Multi-State Survey Measures Parabens in Municipal Wastewater Biosolids

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This study provides new information about the composition and concentrations of 5 parabens—preservatives in pharmaceuticals and personal care products—present in biosolids collected from 14 municipal wastewater treatment plants across the United States.

Chemicals that we use in our everyday lives, including medicines (for example, prescription and non-prescription drugs), personal hygiene products (for example, soaps and disinfectants) and their chemical additives (for example, preservatives), have been determined by the U.S. Geological Survey (USGS) and others to be present in the environment.

Parabens such as methylparaben, ethylparaben, propylparaben, and butylparaben are commonly used biocides in pharmaceuticals and personal care products to prevent harmful yeast, bacteria and mold growth. Their use as pharmaceutical preservatives began in the 1920s and broadened because of their antimicrobial properties. Production and usage of products containing parabens can result in their release to the environment through various waste streams potentially including biosolid (the solid residue left after municipal wastewater treatment) application in urban and agricultural landscapes.

According to a report from the U.S. Environmental Protection Agency in 2006, approximately 8 million dry metric tons of biosolids are produced annually in the United States, about one-half of which is applied to land as fertilizer. This beneficial use of biosolids is widespread, with applications in commercial agricultural settings as well as by homeowners in gardens and landscapes.

Scientists from the USGS, Arizona State University, Colorado State University, and Stony Brook University determined the presence of five commonly used parabens collected from 14 municipal wastewater treatment plants in nine U.S. States to provide baseline concentrations of paraben content in biosolids.

Biosolids from a wastewater treatment plant were loaded onto trucks for transport to the field

Biosolids from a wastewater treatment plant were loaded onto trucks for transport to the field. A team of USGS scientists and their colleagues collected samples of biosolids for analysis from freshly exposed surfaces created by the machinery used to load the biosolids onto trucks.

(Credit: Dana W. Kolpin, USGS Central Midwest Water Science Center. Public domain.)

All five parabens were detected in study samples at concentrations similar to those observed in previously published research. Methyl paraben and propyl paraben were detected in 100 percent of samples, ranging in concentrations from 15.9 to 203.0 nanograms per gram and 0.5 to 7.7 nanograms per gram, respectively. Ethyl paraben, butyl paraben, and benzyl paraben were detected in 63, 42, and 26 percent of samples, respectively, with maximum concentrations of 2.6, 4.3, and 3.3 nanograms per gram, respectively.

A unique aspect of the study was the temporal monitoring conducted at one wastewater treatment plant, which provided insights into temporal and seasonal variations in paraben concentrations. Paraben concentrations in biosolids were greater during the fall and winter compared to spring and summer. These seasonal changes could be related to paraben use patterns or air temperature that may affect paraben degradation during treatment.

The USGS continues to support ongoing science related to identification and quantification of the environmental sources, presence, and magnitude of contaminants in order to understand the actual as compared to the perceived health risks to humans and other organisms.

The adverse effects resulting from human exposure to parabens in the environment are unknown. Human exposure is primarily through use of paraben-containing personal care products or consumption of foods or pharmaceuticals containing parabens. According to the Food and Drug Administration there is not sufficient information showing that parabens, as they are currently used, have any adverse effect on human health, and they are continuing to review published studies on the safety of parabens.

There is evidence that bacteria can develop resistance to parabens. Given their classification as antimicrobials, future research on parabens may focus on the effects of environmental paraben exposures on indigenous microbial communities and other organisms.

This study was supported by the USGS Toxic Substances Hydrology Program, Award Number R01ES020889 from the National Institute of Environmental Health Sciences, and by award LTR 05/01/12 of the Virginia G. Piper Charitable Trust.

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