Children's exposure to tobacco smoke at home can alter their DNA and increase health risks later in life, according to a recent study led by the Barcelona Institute for Global Health (ISGlobal) and published in Environment International. The study, which included data from 2,695 children aged between 7 and 10 years from eight European countries, indicates the need to reduce children's exposure to passive smoking.
Researchers analyzed blood samples from participants aged 7 to 10 years to determine the level of methylation at specific sites in the genome and linked it to the number of smokers in the home. These participants were volunteers from six cohorts of the Pregnancy and Childhood Epigenetics Consortium (PACE).
The researchers identified changes in methylation in 11 genomic regions, known as CpGs, associated with exposure to secondhand smoke. Most of these regions have been previously linked to direct exposure to tobacco in active smokers or during pregnancy. Additionally, six of these regions were associated with diseases for which smoking is a well-known risk factor, such as asthma and cancer.
DNA methylation is a key epigenetic mechanism that can activate or deactivate gene expression and, in certain cases, can silence specific genes, contributing to disease development, according to Agencia SINC. Tobacco smoke can add "marks" on certain parts of the genes through a process called DNA methylation, which can turn genes "on" or "off," affecting how these instructions are read, as reported by Deccan Herald. Gene expression—the process by which information in a gene translates into observable behavior—can be modified by such epigenetic changes.
"Our study shows that passive smoking during childhood leaves a molecular mark, potentially modifying the expression of genes that influence susceptibility to diseases in adulthood," said Marta Cosin-Tomàs, ISGlobal researcher and first author of the study, according to Science Daily. "The results suggest that secondhand smoke in childhood leads to epigenetic changes similar to those observed with intrauterine exposure to tobacco or active smoking. This underlines the urgency of implementing comprehensive measures to reduce childhood exposure to tobacco smoke, both at home and indoors," Cosin-Tomàs added. "It is not a question of appealing to the individual responsibility of families: exposure to tobacco is a public health problem and hides an issue of social inequality. Socio-economic and environmental factors, together with the influence of powerful commercial interests, make it difficult to reduce exposure to second-hand smoke in certain households," Cosin-Tomàs concluded.
Childhood exposure to tobacco smoke increases the risk of respiratory and cardiovascular diseases and can also affect neurological development and immune function. The footprint left by tobacco smoke in DNA methylation can modify the expression of genes that influence the likelihood of developing pathologies in adulthood.
"Postnatal exposure to tobacco smoke alters DNA methylation, which could help explain adverse health effects," researchers warn. These epigenetic changes, including those caused by tobacco smoke, could influence the development of diseases in the future. In 2004, it was estimated that 40% of children worldwide were exposed to tobacco smoke. While the effects of maternal smoking during pregnancy on the epigenome were previously known, this study is among the first to show how exposure to secondhand smoke during childhood can also have harmful effects.
The study included data from eight European countries, including Spain, France, Greece, Lithuania, Norway, the Netherlands, the United Kingdom, and Sweden.
This article was written in collaboration with generative AI company Alchemiq