Ambient formaldehyde levels and allergic disorders among Japanese pregnant women: baseline data from the Osaka maternal and child health study.

PURPOSE: The effects of formaldehyde (FA) exposure on allergic disorders are not clearly understood. This cross-sectional study examined the relationship between FA exposure and the prevalence of allergic disorders in Japan.

METHODS: Subjects were 998 pregnant women. Participants were considered to have asthma, atopic eczema, or allergic rhinitis (including cedar pollinosis) if they had received any medical treatment for any of these allergic disorders during the previous 12 months. Passive air sampling tubes were worn for 24 hours and analyzed for FA.

RESULTS: When FA levels were categorized into four groups, there was a tendency for a positive exposure-response relationship between FA levels and the prevalence of atopic eczema, although the adjusted odds ratio for highest vs. lowest FA categories did not reach statistical significance. When FA levels were categorized into two groups to assess the effects of exposure to high levels of FA on allergic disorders, FA levels of 47 ppb or more were independently associated with an increased prevalence of atopic eczema (adjusted odds ratio = 2.25; 95% confidence interval, 1.01-5.01). The positive association was more pronounced in women with a negative familial allergic history than in those with a positive familial allergic history. No clear association was found between FA levels and the prevalence of asthma or allergic rhinitis.

CONCLUSIONS: FA exposure may be associated with an increased prevalence of atopic eczema in Japanese pregnant women.