The growing prominence of PFAS and other emerging contaminants is reshaping the legal landscape across environmental, tort, regulatory and corporate liability domains. Scientific progress, regulatory evolution, and legacy pollution are converging in ways that demand a deeper understanding of both the technical and legal dimensions of these substances.
As litigation escalates and statutory frameworks evolve, legal professionals increasingly find themselves navigating unfamiliar terrain. The complications arising from chemical persistence, variation in environmental mobility, increases in our understanding of human exposure pathways and toxicological effects, and the widespread historical uses of PFAS raises complex evidentiary challenges, often under conditions of incomplete data and without scientific consensus.
This article presents a structured overview of the current state of PFAS-related issues, recent regulatory and legal developments and the ways in which environmental experts, particularly those with experience in expert witness and technical litigation support, are supporting legal teams in this fast-evolving space.
PFAS and Emerging Contaminants: Scientific and Technical Context
Per- and polyfluoroalkyl substances (PFAS) comprise a diverse class of more than 12,000 synthetic compounds that have been used in industrial and consumer products since the mid-20th century. Their unique chemical structure, characterised by strong fluorinated carbon chains, makes them highly resistant to heat, oil, water and biological degradation.
Common applications historically included:
- Firefighting foams (notably aqueous film-forming foams or AFFF)
- Non-stick cookware
- Water-resistant textiles and carpets
- Food packaging, including paper and cardboard
- Cosmetics and repellents
- Industrial surfactants and emulsifiers
The defining characteristic of PFAS is their environmental persistence which has led to their reference in the media as ‘forever chemicals’. The widespread use and persistence of PFAS has led to the global contamination of soil, groundwater, and surface water, affecting remote ecosystems and public water supplies.
A growing body of toxicological and epidemiological research has linked certain PFAS compounds, such as PFOA and PFOS, to adverse health outcomes. These include increased cholesterol, immune suppression, reproductive and developmental toxicity, thyroid disruption and certain types of cancer. Importantly, many health endpoints have been identified at exposure levels far below historical regulatory thresholds.
Emerging contaminants more broadly include compounds such as microplastics, pharmaceutical residues, novel flame retardants, and industrial chemicals with incomplete regulatory status. As has been the case for PFAS, the scientific understanding of these substances with respect to their environmental degradation and transformation, toxicological impacts, and potential for cumulative exposure risks are at early stages and therefore governments have been slow to regulate these substances.
Legal and Regulatory Developments: A Shifting Framework
Regulatory Landscape
Across jurisdictions, regulatory agencies are moving steadily from advisory guidance toward enforceable limits on PFAS, accompanied by increased monitoring of obligations and liability exposures.
In Canada, PFAS regulation is progressing through both federal and provincial mechanisms. Health Canada has proposed national drinking water objectives for key PFAS compounds, while provinces are integrating PFAS considerations into environmental assessments and remediation programs. Regulatory frameworks continue to evolve in tandem with broader chemical management strategies, including the phased approach to restrict PFAS in firefighting foams, food packaging and in other industries starting this year.
Australia has adopted national guidance values for PFAS in drinking water, groundwater and soil through the Heads of EPAs Australia and New Zealand (HEPA). In June 20205 version 3 of the PFAS National Environmental Management Plan (PFAS NEMP) is Australia’s national guide for managing PFAS contamination in the environment was launched. Australia’s PFAS guidelines were also updated on June 25, 2025, by the National Health and Medical Research Council (NHMRC) with new, lower recommended limits for PFAS in drinking water. Previously the guidelines had recommendations for only three PFAS compounds in drinking water, the new guidelines introduce revised limits for PFOA, PFOS, PFHxS, and PFBS. Several state-level environmental protection authorities have issued complementary guidelines, and there is an active emphasis on site-specific risk assessment, especially related to legacy contamination from firefighting foam use at airports and military bases.
Across Asia, countries such as Japan and South Korea have initiated regulatory measures for selected PFAS compounds, including drinking water standards and product restrictions. However, the scope and enforcement mechanisms vary significantly and in many jurisdictions, formal regulation is still in early development stages.
In the European Union, PFAS are regulated under the REACH framework, with mounting support for a comprehensive restriction covering the entire class of substances. Several EU Member States, led by Germany, the Netherlands, Sweden and Denmark, have jointly submitted a proposal to ban thousands of PFAS compounds, reflecting growing concern over cumulative exposure and the limits of compound-by-compound regulation. The majority all have their own differing regulatory standards, and these can vary within the countries, region to region. National action plans and product-specific restrictions are already in place in various countries, creating a layered regulatory environment. New limits in the Drinking Water Directive, reducing it to 0.5 µg/l for total PFAS and 0.1 µg/l for 20 individual PFAS. and a broader restriction proposal was published by ECHA in August 2025.
In the United Kingdom there are currently no legally binding limits for PFAS in drinking water, though the Drinking Water Inspectorate (DWI) has issued guidance for water companies to monitor PFAS and take action if concentrations exceed 0.1 µg/l. Scotland has recnetly taken a more stringent approach with their standards and are aligned with the EU, Northern Ireland will see the same limits in 2026, as they are still aligned with the EU. There is developing guidance from regulators in the area of risk to human health from PFAS in soil and the government are actively reviewing the UK approach to the regulation of PFAS with evidence being provided by a UK regulators and interest groups. The regulator is also undertaking active research on how can PFAS to improve regulatory guidance on assessment methods in this area. The UK government is consulting on a potential restriction on PFAS in fire-fighting foams under UK REACH, with a consultation running until February 2026
In the United States, the regulations are evolving, the Environmental Protection Agency (EPA) has proposed limiting and updating the Maximum Contaminant Levels (MCLs) for six PFAS compounds in drinking water, including PFOA and PFOS, to 4 parts per trillion, which are expected to be finalised in the near future with it becoming finalized in 2026. Additionally, the EPA is moving to list PFOA and PFOS as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). If finalised, this designation would significantly expand remediation obligations and environmental liability exposure across industries. Parallel regulatory action is also underway at the state level, where standards can be more stringent and vary widely between jurisdictions.
Taken together, these developments reflect an increasingly complex and fragmented regulatory landscape. Variations in standards, testing protocols and compliance expectations across regions create challenges for multinational entities, particularly in managing historical liabilities, aligning operational practices and responding to jurisdiction-specific enforcement actions.
Litigation Trends
The legal response to PFAS contamination has rapidly intensified. Multiple types of litigation have emerged:
- Mass torts and class actions on behalf of individuals claiming personal injury from exposure to PFAS-contaminated drinking water or occupational sources.
- Municipal and state government lawsuits seeking cost recovery for infrastructure upgrades, environmental remediation and public health monitoring.
- Product liability and failure-to-warn claims targeting PFAS manufacturers and increasingly, downstream users and distributors.
- Contractual and property-based litigation involving indemnity claims, asset transactions and due diligence failures related to contaminated sites.
- Insurance coverage disputes, particularly involving historic general liability policies and pollution exclusions.
Litigation often spans decades of activity and may require reconstruction of historical site usage, industrial practices, chemical procurement records and disposal pathways. Given the widespread use of PFAS and the low assessment thresholds now considered relevant, many cases involve multiple potentially responsible parties, creating intricate questions around apportionment and causation.
Evidentiary and Strategic Challenges
Key challenges in PFAS litigation frequently include:
- Establishing the source and timing of contamination in areas with multiple industrial sources
- Quantifying exposure and evaluating dose-response relationships at trace levels
- Understanding the transport and fate of PFAS compounds in various environmental media
- Navigating inconsistent, changing or emerging regulatory standards
- Reconstructing decades-old site operations or disposal practices
In many cases, the ability to present technically robust, comprehensible and defensible evidence can significantly influence settlement positioning, judicial findings and regulatory negotiations.
Supporting the Legal Community: RSK Global Experts’ Role
At RSK Global Experts, we assist law firms, in-house legal departments, insurers and regulatory bodies with a comprehensive suite of scientific and technical services relevant to PFAS and emerging contaminant matters. Our approach combines deep subject matter knowledge with a practical understanding of regulatory proceedings.
Expert Witness Services
Our team includes environmental scientists, chemists, hydrogeologists and engineers who regularly serve as expert witnesses in environmental litigation.
We provide independent analysis and testimony on issues such as:
- The presence and extent of PFAS contamination
- Historical use and industrial pathways of specific compounds
- Environmental fate and transport modelling
- Human health risk assessment
- Technical evaluation of remediation technologies and cost estimates
Expert testimony is presented in formats suited to judicial, regulatory, and arbitration proceedings, with an emphasis on clarity, credibility and evidentiary reliability.
Subject Matter Expert (SME) Support
Our SMEs provide advisory support to legal teams throughout the lifecycle of a matter. This includes document review, expert consultation during discovery, technical assistance in preparing interrogatories or deposition questions and participation in joint expert sessions.
We also assist with early case assessments, support in evaluating opposing expert opinions and input on strategic positioning in multi-party proceedings. Our technical insights help shape arguments around foreseeability, standard of care and the reasonableness of past actions based on the state of knowledge at the time.
Testifying Experts for Regulatory and Civil Proceedings
In addition to expert witness support in litigation, RSK Global Experts provides testifying experts for public inquiries, environmental tribunals and regulatory hearings. These proceedings often involve highly technical submissions and require experts who can withstand rigorous cross-examination while effectively communicating complex scientific matters to mixed technical and non-technical audiences.
RSK’s testifying experts are experienced in presenting evidence before environmental regulators, water authorities, land use commissions and administrative tribunals, both in common law and civil law jurisdictions.
Outlook: The Expanding Scope of Environmental Liability
The trajectory of PFAS and emerging contaminant regulation suggests a sustained increase in litigation and enforcement activity. As detection technologies improve and health risk data evolves, new compounds may join regulatory lists and liability standards may broaden. This has implications for:
- Legacy site owners and historical operators
- Investors and lenders in brownfield redevelopment
- Public-private partnerships in infrastructure
- Insurers evaluating historical exposure and current exclusions
- Manufacturers evaluating chemical substitutions or product reformulation
For the legal profession, the need for scientifically grounded, litigation-ready expertise will continue to grow. Understanding the nuances of emerging contaminants, from their behaviour in the environment to their relevance in statutory interpretation, can be central to successful outcomes.
Conclusion
PFAS and other emerging contaminants represent a significant evolution in environmental law and litigation. They demand careful consideration of both current scientific understanding and historical industrial practices. The complexity of these cases, combined with evolving regulatory frameworks and heightened public concern, requires a multidisciplinary response.
RSK Global Experts brings together the technical depth, litigation experience and regulatory knowledge needed to support legal professionals facing these challenges. Through our expert witness services, subject matter expertise, and testifying expert capabilities, we contribute to clearer analysis, stronger evidentiary positions and more informed decision-making.
For legal teams navigating this evolving field, the access to credible, independent scientific insight is a critical asset.