The effects of air pollution on the human body extend far beyond a tickly throat. Concerns over fertility have already been raised by numerous scientific studies, and researchers have now identified links between air pollution and puberty onset in young girls.
Worldwide, exposure to the fine particulate matter in polluted air causes 7 million deaths every year, according to estimates from the World Health Organization, and more than 1 in 3 Americans live in counties with unhealthy levels of air pollution, the American Lung Society reports.
These tiny particles can penetrate deep into the lungs and cardiovascular tissues, causing heart and lung disease as well as respiratory infections. Moreover, we are increasingly learning that, by entering our bloodstream, these particles can interfere with processes throughout the body, including our reproductive organs.
“Particulate matter contains microscopic solid and liquid droplets that are so small that they can be inhaled into the deepest part of the lungs, enter the bloodstream and reach many downstream target organs, including the ovaries and other reproductive organs,” Robert Hood, a postdoctoral trainee fellow at Emory University’s Rollins School of Public Health, told Newsweek.
In a recent study published in the journal Environmental Health Perspectives, Hood and his team collected data from more than 5,200 girls across the United States to determine if childhood exposure to ambient air pollution could affect the age at which girls had their first period.
“[We] found that higher exposure to PM2.5 throughout childhood was associated with earlier age of [a first period] in a large, prospective cohort of girls in the U.S.,” Hood said.
He went on: “We think that particulate matter may primarily affect puberty onset by disrupting the endocrine system, or more specifically the hypothalamic-pituitary-ovarian axis which is the key regulator of hormones and reproductive development. Another related pathway is through increasing the risk for childhood obesity, which is one of the best-characterized risk factors for earlier puberty onset in girls.
“Although the magnitude of effect was modest, it’s important to remember that relatively small impacts on individuals could result in noteworthy influences on population health,” Hood said.
The age at which a young person starts puberty is influenced by a range of environmental factors as well as genetics, said Anna Merklinger-Gruchala, a researcher at the Andrzej Frycz Modrzewski Krakow University’s Faculty of Medicine and Health Sciences who studies the impact of air pollution on women’s health.
“Girls experience [their first period] at different ages, but usually, in contemporary economically developed countries it occurs between the ages of 10 and 16 years,” she told Newsweek. “The onset of puberty can be influenced not only by genetics but also by environmental factors. But the data on the impact of air pollution is scarce.”
Aside from the inconvenience and potential embarrassment of starting your period before all of your friends do, early-onset puberty can have more serious health consequences.
“Early puberty can be associated with many problems, including mental health, such as changes in behavior, but also physiological consequences,” Merklinger-Gruchala said.
“Earlier puberty increases the risk of obesity and numerous conditions such as hypertension, metabolic syndrome and cardiovascular diseases…. Furthermore, the longer the lifetime exposure to ovarian steroid hormones, the higher the risk of hormone-related cancers, such as breast cancer,” she said.
Early-onset puberty may also affect long-term fertility. “In general, the earlier women start their reproductive years, the earlier they end them, so earlier menarche could mean a quicker onset of reproductive decline leading to menopause, which could impact the ability to conceive in later reproductive years,” Hood said.
Hormonal disruption may also have wide-ranging impacts on the reproductive system. “Any disturbances in the concentration of ovarian steroid hormones can lead to a disruption in the reproductive functions in women, such as subfecundity, variable menstrual cycle length and also miscarriage, stillbirth as well as other poor pregnancy outcomes,” Merklinger-Gruchala said.
“Air pollution exposure may also enhance the risk of polycystic ovary syndrome, characterized by having many small cysts on the ovaries, which is often associated with lacking of ovulation, having high levels of androgens, irregularity of menstrual periods and infertility,” she said.
Although women are born with all the eggs they will ever have, these eggs continue to develop throughout a woman’s reproductive years. “Slow growth and regional and cellular differentiation of the ovary still continues through the onset of puberty, which presents an additional window for environmental exposures, such as air pollution, to disrupt gonadal development,” Hood said.
In other words, air pollution can affect egg cell quality. “Beyond our study, we have some evidence linking air pollution, again specifically particulate matter, with ovarian reserve and [egg cell] maturation, two important parts of female fertility,” Hood said.
Clearly, air pollution poses a public health risk. But what can you do to minimize your exposure?
“On a personal level, people can try to limit their exposure to air pollution, such as avoiding going outside when there are air pollution alerts,” Hood said.
“People can also wear masks during times of high air pollution and ensure the air filters in their homes and cars are replaced regularly. On a larger scale, we can advocate for better control of air pollution and stricter standards for acceptable levels of air pollution,” he said.