First study of its kind shows air pollution may cause painful periods

Women and girls exposed to long-term air pollution can have painful and severe periods, a condition called dysmenorrhea.

An epidemiological study done by open access publisher Frontiers has shown that the risk of developing dysmenorrhea increases 30 times for women and girls who are exposed to air pollutants such as carbon and nitrogen oxides and fine particulate matter (PM).

Frequent severe and painful cramps during menstruation from abnormal contractions of the uterus affects between 16% and 91% of girls and women of reproductive age, of whom between 2% and 29% have symptoms severe enough to restrict their daily activity.

Research done at China Medical University Hospital in Taiwan has proved that pollutants such as nitrogen and carbon oxides and fine particulate matter greatly raise the risk of developing dysmenorrhea.

Long-term data on air quality and public health shows that the risk to develop dysmenorrhea over a period of 13 years (2000-2013) was up to 33 times higher among Taiwanese women and girls who lived in areas with the highest levels of air pollutants compared to their peers exposed to lower levels of pollutants. These results were recently published in the open access journal Frontiers in Public Health.

A common debilitating disorder with no known cure

Dysmenorrhea can be due to hormonal imbalances or due to underlying gynaecological conditions such as endometriosis, pelvic inflammatory disease, ectopic pregnancy, or tumors in the pelvic cavity. Symptoms are often life-long: they include cramps and pain in the lower abdomen, pain in the lower back and legs, nausea and vomiting, diarrhea, fainting, weakness, fatigue, and headaches. In addition to affecting quality of life, dysmenorrhea also has a major socioeconomic impact, as females with dysmenorrhea may be temporarily unable to work, attend school, or engage in leisure activities. Dysmenorrhea has no known cure, but its symptoms may be managed with anti-inflammatory drugs and hormonal contraceptives.

“Research has already shown that women who smoke or drink alcohol during their periods, or who are overweight, or have their first period very young, run a greater risk of dysmenorrhea. Women who have never been pregnant are likewise known to be at greater risk,” said one of the authors, Prof Chung Y Hsu at the College of Medicine, China Medical University, Taichung, Taiwan.

“But here we demonstrate for the first time another important risk factor for developing dysmenorrhea: air quality, in particular long-term exposure to pollution. We don’t yet know the underlying mechanism, but emotional stress in women exposed to air pollutants, or higher average levels of the hormone-like prostaglandins in their body, might be part of the answer. ”

Also read: Celebs like Virat Kohli, Malaika are sipping ‘black water’. Wait, what?

The authors, led by Prof Chia-Hung Kao, director of the department of nuclear medicine and the Center for Positron Emission Tomography (PET) at China Medical University, studied anonymized health measures from a total of 2,96,078 women and girls (approximately 1.3% of the total population) between the ages of 16 and 55. The data came from Taiwan’s Longitudinal Health Insurance Database starting 2000 (LHID 2000), a representative subsample from Taiwan’s nation-wide health insurance database.

The study sample exclusively included women and girls without any recorded history of dysmenorrhea before 2000. The authors looked for a long-term association between the risk of dysmenorrhea and air quality, in particular the mean exposure over the years to air pollutants – nitrogen oxide (NOx), nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), and particles smaller than 2.5 µm in diameter (‘PM2.5’) – obtained from the ‘Taiwan Air Quality Monitoring Database’ of the Environmental Protection Administration.

Air pollutants are an important new risk factor

They found that from 2000 to 2013, 4.2% of women and girls in the studied sample were diagnosed with dysmenorrhea for the first time. As was expected from previous studies, younger women, women with lower income, and women living in more urbanized areas tended to have a higher risk of developing dysmenorrhea. But importantly, the ‘hazard ratio’ (that is, the age- and year-specific risk) of developing dysmenorrhea increased by 16.7 to 33.1 fold for women and girls from the 25% of areas with the highest yearly exposure to air pollutants, compared to those from the 25% of areas with the lowest exposure. NOx, NO, NO2, CO, and PM2.5 levels each contributed separately to the increased risk, but the greatest individual effect was from long-term exposure to high PM2.5.

Also read: Millets in diet can lower risk of diabetes, says study

“Our results demonstrate the major impact of the quality of air on human health in general, here specifically on the risk of dysmenorrhea in women and girls. This is a clear illustration of the need to for actions by governmental agencies and citizens to reduce air pollution, in order to improve human health,” concluded Prof Hsu.

(The original article appeared in blogs.frontiersin.org)