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Polyurethanes and childhood asthma.

BACKGROUND
Asthma is the most common chronic disease of children. Its prevalence in affluent nations has steadily and dramatically increased in recent decades. Genetic and environmental factors play a role in development of atopy and asthma. Imbalance in the immune system favoring respiratory diseases has been linked to exposure to environmental stressors (e.g, biological and chemical) very early in life. Isocyanates, used in the production of polyurethane, can elicit asthma and produce immune responses (e.g, antibodies, cytokines, etc.) typical of atopy.


MATERIAL/METHODS
Numerous medical materials that directly contact human neonates are constructed of polyurethanes. A detailed survey and listing of such materials was undertaken in the neonatal unit of a large urban hospital. Representative samples of polyurethane-containing materials were tested for isocyanate residues using a semi-quantitative colorimetric method.


RESULTS
Isocyanate residues were detected in wound dressings, adhesive films, oximetry sensors, etc, that directly contact neonatal skin.


CONCLUSIONS
Dermal exposure to polyurethane and, thus, to isocyanates could occur early in life through contact with medical materials. In an animal model, dermal exposure to isocyanates leads to dermal sensitization and asthma. We postulate that dermal contact with polyurethane-containing medical materials may be involved in dysregulation of the neonatal immune system and could predispose infants to the development of childhood asthma.