August 15, 2000
Dear Messrs. Farrell, Fields, Fox, and Perciasepe, Ms. Schneider, Ms. Wayland, and Drs. Noonan and Barnes:
As you are aware, over the last two years several EPA programs have begun to use the PBT methodology to evaluate the health and environmental hazards of numerous substances, including not only synthetic organic chemicals, but also metals and their inorganic compounds. Inclusion of metals within the PBT framework has occasioned considerable debate in the scientific community and among groups interested in the regulatory implications of such action. We are writing to express our continued concern with respect to the Agency’s application of its current PBT methodology to metals and their inorganic metal compounds. We believe that there are compelling reasons for the Agency to ask for a review of this scientific policy by its Science Advisory Board (SAB), and to defer including any metals in PBT programs until completion of that review.
The international scientific community has recognized that metals and inorganic metal compounds should be assessed for their potential hazard based on their unique properties, which differ significantly from the properties of synthetic organic chemicals. This point was explained in some detail in January at an Experts Workshop co-sponsored by EPA and several industry scientific research organizations. Participants in the Workshop examined the progress that has been made, through research, to develop a more relevant and accurate approach to assessing the potential hazards of metals and inorganic metal compounds. The results of this research clearly demonstrate the substantial and substantive differences between the data and information needed to apply the PBT approach to synthetic organic chemicals on the one hand, and to evaluate metals and their inorganic compounds in a scientifically valid way, on the other. In the months following the Workshop, other scientific groups have voiced the same opinion. Thus, in a May 2000 Advisory, the SAB noted that "classification of metals as persistent, bioaccumulative toxicants (PBTs) is problematic, since their environmental fate and transport cannot be adequately described using models for organic contaminants." A similar conclusion was reached most recently in the context of the OECD hazard classification harmonization process -- in which the United States is a participant.
The PBT methodology developed by EPA is the product of more than twenty years of research. This body of research and experience has allowed scientists and policymakers to derive simplifying assumptions that can be applied in a reasonable way to evaluate the potential hazards of new and existing synthetic organic chemicals. A parallel process has been underway for the past several years with respect to metals and inorganic metal compounds. As demonstrated at the Experts Workshop in January, this research and the interpretation of its results make clear that metals and inorganic metal compounds behave very differently from organics and cannot validly be assessed using EPA’s PBT criteria. We believe that proper application of this new knowledge of metals will allow the Agency to determine which metals and inorganic metal compounds present potential hazards of a magnitude that requires priority consideration.
Recognition of the unique properties of metals and their inorganic metal compounds and the appropriate application of this knowledge to hazard assessment need not impair the Agency’s ability to meet its mandate to prioritize potentially hazardous substances. The level of knowledge that now exists with regard to the fate and behavior of metals and their inorganic metal compounds will allow and support the derivation of a workable and scientifically valid approach to their hazard evaluation, so that a prioritization process comparable to that for synthetic organic chemicals can be developed.
In sum, major scientific questions have been raised about application of the PBT methodology to metals, and failure to resolve them carries significant negative implications for industry, consumers, and EPA itself. Further, the Agency has underway numerous programs that are expected to apply PBT concepts to metals and their inorganic metal compounds, with serious regulatory consequences. Moreover, several states and counties across the nation (WA, OR, MD, PA, and CA) already are following the Agency’s lead and promulgating "PBT lists" or other regulatory initiatives that include many metals. We believe the evidence will show conclusively that metals should be assessed on their unique properties and that ultimately the conclusions being reached now by the current application of the Agency’s PBT methodology will be demonstrated to be in error. Undoing the decisions that will follow from these erroneous conclusions will be difficult and expensive.
The undersigned urge you to submit to the SAB as soon as possible the issue of the scientific soundness of applying the Agency’s current PBT methodology to metals and inorganic metal compounds. We further urge you to defer any action that would include metals within PBT programs or lists until the SAB has had a chance to issue its opinion on the matter.