If an 80 year old person dyes his hair less often, the chance of cancer is extremely low, but if he dyes his hair frequently over a long period of time, it is possible to cause cancer. Some hair dyes contain phenylenediamine, which can cause cancer. 80-year-olds who dye their hair less frequently and use qualified hair coloring products have a very low chance of causing cancer. This is because even the most carcinogenic carcinogens can only cause cancer if they are absorbed by the human body in a certain amount. However, frequent hair coloring over a long period of time can cause the skin to absorb the chemicals in hair dyes over a long period of time. In addition, the metabolism of the elderly slows down, easily increasing the risk of cancer. It is recommended that 80-year-olds dye their hair no more than twice a year, and the interval between two consecutive times should not be less than half a year. Be sure to choose the regular brand of hair dye, hair coloring before the best skin sensitivity test, hair coloring should be cleaned a few times, do not let the hair dye residue in the hair. Once the scalp appears uncomfortable symptoms, such as redness, swelling, itching, etc., it is recommended to go to the hospital in time for treatment.