Increased levels of heavy metals in children's saliva after exposure to tobacco smoke

New Delhi: Lead and other non-essential heavy metals have been found to be more prevalent in children's saliva after exposure to tobacco smoke, which could lead to biological dysfunction and subsequent health and behavioural issues. Cotinine concentrations as well as metal concentrations were tested in children's saliva by researchers at Pennsylvania State University in the US. Cotinine, a nicotine metabolite found in children's blood or saliva, is analysed to determine how much environmental tobacco smoke (ETS) they have been exposed to.

238 (7.5 years of age and under) out of 1,300 children born in 2003 and 2004 and growing up in the rural areas of Pennsylvania and North Carolina in the US, originally recruited for childhood developmental studies, were investigated for this study published in the Journal of Exposure Science & Environmental Epidemiology.

Lead researcher Lisa Gatzke-Kopp and her team found significant associations between salivary cotinine and salivary levels of essential trace metals such as copper and zinc and of non-essential metals such as lead. Metals such as copper and zinc in trace amounts are necessary for healthy bone development and general metabolism in humans.

Children with higher levels of cotinine were also found to have higher levels of heavy metals in their saliva.

"We were surprised by the levels of heavy metals in children at this age," said Gatzke-Kopp, professor of human development and family studies.

"Our findings suggest that environmental tobacco smoke exposure may be one source of increased children's exposure to heavy metals," she said.

The exposure, the researchers said, is more dire and can increase the frequency and severity of asthma attacks, respiratory infections, cancer and sudden infant death syndrome in those more easily affected by smoke.

"Tobacco smoke contains thousands of chemical compounds, most of which are harmful to humans," said Gatzke-Kopp.

Metals have also been found in vapours of common products used for vaping, cast as a healthier alternative to tobacco-based products, indicating that these products too are capable of being transmitted as second- and third-hand smoke, Gatzke-Kopp said.

The researchers said that it may be possible that a simple saliva test could serve as a non-invasive tool for assessing environmental and occupational exposures to trace metals, even as currently there are no official guidelines for appropriate metal levels in human saliva.

"In the future, established guidelines for saliva tests could provide the basis for further comparisons between salivary metals and behavioral, cognitive or other clinical measures," Gatzke-Kopp explained.