What you may have heard
The Daily Mirror published a story in 2003 claiming that sitting too close to the TV for prolonged periods of time increases cancer risk.
What science tells us
Older TVs gave off low levels of radiation, but modern TVs are built with proper shielding, so people are protected from potential radiation exposures. The television itself does not increase cancer risk but is instead a symbol for a sedentary lifestyle.
Sedentary behavior is spending long periods of time sitting or lying down, whether this is watching TV, reading a book, sitting on a bus, or using a computer. This behavior is separate from the amount of time spent being physically active and the calories burned during exercise, although both a sedentary lifestyle and low levels of physical activity can contribute to other diseases.
Epidemiological Evidence
While certain types of radiation can cause cancer, there is no epidemiological evidence that you will have significant radiation exposure when sitting close to a TV. In contrast, the body burns very little energy while we are sitting and reduced calorie burning is linked to an increased risk of obesity (and higher levels of body fat), heart disease, and cancer (Cancer Research UK). Several published epidemiological studies have concluded that sedentary behavior increases the risk of developing cancer.
Laboratory Evidence/ Supportive Evidence
Laboratory models using animals studied the relationship between exercise and tumor formation. Some studies have shown that exercise can greatly reduce the size of tumors in mice.
IARC Carcinogen Classification:
Not classified.
How to reduce your risk
Becoming both more physically active and less sedentary helps you live a healthier lifestyle and reduces your risk of developing obesity, heart disease, and cancer (Cancer Research UK). Do at least 150-300 minutes of moderate physical activity weekly (this can be walking, running, swimming, doing chores, or even going shopping). Eating a healthy and balanced diet will also help reduce risk of weight gain.
Bottom line
Watching TV and distance to the TV do not cause cancer. However, a sedentary lifestyle (for example, a lot of TV watching) is associated with low levels of physical activity and contributes to increased risk of obesity, heart disease, and cancer.