Table 2 Elements of a PECO statement using PFOA and birth weight as an illustrative example

(P) Population

Condition or disease, characteristics/demographics of the participants. Which setting?, e.g., general population, occupational setting

Laboratory rodents exposed to PFOA in utero, assessed in early postnatal life

Humans that are studied during reproductive/developmental time period (before and/or during pregnancy or development).

(E) Exposures

What are the exposures of interest? What types of chemical(s), what is the timing of exposure that will be considered? Which duration/frequency of exposure or timing of follow-up in relation to exposure?

Exposure to perfluorooctanoic acid (PFOA), CAS# 335-67-1, or its salts prior to mating, or during pregnancy

Exposure to perfluorooctanoic acid (PFOA), CAS# 335-67-1, or its salts during the time before pregnancy and/or during pregnancy for females or directly to foetuses

(C) Comparator

Which exposure groups will be compared to each other (high versus low exposure) (exposure versus control)?

Exposed groups versus vehicle-treated or naïve controls

Humans exposed to lower levels of PFOA than the more highly exposed humans.

(O) Outcome

Which outcomes will be included or covered? Consider adverse effects as well as potential adverse effects.

Body weight during first five days of postnatal development, total litter weight, measures of size such as body length

Effects on fetal growth, birth weight, and/or other measures of size such as length.