imagine, industry required to treat water below 10 ppb wants the standard lifted and those concerned with public drinking water safety want the standard to stay as written.
What is Chromium
Chromium is found naturally in rocks, plants, soil, and animals. The most common forms of chromium that occur in the environment are trivalent chromium (chromium-3) and hexavalent chromium (chromium-6). Chromium-3 is an essential human dietary element. It is found in many vegetables, fruits, meats,and grains. Chromium-6 occurs naturally in the environment but can also be produced by industrial processes. The two largest sources of chromium emission in the atmosphere are from the chemical manufacturing and combustion of natural gas, oil and coal.
What is a Drinking Water Standard
The Safe Drinking Water Act (SDWA) requires the Environmental Protection Agency (EPA) to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. EPA sets enforceable standards for all public drinking water supplies. The drinking water standards, or Maximum Contaminant Levels (MCLs) are based on the best available science to prevent potential health problems. MCLs are set as close to the health goals as possible after considering costs, benefits, and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.
Currently, there is no EPA MCL for just chromium-6. There is a national drinking water standard for total chromium of 100 ppb. Chromium-6 and chromium-3 are covered under the total chromium drinking water standard because these forms of chromium can convert back and forth in water and in the human body, depending on environmental conditions. Measuring just one form may not capture all of the chromium that is present. In order to ensure that the greatest potential risk is addressed, EPA’s regulation assumes that a measurement of total chromium is 100 percent chromium-6, the more toxic form.
Could the Chromium-6 in Groundwater Be NAtural
A groundwater study at Presidio in San Francisco concluded that the source of chromium-6 found in groundwater was from natural sources. There is the possibility that natural chromium-6 could be more widespread in groundwater throughout California. If there is a source of natural chromium-6 in groundwater, it wouldn’t be appropriate to require industry or water treatment plants to treat below what was naturally occurring from the intake water. This is especially true when the EPA approved safe drinking water standard is 10 times higher than the California standard of 10 ppb.
Did California enact a standard that was not economically feasible and unnecessary for the protection of human health?
What’s Next for Chromium-6 in California
California will begin “working quickly” on a new drinking water standard. This sends up all kinds of red flags. There is nothing quick about standards development. The development and refinement of a drinking water standard for a specific compound is a painstaking process that typically takes many years.
The chromium-6 standard should be based on the Federally recommended SDWA standard for human health. If California decides that this standard is not protective of human health, then it needs to be based on extensive toxicological studies and sound science. It should not be based on public opinion, or pressure from industry, or visits from “Erin Brockovich.”
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