* * * The specific level of acceptable risk cannot be identified by scientific analysis, but must rather be the result of a societal decision-making process. Because we have no particular authority or expertise for judging the outcome of a properly constructed social decision-making process on acceptable risk, we have not attempted to make recommendations on this important question.’’ (NAS Report p. 20) Indeed, NAS explicitly acknowledged ‘‘that determining what risk level is
acceptable is not ultimately a questionof science but of public policy.’’ (NAS Report p. 5) Further, NAS noted that the
final outcome of the rulemaking might diverge substantially from the starting point suggested by NAS: ‘‘Finally we have identified several instances where science cannot provide all of the guidance necessary to resolve an issue