Flyer, most skin damage leading to cancer happens in childhood, even though the cancer is decades later.
One very bad sunburn from an unprotected 4 hours in direct sun increases risk far more than a year of light tanning.
Many cosmetics increase risk of sunburn. The two most common offenders are alpha hydroxy acid and salicylic acid. Anything that exfoliates too, as the outer dead layer of skin protects the rest from burn.
The FDA has a suggested warning on photosensitizing cosmetics but does not require it. One of my public interest lawsuits involved such a product and I learned a huge amount about skin cancer and sunburn, but confidentiality means I cannot name it or discuss details.
Almost all whites will have many skin cancers by old age, but the immune system usually catches and destroys the cancers before they are ever detected. An illustration of this is people with damaged immune systems from AIDS get Karposi’s sarcoma, a viral induced skin (and elsewhere) cancer that a healthy immune system is easily able to destroy.
Conversely over avoiding the sun causes depression, sleep disorders, and immune system dysfunction. It also prevents the light tanning that protects the skin and makes the very unhealthy peeling sunburns more likely.
