Staff from the U.S. Environmental Protection Agency’s various offices teamed up on an article titled “Curation of a List of Chemicals in Biosolids from EPA National Sewage Sludge Surveys & Biennial Review Reports” published in Nature on April 19, 2022. The lead author, Tess Richman, is from the Oak Ridge Institute for Science and Education (ORISE) and has been working in EPA’s Biosolids Program for a while now.  She was joined by Elyssa Arnold, formerly with the EPA Office of Water and now with the U.S. Department of Agriculture’s Office of Pest Management, and Antony J. Williams from EPA’s Office of Research & Development in Triangle Park, North Carolina.

The paper documents a major effort by EPA to curate – or scrutinize and compile all the data on all the pollutants identified in biosolids from the 8 biannual reviews and 3 national sewage sludge surveys (see Biosolids Library | US EPA).  EPA aggregated all the chemical name data, standardizing on the CAS Registry Numbers as the primary identifier for further analysis and data quality processes. 

This exercise brought the list of pollutants in biosolids up to 726 chemicals and “structure-based classes” found in biosolids “at least once”.  The list was up to 733 before EPA decided to remove seven nutrients in various forms from the list of “pollutants”.

The list of 726 chemicals is up from the 484 that came from the 3 National Sewage Sludge Surveys (NSSS) done for 1988, 2001 (focused on dioxins), and 2006 (targeting certain contaminants of emerging concern).  In the article, the authors cite inconsistent reporting and failure to cumulatively track pollutants as the reason the number has increased significantly.  Before 2021, the NSSS and biennial reviews were stand-alone efforts and the data had never been compiled like is it now.

To find the new, complete listing of pollutants found in biosolids, go to EPA’s CompTox Chemicals Dashboard: CompTox Chemicals Dashboard (epa.gov).  

Improving the data and making the chemical names consistent with other EPA programs allows for the data to be used in models and makes it easy to find available information about chemical fate and transport, concentrations in the environment, exposure pathways, and toxicity data. EPA currently has concentration data for the 484 chemicals previously identified by the NSSS which it plans to build on.

The new list of pollutants in biosolids will be used by EPA in its upcoming risk assessment process, getting underway this summer with a review of the proposed methodology by the EPA Science Advisory Board.  To learn more about EPA’s process for identifying pollutants in biosolids, read “EPA Releases Biennial Review of Pollutants in Biosolids” from 4/7/21 in News Archives — NEBRA (nebiosolids.org).