A recent issue of Environmental Health Perspectives described a new methodology for performance of systematic review for Environmental Health research and policymaking. The EHP framework, known as the Navigation Guide, sets up a methodology for conducting systematic review in Environmental Health (found at http://ehp.niehs.nih.gov/1307175/). Case studies, focusing on the outcomes of PFOA exposure are described in later articles in the October 2014 issue of EHP (http://ehp.niehs.nih.gov/october-2014/),
Given the potential strengths of systematic review in the identification and quantification of a public health problem, I am concerned that the understanding of the uses of systematic review -- and its associated statistical tests -- will be improperly applied as a proxy for causality.
Before widespread use of systematic review is expanded, the environmental health workforce and policymaking bodies need to obtain more education about the strengths and limitations of systematic review. It has been well-characterized and implemented in evidence-based medicine -- where they are capable of targeting RCTs for their inclusion -- but much of the Environmental Health research is observational in nature, and lacks the consistency in controls that are integrated into the design of RCTs. I have, personally, seen the improper application of systematic review (in my personal opinion) results in order to push specific researchers' agendas -- sometimes having these results published in such noted journals as BMJ Neurology.