Emerging contaminants in environmental due diligence: the risk can arise before the regulation
Why PFAS and other substances outside conventional analytical packages are already beginning to influence investigations, acquisitions, and decisions about industrial assets.
Environmental due diligence is designed to make liabilities visible before they alter the value, timeline, or feasibility of a transaction. The challenge of emerging contaminants, such as PFAS, is the opposite: a substance may have been used for decades and still fall outside the historical scope of investigation, the usual analytical packages, or the guiding values in force.
In an acquisition, the greatest risk does not always show up as a result above a threshold: sometimes it lies in the parameter that was never included in the investigation, and that never entered the price, the schedule, or the contractual strategy. That absence does not prove contamination, but it limits the quality of the decision. The goal of a mature due diligence is to recognize this uncertainty, test its relevance, and convert it into a proportionate action.
A contaminant can be old and still be emerging
“Emerging” does not necessarily mean newly created. The term covers substances whose occurrence, persistence, toxicity, or detectability has gained relevance before a consolidated regulatory response exists. The contaminant may be tied to old processes; what emerges is the evidence, the analytical method, or the possibility of being held liable.
PFAS, 1,4-dioxane, pharmaceuticals, and microplastics are frequently cited in this conversation, but they should not be treated as a homogeneous group, since each topic has its own uses, environmental behavior, and regulatory maturity. In due diligence, the useful question is not which trends are on the rise, but rather whether there is a plausible source, a relevant exposure pathway, and a material consequence for this asset and this transaction.
Why PFAS changed the discussion
PFAS form an extensive family of fluorinated substances used in applications that require resistance to heat, water, or grease, such as firefighting foams, coatings, textiles, and surface treatment processes. There is no single “PFAS” with uniform behavior: composition, mobility, and toxicological evidence vary among compounds. International attention has grown because some PFAS are highly persistent and have been detected far from their original sources, and the Stockholm Convention has moved to control PFOS, PFOA, and PFHxS at different points in time. This does not, in itself, create an investigation value applicable to a Brazilian property, but it does highlight a global trajectory of restriction.
The logic starts from evidence of use and from a source, pathway, and receptor model. Analytical investigation is a possible step within this process, not an automatic starting point.
The blind spot of conventional due diligence
Every investigation is a snapshot, one that depends on the accessible records, the hypotheses formulated, and the substances requested from the laboratory. If the scope was built when a given compound was not yet recognized as relevant, an old report may be technically correct for its time and still fail to answer today's questions.
This is where publications by international consultancies bring PFAS closer to transactional due diligence: the history of products, firefighting foams, waste, effluents, training areas, and neighboring sources can change the risk assessment even before a standardized obligation exists. There is a market convergence in this direction, not a universal legal rule.
It is also important to avoid the opposite shortcut. An unanalyzed parameter represents uncertainty, not contamination; likewise, a laboratory detection does not automatically determine unacceptable risk, a remediation obligation, or a loss of value. Interpretation must consider data quality, concentration, source, exposure, property use, and the framing of the competent authority.
Brazil has already begun to discuss the topic, but the regulation is still in transition
CONAMA Resolution No. 420/2009 (the federal environmental council resolution on soil quality) remains the federal reference for guideline values for soil quality, and its current annex does not present values for PFAS. This does not mean that unlisted substances are legally invisible: Article 12 provides that the applicable values may be defined by the competent environmental agency when investigation is necessary. The text approved by the Technical Chamber for Environmental Quality (Câmara Técnica de Qualidade Ambiental) in July 2026 brings together proposals for seven PFAS: PFOA, PFBS, PFUDA, PFHxS, PFNA, PFOS, and HFPO-DA/GenX. It is a relevant regulatory signal, but the process remains active and should not be presented as a regulation in force.
It is also not appropriate to automatically import limits or procedures from other countries. Foreign criteria can support technical understanding, but they do not replace the Brazilian framework, and the allocation of contractual responsibilities should be analyzed with specialized legal counsel.
Environmental data becomes useful to the decision only when interpreted together with the regulatory, financial, operational, and reputational context. The diagram is conceptual and does not assign fixed weights to the dimensions.
A proportionate approach: investigate by hypothesis, not by anxiety
The best response is progressive: the scope deepens as evidence increases the plausibility of the source and its relevance to the business.
- Reconstruct uses and operations. Consult plans, inventories, purchases, old FISPQ/SDS (safety data sheets), firefighting systems, surface treatment processes, effluents, waste, and changes in occupancy. External sources and neighboring properties may also be relevant.
- Formulate a preliminary conceptual model. Organize sources, release mechanisms, transport media, and receptors. This step distinguishes a generic association with a sector from a verifiable hypothesis for the site.
- Test materiality. Relate the hypothesis to the current and intended use, the planned interventions, the transaction timeline, and the potential for cost or operational restriction.
- Plan a targeted investigation, when justified. Select compounds, matrices, points, laboratory, method, and quantification limits compatible with the decision. References such as USEPA Method 1633A and ITRC guidance are useful, provided they are validated for the Brazilian context.
- Translate uncertainty into a decision. The result may lead to additional investigation, monitoring, cost contingency, timeline adjustment, or contractual treatment, consistent with the available evidence and revised if that evidence changes.
The counterpoint: broadening the scope indiscriminately can also create a problem
Requesting broad panels without a source hypothesis can produce incidental detections, difficulty comparing with applicable criteria, and costs that do not improve the decision. For PFAS, the sampling process itself requires special attention: field materials, equipment, clothing, and personal care products can compromise results at very low levels, and without a quality plan more data does not necessarily mean better information. Proportionality avoids two symmetrical errors: declaring nonexistence merely because nothing was ever analyzed, and concluding materiality merely because something was detected. The balance is a risk-oriented, documented investigation capable of explaining why a given parameter did, or did not, enter the scope.
What this means for buyers, sellers, and lenders
For the buyer, identifying a hypothesis early on does not have to derail the deal: it can improve the pricing of uncertainty, guide a confirmatory investigation, and prevent a technical limitation from surfacing only after the asset has been transferred. For the seller, organizing records of use, product substitution, and waste disposal reduces information asymmetries and makes it possible to respond with evidence, not just with generic statements.
Lenders, insurers, and investors tend to look not only at the concentration found, but at the governance of the topic: has the company acknowledged possible sources? Is there an action plan, with an estimated cost and transparent assumptions? An old report “with no indications” remains useful, but it should not be interpreted as universal coverage of substances that were never investigated.
Conclusion
The value of environmental due diligence lies less in repeating an analytical package and more in asking the questions the asset requires in the present. Emerging contaminants should enter the assessment when there is a historical and technical hypothesis capable of making them material to the transaction. The ongoing revision of CONAMA Resolution No. 420/2009 shows that the PFAS topic has gained ground in the Brazilian debate, but it does not authorize treating a rule still in the making as definitive. The prudent response is to avoid both silence and excess: recognize the gap, calibrate the investigation, and communicate the limits of what is known.
Technical and methodological note
This article is technical and informative in nature and does not constitute a legal opinion. The legislation, the guidance of the competent authority, and the circumstances of each site should be verified as of the date of the decision. Documents revising CONAMA Resolution No. 420/2009 cited in this text are proposals under consideration, not regulations in force. Foreign criteria and methods are technical references, not automatic substitutes for the Brazilian framework. The detection of a substance, in isolation, does not determine the classification of the site or the existence of unacceptable risk.
Sources consulted: CONAMA Resolution No. 420/2009 and documents of its revision (CONAMA/IBAMA) (link pending validation); Stockholm Convention (listings of PFOS, PFOA, and PFHxS); USEPA (characterization of PFAS and Method 1633A); ITRC (sampling and analytical methods for PFAS); international technical publications on environmental due diligence and emerging contaminants. The text of this article is an original synthesis by LZ Ambiental.
LZ Ambiental supports companies and investors in environmental due diligence, in the investigation of contaminated sites, and in building decision-oriented conceptual models. To assess whether emerging contaminants are material to your asset, talk to our technical team.
