As it turns out, the old adage may be right – what you don’t know can harm you.
The Environmental Protection Agency (EPA) regulates 83 contaminants as part of its primary standard on drinking water.
These contaminants include lead, trihalomethanes, asbestos, bacteria and viruses, which if above a certain level, are a risk to human health.
But the EPA also has another list of 30 contaminants that agency monitors but does not regulate.
For many of these contaminants the science is unclear whether they are a health risk to people, while others clearly pose a risk to people.
“The only concern is something we don’t already know, that just started coming up in the newspaper and we don’t know how to test for it or something some people may say it’s bad, but we don’t know whether it’s really bad,” said Jin Shin a water quality manager at the Washington Suburban Sanitary Commission (WSSC), the primary water utility for people in Montgomery and Prince George’s Counties.
Shin said the biggest worry is in water quality is the unknown.
Every five years, the EPA issues a list of 30 contaminants that it requires municipal water utilities to monitor as part the Unregulated Contaminant Monitoring Rule (UCMR), establish under the 1996 Safe Drinking Water Act (SDWA).
As part of the UCMR, selected water utilities are required to conduct water quality test of the unregulated contaminants public available.
While the EPA is able to test for the contaminants by sending them to certified laboratories, each contaminant poses a different potential risk to those who consume it.
Publicly available water quality reports are nothing new for utilities, which are required to publish their test results for the EPA primary and secondary drinking water standards.
But unlike the primary contaminants such as lead or viruses, contaminants on the UCMR list cannot be enforced even if they are at an objectively high level.
One of the contaminants, Chromium-6, made national headlines when the Environmental Working Group (EWG), an environmental nonprofit based in Washington D.C., published a report saying the chemical could be found in the majority of American’s tap water.
Chromium-6 is a naturally occurring chemical and carcinogen.
The EWG report, compiled from publically available drinking water analyses from water utilities throughout the United States, determined trace amounts of the chemical could be found in over 200 million American’s drinking water, including Montgomery County.
According to the 2015 water quality analysis from WSSC, tap water originating from the Patuxent Filtration Plant average .035 micrograms per liter of Chromium-6 a year, while water from the Potomac Filtration Plant average .120 micrograms per liter a year.
David Andrews, a senior scientist from the Environmental Working Group, said the levels of Chromium-6 found in WSSC’s water and most of the country’s tap water concerned him.
“What they do show is that there Chromium-6 that is found in the majority of water samples across the country,” Andrews said.
Even though it is a health hazard and carcinogenic, Chromium-6 in drinking water is not regulated by the EPA.
Instead it is part of the UCMR-3, the third such list put out by the EPA since the passage of the SDWA in 1996.
The EPA’s minimum reporting level for Chromium-6 is, 0.03 micrograms per liter, below the levels of Chromium-6 found in WSSC’s water quality analysis.
While the EPA does not regulate Chromium-6, it does regulated total Chromium. Chromium is an element listed on the Periodic table and found in the environment.
The most typical types of Chromium found in drinking water are Chromium-3 and Chromium-6.
On the contrary, Chromium-3 is not only considered not toxic, but considered a typical dietary need.
Given, Chromium is toxic and chromium-3 is not, the EPA for the purpose of regulation treats total Chromium if it were entirely Chromium-6.
Andrews said the EPA needs to adopted a enforceable standard for Chromium-6, as well as other unregulated contaminants and that lack of regulation for Chromium-6 is revealing to the EPA’s cumbersome process to pass new regulations.
While the EPA has a standard for total chromium, which is 0.1 milligrams per liter that does consider Chromium-6, Andrews said this standard, though enforceable, is not strict enough because it is based off old research on Chromium-6.
Andrews said the EPA standard on total chromium is not good guideline because it is based off of when Chromium-6 was seen as a skin irritant, not a carcinogen.
“There is a standard for total chromium but it is not reflective of the science,” Andrews said.
While most states follow the EPA standard when it comes to contaminants, there is one state that has adopted its own goal when it comes to Chromium-6: California.
California is the only state to adopt a standard or maximum contaminant level (MCL), specifically for Chromium-6, at 0.01 milligrams per liter.
Additionally California has a Public Health Goal, an enforceable aim, at 0.02 micrograms per liter.
The California public health goal is based on what would be a minimum risk to cancer, if someone consumed Chromium-6 over a lifetime.
Unlike California, Maryland has no such separate goals or standards for Chromium-6, instead following the EPA’s guidelines.
“That’s exactly the point of the process. EPA can look at this and give guidelines rather than 50 states giving their own 50 studies,” said Jay Apperson, a spokesperson for the Maryland Department of the Environment.
Shin said WSSC tracks the contaminants on the UCMR list on yearly basis even though they are not required.
Judy Ding, the acting director for Public Works for the City of Rockville said Rockville participated in the last UCMR, but does monitor the contaminants on yearly basis, because it does not have the budget to do so.
“We do that testing on whatever schedule they tell us to do and we send those results directly to the EPA,” Ding said.
Approving a regulation is a long and complicated process. For the EPA, it could be years before a new regulation is handed down.
The majority of the primary contaminants the EPA regulates is codified in the SDWA and did not needed to be put in place by the EPA itself.
Andrews said the EPA’s long process of passing new regulations and improving standards could potentially negatively affect public health.
“This is an example to raise a warning flag about our current regulatory system and the in ability to incorporate new science in its health assessments as well a sit federal regulations for drinking water,” Andrews said.
EPA spokesperson Enesta Jones denied repeated requests for a reporter to interview an EPA official who specializes in water quality standards, saying she would only accept questions submitted by email.
Correction: An earlier version of this story misidentified the employer of David Andrews. He works for the Environmental Working Group.