December 12th, 2017
Objective: Despite multiple published studies regarding the association between formaldehyde exposure and childhood asthma, a consistent association has not been identified. This study reports the results of a systematic review of published literature in order to provide a more comprehensive picture of this relationship. Data Sources: Seven peer-reviewed studies providing quantitative results regarding the association between formaldehyde exposure and asthma in children were identified following a comprehensive literature search. There was heterogeneity across studies with respect to the definition of asthma (e.g., self-report, physician diagnosis). The majority of studies were crosssectional in nature. Data Extraction: For each study, an odds ratio (OR) and 95% confidence interval (CI) for asthma was either abstracted from published results or calculated based on the data provided. Characteristics regarding the study design and population were also abstracted. Data Synthesis: Fixed and random effects models were used to calculate pooled ORs and 95% CIs; measures of heterogeneity were also calculated. The results of a fixed effects model produced an OR of 1.03 (95% CI 1.02-1.04), and random effects model an OR of 1.17 (95% CI 1.01-1.36) both reflecting an increase of 10 µg/m3 of formaldehyde. Both the Q and I2 statistics indicated a moderate amount of heterogeneity. Conclusions: The results indicate that there is a significant positive association between formaldehyde exposure and childhood asthma. Given the largely cross-sectional nature of the studies underlying this meta-analysis, there remains a need for well-designed prospective epidemiologic studies.