The draft risk assessment released by the U.S. Environmental Protection Agency (EPA) delves into the potential human health risks associated with toxic per- and polyfluoroalkyl substances (PFAS), specifically PFOA and PFOS, which are often referred to as “forever chemicals.” These chemicals have been detected in biosolids, also known as sewage sludge. The draft findings indicate that the presence of PFOA and PFOS in biosolids could pose health risks when biosolids are used or disposed of via land application, surface disposal in landfills, or incineration. This draft assessment represents a significant step in the EPA’s ongoing efforts to understand and mitigate the public health impacts of PFAS in biosolids, guiding potential future actions to reduce exposure risks.
Understanding Biosolids
Biosolids are nutrient-rich organic materials resulting from the treatment of domestic sewage in a wastewater treatment facility. They are carefully treated and processed to ensure they can be safely recycled and applied as a soil conditioner. The use of biosolids can improve soil health, promote plant growth, and reduce the need for chemical fertilizers. However, there are regulations and guidelines in place to ensure that biosolids are used in a manner that protects public health and the environment.
What Are Biosolids?
Biosolids are nutrient-rich organic materials resulting from the treatment of domestic sewage in a wastewater treatment facility.
Biosolids are a semi-solid, nutrient-rich byproduct produced from the treatment of wastewater at municipal treatment plants. The term “biosolids” typically refers to sewage sludge that has been treated to meet regulatory standards and can be safely applied to land as a fertilizer or soil conditioner. These biosolids can be beneficially reused to enhance agricultural fields or non-agricultural lands by promoting plant health and productivity. The treatment processes involved in converting sewage sludge into biosolids include stabilization to reduce pathogens and odor, ensuring it meets the safety guidelines set by regulatory authorities for land applications.
The various stages of treatment ensure that the biosolids are transformed into a product that can be safely applied to land. The use of biosolids as a fertilizer or soil conditioner is a sustainable practice designed to recycle nutrients and organic material back into the soil, enhancing soil structure, increasing water retention, and promoting healthy crop growth. It also serves to reduce the volume of waste that would otherwise require disposal in landfills or incineration, presenting an environmentally friendly solution for managing organic waste generated by urban populations.
The Role of Biosolids in Agriculture
Biosolids play a crucial role in agriculture by providing essential nutrients to the soil, which can improve crop yields and soil health. The application of biosolids to farmland is a common practice as it recycles organic matter and nutrients back into the environment. This agricultural use promotes sustainable farming practices by replenishing the essential nutrients needed for plant growth, maintaining soil fertility, and helping to reduce the reliance on chemical fertilizers. Farmers value the use of biosolids for their ability to boost the organic matter content of soil, which can lead to enhanced soil aeration, improved water infiltration, and better root development.
However, the presence of contaminants like PFAS in biosolids raises concerns about the potential risks to human health and the environment. Even though biosolids contain essential nutrients for plants, the detection of PFAS raises questions about the safety of using these materials on crops destined for human consumption. It is crucial that the application of biosolids remains safe for agricultural use, ensuring that crops are free from harmful levels of contaminants that could pose risks to consumer health. This balance between agricultural benefit and environmental safety is at the core of the ongoing scrutiny and regulatory attention surrounding biosolids.
Draft Risk Assessment by the EPA
Focus of the Draft Risk Assessment
The draft risk assessment primarily focuses on a specific population that the EPA believes is most likely to be exposed to PFOA or PFOS through the land application of biosolids or through the consumption of products grown on land where biosolids were used as fertilizer. It models hypothetical human health risks for people living on or near affected sites and those relying on the products of these sites, such as food crops, animal products, or drinking water. By assessing a range of exposure pathways, including direct contact with treated soil and the ingestion of contaminated food and water, the EPA aims to paint a comprehensive picture of the potential health implications of PFAS in biosolids.
The assessment examines various scenarios, taking into consideration different levels of PFAS concentrations in biosolids, varying frequencies and amounts of biosolids applications, and diverse environmental conditions. This nuanced approach allows the EPA to identify specific groups or communities that may be at higher risk of exposure. It also highlights “hot spots” where concentrated use of contaminated biosolids could pose significant health risks and underscores the need for targeted risk mitigation strategies. By focusing on these populations, the EPA hopes to prioritize groups that may face the highest exposure, guiding effective interventions to reduce their risk.
Preliminary Findings and Health Risks
The preliminary findings of the draft assessment suggest that exposure to PFOA or PFOS from biosolids could lead to health risks that exceed the EPA’s acceptable thresholds, sometimes by several orders of magnitude, especially in scenarios involving farms where biosolids are applied frequently and in considerable amounts. The analysis presented in the draft risk assessment highlights that the risks associated with exposure to PFOA and PFOS in biosolids are influenced by several factors, including the concentration of these chemicals in the biosolids, the amount of biosolids applied, and site-specific conditions such as geography, climate, soil conditions, and agricultural practices.
The EPA’s analysis reveals that certain practices, such as applying large quantities of biosolids over extended periods, can result in a build-up of PFAS in the soil and potentially in crops and water sources. For example, continuous application over 40 years could significantly elevate the levels of these chemicals in the environment, raising long-term exposure risks for local populations. It also shows that site-specific variations, like different soil types or climatic conditions, may affect how PFAS behaves in the environment and, consequently, how it might impact human health. The assessment points out that reducing the concentration of PFAS in biosolids or limiting their application can be effective strategies in mitigating these risks.
EPA’s Analysis and Findings
In its recent comprehensive review, the EPA uncovered significant variations in air quality across urban and rural areas, highlighting the ongoing challenges in pollution control. The analysis revealed that while some urban centers have made substantial progress in reducing emissions, rural areas often face persistent issues due to agricultural practices and limited regulatory oversight. These findings underscore the need for tailored strategies that address the unique sources of pollution in different regions. Furthermore, the report calls for increased collaboration between state and federal agencies to implement effective pollution mitigation measures and ensure sustainable improvements in air quality nationwide.
Factors Influencing Risk Levels
The risks are notably higher in cases where biosolids containing 1 part per billion (ppb) of PFOA or PFOS are applied to farmland at a rate of 10 dry-metric-tons per hectare for 40 consecutive years or disposed of in unlined or clay-lined surface disposal units. Even though there is evidence of health risks from such scenarios, the assessment also notes that general food supply safety is not compromised broadly by the use of biosolids with PFAS when managed under safe practices. This suggests that while targeted interventions are necessary in high-risk areas, widespread agricultural use of biosolids does not pose a universal threat to the safety of the food supply.
Understanding these influencing factors allows for a more precise approach to risk management. For instance, tailored practices can ensure safer application rates, appropriate disposal measures, and effective monitoring and regulation of PFAS concentrations in biosolids used in agriculture. Furthermore, it highlights the importance of continued research and data collection to refine these strategies, adapting them to specific environmental conditions and evolving scientific knowledge. This careful balance between the benefits and risks associated with biosolids use is key to protecting public health while supporting agricultural productivity.
Hot Spots and Specific Farming Operations
The EPA acknowledges that certain “hot spots” or specific farming operations might exhibit higher levels of PFOA or PFOS due to the application of contaminated sludge. This underscores the necessity for collaboration with affected farming operations and other federal agencies to fully assess the risks and support impacted farmers. Identifying and addressing these areas requires a concerted effort between regulatory bodies, researchers, and the agricultural community to implement targeted measures that can effectively mitigate localized risks. This might include enhanced monitoring systems, alternative soil management practices, or the development of cleaner biosolid treatment technologies.
A clear trend identified in the risk assessment is that reducing the concentration of PFOA and PFOS in biosolids or decreasing the amount of biosolids applied to land can significantly lower the associated risks. This relationship indicates that by mitigating the input of these contaminants into the biosolids production process, overall human health risks can be markedly reduced. Prioritizing source reduction and treatment methods that effectively remove or neutralize PFAS before biosolids are applied to land will be critical in safeguarding both public health and agricultural productivity. Collaborative efforts at both the federal and state levels, alongside partnerships with the private sector, will be essential in driving these innovations forward.
Federal and State Response
EPA’s Strategic Roadmap
Under the Biden administration, the EPA has taken unprecedented steps to advance research, establish policies, and protect public health from PFAS exposure. This includes the PFAS Strategic Roadmap, which provides tools to restrict PFAS entry into the environment and hold polluters accountable. The roadmap also encourages states to use their regulatory abilities to mandate the removal of PFAS from industrial discharges before they reach wastewater treatment plants. This proactive approach aims to tackle the problem at its source, reducing the burden on wastewater treatment facilities and ensuring that biosolids produced are safer for agricultural and other uses.
The PFAS Strategic Roadmap outlines a series of planned actions, including expanding research into PFAS alternatives, promoting public awareness about PFAS risks, and enhancing regulatory frameworks to address PFAS contamination comprehensively. One key element of the roadmap is the implementation of stricter guidelines for industries known to discharge PFAS, as well as increased monitoring and enforcement of these regulations. By working closely with state and local governments, the EPA seeks to build a cohesive strategy that addresses both existing contamination and prevents future PFAS releases into the environment.
Technology-Based Limits and Industrial Sectors
Operational advances include the EPA’s planned technology-based limits on discharges from several industrial sectors that are known sources of PFAS, such as PFAS manufacturers, electro- and chrome-platers, and landfills, as part of the Effluent Limitations Guidelines program. These limits aim to reduce the concentration of PFAS in industrial effluents, ultimately decreasing their prevalence in municipal wastewater and biosolids. Industry-specific standards are crucial in targeting the primary sources of PFAS pollution, holding those responsible accountable, and incentivizing the adoption of cleaner technologies and practices.
The contamination of biosolids with PFOA and PFOS occurs through wastewater treated at municipal facilities, which receive these chemicals from diverse sources, including industrial sites and households. PFAS can enter the municipal wastewater systems from consumer products like non-stick cookware, waterproof clothing, and certain cosmetics. Even though wastewater treatment plants do not intentionally add these chemicals, the widespread use and historical accumulation of PFAS in various products lead to their presence in treatment plant influents and subsequently, in the biosolids. Addressing PFAS at the industrial and consumer product level is essential in reducing their overall environmental footprint and mitigating the risks associated with contaminated biosolids.
Impact on Wastewater and Sewage Sludge
Wastewater pollution significantly affects the quality of sewage sludge produced by wastewater treatment plants. Contaminants present in wastewater, such as heavy metals, pharmaceuticals, and microplastics, end up concentrating in the sludge. This raises serious environmental and public health concerns, as sewage sludge is often used in agriculture or disposed of in landfills. Effective management and treatment of wastewater are essential to mitigate the impact on sewage sludge and ensure compliance with environmental regulations. Moreover, addressing wastewater pollution at the source can greatly reduce the burden on treatment facilities and lead to a more sustainable and safer sludge management approach.
The draft risk assessment underscores the significant challenge posed by PFAS contamination in wastewater and sewage sludge. Municipal waste treatment facilities have traditionally focused on removing conventional pollutants and pathogens, but not necessarily chemicals like PFAS that persist in the environment. The presence of these “forever chemicals” in incoming wastewater poses a complex problem, as they are resistant to degradation and can pass through traditional treatment processes largely unchanged. This persistence not only threatens the quality of biosolids produced but also implicates broader environmental and public health risks when treated wastewater is discharged into natural water bodies.
The contamination of biosolids with PFOA and PFOS highlights the need for enhanced wastewater treatment technologies that can effectively remove or neutralize PFAS before they accumulate in biosolids. Current efforts and research involve exploring advanced treatment methods, such as activated carbon filtration, ion exchange, and advanced oxidation processes, which show promise in reducing PFAS levels. These technologies must be integrated into existing wastewater treatment infrastructures in a cost-effective manner, ensuring they are accessible and feasible for widespread adoption by treatment plants across the country.
Future Actions and Risk Management
The draft risk assessment is a crucial tool for understanding the scope and scale of PFAS contamination in biosolids. Once finalized, it will assist the EPA in determining appropriate risk management measures, which may include regulatory actions under the Clean Water Act. The agency’s ongoing efforts, such as setting national drinking water standards for PFAS and designating PFOA and PFOS as hazardous substances under the Superfund law, reflect a comprehensive strategy to tackle PFAS pollution. The comprehensive risk management approach considers various factors, including direct regulatory measures, industry accountability, and public awareness campaigns, to mitigate PFAS exposure and its associated health risks.
Future actions will likely involve stronger collaboration between federal, state, and local agencies to monitor and manage PFAS levels in biosolids and the environment. This could include revising allowable limits for PFAS in biosolids, enhancing testing and reporting requirements for wastewater treatment facilities, and developing remediation techniques for contaminated sites. Stakeholders across different sectors, from agriculture to industry, will need to work collectively to implement effective solutions that protect public health while ensuring sustainable practices. Moreover, ongoing research and technological advancements will play a critical role in discovering new ways to efficiently eliminate PFAS from wastewater and biosolids.
State-Level Initiatives
Several states have proactively begun monitoring PFAS levels in sewage sludge and have published their findings. These state-level initiatives will be instrumental in providing additional data and insights that can inform national standards and policies. The EPA’s draft risk assessment cites these state reports and other peer-reviewed literature, consolidating existing data to provide a broader understanding of the occurrence and risks of PFOA and PFOS in biosolids. By leveraging this state-level data, national regulations can be more accurately tailored to address specific regional conditions and pollution sources, ensuring a more effective response to the PFAS challenge.
The collaboration between state and federal efforts enhances the overall effectiveness of risk mitigation strategies. States adopting stringent PFAS regulations and conducting rigorous monitoring provide valuable models for best practices that can be replicated or adapted by other regions. These initiatives also foster innovation in treatment technologies and regulatory frameworks, potentially leading to more universal solutions to PFAS contamination. Engaging local communities and stakeholders in these processes is essential for ensuring that measures are practical, widely accepted, and successful in reducing PFAS levels in both biosolids and the broader environment.
Conclusion
The U.S. Environmental Protection Agency (EPA) released a draft risk assessment focusing on the potential human health risks posed by toxic per- and polyfluoroalkyl substances (PFAS), specifically PFOA and PFOS, often called “forever chemicals.” These substances have been detected in biosolids or sewage sludge. According to the draft, the presence of PFOA and PFOS in biosolids could present health risks when these biosolids are used or disposed of through land application, surface disposal in landfills, or incineration. This assessment is a crucial step in the EPA’s ongoing effort to comprehend and mitigate the public health impacts of PFAS found in biosolids, steering possible future actions aimed at reducing exposure to these chemicals. The Agency’s work highlights the persistent nature of PFAS and the importance of understanding their long-term effects on human health and the environment. This insight is aimed at developing better management practices and regulatory actions to ensure public safety.