There was a very interesting essay that circulated earlier this year called "Is sunscreen the new margarine?" [1]. It was on the front page of HN [2].

According to the article there's also some evidence that long-term sun exposure correlated with a decreased risk of melanoma (outdoor workers have half the melanoma rate of indoor workers!). The hypothesis is that a tan protects against the DNA damage that causes it.

Some of the researchers quoted in the article believe that dermatology has gone too far in considering UV exposure a health risk, and that we're due for a correction in that thinking, because there's too much evidence that UV light is, in fact, healthy.

[1] https://www.outsideonline.com/2380751/sunscreen-sun-exposure...

[2] https://news.ycombinator.com/item?id=18890475