Table 1.

PECO criteria.

PECO element	Description
Populations	Human: Any population and life stage (occupational or general population, including children and other potentially sensitive populations). Animal: Nonhuman mammalian animal species (whole organism) of any life stage (including preconception, in utero, lactation, peripubertal, and adult stages).
Exposures	Relevant forms: $\sim 345$ PFAS chemicals represented by structures and substances identified in the Excel File (Excel Table S1 and Excel Table S21). Human: Any exposure to PFAS via the oral and inhalation routes because these are the most relevant routes of human exposure and typically the most useful for developing human health toxicity values. Studies are also included if biomarkers of PFAS exposure are evaluated (e.g., measured PFAS or metabolite in tissues or bodily fluids) but the exposure route is unclear or reflects multiple routes. Other exposure routes, including dermal, and mixture-only studies (i.e., without effect estimates for individual PFAS of interest) are tracked during title and abstract screening and are tagged as “potentially relevant” supplemental material. Animal: Any exposure to PFAS via oral or inhalation routes. Studies involving exposures to mixtures are included only if a treatment group consists of exposure to a PFAS alone. Other exposure routes, including dermal or injection, and mixture-only studies are tagged as “potentially relevant” supplemental material.
Comparators	Human: A comparison or referent population exposed to lower levels (or no exposure/exposure below detection limits) or exposed for shorter periods of time. However, worker surveillance studies are considered to meet PECO criteria even if no referent group is presented. Case reports describing findings in 1–3 people in nonoccupational or occupational settings are tracked as “potentially relevant” supplemental material. Animal: A concurrent control group exposed to vehicle-only treatment and/or untreated control (control could be a baseline measurement).
Outcomes	All health outcomes (cancer and noncancer).

Note: The definitions in the table follow standard template language that is used in systematic evidence maps developed by the US EPA^27,28,32 and have only been adjusted, where appropriate, for the specific needs of this SEM. CASRN, Chemical Abstract Service registry number; DTXSID, DSSTox substance identifier; PECO, Populations Exposures Comparators Outcomes; PFAS, per- and polyfluoroalkyl substances; SEM, Systematic Evidence Map.

^a Full chemical lists of included Expanded PFAS chemicals, DTXSIDs, CASRNs, and synonyms are provided in the supplemental material (Excel Table S1 is the “PFAS 430” list and Excel Table S2 is the “Additional PFAS” list).