Should any subgroups of PFAS be excluded from quantitative risk assessment considerations (if yes, which & why)?

Answer Explanations

• Yes

  Expert 7

  Fluoropolymers (polymeric compounds) should be excluded. (Deloitte, 2015; Henry et al., 2018)
  Clear statements need to be made as to side-chain fluorinated compounds – if they are stable or degrade (under which conditions and at which stage in use?)
  Clear statements as to experimental proof or extrapolation.
  In general, conditions that do not occur do not need to be assessed (since often they disturb the assessment)

  Additional Reference:
  Bio by Deloitte (2015). Technical assistance related to the review of REACH with regard to the registration requirements on polymer - Final report, pp. 235.

• Yes

  Expert 10

  For quantitative risk assessment, it would be cost and data limiting to include all PFAS. A compromise must be sought and fewer PFAS will need to be grouped for quantitative risk assessment as discussed above. Again, I emphasize that quantitative risk assessment is completely different from some other management strategies (i.e. restriction) of PFAS as a class, based on their extremely high persistence, going forward.

• Yes

  Expert 8

  Yes, any individual or subgroup of PFAS that humans are not exposed to or which are not bioavailable. Certain fluoropolymers would be excluded such as the fluoropolymers of low concern which are described by Henry et al. (2018).

• Yes

  Expert 4

  IF subgroups are determined based on production/use, and IF approval is required to introduce new PFAS into commerce, CURRENT risk assessment could exclude categories of substances that have never been used.

• No

  Expert 6

  Preferably no exclusions, but a lack of suitable data may force a more pragmatic approach.

• No

  Expert 5

  With respect to the definition of PFAS chemicals in Question 1.1, all PFAS chemicals (all subgroups) should be addressed in the quantitative risk assessment. The quantitative risk assessment should follow a problem formulation in which pertinent details and procedures of the assessment are described. A quantitative assessment may begin with a screening evaluation, which may be completed on the basis of several assumptions necessary to fill data gaps. For some chemical subgroups, a screening evaluation may indicate negligible risk, especially when compared to the risk from other subgroups, or the Cumulative Assessment Group as a whole. If that is the case, resources maybe conserved or better expended by focusing on other subgroups. So, while all subclasses should be included in the quantitative assessment, a reasoned decision to exclude their consideration from the final stages of the risk assessment may be quite valid.

• Yes

  Expert 11

  I would look to excluding PFAS compounds that are not likely to cross a membrane, are chemically unreactive, and have physical and chemical properties that do not favor exposure (low vapor pressure, low solubility, and no potential for bioaccumulation). However, a quantitative risk assessment should be performed to justify the exclusion.

• I cannot answer

  Expert 3

  Insufficient knowledge of PFAS chemistry precludes an answer by this reviewer. Toxicological and human data are too limited to support exclusion of any group.

  Exposure scenario-specific information can be used to exclude groups of PFAS not likely to contribute to human exposure of a particular evaluation of risk.

  I don't see a good basis for excluding shorter half-life PFAS from consideration. The reported half-lives in humans are still on the order of weeks to months rather than hours.

• No

  Expert 1

  One could argue that polymers should be excluded from the list because they are less likely to cross biological barriers, but their production, use and incineration may also generate long-chain PFAS.