Drugs in Drinking Water
Pharmaceuticals and personal care products in the drinking water- are biosolids to blame?
Well, in a very general sense, the answer is yes. We have biosolids because we have people. We also have animal manure because most of us people are not vegetarians and we like to have the occasional steak or fried chicken. Pharmaceuticals and personal care products are everywhere in our environment, including birds, fish and polar ice caps. This is because of two things: with over 7 billion people on the planet finding any place or animal not impacted by our presence is very difficult, and we now have tools to detect chemical compounds in extraordinarily low concentrations.
The library this month is all about pharmaceuticals and personal care products in our groundwater and drinking water. This comes from a request from our local Department of Ecology where a well sample showed signs of anthropogenic influence in the parts per trillion level, at typically 1 to 2 parts per trillion over the detection limit. What exactly is a trillion? A trillion is a thousand billion which, in turn, is a thousand million.
1 part per trillion = 1 in 1 000 000 000 000
To answer the question “are biosolids to blame?” we have 5 articles that present results from groundwater surveys where people have looked for pharmaceuticals and other signs of human impact. If you take 7 billion humans and combine those with the parts per trillion you are bound to find something, and all of the papers in the library did this exercise. I could stop this blurb right here, but I won’t. You can also stop reading right here, and I won’t blame you if you do.
The first paper is a survey of the literature- always a good way to start. The authors divide pharmaceuticals into 24 classes, of which 4 main groups dominate the literature and concerns. Those groups are:
• NSAIDs -- non steroidal anti inflammatory drugs (ibuprofen and diclofenac) • Anticonvulsants -- read carbamazepine as the main culprit
• Lipid regulators -- drugs to lower cholesterol such as gemfibrozil or lopid.
The first table is an exhaustive (or exhausting) list of different types of drugs and some of their metabolites along with references. One great illustration shows pathways of drugs to water, with households and animal farming as the two points of origin. If you want to skip the article and just look at the figure, here it is:
The next table tells you the percentage of each compound ends up in your pee, a/k/a excretion rates of different pharmaceuticals. Importantly, we don’t absorb a high percentage of the pills we take. Further illustrations report concentrations in surface waters for NSAIDS and antibiotics from a wide range of data sources primarily in the US and Europe, and the report discusses likely fates in the environment.
The second paper is a broad survey of US drinking waters, including water from 19 water utilities servicing 28 million people. Source water (rivers and lakes primarily) were also sampled. Pharmaceuticals were found, typically at concentrations less than 10 ng l or 10 ppt and were more common in source waters than in water following treatment: ”The 11 compounds which were detected in greater than half of source waters were atenolol, atrazine, carbamazepine, estrone, gemfibrozil, meprobamate, naproxen, phenytoin, sulfamethoxazole, TCEP, and trimethoprim.”
It turns out that the type of chemical oxidation used at the plant (ozone or chlorine) impacts whether compounds will be identified. The paper tabulates compounds, minimum detection limits, ranges of concentrations in source and treated waters and removal efficiencies. To reiterate the initial point, between the 7 billion and parts per trillion, if you look, you will find something.
The third paper focuses on waters in Southern California, where source water for drinking is from the Colorado River and the CA State Water Project. Concentrations of compounds in source waters were highest when water flows were lowest and at the high points concentrations were comparable to those in reclaimed wastewaters. No surprise, based on the first two papers. Concentrations were also generally lower in the treated waters in comparison to the source waters. The authors cite wastewater discharge into the source waters as the primary source of the compounds.
What if your drinking water comes from a well instead of a river? The last two papers in the library focus on concentrations of these compounds (here also personal care products and other anthropogenic indicators as well as pharmaceuticals) in groundwater.
The first of the two groundwater studies is from the USGS group that has been a leader in finding these compounds in waters, soils and biosolids. They sampled waters where impacts were expected -- near landfills, unsewered communities and animal feedlots. They found at least one detect in 81% of the 47 sites sampled. The most common detects were insect repellants (35%), bisphenol A (30%), tri(2chloroethyl) phosphate [a flame retardant] (30%), sulfamethoxazole [antibiotic] (23%) and 4- octylphenol monoethoxylate [from detergents] (19%). They note that some of the hits may have come from the process of installing the sampling wells.
The second groundwater study sampled wells in Cape Cod, MA, where most residents are on septic systems. Twenty wells were sampled for 92 compounds and at least one of those 92 were found in 75% of the wells. The most commonly found compounds were an antibiotic (60% of the samples) and perfluorooctane sulfonate,- a surfactant (40% of the samples). It appears that many of the residents in Cape Cod got the Stainmaster carpets. Nitrate concentrations in water were strongly correlated with PCPPs. Septic systems are the source of the nitrates, and nitrates are much easier and cheaper to test for than pharmaceuticals.
There you have it. As I said early on in this summary, pristine waters are hard to find. Even if you buy bottled, that bottle is often plastic and will often leave some trace. Buying bottled also leads to huge issues of waste and more evidence of our imprint on this planet. Lowering our environmental footprint is the solution here, not banning biosolids.
Sally Brown, University of Washington