Teen girls exposed to secondhand smoke in the home have a greater risk of developing heart disease than teen boys, according to a study released today by the Journal of Clinical Endocrinology and Metabolism.
Secondhand smoke contains hundreds of toxic chemicals and is known to cause several different health problems — including coronary heart disease, lung cancer, asthma attacks and respiratory infections in children, and sudden infant death syndrome, according to the CDC. Previous research has established that secondhand smoke is also tied to low levels of high-density lipoprotein cholesterol (HDL), a particle that helps protect against heart disease. A 2011 study found that secondhand smoke decreases HDL in children, but the current research, by scientists at the University of Western Australia School of Medicine and Pharmacology, is the first to separate the effects of secondhand smoke by gender.
Unlike “bad” low-density cholesterol (LDL) that builds up in your arteries and leads to heart disease, HDL grabs excess cholesterol out of the bloodstream and transports it to be broken down in the liver. Low HDL has been associated with high risk for cardiovascular disease in adults. Since cardiovascular disease is the leading cause of death among women, the researchers were interested in examining potential gender differences in the health risks associated with second hand smoke.
Researchers analyzed health data from a selection of 1,754 children followed from birth until age 17 in a prior study. After the children turned 17, they answered survey questions regarding their nutrition, physical activity, and drug and alcohol use, as well as their own cigarette consumption. Doctors assessed their height, weight, body mass index (BMI), blood pressure, artery health, and blood biochemistry. The data also included information on the children’s exposure to secondhand smoke throughout their lives, as reported by their caregivers .
From birth to 17, 48 percent of the children were exposed to secondhand smoke at home, and more fathers smoked than mothers. Twenty one percent of the adolescents reported being current smokers, but their data were excluded from the analysis of the health effects of second hand smoke. The researchers looked at the interactions of multiple variables in their statistical model, and found that high levels of HDL were associated with breastfeeding as infants and low BMI. After those factors were controlled, second hand smoke exposure since birth was related to low levels of HDL in girls, but not in boys.
In addition, in a separate analysis of the adolescents who reported using cigarettes themselves, low HDL levels were present in female teen smokers but not in males. A 2010 study found the same effect in adult smokers: the women in the sample had low HDL, but the men did not.
While excessive exposure to secondhand smoke is obviously harmful to everyone, the results suggest that females may be even more adversely affected than males. The development of heart disease is known to depend on a complex relationship between environmental, genetic and biological factors, and hormones or other aspects that differ by gender could play a role in modulating how those factors interact.
Though more men than women typically smoke, recent research has found that smoking poses a 25 percent greater risk for coronary heart disease in women. Another report from 2013 also highlighted the fact that women are more susceptible to health problems from smoking than men, but emphasized that quitting even later in life can reverse some of the effects.
In addition to putting strain on their children’s hearts and lungs, parents who smoke could be setting their children up for health problems in other ways — children from households where parents smoke are more likely to smoke themselves when they are older, according to a study from researchers at New York University. Today’s research provides more evidence for why quitting is important now, and suggests that interventions to combat parental smoking habits could have both long and short-term benefits.