Covered this one before but partial myth likely started to keep kids away from expensive equipment or blocking the screen but- partial
Truth. The “get cancer” or “ruin eyes” could largely be traced to the construction of many older televisions and the quantity and types of radiation output by the tubes within the set. These types of radiation tend to vastly lose energy with distance so sitting back just a bit is generally enough to protect you from potential harm.
Newer technology had less harmful radiation output and modern screens generally don’t use tubes and the types of electronics that are known to cause those types of harms in those manners. So at one point it would have generally been good advice to stay back from the screen for safety but the average person doesn’t know how their devices work and this was even worse further back in the history of the relatively new technologies like home pictures.
Truth. The “get cancer” or “ruin eyes” could largely be traced to the construction of many older televisions and the quantity and types of radiation output by the tubes within the set. These types of radiation tend to vastly lose energy with distance so sitting back just a bit is generally enough to protect you from potential harm.
Newer technology had less harmful radiation output and modern screens generally don’t use tubes and the types of electronics that are known to cause those types of harms in those manners. So at one point it would have generally been good advice to stay back from the screen for safety but the average person doesn’t know how their devices work and this was even worse further back in the history of the relatively new technologies like home pictures.