My experience seems to hold true to the intermittent sun exposure – short periods of intensive exposure in my younger years, bad burns once or twice or more per summer etc… as opposed to regular long term chronic exposure without blistering burns.
I have an idea of how the whole chronic/intermittent paradox thing works: it’s all just correlation.
People who are chronically exposed to the sun are said to get melanoma at lower rates. Farmers, line workers, and others who work outside just don’t get it as often as office workers who get sunburns on their yearly vacations to the beach. The theory is that either chronic exposure is protective or that burning occasionally is somehow relatively riskier.
My speculation is simply that white people who choose to work in the sun are more likely to have darker skin than white people who choose to work inside. Fair skinned people, knowing that they burn if they go outside unprotected, are more likely to pursue inside jobs. However, being that fair skin is a risk factor all by itself, regardless of how well we protect ourselves, office workers are STILL more likely to get melanoma than their sun beaten counterparts who work out in the heat.
A great example is that of my father, a farmer. He has plenty of moles, just like I do. However, he has a year-round tan, and by the middle of the summer, his skin color is a lot more like coffee than milk. As a result, he didn’t get melanoma when he was thirty two years old like I did.