Exposure to passive smoking can induce changes in children's genes, similar to active smoke: Study

New Delhi: A second-hand or passive exposure to cigarette smoke could change how children's genes express themselves, similar to that in active smokers, thereby making them more vulnerable to disease as adults, according to a study.

The findings, published in the journal Environment International, highlighted why children's exposure to second-hand smoke needs to be reduced.

"Our study shows that second-hand smoke during childhood leaves its mark at the molecular level and can alter the expression of genes that influence disease susceptibility in adulthood", first author Marta Cosin-Tomàs, a researcher at the Barcelona Institute for Global Health (ISGlobal), said.

While genes in one's DNA act as an instruction manual for the body, environmental factors, such as tobacco smoke, can affect 'gene expression', or how the manual is read.

Gene expression is how information in a gene translates into observable behaviour. 'DNA methylation' is one of the main processes involved that can turn a gene 'on' or 'off'.

In certain cases, DNA methylation can silence specific genes and contribute to disease development.

Analysing blood samples of nearly 2,700 children aged 7-10 years from across eight European countries, including Spain and France, the team found an increased DNA methylation in 11 regions on the genome -- one's entire DNA -- among children exposed to passive smoking.

Most of these regions have been previously linked to a direct or first-hand exposure to tobacco in active smokers or during pregnancy, the researchers said.

Further, six of these 11 regions were found to be associated with diseases, such as asthma or cancer, the risk of which is known to increase with smoking.

"The results suggest that second-hand smoke in childhood leads to epigenetic changes (changes in gene expression) similar to those observed with intrauterine exposure to tobacco or active smoking," senior author Mariona Bustamante, an ISGlobal researcher, said.

"This underlines the urgency of implementing comprehensive measures to reduce childhood exposure to tobacco smoke, both at home and indoors," Bustamante said.

The participants were recruited from the 'Pregnancy and Childhood Epigenetics' (PACE) Consortium.