On March 14th, the U.S. Environmental Protection Agency (EPA) took two significant actions with the potential to significantly impact biosolids management. On that date, EPA published a notice in the Federal Register announcing the meeting schedule for the Science Advisory Board (SAB) Biosolids Panel. EPA also announced its proposed draft Maximum Contaminant Levels for several per- and polyfluoroalkyl substances (PFAS) in drinking water. Both actions have been expected for a while now. The EPA began the process of establishing the SAB back in September of 2021 with a call for experts to serve on the panel. EPA’s PFAS Strategic Roadmap from October 2021 announced its intent to develop MCLs on a fast-track.
The March 14th Federal Register notice that the EPA SAB will begin its work contained basic information on the SAB’s charge as well as details on the meeting schedule. EPA’s stated goal for this panel is to help modernize, standardize, and streamline the biosolids risk assessment process. The FR notice was followed closely by outreach to biosolids stakeholders from EPA Headquarters Biosolids Program.
In an email sent out on March 15th, Elizabeth (Betsy) Behl, Director of the Health and Ecological Criteria Division in the Office of Science and Technology under EPA’s Office of Water, explained:
“EPA is proposing a three-step process to (1) prioritize the risk assessment of chemical pollutants reported in biosolids, (2) conduct screening-level risk assessments using a customized model for this purpose, and (3) conduct more refined risk assessments for chemicals that pose the greatest potential risk to human health or the environment. The use of a scientifically defensible prioritization method and screening-level model will aid the agency in focusing resources on chemicals in biosolids that have the greatest potential to result in risk to human health and the environment. The screening process may also identify areas of research needed to address data gaps and uncertainties. Refined risk assessments will be conducted for chemicals that do not pass the screening-level assessment. EPA is seeking input on the three-step process and the scientific credibility and usability of the model.”
In addition to a peer-review of EPA’s overall risk assessment approach, the SAB is being asked to review EPA’s Biosolids Screening Tool (BST) for its scientific credibility and usability. The BST will be used for screening-level assessments. EPA has provided this model to the SAB pre-loaded with 4 chemicals along with a User’s Guide. According to EPA sources, the 4 chemicals are acetominophen, aluminum, benzo(a)pyrene, and triclosan, examples of a pharmaceutical, a metal, a polycyclic aromatic hydrocarbon (PAH), and a pesticide (anti-microbial), in that order. They were chosen to emphasize the range of chemicals that need to be assessed and do not necessarily represent the most -- or least -- risky chemicals. All this information, including the BST model, is available for download by the public. For more information on the SAB including the meeting agenda and materials, go to https://sab.epa.gov/ords/sab/f?p=100:18:7435319323204:::RP,18:P18_ID:2610.
The SAB meeting schedule is as follows:
April 5th – virtual meeting from 1 to 4 pm EST
May 2nd and 3rd – Virtual/in-person meeting from 9:30 am to 4 pm EST
May 31st – virtual meeting from 1 to 4 pm
Dr. Sylvie Brouder of Purdue University will serve as Chair of the SAB Biosolids Panel.
The public can submit comments to the SAB but it’s not like submitting comments on draft regulations. The SAB would welcome technical/scientific information to inform its work. See https://sab.epa.gov for more information on providing comment to the SAB.
Although not specifically addressing PFAS, the EPA methodology -- following scrutiny by the SAB -- will allow for very efficient screening and risk assessment of any pollutants of concern in biosolids. According to Behl’s email,
“As this SAB process proceeds, EPA is separately working to develop refined risk assessments for PFOA and PFOS, based on the latest science and consistent with the Agency’s PFAS Strategic Roadmap. EPA identified PFOA and PFOS as priority areas for risk assessment in 2019 and expects to complete these risk assessments by the end of 2024. EPA may use the SAB’s feedback in the final refined PFOA and PFOS risk assessments.”
The U.S. EPA is required to review pollutants in biosolids under Section 405(d) of the Clean Water Act. For a good article on how that process works, see NEBRA news article from April 7, 2021 (EPA Releases Biennial Review of Pollutants in Biosolids) or see EPA’s website: Biennial Reviews of Sewage Sludge Standards | US EPA.
Also as expected, the U.S. Environmental Protection Agency announced on March 14th its proposed stringent limits on PFAS in drinking water. These Maximum Contaminant Levels (MCLs) came down to the current limits of detection in the laboratory for PFOA and PFOS, the two most-studied long-chain PFAS compounds which are being phased out of production by 3M globally after stopping manufacture and use in products in the U.S. back in 2002. See Toxic timeline: A brief history of PFAS | Searchlight New Mexico (searchlightnm.org) for a timeline of the PFAS problem.
The proposed limits are as follows:
PFOA: 4 parts per trillion (ppt)
PFOS: 4 ppt
PFNA, PFHxS, PFBS, and HFPO-DA (commonly referred to as GenX Chemicals) will be grouped together under a Hazard Index formula where the limit will be 1.0 (no units). EPA will be providing access to an online calculator for the Hazard Index formula. It’s not clear how the Hazard Index would be implemented or enforced.
According to the EPA press release, EPA requests input on the proposal from all stakeholders. Comments should be submitted through the public docket, identified by Docket ID No. EPA-HQ-OW-2022-0114, at www.regulations.gov. As of this date, it has not been published in the Federal Register. For more information on this proposal, please visit EPA’s PFAS webpage [Per- and Polyfluoroalkyl Substances (PFAS) | US EPA].
Once the Federal Register notice is published, the public will have 60 days to comment. EPA will not be extending the deadline. EPA will be holding a public hearing on May 4, 2023, where members of the public can register to attend and provide verbal comments to EPA on the rule proposal. The deadline to register to speak is April 28, 2023. For questions related to the public hearing, contact PFASNPDWR@epa.gov.
There could be major implications for the practice of land applying biosolids if these MCLs are used as end points in the fate-and-transport models, such as the one being worked on by the Massachusetts Department of Environmental Protection. Research studies, such as the National Collaborative PFAS Study being conducted by Dr. Ian Pepper of the University of Arizona, (12) National Collaborative PFAS Study - YouTube, and those being done under EPA’s National Priorities grants looking at pollutants in biosolids [National Priorities: Evaluation of Pollutants in Biosolids Grants | US EPA] are more important than ever.