Unravelling the magnitude and drivers of PFAS trophic magnification: a meta-analysis – Nature

Executive Summary

A global-scale meta-analysis of 119 food webs reveals that Per- and polyfluoroalkyl substances (PFAS) represent a significant and quantifiable threat to global ecosystems and the achievement of the Sustainable Development Goals (SDGs). On average, PFAS concentrations double with each trophic level increase (mean Trophic Magnification Factor [TMF] = 2.00), indicating severe bioaccumulation that directly undermines SDG 14 (Life Below Water) and SDG 15 (Life on Land). Notably, the industrial alternative F-53B exhibits the highest magnification (TMF = 3.07), a critical finding that challenges SDG 12 (Responsible Consumption and Production), as this compound currently lacks significant regulatory scrutiny. The analysis identified that methodological disparities across studies are the dominant source of variability in magnification estimates, hindering accurate risk assessment. This synthesis establishes PFAS as persistent trophic multipliers and provides a framework to prioritise high-risk compounds. The findings call for stricter global regulation and harmonised biomagnification assessments to protect ecosystem integrity and public health, in line with SDG 3 (Good Health and Well-being) and SDG 6 (Clean Water and Sanitation).

Introduction: PFAS Contamination and the Sustainable Development Goals

The increasing destabilisation of ecological networks by human activities, particularly through contamination by persistent toxic chemicals, poses a direct threat to global sustainability. Per- and polyfluoroalkyl substances (PFAS), engineered for durability, have led to global environmental infiltration, undermining progress towards key Sustainable Development Goals.

• SDG 14 (Life Below Water) & SDG 15 (Life on Land): The persistence of PFAS threatens the integrity of aquatic and terrestrial food webs, accelerating biodiversity decline.
• SDG 6 (Clean Water and Sanitation): The widespread presence of PFAS in water sources, from industrial zones to remote habitats, compromises water quality for both ecosystems and human consumption.
• SDG 3 (Good Health and Well-being): Trophic magnification concentrates PFAS in apex predators, including humans, at levels far exceeding environmental background concentrations, creating significant health risks.

Inconsistent reporting on PFAS trophic magnification has hindered predictive modelling and regulatory action. This report presents a global meta-analysis to quantify PFAS biomagnification, resolve ambiguities, and provide a scientific basis for policies that support the SDGs.

Global Meta-Analysis Findings

Systematic Review Overview

The meta-analysis synthesised data from 64 studies, providing a comprehensive global dataset.

• Scope: 1,009 Trophic Magnification Factors (TMFs) were analysed from 119 food webs and 72 distinct PFAS compounds.
• Ecosystem Focus: 85% of the food webs studied were aquatic (freshwater, marine, and estuarine), highlighting the profound impact of PFAS on achieving SDG 14.
• Geographic Bias: A significant bias towards the northern hemisphere (East Asia, Europe, North America) was observed, indicating a critical data gap for the southern hemisphere.
• Compound Focus: Legacy compounds like PFOS were most studied, while emerging PFAS represented only 1% of TMFs, pointing to a need for more research on newer chemical threats.

Overall Trophic Magnification

The analysis revealed a statistically significant overall TMF of 2.00. This indicates that, on average, the concentration of PFAS doubles with each successive trophic level. This finding provides stark evidence of biomagnification, directly threatening the health of organisms at the top of food chains and compromising the stability of ecosystems central to SDG 14 and SDG 15. However, magnification varied considerably among different PFAS compounds.

Compound-Specific Magnification and Regulatory Gaps

Analysis of individual compounds identified twelve PFAS with significant trophic magnification. This data is crucial for prioritising regulatory action to support SDG 12 (Responsible Consumption and Production).

1. F-53B: TMF = 3.07 (Highest magnification). This industrial replacement for PFOS is largely unregulated internationally, posing a severe and unaddressed risk.
2. PFOS: TMF = 3.02. A legacy compound regulated under the Stockholm Convention.
3. PFDA: TMF = 2.80.
4. PFUnDA: TMF = 2.41.

The high TMF of F-53B demonstrates a failure in sustainable chemical management, where a replacement substance proves more bioaccumulative than the one it replaced. This “regrettable substitution” undermines the principles of responsible production.

Primary Drivers of Variability

The meta-regression model explained 85% of the variation in TMFs, revealing that methodological choices, rather than ecological differences, were the primary drivers of variability. This lack of standardisation is a major barrier to effective global monitoring and regulation, impacting the collaborative efforts needed for SDG 17 (Partnerships for the Goals).

• Sample Type: TMFs calculated using tissue-specific samples (e.g., liver, muscle) were 50% higher than those based on whole-organism samples, leading to potential overestimation of risk.
• Concentration Normalisation: TMFs based on non-normalised concentrations were 44% higher than those adjusted for lipid or protein content.
• Data Handling: The method used to handle undetected values was also a significant predictor of TMF.

Discussion: Implications for Sustainable Development

Threats to Ecosystems and Human Health (SDGs 3, 14, 15)

The evidence for PFAS amplification up the food chain confirms a significant threat to biodiversity and health. The doubling of concentrations at each trophic level places apex predators at extreme risk, potentially destabilising food webs and reducing ecosystem resilience. For humans, consumption of contaminated wildlife and fish from the upper trophic levels presents a direct pathway for exposure to toxic chemicals, jeopardising SDG 3 (Good Health and Well-being).

The Case of F-53B: A Challenge to Responsible Production (SDG 12)

The finding that F-53B, a replacement for PFOS, exhibits the highest trophic magnification is a critical indictment of current chemical management practices. This highlights a pattern of “regrettable substitution” where phased-out chemicals are replaced by alternatives with equally or more hazardous properties. This practice is fundamentally at odds with SDG 12, which calls for the environmentally sound management of chemicals and wastes throughout their life cycle to minimise their adverse impacts on human health and the environment.

The Need for Global Standards and Policy Action (SDGs 6, 17)

Methodological inconsistencies across studies obscure the true ecological risks of PFAS biomagnification, undermining effective risk assessments and delaying targeted regulations. To protect global water resources (SDG 6) and ecosystems (SDGs 14 & 15), a harmonised international approach is essential. Achieving this requires robust partnerships (SDG 17) among researchers, regulatory bodies, and industry to establish standardised protocols for biomagnification assessment. Such standards are a prerequisite for creating evidence-based policies that can effectively curb the production and release of bioaccumulative chemicals.

Recommendations for Future Research and Policy

To improve the accuracy of TMF estimation and support evidence-based policymaking aligned with the SDGs, the following actions are recommended:

1. Standardise Sampling Methodologies: Researchers should convert tissue-specific concentrations into whole-body equivalents to ensure comparability across trophic levels. Where this is not possible, analysis of multiple tissues is recommended.
2. Enhance Reporting Transparency: Studies should report TMFs using both non-normalised and protein-normalised concentrations to facilitate cross-chemical comparisons and standardisation.
3. Improve Trophic Level Estimation: Researchers should evaluate the sensitivity of their results to variations in the chosen nitrogen isotope trophic enrichment factor (TEF) to avoid misrepresenting biomagnification patterns.
4. Strengthen Chemical Regulation: Policymakers must take urgent action to regulate high-risk compounds like F-53B. Global treaties and national regulations should be expanded to prevent the widespread use of unassessed, highly bioaccumulative chemical alternatives, thereby promoting truly responsible production and consumption patterns (SDG 12).

Analysis of Sustainable Development Goals (SDGs) in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

1. SDG 3: Good Health and Well-being

   • The article directly connects PFAS contamination to health risks. It states that PFAS threaten ecosystems due to their “toxicity” and that their concentration in apex predators, “including humans,” can exacerbate “health crises across species.” This highlights the goal of ensuring healthy lives and promoting well-being.

2. SDG 6: Clean Water and Sanitation

   • The article discusses the “global environmental infiltration” of PFAS, which has led to their presence in “water and wastewater.” This links the issue to the need for clean water and the management of water pollution.

3. SDG 12: Responsible Consumption and Production

   • The article addresses the production and use of PFAS, noting they are “synthetic chemicals specifically engineered for durability” and are used in “more than 200 categories of products.” The call for “stricter PFAS regulation” and the discussion of industrial alternatives like F-53B directly relate to achieving environmentally sound management of chemicals and promoting sustainable production patterns.

4. SDG 14: Life Below Water

   • A significant portion of the analysis focuses on aquatic ecosystems. The meta-analysis includes “119 aquatic and terrestrial food webs,” with 85% being aquatic (freshwater, marine, estuarine). The article’s core finding of PFAS bioaccumulation and trophic magnification demonstrates a direct threat to the health and integrity of aquatic life.

5. SDG 15: Life on Land

   • The article also examines terrestrial food webs and notes that PFAS contamination is “permeating ecosystems from industrial zones to remote habitats.” It warns that this contamination “accelerates biodiversity decline and amplifies vulnerabilities across ecosystems,” which directly pertains to protecting terrestrial ecosystems and halting biodiversity loss.

Specific SDG Targets Identified

2. What specific targets under those SDGs can be identified based on the article’s content?

1. Target 3.9: Substantially reduce deaths and illnesses from hazardous chemicals and pollution

   • The article’s emphasis on the “known toxicity” of PFAS and the risk of “exacerbating health crises across species” by concentrating in predators, including humans, aligns with this target’s goal of reducing illnesses from chemical contamination in air, water, and soil.

2. Target 6.3: Improve water quality by reducing pollution

   • The research highlights that PFAS have led to “global environmental infiltration, permeating ecosystems,” and specifically mentions their presence in “water and wastewater.” The study’s findings support the need to reduce the release of hazardous chemicals into water bodies to improve quality, as outlined in this target.

3. Target 12.4: Environmentally sound management of chemicals and all wastes

   • The article’s call for “stricter PFAS regulation to curb cascading ecological and health impacts” is a direct reflection of this target. The analysis of industrial alternatives like F-53B, which shows even higher magnification than the compound it replaced, underscores the importance of managing chemicals throughout their lifecycle to minimize their adverse impacts.

4. Target 14.1: Prevent and significantly reduce marine pollution

   • The study’s focus on aquatic food webs and the finding that “PFAS concentrations double with each trophic level increase” in these environments provides evidence of the pervasive nature of chemical pollution in marine and freshwater systems. This directly supports the objective of reducing pollution from land-based activities.

5. Target 15.5: Take urgent action to halt the loss of biodiversity

   • The article states that contamination by persistent toxic chemicals like PFAS is a “pervasive and escalating threat” that “accelerates biodiversity decline.” The destabilization of food webs through trophic magnification is a mechanism that contributes to the degradation of natural habitats and threatens species, aligning with the urgency of this target.

Indicators for Measuring Progress

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

1. Trophic Magnification Factor (TMF)

   • The TMF is the central quantitative metric of the article, defined as “the increase in the concentration of a chemical compound per trophic level.” The study provides specific TMF values for PFAS as a group (mean TMF = 2.00) and for individual compounds (e.g., F-53B TMF = 3.07). This indicator can be used to measure the bioaccumulation potential of chemicals in ecosystems, directly tracking progress towards reducing the impact of hazardous substances (Targets 3.9, 12.4, 14.1, 15.5).

2. Concentration of PFAS in Environmental Media and Biota

   • The article is based on measuring PFAS concentrations in various organisms (e.g., “whole-organism, tissue-specific”) and implies their presence in water and soil. Monitoring these concentrations over time serves as a direct indicator of pollution levels and the effectiveness of regulations aimed at reducing chemical releases (Targets 6.3, 12.4, 14.1).

3. Food Web Integrity and Biodiversity

   • The article implies that the health of food webs is an indicator of ecosystem stability. It states that PFAS contamination “risks destabilising ecological hierarchies and exacerbating health crises across species.” Therefore, monitoring the structure, species diversity, and resilience of food webs in contaminated areas can serve as an indicator of progress towards halting biodiversity loss and protecting ecosystems (Targets 14.1, 15.5).

Summary Table of SDGs, Targets, and Indicators

4. Create a table with three columns titled ‘SDGs, Targets and Indicators” to present the findings from analyzing the article.

Source: nature.com