Street lamps can increase your risk of thyroid cancer by up to 55%, the study shows

Living in an area with high levels of artificial light outdoors can increase the chance of developing thyroid cancer – neon light increases the risk by 55%, the study shows.

Researchers at the University of Texas Health Science Center looked for a link between people who develop thyroid cancer and artificial light levels in the open air.

They analyzed data from a cohort of 464,371 participants tracked for about 13 years as part of the NIH-AARP diet and health study – then analyzed satellite imagery to estimate light levels in the areas where people involved in study.

They found that those in areas with the highest level of night light pollution have a 55% higher risk of developing thyroid cancer than those in areas with low light.

They believe that one reason for the connection is that night light suppresses melatonin, a modulator of estrogen activity – which can have an antitumor effect.

Over the past century, night landscapes – especially in cities – have changed dramatically due to the rapid rise of electric light, the study’s authors said.

Studies have also reported an association between higher levels of night light measured by satellite and increased risk of breast cancer.

Because some types of breast cancer may have something in common with thyroid cancer, lead author Qian Xiao and colleagues decided to hunt an association between night light and the subsequent development of thyroid cancer.

They used the NIH-AARP Diet and Health Study – which contains data on hundreds of thousands of people between the ages of 50 and 71 – recorded in 1995 and 1996.

Xiao then analyzed satellite images of each house to determine if those living in bright areas were more likely to develop thyroid cancer.

The team then examined state cancer registry databases to identify thyroid cancer diagnoses by 2011 and found 856 cases among the 464,371 volunteers.

“Compared to the lowest quintile of light at night, the largest quintile was associated with a 55% higher risk of developing thyroid cancer,” Xiao said.

The association was primarily led by the most common form of thyroid cancer, called papillary thyroid cancer, and was stronger in women than in men, he found.

In women, the association was stronger for localized cancer, with no signs of spreading to other parts of the body, while in men, the association was stronger for more advanced stages of cancer, the team found.

The association appears to be similar for different tumor sizes and for participants with different demographic characteristics and body mass index.

The researchers noted that further studies are needed to confirm their findings.

If confirmed, it will be important to understand the mechanisms underlying the relationship between night light and thyroid cancer, Xiao said.

Scientists have observed that light at night suppresses melatonin, a modulator of estrogen activity that can have important antitumor effects.

Also, light at night can disrupt the body’s internal clock (or circadian rhythms), which is a risk factor for various types of cancer.

“As an observational study, our study is not designed to determine causation,” Xiao said, adding that “we do not know if higher levels of light in the open air at night lead to an increased risk of thyroid cancer.”

“However, given the well-established evidence supporting a role in night light exposure and circadian interruptions, we hope that our study will motivate researchers to further examine the relationship between night light and cancer.” said Dr. Xiao.

“Recently, efforts have been made in some cities to reduce light pollution, and we believe that future studies should assess whether and to what extent these efforts have an impact on human health.”

The findings were published in the journal Cancer.