Environmental exposures and atopic dermatitis: an umbrella review of systematic reviews and meta-analyses.

BACKGROUND

Atopic dermatitis (AD) is a common chronic inflammatory skin disorder with a substantial global burden. Although multiple studies have investigated the impact of environmental exposures on AD, a comprehensive review integrating children, adults, and mixed-age populations is lacking. This study aimed to synthesise current evidence on environmental risk factors for AD and examine age-specific susceptibility.

METHODS

We systematically searched PubMed, Embase, and Web of Science up to March 2026 for systematic reviews and meta-analyses on environmental exposures and AD risk. Exposures were categorised as: microbe- and immune-related factors (antibiotics and helminth infections), environmental pollution and chemicals (air pollution, per- and polyfluoroalkyl substances (PFAS), heavy metals, pesticides), and lifestyle or residential factors (active and passive smoking, pet exposure, urban environment, light at night, indoor fuel use). Eligible studies reported pooled effect estimates including odds ratios (ORs), relative risks (RRs), or hazard ratios (HRs) with 95% confidence intervals (CIs), or clear directional associations. Data extraction prioritised fully adjusted estimates, dose-response relationships, and age-stratified findings. Methodological quality was assessed using A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2). Evidence synthesis focused on effect direction, statistical significance, heterogeneity (I2), and overlap of primary studies, without recalculating original estimates.

RESULTS

Twenty systematic reviews and meta-analyses were included. In children, antibiotic exposure and both active and passive smoking were consistently associated with increased AD risk, while prenatal exposure to PM₂.₅ and nitrogen dioxide (NO₂) also elevated risk. In adults, smoking and air pollution showed stable positive associations. In mixed-age populations, PM₁₀ exposure and urban residence were linked to higher AD risk. Evidence for other exposures, including PFAS, heavy metals, pesticides, helminth infection, pet exposure, light at night, and indoor fuel use, remained limited or inconsistent.

CONCLUSION

Antibiotic exposure, smoking, and air pollution are the most robust environmental risk factors for AD across age groups, whereas other exposures require further investigation. Targeted interventions and environmental management may contribute to AD prevention and control.