Converting categorical risk estimates into continuous effects in environmental health systematic reviews and meta-analyses.

the proposed method provides a practical and replicable approach for converting categorical risk estimates into continuous effect estimates, enabling the harmonization of heterogeneous exposure categories across studies. This allows comparability and enables to carry out meta-analyses even in settings with a limited evidence base, where the addition of a single study can meaningfully contribute to the pooled estimate. The method helps overcome a frequent source of heterogeneity in environmental epidemiology, enhancing the robustness, precision, and interpretability of meta-analytical results. Applying methods such as the one here presented to systematic reviews and meta-analyses in the field of environmental epidemiology - where commonly potential effects of exposures are highly uncertain, as in the case of municipal solid waste disposal sites - more valid and robust estimates of the effects of specific environmental exposures can be obtained, therefore providing a stronger evidence base to inform public health decision-making.