Serum heavy metal levels are associated with asthma, allergic rhinitis, atopic dermatitis, allergic multimorbidity, and airflow obstruction

Heavy metal exposure is a major public health issue that has increased during industrial development because air pollution, heavy automobile traffic, use of agricultural chemicals, contaminated irrigation water, and smoking have increased exposures via inhalation, ingestion, and skin contact.1 Heavy metal exposure is also associated with preferential biased activation of the TH2 pathway, which functions in the pathogenesis of allergic disease.2 Although nonclinical studies have identified a relationship between heavy metal exposure and allergic disease,2 there is controversial epidemiologic evidence regarding the relationship between serum levels of heavy metals and asthma (positive association3,4 and no association5,6), atopic dermatitis (positive association7 and no association8), and airflow obstruction,9 and only a few studies have investigated the effect of serum levels of heavy metals on the development of allergic rhinitis and/or allergic multimorbidity.