Personal care products disrupt the human oxidation field.

Summary

Using real-world personal care products, the authors show that lotions reduce formation of the OH precursor 6-MHO and fragrance ethanol acts as a major OH sink, suppressing the human oxidation field. Multiphase kinetic and CFD modeling explain how reactive species evolve indoors, highlighting implications for indoor air chemistry and human exposures.

Key Findings

• Body lotion application reduced formation of 6-methyl-5-hepten-2-one, a key precursor for OH generation near skin.
• Volatile ingredients in many PCPs increased gas-phase OH loss; ethanol in fragrances acted as a dominant OH sink despite terpene content.
• Combined multiphase chemical kinetics and CFD modeling reproduced indoor concentration dynamics of reactive species and suppression of the human oxidation field.

Clinical Implications

While not a clinical trial, the findings inform public health counseling and product formulation choices (e.g., ethanol-rich fragrances) and support ventilation strategies to mitigate potential oxidative chemistry perturbations in indoor environments.

Limitations

• No direct clinical or health outcomes were measured
• Tested a limited set of products; results may vary with different formulations and individual emission profiles

Future Directions

Quantify health-relevant endpoints and evaluate broader product classes and ventilation scenarios to translate mechanistic insights into exposure guidelines.