The need for standard methods for exposure classification in environmental epidemiology: Case study - pesticide emissions from cultivated agriculture

Abstract

Background/Aim: The use of systematic reviews and meta-analysis and replication studies has become important in environmental epidemiology, namely when existing studies have inconsistent results. The ability to assess composition and completeness of exposure metrics is critical in this process. The aim of our study is to demonstrate the value of a standardized evaluation tool designed to ascertain whether critical determinants of exposure are incorporated in exposure metrics for epidemiology studies assessing residential exposure to fugitive pesticide emissions from cultivated agriculture (PECA). Methods: We conducted a critical review of 89 peer-reviewed articles, including 64 epidemiological studies, concerning the relevance of determinants of exposure in their PECA exposure metrics. We employed a tool designed to evaluate geospatial exposure assessment (GISEAM). We considered 21 known or suspected determinants of PECA exposure. We analyzed quality of (consistency and quantification), and compared results to a STROBE (Strengthening the Reporting of Observational studies in Epidemiology) score for each study. Results: We observed much lower overall GISEAM quality (40%; IQR 31-52%) versus STROBE scores for overall epidemiologic study design (median score 86%; IQR 77-91%), as well as a low coefficient of correlation between scores (rs = 0.2), yet near significant correlation (p = 0.077). Across majority of studies, we found significant omission or miss-quantification of key fate/transport and spatio-temporal exposure factors relevant to exposure and health risk from PECA. For example wind, a known factor in fate/transport of airborne emissions, was including in only 10% of studies. Each concluded that wind direction and/or velocity improved the accuracy of their metric. Conclusions: Our study clearly demonstrates the added value of employing a standardized tool for design and evaluation of environmental epidemiological studies related to PECA. Our findings have broad implications for optimizing environmental epidemiology risk analyses in public health related research, protective policy, and regulation.