Improving weight of evidence approaches to chemical evaluations.

Federal and other regulatory agencies often use or claim to use a weight of evidence (WoE) approach in chemical evaluation. Their approaches to the use of WoE, however, differ significantly, rely heavily on subjective professional judgment, and merit improvement. We review uses of WoE approaches in key articles in the peer-reviewed scientific literature, and find significant variations. We find that a hypothesis-based WoE approach, developed by Lorenz Rhomberg et al., can provide a stronger scientific basis for chemical assessment while improving transparency and preserving the appropriate scope of professional judgment. Their approach, while still evolving, relies on the explicit specification of the hypothesized basis for using the information at hand to infer the ability of an agent to cause human health impacts or, more broadly, affect other endpoints of concern. We describe and endorse such a hypothesis-based WoE approach to chemical evaluation.

Animal cloning and the FDA--the risk assessment paradigm under public scrutiny.

The evidence gathered thus far--ultimately to be published in the Draft Risk Assessment on Animal Cloning--indicates that there are no unique risks associated with animal cloning.

Food Animal Residue Avoidance Databank (FARAD): An Automated Pharmacologic Databank for Drug and Chemical Residue Avoidance.

The Food Animal Residue Avoidance Databank (FARAD) is a comprehensive computerized databank of regulatory and pharmacologic information useful for mitigation of drug and chemical residue problems in food-producing animals. For drugs, the databank contains information on proprietory products, labelled indications for use, and approved withdrawal and milk discard times. For drugs and chemicals, data are available on physiochemical properties of the chemical or generic drug, on tissue, egg and milk tolerances of these compounds, and on their pharmacokinetic behavior. This latter category is the most unique aspect of FARAD as it involves an extensive statistical analysis of published data, which results in estimates of the rates of depletion of these compounds in target animal species. These data have not been previously available. All data in FARAD are linked to specific sources which are listed in a citation file. Finally, resources produced as a result of USDA Residue Avoidance Program projects are listed in the database. Access to the databank is available at three regional access centers in California (916-752-7507), Illinois (217-333-3611) and Florida (904-392-4085), while the databank is maintained at a data analysis and support center in North Carolina. FARAD presently contains over 7,000 records with information on 250 compounds, and is supported by the USDA-Extension Service's Residue Avoidance Program.