Relationship between hair cadmium levels, indoor ETS exposure and wheezing frequency in children

Cadmium (Cd) is a toxic heavy metal and the components of tobacco and scalp hair effectively reflect a long-term environmental exposure.

The aim of this study was to assess the concentration of Cd levels in the hair of children with recurrent wheezing, and to evaluate the predictors of elevated Cd levels with a focus on anthropometric, environmental, and dietary factors.

In this case-control study, scalp hair was obtained from 65 children with recurrent wheezing (RW) and from 65 healthy children (HC). Hair Cd concentrations were determined by ICP-MS.

Median (IQR) hair Cd levels were 0.22 μg/kg (0.10-0.35) in RW group and 0.12 μg/kg (0.04-0.23) in HC group (p = 0.013). Multivariable logistic regression model results showed that being a child with RW (OR = 6.28; p = 0.001), ETS exposure at home (OR=22.56; p < 0.001), and mother's education level (OR = 0.49; p = 0.020), are the major predictor variables for elevated hair Cd levels (cut off >0.17 μg/kg). In RW group, multivariable logistic regression results showed that hair Cd levels of >0.17 μg/kg was significantly predictive of having three or more wheezing episodes in RW group after adjustment for ETS exposure at home (OR = 5.48; p = 0.012).

We demonstrated that the more children are exposed to ETS at home, the more they are exposed to heavy metals like Cd. Especially children who have had three or more wheezing attacks over the last six months are much more susceptible than the other asthmatic and non-asthmatic children, and Cd exposure aggravates their asthmatic status.