When a father smokes, a child's risk of developing leukemia increases, even if dad's smoking was before conception, a new study reports.
While previous studies have linked smoking to leukemia risk in adults, this is the first time there has been a correlation between parental smoking and leukemia risk in children. Even more, the link seems to go beyond second-hand smoke, to the point where a father smoking even years before conception seems to have a great impact on leukemia risk.
Previous studies have linked smoking to leukemia in adults but never in children. So, Dr. Jeffrey S. Chang and colleagues from the University of California, Berkeley, looked at the medical history of 287 children with various types of leukemia, mostly acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), the most common forms of childhood cancer, and over 400 children without leukemia. Forty percent of the participants were Hispanic.
The parents of these children were asked about their smoking habits both before conception, during pregnancy and after their child was born. While 224 of the mothers involved in the study smoked, with over 60 percent smoking at some point before, during or after pregnancy, the researchers were unable to establish any link between maternal smoking and leukemia risk.
As for the fathers, 255 smoked at some point, with 60 percent smoking either before, during or after pregnancy. However, those who smoked prior to conception were four times more likely to have a child with AML than those who refrained from smoking during this period. There was some increased risk of having a child with ALL as well.
However, only 16 children in the study had AML, so further studies would be needed to completely prove the correlation between a father's smoking and the risk of leukemia.
If the connection does exist, Chang suggests that smoking may cause genetic changes that affect a man's sperm, increasing the chance that an increased risk of leukemia will be passed on to a child during conception.
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Regardless, Chang points out that this study highlights the importance for both the mother and father to stop smoking prior to starting a family. "Currently, the public is generally more aware of the detrimental effect of maternal smoking during pregnancy on the health of the fetus," he wrote in the American Journal of Epidemiology, where the study was published.
"The knowledge of a potentially harmful effect of paternal smoking exposure may provide men with a stronger incentive to quit smoking," he added.
