INSIGHTS ALONG THE PATH TO SUSTAINABILITY| November 30, 2005

Municipal Sludge Disposal and Sustainable Agriculture: A Pilot Study Showcasing the Challenge of Combining the Two

ROLF U. HALDEN, PHD, PE, Assistant Professor, Department of Environmental Health Sciences, JHSPH (Presenter)
AMIR SAPKOTA, PH.D., Postdoctoral Fellow, Department of Environmental Health Sciences, JHSPH
JOCHEN HEIDLER, M.S., Doctoral Student, Department of Environmental Health Sciences, JHSPH
JOCELYN KEEHNER, Research Intern, Department of Environmental Health Sciences, JHSPH

SUMMARY

This pilot study sought to elucidate the environmental behavior of triclocarban, N-(4-chlorophenyl)-N'-(3,4-dichlorophenyl)urea, a non-agricultural polychlorinated diphenyl urea pesticide, used primarily as an antibacterial additive in personal care products. Mass-produced at rates approaching one million pounds per year, triclocarban had managed to escape the attention of environmental chemists and toxicologists for almost half a century. In 2004, our research group developed an analytical method for triclocarban and published the first peer-reviewed environmental occurrence data for the U.S since introduction of the chemical in 1957. Study results demonstrated that TCC resists aerobic and anaerobic biodegradation during municipal wastewater treatment and accumulates to mg/kg quantities in municipal sludge used as an agricultural fertilizer in the production of citrus fruits and other crops. The hypothesis of the proposed study was that agricultural plants (e.g., oranges, green salad, carrots, soy beans, and carrots) take up triclocarban from sludge-amended soils, thereby leading to unwanted ingestion and human exposure to the potential carcinogen/mutagen TCC and to its toxic and carcinogenic breakdown products. Specific aims of the project were to (A) determine the persistence of triclocarban in soil, (B) study whether the compound is taken up and accumulated in plants grown on sludge-amended soils, and (C) determine the presence of the compound in citrus fruits that traditionally are grown using municipal biosolids as a soil conditioner and fertilizer. Study results will be presented and discussed in the context of regulatory activities by the U.S. Environmental Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA).

PRESENTER BIOGRAPHY

Rolf Halden graduated from the Technical University of Braunschweig, Germany, with a M.S. in Biology, and earned a M.S. and Ph.D. in Civil/Environmental Engineering from the University of Minnesota. He is a certified Professional Engineer who specializes in water quality issues and bioremediation, i.e., the use of microorganisms for environmental restoration. Prior to joining Johns Hopkins, Dr. Halden was an Environmental Scientist and Project Leader at the Lawrence Livermore National Laboratory Superfund Site 300. Since joining JHU in 2001, Dr. Halden has conducted research on the fate of anthropogenic compounds in the environment and on the structure and dynamics of microbial communities responsible for the transformation and detoxification of anthropogenic pollutants, including pharmaceuticals and personal care products (PPCPs). Dr. Halden is a member of the JHU Center for Water and Health and currently serves on the Maryland State Water Quality Advisory Committee.