SHEFFIELD, United Kingdom — Parents who smoke around their young sons significantly increase the risk that their future grandkids will develop asthma.
Researchers from the University of Melbourne say children whose fathers were exposed to secondhand smoke while they were growing are more likely to end up with the breathing disorder.
The danger further increases in cases where those young boys go on to become smokers themselves. Studies suggest that passive smoking alters genes which families pass down through the generations. The mutations, carried in sperm, end up as a part of the fetus before they are even born.
“We found that the risk of non-allergic asthma in children increases by 59% if their fathers were exposed to second-hand smoke in childhood, compared to children whose fathers were not exposed. The risk was even higher, at 72%, if the fathers were exposed to second-hand smoke and went on to smoke themselves,” says lead study author Jiacheng Liu in a media release.
Avoiding smoking is the best way to reverse the damage
The team analyzed data from the Tasmanian Longitudinal Health Study, the largest and longest of its kind. It has tracked participants’ respiration since 1968.
Results highlight how smoking can damage health not only for smokers and their children, but also their grandchildren.
“Our findings show how the damage caused by smoking can have an impact not only on smokers, but also their children and grandchildren. For men who were exposed to second-hand smoke as children, our study suggests that they can still lower the risk they pass on to their own children, if they avoid smoking,” says co-lead author Dr. Dinh Bui.
The study included 1,689 boys, comparing those diagnosed with asthma by the age of seven.
It also looked at whether the fathers grew up with parents who smoked when they were under the age of 15 and if they were current or former smokers.
“We can’t be certain of how this damage is passed on through generations, but we think it may be to do with epigenetic changes. This is where factors in our environment, such as tobacco smoke, interact with our genes to modify their expression. These changes can be inherited but may be partially reversible for each generation,” says Professor Shyamali Dharmage, leader of the Tasmanian Longitudinal Health Study.
“It’s possible that tobacco smoke is creating epigenetic changes in the cells that will go on to produce sperm when boys grow up. These changes can then be passed on to their children.”
‘We need to protect children from this damage’
According to the Asthma and Allergy Foundation of America, roughly 25 million Americans have asthma. It is the most common long term medical condition in children, with more than five million receiving treatment. Environmental factors, such as pollution, are common triggers.
“Asthma is a common, long-term lung condition that affects children and adults and usually requires ongoing treatment,” says Prof. Jonathan Grigg, chair of the European Respiratory Society’s Tobacco Control Committee, who did not take part in the research.
“We already know that smoking and being exposed to second-hand smoke can increase asthma risk. This study adds to growing evidence that the damage caused by tobacco smoke can be passed on to children and even to grandchildren. We need to protect children from this damage with measures to discourage smoking and support to help smokers quit.”
The findings are published in the European Respiratory Journal.
South West News Service writer Mark Waghorn contributed to this report.