Source Article: Bernot, M.J., J.C. Becker, J. Doll, and T.E. Lauer. 2016. A national reconnaissance of trace organic compounds (TOCs) in United States lotic ecosystems. Science of the Total Environment 572: 422-433. https://doi.org/10.1016/j.scitotenv.2016.08.060
Imagine how many consumer products you might use in a given day. This morning you probably used some form of soap or shampoo, some toothpaste, maybe you took a medication like ibuprofen. I’m probably missing a few in this list. Got your number? Now amplify that by millions of people around the world also using the same products, or more, every day.
What happens to the ibuprofen that our body doesn’t metabolize? What happens to the fragrances in our soaps, or the sunscreen we wash off in the shower? Scientists are following those products down the drain to understand where the thousands of chemical compounds we use each day end up.
Several studies have documented the presence of these human products, also called “trace organic compounds” or TOCs, in freshwater systems both in the U.S.1,2 and abroad3,4. TOCs can include anything we use in our everyday lives from antibiotics to hand soap to bug spray. In the past few years, researchers aimed to add to this topic by trying to document not only what compounds we might find in our waterways, but also what factors might predict which and how many TOCs are present.
How Do TOCs Get into Waterways?
One of the main ways these compounds enter the environment is through the wastewater stream5. Essentially, after we use products or take medicine, the compounds our bodies don’t use go down the drain and into wastewater systems. Our current systems in the U.S. aren’t designed to filter out these compounds. As a result, hundreds of different chemicals are measured in our waterways at tiny concentrations.
In addition to the wastewater stream, several smaller pathways such as animal feeding operations, leaky septic tanks, and overall runoff may add to total TOCs in a water system. The hundreds of types of potential products traveling through several pathways make TOCs in waterways a particularly complex issue.
Why is This a Problem?
The effects of TOCs in the environment still aren’t well understood. Organisms can be exposed to small concentrations of lots of chemicals over time, and it isn’t clear how this exposure impacts stream ecosystems. Not to mention, we don’t understand how human health may be impacted when rivers and lakes become chemical cocktails. The Environmental Protection Agency has not set standards for the presence of many of these compounds in drinking water, highlighting the need for more information to understand how we should regulate these compounds in the future.
What? Where? How Many?
Researchers from Ball State University in Indiana, U.S. collaborated with university and community groups to sample 42 different sites spanning 25 states across the U.S. At each site (think streams and rivers), researchers took water and sediment samples, and analyzed them for the presence of 33 different TOCs including things like caffeine, sucralose (an artificial sweetener), common antibiotics and other medications. The team also looked at other factors such as nutrient levels in the water and population demographics to see if any of these could be used to predict TOC concentrations.
TOCs were found in 93% of the water samples taken. Only one site in Oregon didn’t have any TOCs detected in the water at all. In contrast, the researchers found TOCs in only half of the sediment samples, and the concentration was up to 1,000 times lower in some samples – making the case that these compounds stay dissolved in the water. This means that dissolved compounds may be more likely to enter drinking water facilities, and potentially reach our faucets.
The most frequently detected TOC was sucralose: it was found at 87.5% of sites, and at the highest concentration of any of the TOCs studied. The other two most common compounds found were caffeine and sulfamethoxazole, which is a widely-used antibiotic. At most sites, multiple compounds were detected, some with 19 in a single sample. The number of compounds found in each water sample was correlated with how many people lived in that area, and how much of the land was developed. However, the total concentration of compounds didn’t correspond with the number of people. For example, a higher population may have meant a larger number of different TOCs in the water, but not necessarily a greater total amount in terms of concentration.
What’s Next for TOCs?
Even though this study focused on only a small subset of the potential compounds we could find in the environment, it adds to the body of evidence that TOCs are essentially being found in waterbodies across the globe. While researchers found a few leads into predicting factors for how many compounds might be found in a stream or river, they acknowledge there is still a lot of work to be done on this issue.
It’s clear that when we use man-made products, the ingredients in those products don’t always end with us. More information on this issue might influence what products we use each day, as we track more and more of them down the drain.
- Kolpin, D. W., E. T. Furlong, M. T. Meyer, E. M. Thurman, S. D. Zaugg, Barber, L.B., Buxton, H.T., 2002. Pharmaceuticals, hormones, and other organic wastewater contaminants in US streams, 1999-2000: A national reconnaissance. Environ. Sci. Technol. 36(6), 1202-1211.
- Bernot, M.J., Justice, J.R., 2014. Survey of PPCPs in the US. In: Diaz, S., Barceló, D. (Eds.), The Handbook of Environmental Chemistry: Personal Care Products in the Aquatic Environment. Springer.
- Ellis, J.B. 2006. Pharmaceutical and personal care products (PPCPs) in urban receiving waters. Environ. Pollut. 144(1), 184-189.
- Hughes, S.R., Kay, P., Brown, L.E., 2013. Global synthesis and critical evaluation of pharmaceutical data sets collected from river systems. Environ. Sci. Technol. 409, 4553–4563
- Boxall, A. B. A., M. A. Rudd, B. W. Brooks, D. J. Caldwell, K. Choi, S. Hickmann, E. Innes, K. Ostapyk, J. P. Staveley, T. Verslycke, G. T. Ankley, K. F. Beazley, S. E. Belanger, J. P. Berninger, P. Carriquiriborde, A. Coors, P. C. DeLeo, S. D. Dyer, J. F. Ericson, F. Gagne, J. P. Giesy, T. Gouin, L. Hallstrom, M. V. Karlsson, D. G. J. Larsson, J. M. Lazorchak, F. Mastrocco, A. McLaughlin, M. E. McMaster, R. D. Meyerhoff, R. Moore, J. L. Parrott, J. R. Snape, R. Murray-Smith, M. R. Servos, P. K. Sibley, J. O. Straub, N. D. Szabo, E. Topp, G. R. Tetreault, Trudeau, V.L., Kraak, G.V.D., 2012. Pharmaceuticals and personal care products in the environment: What are the big questions? Environ. Health. Perp. 120(9), 1221-1229.