Report on the Technical Review Workshop on the Reference Dose for Aroclor 1016
Risk Assessment Forum
This report includes information and materials from a technical review workshop organized by the EPA's Risk Assessment Forum for EPA's Reference Dose/Reference Concentration (RfD/RfC) Work Group. The meeting was held in Washington, DC in May 1994. The subject of the review was the Integrated Risk Information System (IRIS) RfD entry for Aroclor 1016, a polychlorinated biphenyl (PCB). The expert technical review panel was convened to independently evaluate whether the RfD for Aroclor 1016 is based on a scientifically responsible analysis that represents full consideration of the available data and clear articulation of that analysis in the IRIS RfD entry. EPA asked the expert review panel to concentrate on technical issues concerning the selection of a principal study, selection of critical effects, selection of uncertainty factors, and weight-of-evidence conclusions. EPA also requested panel members to consider four broad options for the Aroclor 1016 RfD as potential recommendations to the RfD/RfC Work Group.
In general, technical reviewers found the principal study to be well conducted. However, a major barrier to the workshop panel's review was the unavailability of data collected in the critical study. The absence of information was attributable to the time that had elapsed since the study was completed in 1980 and the objective of the study, which did not concern development of an RfD. The workshop panel proposed a two-tiered recommendation. The first part was to recalculate exposure levels and the no observed adverse effect level (NOAEL) based on the measured (actual) concentrations in feed. The second part was to obtain and analyze chromatogram and maternal weight data from the critical study. The group was split concerning the degree of confidence that could be placed on the RfD, pending the outcome of additional data analysis. Eight of the twelve panel members assigned "medium" confidence, two "very low" or "highly uncertain" confidence, one "indeterminate," and one member said that no confidence statement could be made.
Note: a complete electronic version of this document that preserves its original appearance (such as in a pdf file format) is not currently available. However, a scanned version is available in image or text format from EPA's National Environmental Publications Information System. Paper copies may be ordered from the National Technical Information Service.
Report on the Technical Review Workshop on the Reference Dose for Aroclor 1016. U.S. Environmental Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/R-94/006, 1994.