Researchers warn that women with long-term exposure to several types of air pollutants are more likely to complain of dysmenorrhea, the medical term given to menstrual pain that precedes or accompanies periods.

Study, shows, for, the, first, time, that, pollution, increases, risk, of, painful, periods
Pain during menstruation is called dysmenorrhea: this dysmenorrhea is said to be "primary" when it appears at the first menstruation in the adolescent and "secondary" when it occurs in the young woman after puberty. 

What causes dysmenorrhea?

In the latter case, a disease is looked for such as endometriosis, uterine fibroids or polyps. The causes of dysmenorrhea can also be a copper intrauterine device, especially if it is displaced, or a change in hormonal contraception. In the journal Frontiers in Public Health, researchers from the China Medical University Hospital in Taiwan claim to have identified another factor, directly related to the environment: pollution.

They claim that long-term exposure to air pollutants such as nitrogen dioxide, carbon monoxide and fine particles significantly increases the risk of developing dysmenorrhea. Using long-term air quality and public health data retrieved from national databases, their study shows that the risk of developing dysmenorrhea over a 13-year period was up to 33 times higher for women and girls who lived in areas with the highest levels of air pollutants compared to their peers exposed to lower levels of pollutants.

Pollution increases the secretion of prostaglandins

Symptoms of dysmenorrhea include cramping and pain in the lower abdomen, pain in the lower back and legs, nausea and vomiting, diarrhea, fatigue, malaise and headaches. In addition to reducing quality of life, dysmenorrhea also has a major socio-economic impact, as women with the condition may be temporarily unable to work, attend school or engage in leisure activities. While there is no known cure, symptoms can be treated with non-steroidal anti-inflammatory drugs (which decrease the secretion of prostaglandins that cause pain) and hormonal contraceptives.

"Research has already shown that women who smoke or drink alcohol during their periods, who are overweight or who have their first period at a young age, are at greater risk of dysmenorrhea. Those who have never been pregnant also have a higher risk of dysmenorrhea. But here we show for the first time another important risk factor for dysmenorrhea: air quality, especially long-term exposure to pollution," says Prof. Chung Y. Hsu, one of the authors of the study. The hypothesis is that pollutants promote the production of a higher level of prostaglandins: these substances are synthesized in the tissues and act on muscle tone, including uterine contractility.

Fine particles, the most dangerous pollutant

The researchers studied the health data of 296,078 women aged between 16 and 55 years over a period from 200 and 2013, all with no recorded history of dysmenorrhea. They looked for a long-term association between the risk of dysmenorrhea and air quality, specifically exposure over several years to different types of air pollutants: nitrogen oxide, nitric oxide, nitrogen dioxide, carbon monoxide, and particulate matter less than 2.5m in diameter (PM2.5). The results showed that during the study period (2000 to 2013), 4.2% of women in the study sample were diagnosed with dysmenorrhea for the first time.

In particular, younger women, women with lower incomes, and especially those living in more urbanized areas had the highest risk of developing dysmenorrhea during the study period. Thus, the age- and year-specific "hazard ratio" of developing dysmenorrhea increased 33.1-fold for women living in areas with the highest annual exposure to pollutants, compared to those living in areas with the lowest exposure. While each pollutant contributed separately to the increased risk, the largest individual effect came from long-term exposure to fine particulate matter (PM2.5).

Since 2013, outdoor air particulate matter has been classified as a human carcinogen by the International Agency for Research on Cancer. The toxicity of these particles comes from both their composition and their size, knowing that the finer they are, the more they are able to penetrate deep into the body and pass through the bloodstream to other organs. "Our results show that the overall impact of air quality on health, but specifically on the risk of dysmenorrhea. This is a clear illustration of the need for action by government agencies and citizens to reduce air pollution," concludes Prof. Chung Y. Hsu. Hsu.