Cancer: strong night light may cause high risk of thyroid cancer

Cancer: strong night light may cause high risk of thyroid cancer, women should be especially vigilant.

Nowadays, metropolises all over the world are already “cities that never sleep.” The brighter the lights, the more lively the cities appear. However, while the bizarre lighting brings a sense of fashion, it also brings health risks. Recently, a new study published in the peer-reviewed journal Cancer of the American Cancer Society pointed out that too much artificial light at night will increase the risk of thyroid cancer.

The researchers analyzed data from the National Institutes of Health-American Association of Retirees Diet and Health Research, recruited American adults aged 50-71 who were registered from 1995 to 1996, and compared the satellite image data with 2011 Data from the State Cancer Registry were compared to assess the relationship between nighttime light levels and the incidence of thyroid cancer in each participant’s area.

Among the more than 460,000 participants, there were 856 patients with thyroid cancer, including 384 men and 472 women. Combined with night light intensity, the researchers found that compared with the 20% of people who had the lowest exposure to artificial light at night, the 20% of people who had the highest exposure to artificial light at night had a 55% higher risk of thyroid cancer. Among them, the increased risk of papillary thyroid cancer is the most obvious.

In addition, the researchers also found that women are more susceptible to artificial light, and their increased risk of thyroid cancer is more obvious than that of men.

Why does light at night cause thyroid cancer?

Research author Qian Xiao, an assistant professor at the University of Texas Health Science Center in Houston, pointed out that strong night light will inhibit the secretion of natural melatonin, which is a modulator of estrogen activity. Too low melatonin activity may reduce the body’s ability to fight tumors. The strong light at night disturbs the body’s circadian rhythm and is also a risk factor for cancer.

Dr. Shuchie Jaggi, physician at the Endocrinology, Diabetes and Metabolism of Northwell Health Center in New York, believes that night light may affect hormones and thereby affect the thyroid.

Previously, studies have shown that the higher the nighttime light level measured by satellites, the higher the risk of breast cancer. It is possible that breast cancer and thyroid cancer have a common hormone-dependent mechanism.

But the study also has shortcomings. Jaggi believes that the study relies on satellite images and can only check the outdoor lighting level at night, but cannot check whether people are also turning on indoor lights, and cannot rule out the influence of indoor lighting.

In this regard, the study author said that the current conclusions are not enough to prove that night light can cause thyroid cancer, but only prove that there is a connection between the two. Given the solid evidence supporting nighttime lighting and circadian rhythm disturbances, it is hoped that this study will inspire researchers to further study the relationship between nighttime lighting and cancer and other diseases.

(source:internet, reference only)

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