Smoking around children increases the chance of having grandchildren with asthma, study says

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Researchers from institutions in Australia, Sri Lanka, the UK and Norway have found that exposure to tobacco smoke in childhood and adolescence can affect the health of the next generation, increasing the chances of asthma.

Scientists have found that a child’s risk of having non-allergic asthma at age 7 increases by 59% when their father was exposed to cigarette smoke before age 15 (prepubertal period) and by 72% if the father, in addition to having been exposed, became a smoker.

“Our findings offer the first evidence of transgenerational transmission of an adverse impact of secondhand smoke exposure on prepubertal parents,” the scientists say in the article published in the European Respiratory Journal.

The study used information collected in 1968 and 2010 from 1,689 pairs of parents and children in the TAHS (Tasmanian Longitudinal Health Study), which gathers data from relatives from several generations and follows participants over the years.

The researchers verified and cross-referenced tobacco smoke exposure in childhood and early adolescence; diagnosis of asthma (allergic or non-allergic) at age 7; and cigarette consumption.

“It is a very interesting study for reasons such as pointing out that exposure to passive smoking before the age of 15 years altered the spermatids (precursor cells of spermatozoa) and contributed to the child having asthma”, comments pulmonologist Paulo César Corrêa, coordinator of the Smoking at SBPT (Brazilian Society of Pulmonology and Tisiology) and professor at Ufop (Federal University of Ouro Preto).

Scientists believe the effect is related to epigenetics, when environmental stimuli alter the way the organism reads DNA sequences. “When a boy is exposed to tobacco smoke, it can cause epigenetic changes in his germ cells. These changes will later be inherited by his children, with adverse impacts on their health,” says Dinh Bui, professor at the University of Melbourne and author. study senior.

The researchers had already investigated the relationship between parents who smoked before the age of 15 and the increased risk of asthma in their children – in Brazil, according to Pense (National School Health Survey), 15.6% of boys aged 13 to 15 years have smoked cigarettes at least once in their lives – and one research complements the other. They show that there is both an effect of passive and active smoking and that the former potentiates the former.

Thus, parents’ avoidance of active smoking may also reduce the risk of non-allergic asthma in their children, the scientists assume. For them, a hypothesis for this phenomenon would be a process of epigenetic reprogramming in each generation, a maintenance mechanism to avoid the accumulation of damage in the DNA reading. This issue, however, lacks studies.

“There is a critical exposure period. If I go through it without being exposed, I won’t have the effect. The problem happened to people who were exposed in this window. Thinking about the system, the ideal would be to protect this population as much as possible during this period so as not to harvest this result later”, defends Corrêa.

The researchers also point out that the increased risk was for non-allergic asthma, a poorly understood subtype that responds poorly to the use of inhaled corticosteroids, the famous firecrackers, and is therefore more difficult to treat.

Corrêa argues that asthmatics are still treated equally, due to the way the disease manifests itself, but there is an effort to understand the causes of each subtype and offer more specific treatments. “If I give inhaled corticosteroids to a patient who has non-allergic asthma, for example, he does not improve. It is not for him. In the future, we will be able to have medications that work for this type of case”, he predicts.

The current study and the authors’ future investigations can contribute to this journey. “We will investigate whether the increased risk of asthma in children due to exposure to their parents persists into adulthood. We will also investigate the impact of passive exposure to parental smoke on other allergic diseases and on children’s lung function”, says Bui.

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