Sixty years since Silent Spring: a map of meta-analyses on organochlorine pesticides reveals urgent needs for improving methodological quality.

Rachel Carson’s Silent Spring inspired a wave of research on the impacts of organochlorine pesticides, followed by a subsequent wave of meta-analyses. These meta-analyses are now routinely used to inform policy decisions. However, the methodological quality of meta-analyses on organochlorine pesticides remains largely unknown. Here, our study systematically maps and evaluates the methodological quality of 105 meta-analyses synthesizing 3,911 primary studies. Concerningly, we find that 83.4% of the meta-analyses exhibit low methodological quality. Importantly, such meta-analyses are commonly cited in policy documents, suggesting poor quality meta-analyses are misinforming policies. We also found a paucity of meta-analyses on wildlife despite ample primary evidence. Furthermore, our bibliometric analysis shows a limited number of meta-analyses originating from the developing countries, where organochlorines are still used to combat vectors of fatal diseases. Finally, we quantified the positive impact of using reporting guidelines and we provide recommendations for readily implementable methodological improvements.