Assessing Environmental Justice in Mexico: How Polluting Industries and Healthcare Disparities Impact Congenital Heart Defects.

Background: Congenital heart defects (CHDs) are the most prevalent birth defects globally and the second leading cause of death in Mexican children under five. This study examines how industrial activity and social vulnerabilities independently and jointly influence CHD incidence across 2446 Mexican municipalities from 2008 to 2019.

Methods: Using negative binomial regression models, we evaluated associations between polluting industries, healthcare access, and CHD incidence. We analyzed these factors independently, jointly, and through interaction terms to assess potential effect modification by healthcare access. Incidence rate ratios (IRRs) and 95% confidence intervals were estimated across healthcare access strata.

Results: Municipalities without healthcare facilities were more likely to host polluting industries, highlighting structural inequities. The presence of polluting industries was associated with increased CHD incidence, even after adjusting for healthcare access. For instance, municipalities with poor healthcare access and two or more polluting industries exhibited a 42% higher CHD incidence (IRR = 1.42, 95% CI: 1.25-1.60) compared to a 26% increase in municipalities with better healthcare access (IRR = 1.26, 95% CI: 1.02-1.57).

Conclusions: These results show how environmental pollutant exposure and social vulnerabilities interact synergistically, disproportionately impacting socially vulnerable populations. Targeted policy interventions addressing both environmental pollution and healthcare inequities are crucial. Further research is also needed to clarify the mechanisms linking pollution to CHDs and to guide public health strategies aimed at reducing these disparities in Mexico.