Building on the first meeting at the 22nd Cochrane Colloquium in India, involving experts in toxicology, public health, animal testing, biostatistics, and systematic review methods, we propose the work groups for developing a handbook for systematic review methods related to toxicology including nonhuman toxicology (NHT) and studies on mechanisms of toxicity. Nonhuman toxicology and studies on mechanisms of toxicity are two of the three important domains of knowledge relevant to evaluating harms associated with environmental [and occupational] exposures; these are the sources of information that are currently relied upon by regulatory agencies and international agencies in reaching policy decisions concerning these exposures. Because of recommendations to incorporate systematic methods in this process, there is increasing interest in developing and validating systematic review methods for NHT. This handbook is limited to developing and validating methods for hazard identification, which is a qualitative finding of harm. We make this limitation because this is the first critical step in decision making in environmental and occupational health. There is considerable variation in policy approaches to the second step in decision making, which involves the quantitative assessment of risks [as a function of hazard and exposure]. This handbook accepts that the prevention of harms is the goal of decision making in environmental and occupational health as expressed by all national and international agencies; this goal introduces an emphasis on the application of study methods and statistical analyses that are validated as sensitive.
In the future we may expand our work group and seek a partnership with these existing Groups to develop an additional handbook on the evaluation of human studies. Eventual integration of human and non-human findings and conclusions will need to be considered, in light of their importance for decision makers and regulators.