Phthalates, Bisphenols, and Childhood Allergic Phenotypes: Findings from Two Birth Cohort Studies

  1. Thomas Boissiere-O’Neill
  2. Nina Lazarevic
  3. Anne-Louise Ponsonby
  4. Peter D. Sly
  5. Aimin Chen
  6. Tamara L. Blake
  7. Jeffrey R. Brook
  8. Cassidy Du Berry
  9. Louise King
  10. Piushkumar J. Mandhane
  11. Theo J. Moraes
  12. Elinor Simons
  13. Padmaja Subbarao
  14. Dwan Vilcins
  15. CHILD investigator groups
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Abstract

Background

Phthalates and bisphenols may contribute to childhood allergic outcomes, but whether these are differentially associated with atopic or non-atopic phenotypes is uncertain. We investigated whether early-life exposure to these chemicals differentially impacts atopic and non-atopic allergic outcomes.

Methods

We used two prospective birth cohorts to investigate distinct exposure windows. The Barwon Infant Study (n = 797) measured urinary phthalate and bisphenol metabolites at 36 weeks’ gestation. The Canadian Healthy Infant Longitudinal Development Study (n = 993) measured phthalate metabolites at 3, 12, and 36 months. Atopy was assessed via skin prick tests at 4-5 years. Outcomes included asthma, wheeze, eczema, and rhinitis at 4-5 years. Models were stratified by atopy. We modelled exposure mixtures using quantile G-computation and Bayesian kernel machine regression.

Results

Phthalate mixtures were associated with increased asthma risk in both exposure windows. Prenatal phthalate mixtures were more strongly associated with non-atopic asthma (adjusted risk ratio [aRR] = 1.83; 95% confidence interval [CI]: 1.10-3.04), with evidence of effect modification by atopy (p = 0.02 for interaction). Postnatal phthalate mixtures were associated with non-atopic asthma (aRR = 1.82, 95% CI: 1.19-2.78), though the association did not differ by phenotype (p = 0.45 for interaction). Phthalate mixtures showed U-shaped (prenatal) and inverse U-shaped (postnatal) associations with atopic asthma, and linear associations with non-atopic asthma. There was little evidence of associations for other allergic outcomes.

Conclusion

Early-life exposure to phthalates may differentially influence the risk of childhood atopic and non-atopic asthma. Future studies are needed to confirm these associations.

HIGHLIGHTS

  • We used two birth cohorts to examine distinct exposure windows to phthalates.

  • Pre-and postnatal phthalate exposure was associated with increased asthma risk.

  • Pre-and postnatal associations with asthma differed by atopic status.

  • There was little evidence of association with other allergic outcomes.

Article activity feed

  1. Version published to 10.1101/2025.04.19.25325915 on medRxiv