FDA Finds High Systemic Absorption of Sunscreen Ingredients
https://www.medscape.com/viewarticle/912651?src=soc_tw_190506_mscpedt_news_mdscp_sunscreen&faf=1"Matta and colleagues found that on day 1 after 4 applications, 23 of 24 subjects had systemic concentrations greater than 0.5 ng/mL for all active ingredients in the formulation applied. This is the Threshold of Toxicological Concern (TTC) FDA adopted to approximate the highest plasma level below which the carcinogenic risk of any unknown compound would be less than 1 in 100,000 after a single dose.
Systemic levels above 0.5 ng/mL were reached quickly: within 6 hours after the first application of avobenzone, 2 hours after application of oxybenzone, and 6 hours after application of octocrylene.
Moreover, the concentration of the agents continued to increase over time, indicating drug accumulation. With avobenzone, the maximum plasma concentration was 4.3 ng/mL at 67.5 hours with one formulation, whereas the maximum oxybenzone reached was 209.6 ng/mL at 57.0 hours with a different formulation."
Meanwhile... a higher fat (aka ketogenic or Mediterranean diet) seems to offer protection from the Sun:
https://www.ncbi.nlm.nih.gov/m/pubmed/20137053/When you look at graphs of skin cancer rates, they have been increasing since the early 70s, coinciding with the push to a low fat diet. And people used used to spend a *lot* more time outside ("unprotected") than they do today, yet the rates were dramatically lower. Whether it's a protective effect of the higher fat diets we used to eat, or a negative effect of the higher carbohydrate diets (aka the "plant based diets" being pushed today) is a good question.