Environmental tobacco smoke (ETS) exposure in children with asthma-relation between lead and cadmium, and cotinine concentrations in urine

There were strong associations between the ETS exposure index and U-cotinine (rs=0.62; P<0.002) and nicotine in house dust (rs=0.77; P<0.001). There was a strong positive correlation between lead and cadmium concentrations in both fine (rs=0.86; P<0.001) and coarse dust (rs=0.57; P=0.02). Although, there was a tendency for a relation between nicotine and lead concentrations in fine dust (rs=0.52; P=0.06), no other significant associations were found between house dust metals and nicotine concentrations. U-Cd correlated well with U-cotinine (rs=0.50; P=0.02). Further, U-Pb were associated with U-cotinine, however not statistically significant (rs=0.41; P=0.06). A probable explanation is a direct inhalation of side-stream smoke containing heavy metals and/ or an increased pulmonary uptake, due to a small airways disease in children with asthma.