We helped two South Carolina municipal water facilities evaluate the effectiveness of their treatment plants in removing pharmaceuticals and personal care products (PPCPs) from wastewater. We found that both secondary-treatment-level facilities reduced most of these chemical contaminants by 90 percent, and that, while PPCPs were found in Charleston Harbor, the acute risk to animals in the harbor appeared low. These results may guide future treatment plant improvement decisions in coastal areas.
Why We Care
Over-the-counter, prescription, and veterinary drugs, as well as chemicals found in cosmetics and common household products wash down the drain and into our sewage systems. From there, they may enter our coastal waters. Over 100 PPCP contaminants are found in environmental samples and drinking water. Aquatic animals are continually exposed to PPCPs in the water and, because the products are designed to work at low doses, there is concern that even low concentrations could be harmful. Wastewater treatment plants are not designed to remove PPCPs, and we don’t know which treatment methods are most effective. There is a need to know which PPCPs are in our water and how to remove them and to develop tests to detect the subtle impacts of continual exposure of low-dose PPCPs on aquatic animals.
What We Are Doing
Because PPCPs are a relatively new problem, we are developing new analytic methods to measure them. For this project, we developed measurement methods for the 19 PPCPs we thought we were most likely to find. Then we collected sewage influent and effluent samples from the two treatment plants, and from Charleston Harbor, once a month for 12 months. Comparing chemical concentrations in the influent and effluent allowed us to evaluate the effectiveness of the two treatment plants in removing PPCPs. Measuring PPCPs in the harbor helped us understand the cumulative impact (with respect to the chemical loading) of PPCPs from all sources. Finally, monitoring for a year allowed us to detect seasonal trends in PPCP concentrations. We also compiled information on the number of prescriptions, chemical characteristics, and the environmental detection for more than 300 different PPCP compounds. This information is available to other scientists, resource managers, and the public as a Web-accessible database: http://products.coastalscience.noaa.gov/peiar/.
What We Found
We detected 11 different PPCPs in sewage influent, nine in sewage effluent samples, and seven in water samples from Charleston Harbor. Both plants removed 100 percent of two of the PPCPs. The concentrations of most PPCPs in harbor water samples were more than 90 percent lower than influent samples and at least 10 times lower than effluent samples. The chemicals that made it through the treatment plants were further diluted when released into the harbor. Our research indicated that acute risk to aquatic species from the individual PPCPs measured was low.
While the assessment in Charleston Harbor is complete, we remain concerned about risks from chronic exposure to low concentrations of PPCPs and complex mixtures of PPCPs. We are continuing to develop new methods to detect impacts of chronic exposure on marine animals and to measure additional PPCPs. Methods are being developed for a wide range of pharmaceutical compounds that include synthetic hormones, lipid regulators, antibiotics, and antidepressants.