PFAS in a Phase I

A past use, a record or the user's own question raises per- and polyfluoroalkyl substances (PFAS). The standard covers hazardous substances as the federal cleanup law defines them, and petroleum products. Whether PFAS are within the assessment depends on four things: which substance is in question, whether the federal list of hazardous substances carries it when the work is done, what the user or state law adds for one it does not carry, and whether a release puts it at the subject property.

What the answer turns on

Which substance. PFAS names more than one substance, and the standard's definition of a hazardous substance takes in what is designated or listed under the federal provisions it names (E1527-21, 3.2.36). Establish which substances the use or the record involves, by name, and by CAS number where the source gives one.
Whether the federal list carries it. One of those provisions is section 102 of the federal cleanup law. The standard's appendixes are nonmandatory; the legal background appendix places the agency's list under that section in 40 CFR part 302 (E1527-21, 3.2.36, X1.1.2, footnote 36). In the edition revised as of July 1, 2025, that part's table lists perfluorooctanoic acid (PFOA), CAS 335-67-1, and perfluorooctanesulfonic acid (PFOS), CAS 1763-23-1, and, without a CAS number, each acid's salts and structural isomers, all coded as designated under section 102(a) (40 CFR 302.4). In the body of the standard, a substance not defined as a hazardous substance is a non-scope consideration unless or until it is classified as one under that law (E1527-21, 13.1.5.15). The non-scope appendix gives PFAS as an example of what it calls emerging contaminants, which may not be, or may not yet be, so defined, and says that if and when they are, they are to be evaluated within the practice (E1527-21, X6.10). The assessment is based on conditions when its parts were completed (E1527-21, 4.5.5). Check the table as it stands when the work is done.
What the user or state law adds. For a substance the federal law does not define as a hazardous substance, the body of the standard says the user may still decide to put it in the scope of work, and that no assessment of a non-scope consideration is required for all appropriate inquiries as the practice defines them (E1527-21, 1.1.4, footnote 3, 13.1.2). A service beyond the practice should be agreed between the user and the environmental professional before the assessment starts (E1527-21, 1.4). The non-scope appendix adds that where state law treats such a substance as hazardous, and the assessment also serves state requirements or the user directs, it is permissible to analyze or discuss it as any other non-scope consideration (E1527-21, X6.10). Oregon's cleanup rules count six PFAS as hazardous substances (Oregon).
Whether a release puts it at the subject property. A substance the list carries is weighed as any other hazardous substance: the definition of a recognized environmental condition (REC) asks whether it is present or likely present at the subject property owing to a release or a likely release, or present where conditions make a future release a material threat (E1527-21, 3.2.73). The standard gives no list of uses that involve PFAS and no screening step for them, and the practice includes no sampling (E1527-21, 7.4). Oregon's agency says it is investigating primarily airports, military installations and municipal fire training areas, and generally detects high levels where aqueous film-forming firefighting foam was used (Oregon). The history of uses helps weigh whether past uses led to RECs, and a specific use tells more than a general one (E1527-21, 8.3.1, 8.3.7).

The records that bear on it

The federal lists. The handbook's chemical pages show which federal lists carry a CAS number. One is the list of toxic chemicals for release reporting, which the standard's definition of a hazardous substance does not name. In the same edition its PFAS paragraph lists 205 CAS numbers, both acids among them (40 CFR 372.65(d); E1527-21, 3.2.36). Table 302.4's own note says that where a substance name and its listed CAS number disagree, the name is the official way to tell whether a substance is reportable, and that some numbers are given only for parent compounds (40 CFR 302.4).
Uses and materials. Before the site visit the owner, key site manager and user are asked for safety data sheets, environmental permits and site investigation reports (E1527-21, 10.8.1).
Government records. State PFAS sampling and monitoring data are not among the standard sources. Additional records are checked when the professional judges them reasonably ascertainable, useful enough, and generally obtained in local practice (E1527-21, 8.2.4).

What the federal rule says

The inquiry rule (40 CFR part 312) does not name PFAS. For a party seeking the liability protections, the investigations it requires are

to identify conditions indicative of releases or threatened releases, as defined in CERCLA section 101(22), of hazardous substances, as defined in CERCLA section 101(14).

40 CFR 312.1(c)(1), edition revised as of July 1, 2025

How it is written up

A use or a record becomes a finding when the professional judges it may indicate presence or likely presence at the subject property, and the opinion reasons for or against calling it a REC (E1527-21, 12.5, 12.6).

Where the professional concludes the substance is present or likely present at the subject property owing to a release or a likely release, the opinion gives the grounds: the substance, the use or the record, the release or why one is likely. Unless judged a de minimis condition or a historical REC, the REC is listed in the Conclusions, and the professional should give an opinion on additional investigation, if any (E1527-21, 3.2.20, 3.2.39, 12.7, 12.8).

Where the professional concludes otherwise, the opinion gives its reasoning on the same facts (E1527-21, 12.6).

For a substance that is neither a hazardous substance nor a petroleum product, work the user has asked for is an additional service, which may take in business environmental risk: it should appear in the report only as the terms of engagement specify, and additions to the practice are listed (E1527-21, 4.4, 12.10, 12.11). The suggested report format in Appendix X5 has a section for non-scope services (E1527-21, X5.7).

Observation of part of the subject property on the site visit, or an interview with the key site manager, may be what cannot be had. Required information that good faith efforts could not obtain is a data gap, significant if it affects the ability to identify a REC: named in the Findings with the sources consulted, discussed in the Opinions and listed in the Conclusions (E1527-21, 3.2.19, 3.2.78, 12.5.1, 12.6.2, 12.7).

This page is general reference for environmental professionals. It does not classify any property. ASTM E1527-21 is the standard and is not reproduced here; the judgment of the environmental professional on the facts governs.