Journal of Science Policy & Governance
​Volume 19, Issue 01 | November 01, 2021

Policy Memo: Unsafe at Low Levels: Adopt a Federal MCL for 1,2,3-Trichloropropane in United States’ Drinking Water

B. Hope Hauptman (1), Colleen C. Naughton (2)
  1. University of California Merced, Environmental Systems Graduate Group, Merced, CA
  2. University of California Merced, Department of Civil and Environmental Engineering, Merced, CA

Corresponding author: bhauptman@ucmerced.edu
Keywords: TCP; policy analysis; drinking water pollution, maximum contaminant level​

Executive Summary

​1,2,3-trichloropropane (TCP) is a toxic, man-made chemical used widely in agricultural and other contexts from the 1940s to the 1980s. TCP has settled into the groundwater supplies nearly everywhere it was used. In 2009, the Environmental Protection Agency (EPA) included TCP on the Third Contaminant Candidate list (CCL3) and listed the safe oral reference dose (RfD) for TCP at 0.004 milligrams per kilogram per day. Since then, we have learned that the scope of the TCP contamination problem is greater than first understood. At least 13 states and one territory have contaminated wells. Animal studies show that TCP is a potent carcinogen, and toxicology studies suggest that TCP is unsafe at levels at and above its 5 ppt detection limit. Three states, California, Hawaii, and New Jersey have adopted enforceable maximum contaminant levels of TCP in groundwater. As other states become aware of contamination levels, it is likely that some of them will also regulate TCP, but that could take many years. Federal legislation could mandate EPA advisories sooner than state legislation. The EPA has used the detection limit as the maximum for at least one other chemical, 1,2-Dibromo-3-chloropropane (DBCP), a common co-contaminant of TCP. We recommend that the EPA adopt TCP’s lowest detection level, 5 ppt, as the federal maximum contaminant level

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Background header image from U.S. Air Force by Alex Grotewohl through a Public Domain license
​B. Hope Hauptman is a third-year graduate student in Environmental Systems at the University of California Merced. Key objectives of her research are to understand historical land use patterns and 1,2,3-trichloropropane (TCP) contamination in California's Central Valley and to address social equity issues surrounding drinking water quality globally.  Ms. Hauptman recently published a systematic review of drinking water treatment methods for 1,2,3-trichloropropane (TCP) in the Journal Water Sanitation and Hygiene for Development. She previously taught high school science in the San Francisco Bay Area for over ten years and was a Volunteer Science Educator in the U.S. Peace Corps in Kenya. She earned a B.S. in Microbiology and Molecular Genetics (MMG) at University of California, Los Angeles and an MS in Instructional Science and Technology from California State University Monterey Bay.
 
Dr.  Colleen C. Naughton is an Assistant Professor in Civil and Environmental Engineering at the University of California Merced. Her lab co-designs sustainable Food-Energy-Water Systems for and with the UnderServed (FEWS-US) nationally and globally. The FEWS-US lab develops and utilizes methods in Life Cycle Assessment (LCA), Geographic Information Systems (GIS), integration of anthropology and engineering, and science policy. Prior to joining UC Merced, Dr. Naughton was an American Association for the Advancement of Science (AAAS) Science and Technology Policy Fellow in Washington D.C. She is a Returned Peace Corps Water, Sanitation, and Hygiene Volunteer from Mali, West Africa, and University of South Florida (M.S. and PhD.), and Purdue (B.S.) alumni in Civil Engineering.
 
Acknowledgements
The authors would like to acknowledge the contributions of Dr. Paul Tratnyek, professor at the Oregon Health & Science University School of Public Health, for providing background materials and sharing his knowledge of TCP contamination with the co-authors and to California State librarian Bradly Seybold for supplying the Pesticide Use Reports.

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