Systematic review is one approach to develop a comprehensive, well-synthesized evidence base to support environmental decisions. Systematic review is a structured and highly documented process for gathering and synthesizing evidence from existing studies, to form conclusions that are supported by the available evidence. Given its rigor and transparency, systematic review can be useful in informing decisions that may be controversial or subject to legal challenges. It is also useful for identifying knowledge gaps and addressing questions with inconsistent findings in the literature. The U.S. Environmental Protection Agency’s Office of Research and Development is currently conducting systematic reviews on human health and environmental questions (e.g., effects of a chemical on human health, effects of nutrient pollution on stream ecosystems). Through these reviews, we have learned several lessons for future improvement. First, client communication throughout the process is needed. Systematic reviews are time and resource intensive, so ensuring that the end result will address the client’s need is critical. Decisions with shorter timelines (or sparser evidence bases in the published literature) may be better addressed using fit-for-purpose assessment methods, rather than systematic review. Evidence banking and technologies such as machine-learning and literature-screening software can improve efficiency of the systematic review process. Finally, it is important to consider how to disseminate systematic review results in ways that are most useful to multiple end users (e.g., decision-makers, other researchers).
- Sylvia Lee, Ph.D., ORISE Research Participant – Postdoctoral Fellow, USEPA