biosolids application

July 28, 2020 | Biosolids, Policies + Regulations

Scientific Rebuttal To EPA Inspector General Report On Pollutants In Biosolids


The U.S. Department of Agriculture’s Multistate Research Committee, known as W4170, completed a scientific rebuttal to the U.S. Environmental Protection Agency’s (EPA) Office of Inspector General (OIG) report issued in November 2018 titled “EPA unable to assess the impact of unregulated pollutants in land-applied biosolids on human health and the environment.” The W4170 is the latest iteration of USDA research committees that have been studying beneficial use of residuals to improve soil health and protect public and ecosystem health. This research work has been going on for 45 years and helped establish the basis of current EPA biosolids management regulations found in 40 CFR Part 503 — the EPA biosolids regulations. The North East Biosolids and Residuals Association (NEBRA) prepared this summary of the OIG findings and the W4170 rebuttal.

The 2018 OIG report criticized EPA for failure to assess 352 pollutants found in biosolids/residuals, including 61 considered acutely hazardous or defined as hazardous or priority pollutants under other federal environmental laws. Some of the list of pollutants came from EPA’s own Biennial Review that is required under Part 503. The OIG report also cited 291 “unlisted” pollutants that, they claimed, EPA had not assessed. The report by W4170 addresses both the listed and unlisted pollutant exposure risks from beneficial reuse of biosolids and tries to put them in perspective.

The OIG report has been used as justification to discontinue or hinder beneficial reuse programs across the country, notes NEBRA: “The W4170 research committee’s response to the OIG report is a much welcomed, albeit delayed, refutation of what EPA’s Office of Water characterized in its initial response to the OIG report as lacking science and context as well as being alarmist and biased. EPA pointed out that the mere presence of the pollutants mentioned in the OIG report does not indicate risk.”  The W4170 response agrees, concluding: “The OIG report alleged that ‘…[EPA] lacked the data or risk assessment tools needed to make a determination on the safety of 352 pollutants found in biosolids…’ Our review of literature showed extensive data and risk assessment, some conducted by USEPA, exists for the pollutants listed by OIG. In short, the above statement in the OIG is inaccurate and alarmist.”

The W4170 report points out that — concentration-wise — there are many other much greater sources of human exposure to almost all of these pollutants than from their presence in biosolids/residuals.  There were, however, several chemicals that the W4170 report suggests require further study, including several persistent pharmaceuticals.  The work on the W4170 report included extensive literature research/citations.  The review of the unlisted chemicals was broken down into groups of chemicals such as antibiotics/antimicrobials, metals, brominated flame retardants, dioxins, pharmaceuticals, hormones, pesticides, and pathogens.  The report also contains a section summarizing “PFAS: A Challenging Current Concern.”

In the aftermath of the OIG report, the Water Environment Federation (WEF) organized a national biosolids convening meeting in November 2019 at which EPA was urged to reinvest in its biosolids program and increase regulatory oversight and compliance activities with respect to the Part 503 program.  At that meeting, EPA acknowledged that there were areas where improvements were needed, and was working on convening a meeting with all the state and tribal biosolids coordinators, hiring additional staff to do the risk assessment work, and fast-tracking the risk assessment work. Due to COVID-19, the meeting has not been held. However, WEF hosts monthly meetings with EPA and various stakeholders such as the Water Research Foundation, the National Association of Clean Water Agencies, NEBRA and other regional biosolids organizations to better coordinate activities to improve biosolids management and enhance opportunities for beneficial reuse.


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