Streetlights May Increase Your Risk of CANCER: People who live near artificial neon lights are up to 55% more likely to be diagnosed with thyroid cancer, the study warns.
- Researchers looked for cancer cases in a survey of adults ages 50 to 71
- They then looked at the level of nocturnal light pollution in the vicinity of volunteers’ homes
- There was a remarkable increase in the incidence of thyroid cancer in areas of high light
- The team could be dealing with lower melatonin levels as a result of the light
Living in an area with lots of artificial light outdoors can increase the chance of developing thyroid cancer – using neon lights increases the risk by 55 percent, research shows.
Researchers at the University of Texas Health Science Center looked for a link between people who developed thyroid cancer and levels of artificial outdoor light.
They looked at data from a cohort of 464,371 participants who were followed for approximately 13 years as part of the NIH-AARP diet and health study – and then analyzed satellite images to estimate light levels in the areas where the people involved in the study were, lived.
They found that those in areas with the highest levels of night light pollution had a 55 percent higher risk of developing thyroid cancer than those in areas of low light.
They believe one reason for the link is that light at night suppresses melatonin, a modulator of estrogen activity – which may have an anti-tumor effect.
Living in an area with lots of artificial light outdoors can increase the chance of developing thyroid cancer – using neon lights increases the risk by 55%, study shows
Over the past century, nocturnal landscapes – especially in cities – have changed dramatically due to the rapid growth of electric light, the study authors said.
Studies have also reported an association between higher satellite-measured levels of nighttime light and an increased risk of breast cancer.
Since some breast cancers may have a common link with thyroid cancer, lead author Qian Xiao and colleagues decided to look for a link between night light and the later development of thyroid cancer.
They used the NIH-AARP Diet and Health Study – with data from hundreds of thousands of people ages 50 to 71 – recorded in 1995 and 1996.
Xiao then looked at satellite images of each of their homes to determine if those who lived in high-light areas were more likely to develop thyroid cancer.
The team then examined the state’s cancer registry databases to identify thyroid cancer diagnoses up to 2011 and found 856 cases among the 464,371 volunteers.
“Compared to the lowest quintile of light at night, the highest quintile was associated with a 55 percent higher risk of developing thyroid cancer,” said Xiao.
“The association was mainly caused by the most common form of thyroid cancer called papillary thyroid cancer, and it was stronger in women than in men,” he discovered.
In women, the association was stronger for localized cancer without signs of spread to other parts of the body, while in men, the association was stronger for more advanced stages of cancer, the team found.
The association was found to be similar for different tumor sizes and between participants with different demographics and body mass index.
The researchers noted that additional studies are needed to confirm their findings.
If confirmed, it will be important to understand the mechanisms underlying the relationship between light at night and thyroid cancer, Xiao said.
The scientists noted that light at night suppresses melatonin, a modulator of estrogen activity that may have important anti-tumor effects.
Also, light at night can disrupt the body’s internal clock (or circadian rhythms), which is a risk factor for several types of cancer.
They found that those in areas with the highest levels of night light pollution had a 55 percent higher risk of developing thyroid cancer than those in areas with low light
‘As an observational study, our study is not intended to establish causality,’ said Xiao, adding ‘we don’t know whether higher levels of outdoor light at night lead to an increased risk of thyroid cancer. ‘
“However, given the proven evidence supporting a role of light exposure at night and circadian disruption, we hope our study will motivate researchers to further explore the relationship between nighttime 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 evaluate whether and to what extent such efforts affect human health.”
The findings are published in the journal Cancer.