Why Are Cancer Rates in Young People Climbing?

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 percent per year.¹ At the same time colorectal cancer diagnoses in young people are increasing at 2 percent 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

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 percent blue content. By 2016, 15 percent of household bulbs had been replaced by LEDs with typically 15 percent blue content, and by 2018 33 percent of light bulbs were these blue-rich LEDs.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 percent 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. Special retinal ganglion receptors in our eyes detect blue light wavelengths between 440-495 nm. This signal informs the circadian clock 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 Institutes 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; 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 percent 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.

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 blue-free lighting at night.