Sunlight: an environmental toxin for humans. A primer to advise patients.

Sunlight causes acute toxic effects such as sunburn, local and systemic immune suppression, and long-term adverse effects including photoaging and skin cancer. The degree of damage depends on the overall exposure-dose and individual susceptibility. Various strategies should be employed to minimize sun-exposure damage, including proper use of sunscreens and exposure avoidance. Public education might best be focused on protecting children and promoting awareness of photoaging changes in adults.