Does LED light cause cancer?
Our society relies heavily on artificial light. One type of light is LED - light that is emitted by a diode that uses electroluminescence to generate light. Briefly, as current passes through a semiconductor diode, electrons from two sides meet at a junction, and energy in the form of light is released.
Some people have concerns that LED light could be a possible carcinogen. However, the scientific evidence is quite clear on the matter: exposure to LED light at most wavelengths does not cause cancer. In fact, there is a robust body of evidence indicating that LED light can be used to kill cancer cells, and thus contribute to cancer treatment.
Indeed, multiple wavelengths of LED light, particularly in the blue spectrum, have been shown to inhibit the growth of multiple types of cancer cells. An impact on colorectal cancer through inhibition of cancer-associated fibroblasts (a type of cell that remodels the environment around the tumor allowing the cancer to spread) was demonstrated in a study [1].
Another study provided insight into a mechanism of blue LED light killing colorectal cancer cells by increasing the presence of reactive oxygen species leading to DNA damage [2]. Reactive oxygen species are highly reactive molecules that disrupt other molecules by entering into bonds with them - including the DNA.
White LED light has been found to inhibit the growth of melanoma cells (a type of skin cancer), after a 9-hour exposure [3].
However, it is important to note that certain wavelengths of light may cancer-promoting. A study on mice found that exposure to LED light at a wavelength of 642 nm enhanced the proliferation of skin tumors [4].
LED light in cancer medicine: current research
There is a robust body of evidence that suggests a potential role of LED light in cancer treatment. Some of the therapeutic effects include inhibition of tumor growth, induction of cell death, and potential effects in the tumor microenvironment.
Blue LED light in cancer treatment
Blue LED light (specifically the 465 nm wavelength) was used to irradiate colorectal cancer cells for 30 minutes, which resulted in suppressed tumor growth, and induction of autophagy-related genes [1]. Autophagy is a type of cell death where the cell self-digests its contents. Another study, also on colorectal cancer, concluded that blue LED light can inhibit the polarization of cancer-associated macrophages to the M2 type [5]. The M2 cancer-associated macrophages are a type of immune cell that is recruited by a tumor by a series of chemical signals and reprogrammed into a function to remodel the tumor's surroundings, allowing it to spread.
Red LED light in cancer treatment
Red LED light (660 nm wavelength) has been shown to reduce the proliferation of breast cancer cell lines. A study found a reduction of cell viability by 40% upon exposure to red LED light [6].
White LED light in cancer treatment
White LED light has been investigated in the treatment of skin cancer. One study found that after a 9-hour exposure, the viability of human melanoma cells decreased by 70% [3].
The available evidence suggests that all types of LED light achieve these anti-tumor effects by inducing DNA damage, and increasing the presence of the harmful reactive oxygen species in the cancer cell [2].
Can other types of artificial light cause cancer?
While LED light does not cause cancer, there are other types and wavelengths of light that are associated with cancer risk.
UV light
UV light is a known carcinogen. There are three types of UV light, namely UVA (315-400 nm), UVB (280-340 nm), and UVC (254 nm), all of which are associated with cell death, and transformation of cells to cancerous [7]. This is the main reason why exposure to sunlight, which contains UV radiation, is the primary risk factor for skin cancers [8]. Additionally, UV light is a component of other artificial illumination systems, such as halogen quartz light bulbs; these have also been implicated in cancer risk, albeit in mouse models [9].
Light pollution and cancer
Light pollution and exposure to artificial light at night have been associated with an increased risk of breast cancer [10]. This highlights the importance of maintaining a healthy sleeping pattern and minimizing exposure to powerful artificial light sources at night if possible.
Summary: LED lights and cancer
In conclusion, while some wavelengths of LED light may cause cancer in animal models, there is an overwhelming body of evidence indicating that LED light does not cause cancer, and is in fact useful in cancer treatment.
However, other types of light, including UV light, are associated with an increased risk of cancer, as is exposure to light pollution and strong sources of artificial light at night.