Would it worry you if you knew that traces of chemicals – an insect repellant, an agricultural pesticide, an anti-bacterial hand cleaner – were routinely being found in your tap water or in the river or groundwater that your public water system draws from before treating and filtering it?
If the concentration of the contaminant was very low, parts per billion or parts per trillion, would you still worry?
Maybe you should be concerned about some chemicals. Maybe you don’t have to worry about others.
But hundreds of chemicals are being found in water these days. In many cases, the discoveries are the result of new testing techniques that allow chemicals to be detected and measured at far lower concentrations than before.
In response to those discoveries and concerns about them, the 2009 Minnesota Legislature approved a two-year $1.3 million appropriation for the state Health Department to research 10 “contaminants found in Minnesota drinking water for which no health-based drinking water standard exists.”
The money came from the sales tax increase that Minnesotans approved in a 2008 constitutional amendment. The appropriation’s purpose was to allow the Health Department to study and offer advice to the public and regulatory agencies on some potentially worrisome chemicals, even in circumstances where there has not been enough scientific research to say definitively that the chemicals are dangerous for human consumption or in what concentrations they are dangerous.
Funding to continue the effort is included both in Gov. Mark Dayton’s budget and in legislative appropriation bills.
The Freshwater Society interviewed Pamela Shubat, who supervises the Health Risk Assessment Unit of the Health Department and is in charge of the new program. Shubat, who has worked for the Health Department of 22 years, earned a doctorate in pharmacology and toxicology from the University of Arizona. The transcript of that interview, edited for clarity and brevity, follows:
What are Contaminants of Emerging Concern?
Our program is about drinking water. What we’re concerned about are chemicals that have the potential to end up in water – lakes, rivers, streams – or to migrate to groundwater. Either we don’t know much about the chemicals’ toxicity, or we have new information that leads us to believe they should be re-evaluated.
So, are there chemicals in our drinking water that we should be concerned about? And how did they get there?
Some certainly are. We know substances that are part of consumer products – fabric, plastic, paints – have the potential to break down, to create contaminated dust and air. Contaminants that concern us also end up in landfills, or, during manufacture, are dumped into water. In either case, they eventually can leach into groundwater. We also deliberately expose ourselves to a lot of chemicals that we don’t know much about through the use of shampoos and lotions we put on our skin. We also take medicines that end up getting flushed down the drain.
Briefly, what are the chemicals, or some of the chemicals, the Health Department has analyzed since this program began?
We deliberately selected different classes of substances for our first year or two of study. We selected chemicals in consumer products, such as preservatives, disinfectants, flame retardants. We selected pesticides, industrial chemicals and drugs.
What do we know now that we did not previously know, about the chemicals you analyzed?
When we evaluated a chemical called 1,2,3-Trichloropropane, an industrial chemical found in paints and soil fumigants, we learned there was a new analysis of its carcinogenicity. It’s a more potent carcinogen than previously thought. We chose another chemical, Pyraclostrobin, an agricultural fungicide used to kill mold, because we learned it was being used in larger amounts in Minnesota than in previous years. And in some cases, we chose a chemical because we thought the health effects had been poorly studied in the past, for example, endocrine disruption.
Explain what endocrine disruption is.
An endocrine disruptor changes the production or effect of hormones. Hormones regulate multiple systems and processes in the body, such as metabolism and maturation.
What is an example of something you learned?
Well, for 1,2, 3-Trichloropropane, that industrial chemical, the analysis showed that it had been tested for in the past in drinking water and in other waters, and we didn’t find it. Well, it’s because our detection limit wasn’t low enough to find it at a level that we now think might be a concern.
Parts per trillion?
Yes, parts per trillion. We previously were looking at parts per billion.
Who do you hope will use this information? What kind of decisions will they base on it?
One of the most important steps is to find out who is monitoring for emerging chemicals and ask them to nominate substances for us to work on. We are soliciting nominations from state and federal agencies doing work in Minnesota, and we hope those agencies will use our information to evaluate whether they need to do more monitoring and management of chemicals. We are asking the public to nominate chemicals, and we hope to provide the public with information about how to avoid exposure to these chemicals.
What kind of research and regulation does the Health Department normally do on drinking water?
Minnesota, like every other state, carries out the mandates of the Safe Drinking Water Protection Act. We receive federal funding to ensure that community water supplies are regularly monitored and inspected to keep people from being exposed to contaminants that we already know may be a health concern.
Do you set maximum levels for the presence of certain chemicals in water that goes into public drinking water systems? As it comes out?
The Safe Drinking Water Act requires states to use maximum contaminant levels that are established at the federal level. These are used to ensure the water delivered to homes meets those requirements. When we don’t have a federal standard, we develop health-based guidance for the purpose of establishing a concentration in water that a person could drink, for one day or a lifetime without a health risk.
What about private drinking wells?
The well owner is responsible for deciding whether there is reason to test the water. We recommend testing well water for coliform bacteria once a year and for nitrate every two or three years. If bacteria or nitrates are present, that may indicate pollution on the landscape or that the well needs repair
Will the work you’re doing on Chemicals of Emerging Concern eventually end up as new regulations?
Not necessarily. The substance may be so poorly studied that we have a difficult time developing a standard, or value, using our traditional techniques. We may have to use new techniques, or deviate from the methodology that is currently in rule. We call that “Risk Assessment Advice,” and it may actually be qualitative, rather than quantitative. We may just tell people how they can reduce their exposure.
So, is the work that the Clean Water Fund is paying for in the CEC Program simply expanding the number of chemicals you can afford to analyze each year, or is it aimed at providing a different level of advice from what you could offer under your current procedures?
We are using the Clean Water funding to take a more proactive approach. Until this funding became available and we could expand our staffing, we spent our time developing guidance for those substances that are found in Minnesota’s groundwater and people were being exposed to. We had so much work on our hands that we couldn’t spend time exploring what substances people had not yet found in drinking water but were maybe being found in the source water going into water treatment and distribution systems. This program looks at surface water – lakes and streams – as well as groundwater.
One of the chemicals you have looked at so far is Triclosan, a chemical commonly found in anti-bacterial soaps. Why did you research it, and what were you able to say about it?
Triclosan has been found in many surface waters, and lakes and streams throughout Minnesota in studies by the United States Geological Survey and others. We learned that Triclosan is an endocrine disrupter, and we have established health-based guidance based on endocrine disruption. We didn’t have a Triclosan value before that.
You also looked at a chemical compound whose shorthand name is “DEET,” which is widely used in insect and tick repellants. Why did you analyze what’s known about DEET, and what advice did you give consumers?
This is a popular product. That’s obvious when you look at some of the data and see that it shows up frequently in water samples from surface water. Although DEET does have some toxicity, we also know that it has important uses in insecticides. We worked closely with the folks in Infectious Diseases at the Health Department, who are concerned about the transmission of West Nile Virus and other illnesses spread by mosquitoes. We were careful to put into our publications that we do recommend use of mosquito repellants, and that a certain level of DEET – 30% – is considered effective and safe.
With both Triclosan and DEET, aren’t most people probably going to get much more exposure through personally applying it to their bodies than they ever will get from consuming it in drinking water?
That is an excellent question. We’ve been talking about that a lot recently. One answer is, we really don’t know until we begin to do the chemical reviews whether or not it’s going to be a hazard in drinking water. But ,yes, of course, with most of these substances, the exposure is likely to be far greater from the purposeful use of the chemical. It may be that our advice for the public is: You don’t have to worry about what’s in the water. If you want to reduce your exposure, there are better ways to do that.
What have I not asked you that I should have?
We would like a lot of feedback on this program. We really welcome public scrutiny and public input. We want to use these dollars wisely, and this is a perfect time for people to weigh in on the ways we can direct our work to both protect public health and inform researchers they could target their efforts.