Drinking Water Contamination

Barbara S. Minsker
Professor, Environmental Systems Engineering, University of Illinois
Monday, March 10, 2008; 10:45 AM

A vast array of pharmaceuticals-- including antibiotics, anti-convulsants, mood stabilizers and sex hormones -- have been found in the drinking water supplies of at least 41 million Americans, an Associated Press investigation shows. Concentrations of these pharmaceuticals are, however, tiny, measured in quantities of parts per billion or trillion and far below the levels of a medical dose. Also, utilities insist their water is safe.

But the presence of so many prescription drugs and over-the-counter medicines like acetaminophen and ibuprofen in so much of the drinking water supply is heightening worries among scientists of long-term consequences to human health.

Barbara S. Minsker, professor of Civil and Environmental Engineering and director of the Hydrology Group at the University of Illinois, was online Tuesday, March 11, 10:45 a.m. ET to discuss the investigation and consumer concerns about health risks.

A transcript follows.


Barbara S. Minsker: Hello, this is Barbara Minsker at University of Illinois Urbana-Champaign. I look forward to your questions.


Newport News, Va.: Professor Minsker, I have two questions.

First, do you think the popular news stories about this are blowing it out of proportion? Yesterday morning I saw CNN online running huge headlines on how the U.S.'s drinking water is contaminated with all these chemicals. Only when I clicked on the article and read past the summary paragraph did I see that the traces are infinitesimally slight, and that this isn't a new or sudden situation. Most other news stories I've seen (including the Post's) are about the same. Frankly, it seems like this almost sensationalistic journalism will only encourage the public to buy more bottled water -- which is usually the exact same water, just in a less environmentally-friendly package.

Second, do you know of any reports of allergic or adverse reactions to these traces of drugs in our water? I know that many people are allergic to certain medicines, so it seems like allergic reactions after drinking contaminated water would be a logical concern. If not, are the concentrations just too low to trigger a reaction? (And if the concentrations are that low, are they really enough that I or any other reasonably healthy person needs to be concerned?)

Barbara S. Minsker: The issue of pharmaceuticals in drinking water has been known for some time - I've certainly heard about it for several years - and most likely led to this more widespread study. The levels are so low that no one knows whether they are harmful or not, and more study on the human health effects is certainly needed. I have not heard of any reports of allergic reactions to the water, but it would be difficult to separate them from day-to-day exposure we get from many other chemicals in our lives, through food, household chemical use, etc.


Chicago, Ill.: So we've learned the bad news, but the AP story doesn't offer any current solutions...Are ALL bottled waters unsafe as well?The story mentions the well-known bottled waters that are city water packaged in plastic containers as not being safe alternatives, so what, if any, options are there?

Barbara S. Minsker: Most of our water supplies (including bottled water) draw from water that is continually recirculated across large areas of the country and ultimately the planet through atmospheric transport (e.g., PCBs have been found in polar bears, and they sure didn't get there from direct exposure). The only exception would be deep aquifers from ancient sources, but even those can get mixed with other waters when wells are drilled or during treatment and distribution/bottling. I don't think there is any way to avoid this issue until more research is done to figure out where the chemicals are coming from, what their effects are, and how they can be removed.


Arlington, Va.: Okay, so if one is going to err on the side of caution and avoid drinking tapwater, what are the alternatives? Much bottled water will have the same issues, as will tapwater run through home purifiers such as Brita.

What do you suggest?

Barbara S. Minsker: There is no evidence that home purifiers will remove these contaminants. I asked one of my colleagues who is a drinking water treatment expert (Chuck Haas, Drexel University) about removal and he thinks reverse osmosis systems would be the only effective approach for broad spectrum removal, but they're relatively uncommon (and not available in home form, as far as I know).


Ft. Washington, Md. : How did the medications get into or watr supply?

Barbara S. Minsker: The medications could get directly into our water supply either by people directly flushing medicines or through their bodies the old fashioned way! The wastewater is treated and usually discharged to surface water (rivers, lakes), where downstream it enters other water supplies. The treatments have not been designed to remove pharmaceuticals, although I'm sure we will see moves to make that happen. More indirect exposure paths also could exist, such as landfills with medications leaking into groundwater supplies, but given how widespread the chemicals are being found, this seems unlikely to be the primary source.


Washington, D.C.: Does boiling water have any affect on the drugs-in-water problem?

Barbara S. Minsker: Seems unlikely, since they are neither volatile chemicals (that would vaporize when heated) nor biological organisms (that would be killed when boiled).


Fairfax, Va.: I have to wonder about the potential for these contaminants to impact those of us with chronic health problems. I have celiac disorder, an autoimmune condition that affects the digestive system dramatically. I cannot have gluten, which may not be found in the water supply - but I react violently to some of the drugs mentioned as widely present in the water, such as naproxen sodium. I continue to have digestive difficulties in spite of rigorous avoidance of gluten; is it worth considering whether the water supply might be a source of trouble for me?

Barbara S. Minsker: Hard to say whether these low levels would make a difference in your case or not. You could do an experiment by changing your water supply for a few weeks and seeing if it makes a difference. See if you can find a bottled water that comes from a relatively untouched source. Of course, whether or not you can believe the claims on the bottle is an open question - I have heard that many of the bottled water companies just treat tap water with ozone to remove the chlorine taste and then sell it. I have had immune system problems in the past, stemming from food allergies, and found that the chlorine in tap water gave me stomach aches - fortunately a simple home filter removes that.


Arlington, Va.: While small concentrations of pharmaceuticals may not be harmful to humans in the short term, what about fish and other aquatic life in the rivers?

Barbara S. Minsker: No one knows about the aquatic life either, as far as I know. One question is always whether the chemicals bioaccumulate, meaning that they are absorbed into fat tissue and in that way increase in organisms over time. Chemicals like PCB act in this way and can be a serious concern for mammals (like us!) since the chemicals can concentrate in milk. I haven't checked on these chemicals to see if they are bioaccumulators or not.


Alexandria, Va.: I'd guess that a lot of people, most people, are going to want to blame the water company for not ensuring our safety, and they certainly have to accept part of the blame.

But if I take an ibuprofen or two for a sore back, and that ends up in the water supply (eventually), shouldn't we be looking at the pharmaceutical companies to make drugs that are more completely absorbed? If I take a 200 mg capsule of ibuprofen how much am I passing along for it to be measurable in the water supply?

Barbara S. Minsker: That's a good question. I don't know how much gets absorbed vs passed on, but I'm sure the pharmaceutical companies do know and calculate dosages accordingly. One way around it could be a more direct drug delivery mechanism into the bloodstream, like shots, but that's harder for consumers to do (and more unpleasant!), or some of the newer skin patch or sub-dermal delivery.


New York: The "spin" this morning is that these drugs are overwhelmingly waste from individual users. I suppose it's just a coincidence the concentrations are so high in Northen New Jersey, the home to America's pharmaceutical industry? Or, is this just the media "overwriting" the science to serve its advertisers?

Barbara S. Minsker: I don't see how anyone could know that it's primarily waste from individual users, although it certainly has to be a contributor. I hadn't read that the concentrations were higher in northern NJ - that would be an interesting one to tackle, but really what is needed is an intensive research effort to identify the key sources. I'm leading an effort called the WATERS Network (, sponsored by the National Science Foundation, which is proposing that we deploy a network of observatories around the country to study water systems as large scale coupled human and natural systems, using emerging sensors and information technology. We're interested in exactly this type of question, if we can get support from Congress to build the network.


Boston, Mass.: What is the alternative?Do we need to start drinking bottled water instead of tap water?

Is the bottled water free of comtamination with medicinal drugs?

Barbara S. Minsker: No, there is no guarantee. Many of the bottled water companies just re-treat tap water to remove the chlorine and then sell it. There are far fewer regulations on bottled water and I doubt that their claims for "pure" sources are ever checked. Even pure sources (e.g., from old underground sources) could get mixed with newer water when wells are dug or during treatment or bottling.



Do on-the-spigot water filters do anything for this problem?

Barbara S. Minsker: I hear from my colleagues who study water treatment that they do not.


Alexandria, Va.: I'm assuming most of these trace levels is due to excreting them from our bodies as opposed to dumping pills down the toilet. True?

Barbara S. Minsker: That seems likely, but no one knows for sure without further study. We used to be told that flushing was the safest way to dispose of medications so that children wouldn't eat them out of the garbage, so some people may still be flushing.


San Francisco, Calif.: Can pharmaceutical contaminants be eliminated in the home by reverse osmosis filtration?

Barbara S. Minsker: I've never heard of reverse osmosis systems being available for home use, but if they were then this might be an effective approach.


Washington, D.C.: So is bottled water the only option for those of us who are now wary of the contaminants in the municipal supply? But doesn't a lot of bottled water come from municipal sources as well? Is the Poland Springs/Dasani/etc., purifying process any better to use? Thanks!

Barbara S. Minsker: Yes, bottled water often comes from municipal sources and it's hard to know whether their claims of "pure" sources are true or not. Even deep aquifers can get contaminated when wells are installed or during distribution of treatment, though. Also bottled water companies are less regulated than municipal supplies.


Arcata, Calif.: I am a psychiatrist from California, and I believe that 90-plus percent of drug traces in our water supply are because of unused drugs that are flushed away. There needs to be a national program telling people how to get rid of unused or outdated drugs responsibly. I advocate returning them to the pharmacy who would return them to the manufacturer for disposal, and that this cost should be factored into the drug price.

Barbara S. Minsker: We don't have enough data to know whether they're coming from direct flushing or through humans, but I think your suggestion is an excellent one while we study the sources in more detail.


Rockville, Md.: Parts per trillion? As far as that goes, they might as well talk about astrology or ghosts. I will never worry about a part per trillion. Unless it is radioactive, of course.

Barbara S. Minsker: It is an extremely low level and we really don't know what, if any, human health effects there are at such low levels. It's also very difficult and expensive to do toxicological (lab studies on rats or mice) or epidemiological (surveying humans) studies for such low levels, since you need very large samples of rats/humans to control for natural variability in responses.


Arlington, Va.: Obviously, this issue if of vital concern to the entire population. But, do you have any additional warnings or advice for pregnant women?

Barbara S. Minsker: I have two young children and when I was pregnant I did try to avoid as many chemicals as I could by buying organic food, e.g., just to be safe. It's really a personal choice how far you want to take it, since it's not known whether the pharmaceuticals have any effect or not. The major question is whether you can avoid it, and whether bottled waters that say they are from "pure" ancient sources really are, and have not been contaminated along the way. E.g., I believe there can be some health effects from the plastic in the bottles too, so it's possible it just can't be avoided. If you live in an area that takes its water from a deep aquifer, you certainly would have less concerns from pharmaceuticals, but there are naturally occurring contaminants even there (e.g., arsenic in some places). Not sure you can win on completely avoiding low levels of contaminant exposure in our society, regardless of what you do, so best not to lose sleep over it!


Silver Spring, Md.: Other than possibly households with small children in them (who might be tempted to rumage through waste baskets), is there any reason anyone should be flushing their old meds into the water system rather than simply throwing them out? It wastes water, for one thing. I don't get why people would do that.

Barbara S. Minsker: I believe the advice to flush medications did come from concerns about young children eating them. That advice has now been changed, but some people may not have heard and may still flush them. However, some of the chemicals may come through people's bodies who take the medications, not through flushing. There need to be studies to figure out where it's coming from, since that is harder to address.


Palo Alto, Calif. : Apologies in advance for a dumb question: How do we get our local municipal water districts to test water, report to the community, take remedial action and keep on top of this shocking situation?

Barbara S. Minsker: I'm sure the water companies are already hearing from people and will be taking steps to try to modify their treatment systems to remove the contaminants.


Fort Washington, Md.: Simple question since I drink about 3 quarts of water a day not including tea, coffee, etc., should I start drinking distilled water?

Barbara S. Minsker: Distilled water tastes awful, and I don't know whether it removes these chemicals or not.


Barbara S. Minsker: Thanks everyone for your questions, and I have to go now. The best thing you can do is encourage Congress to invest in more water research to better understand how chemicals are moving through our environment and affecting our water supplies. Water research has been woefully underfunded for many years, despite increasing problems with both amount and quality of water in the environment and in our taps. The WATERS Network ( is proposing a national network of observatories to study exactly this sort of large-scale problem using emerging sensors and information technology. We just released our draft science, education, and design strategy document on our web site and it is open for public comment on an online blog. Please help us build support to better understand and manage our water systems for the future.


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