Cancer Rates are Climbing in Young People -- Might Blue-Rich LEDs be responsible?

The recent dramatic rise of cancers in young people parallels the widespread introduction of blue-rich LED lights and screens.

It took the news of Princess Kate’s cancer diagnosis to bring public attention to what epidemiologists have known for some time. The rate of new cancer diagnoses in young people has been climbing steeply in recent years.

Since 2016, breast cancer diagnoses in women aged 20 - 49 years have been accelerating at nearly 4% per year.¹ At the same time colorectal cancer diagnoses in young people are increasing at 2% per year. In contrast, before 2016 cancer diagnoses crept up at a much slower rate. Cancer specialists are struggling to explain this sudden acceleration.²

A sudden ramp up in breast cancer diagnosis rates after 2016 parallels the introduction of blue-rich LED lights into our homes. (Modified from Xu et al 2024)

What they have overlooked is that this extraordinary rise in cancer in young people parallels the introduction of blue-rich LED lights into their homes, and the display screens they stare at in the evening hours. This blue-rich light exposure in the evening has been shown to suppress the cancer-controlling hormone melatonin and disrupt the timing of our circadian clocks. As a result cancer cells are no longer suppressed and multiply much quicker.

In 2014, virtually everyone still used incandescent and halogen light bulbs at home in the evening with a relatively low 4% blue content. By 2016 15% of household bulbs had been replaced by LEDs with typically 15% blue content, and by 2018 33% of light bulbs were these blue-rich LEDs. Today with the ban implemented on the sale of incandescent, and halogen light bulbs, more than 80% of lamps used in the evening in our homes are blue-rich LEDs.

Most white LED lights and display screens emit a strong blue peak in the light spectrum.  Blue light wavelengths between 440-495 nm are detected by special retinal ganglion receptors in our eyes. This is the signal that informs our circadian clocks whether it is day or night. A considerable body of research shows that too little blue light exposure during the day and excessive blue light at night increases the risk of cancer and many other conditions including obesity, diabetes and heart disease.³ Light exposure at night has been recognized as a carcinogen by the World Health Organization and the National Toxicology Program of the National Instates of Health.

When we look back in history before the invention of electric light, breast cancer and colorectal cancers were rare diseases. The candlelight and firelight used in the evening had very little blue content and hence melatonin levels and circadian rhythms were not disrupted.

Breast cancer rates quadrupled between 1970 and 2010 as workplaces became lit with blue-rich fluorescent light and 20% of the workforce became employed in 24/7 business operations and exposed to this blue-rich light at night. But these blue-rich fluorescent lights were rarely used in the home.

Now cancer rates are ramping up again as our homes become lit with bright blue-rich LEDs, and LED screens become larger and brighter.

The reason is staring us in the face. It is now time to take action and insist on lighting that is blue-free at night.

1. Xu S, Murtagh S, Han Y, Wan F, and Toriola AT, (2024) Breast Cancer Incidence Among US Women Aged 20 to 49 Years by Race, Stage,and Hormone Receptor Status. JAMA Network Open.;7(1):e2353331. doi:10.1001/jamanetworkopen.2023.53331

2. Ledford H (2024) Why Are So Many Young People Getting Cancer? What The Data Say Nature 627: 258-260

3. Moore-Ede M (2024) THE LIGHT DOCTOR: Using Light to Boost Health, Improve Sleep, and Live Longer. CIRCADIAN Books https://thelightdoctor.com/