PROP 65 1,000-FOLD UNCERTAINTY FACTOR: MODIFYING LEGISLATION STALLED

PROP 65 1,000-FOLD UNCERTAINTY FACTOR: MODIFYING LEGISLATION STALLED in the California Assembly Environmental Safety and Toxic Materials Committee following a March 28 hearing. A.B. 42, amending "The Safe Drinking Water and Toxic Enforcement Act," needed seven affirmative votes to pass out of committee, but received only six. Four of the five Democrats on the committee who were present voted against the measure; all five Republicans voted in favor of it and three Democrats were not present. The amended bill will be reconsidered by the committee at an April 11 meeting, possibly with additional amendments. Introduced by Assemblyman Bill Jones in December, the legislation proposes to revise the levels at which warning labels are required for products containing ingredients listed as reproductive toxicants "to reflect good science." The Jones bill would change Proposition 65's current 1,000-fold uncertainty factor to a one-in-100 ceiling beyond which products containing toxicants on the state's list would not be required to bear consumer warning labels. A.B. 42 also would require the California Health & Welfare Agency, in tandem with the governor's Scientific Advisory Panel (SAP), to adopt individual uncertainty factors for each ingredient if the information is available, and to set standards for the calculation of uncertainty factors. Witnesses opposed to the bill included Diane Fisher, PhD, of the Environmental Defense Fund; Campaign California's Paul Van Dyke; and representatives from the AFL-CIO and the Sierra Club. Testifying in favor of the measure were FDA Office of Toxicological Sciences Acting Director Robert Scheuplein, PhD; University of California at Davis Medical School Professor Andrew Hendricks, PhD; and SAP Chairman Wendell Kilgore, PhD. The bill reflects recommendations made earlier this year by the SAP in its response to three questions posed by Jones. He had asked the SAP and others if the use of an across-the-board 1,000-fold safety factor was scientifically appropriate and consistent with the approach generally recommended or adopted by scientists involved in health regulation. If not, he asked the panel to recommend alternative safety factors and suggest criteria for selecting the proper safety factor to apply in particular circumstances. In response, the panel stated that "it is inappropriate to propose applying a rigid factor" since "neither a 1/1000 uncertainty factor nor any other specific level can be used for a large number of substances because such values are not scientifically defensible." The panel suggests that each substance be evaluated on a "chemical-by-chemical basis, where a weight-of-evidence judgment could be made." Former FDA Commissioner and Stanford Professor Donald Kennedy, PhD, in a March 28 response to questions posed by Assemblyman Jones, agreed with the SAP that "no rigid uncertainty or safety factor is scientifically justified." He added that "expert scientific judgment must always be applied to determine the appropriate uncertainty or safety factor for a particular chemical, taking into account all of the scientific information available for that chemical." California Health & Welfare Agency's Steven Book, PhD, science advisor to the secretary, also encouraged a more flexible approach to uncertainty factors. In a March 17 letter to Jones, he said that the benefit of such an approach is that "some scientific judgment could enter into the consideration of reproductive toxicity, instead of using an arbitrary and sometimes unduly restrictive 1,000-fold approach" and that those who use chemicals would be encouraged to develop more information about them.