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High asthma risk for sons of fathers exposed to second-hand smoke – Australia study

Research has showed that fathers who smoke around their sons boost the asthma risk by nearly three-quarters for their future grandchildren – and not only are children whose dads were exposed to second-hand smoke when growing up more prone to the breathing disorder, but the risk rises if the offspring becomes a smoker himself.

Passive smoking is believed to alter genes which pass down the generations, said the University of Melbourne researchers. The mutations are carried in sperm.

Lead author Jiacheng Liu said: “We found the risk of non-allergic asthma in children increases by 59% if their fathers were exposed to second-hand smoke in childhood, compared with 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.”

His team analysed data from the Tasmanian Longitudinal Health Study (TLHS), the largest and longest of its kind. It has tracked participants’ respiration since 1968, reports The Independent.

Results highlight how smoking can damage health not only for smokers and their children but also their grandchildren, the team said.

Co-lead author Dr Dinh Bui said: “Our findings show how the damage caused by smoking can have an impact not only on smokers, but also on their children and grandchildren.

“For men who were exposed to second-hand smoke as children, our study suggests they can still lower the risk they pass on to their own children, if they avoid smoking.”

The study included 1 689 boys, comparing those who had been 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 15, and who were current or former smokers.

Professor Shyamali Dharmage, head of TLHS, said: “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.

“It is possible 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.”

Asthma is the most common long term medical condition in children, triggers including environmental factors, such as pollution.

Professor Jonathan Grigg, chair of the European Respiratory Society’s Tobacco Control Committee, who was not involved in the research, said: “Asthma is a common, long-term lung condition that affects children and adults and usually requires ongoing treatment.

“We already know smoking and being exposed to second-hand smoke can increase asthma risk. This study adds to growing evidence the damage caused by tobacco smoke can be passed on to children and even to grandchildren.

Study details

Pre-pubertal smoke exposure of fathers and increased risk of offspring asthma: a possible transgenerational effect

Jiacheng Liu, Gayan Bowatte, Jonathan Pham, Jennifer Perret, John Holloway, Adrian Lowe, John Burgess, Cecilie Svanes, Paul Thomas, Melissa Russell, Bircan Erbas, Caroline Lodge, David Martino, Gita Mishra, Michael Abramson, Eugene Walters, Shyamali Dharmage, Dinh Bui.

Published in European Respiratory Journal on 4 August 2022

Extract
Asthma is a major non-communicable disease in children [1]. Pre- and post-natal exposure to tobacco smoke are major risk factors for childhood asthma [1, 2]. While there is evidence that mothers' intrauterine exposure to second-hand smoke is associated with asthma in the offspring [3, 4], there is also increasing concern that fathers who start smoking before completing puberty may elevate the risk of asthma in their offspring [4, 5]. The suggestion is that this may be as a result of epigenetic changes to sperm precursor (stem) cells during gonadal maturation [4, 5]. However, this is rather speculative, and as yet little is actually known about whether fathers' passive smoke exposure throughout childhood to puberty is indeed associated with increased asthma risk in their offspring.

 

The Independent article – Fathers who smoke risk giving asthma to grandchildren, study says (Open access)

 

European Respiratory Journal article – Pre-pubertal smoke exposure of fathers and increased risk of offspring asthma: a possible transgenerational effect (Open access)

 

See more from MedicalBrief archives:

 

Prenatal BPA exposure linked to asthma in girls – Meta-analysis of 8 European birth cohorts

 

South African childhood asthma guidelines 2021

 

GINA: Over-reliance on reliever pumps linked to increased risk of asthma attacks

 

Breastfeeding and risks of allergies and asthma

 

 

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