Sunscreen Toxicity: Myth Or Fact?
The big questions around skincare seem to be “how much is enough? and “how much is too much (toxicity and melanoma risk claims)? According to research: here are some leads to an answer:
So we all know that we have to reapply sunscreen. According to Heerfordt et al. (2018), “Participants had missed a median of 20% of their available body surface after a single application. After double application they had missed 9%. “
Ok so if we double apply it should be enough, right? No one knows because there has been such a debate around this in the research community. As of right now there are no published peer reviewed articles that clearly answer how frequently sunscreen should be applied.
Now onto the second question: can we really get some sort of health complication from the over use of sunscreen (talking to all my friends with a bottle for every room). Here’s what I found:
“The strength of the association between risk of skin cancer and sunscreen use has constantly decreased since the early 1980s, and the association was no longer statistically significant from the early 1990s. While the current evidence suggests no increased risk of skin cancer related to sunscreen use, this systematic review does not confirm the expected protective benefits of sunscreen against skin cancer in the general population.” de Silva et al. (2019).
So it seems the the current focus is now on nanoparticles found in recent sunscreen formulations and their downstream impact on our health.
“Another type of sunscreen called physical sunscreens are delivered to the skin surface to block and scatter UV radiation. In physical sunscreens, the minerals, titanium dioxide and zinc oxide are the main active ingredients. “
“These minerals are often processed to nanoscale particles to improve texture, coverage and feel of sunscreens on skin while maintaining the optical properties needed to protect the skin from UV. There is a perceived risk of these nanoparticles penetrating into the viable skin strata despite evidence to the contrary. Complicating this situation further is measuring nanoparticle delivery into the skin is extremely difficult” (Yamada et al. 2020)
Ok so pretty scary but wait- there’s hope:
“We believe effective sunscreen removal could minimize toxicity and help to manage the perceived health risk. One significant step forward in managing delivery and removal is to thoroughly understand the delivery characteristics of sunscreen ingredients from the sub-cellular level to multi-cellular to stratified epithelium and ultimately the macro (i.e. clinical) level.” (Yamada et al. 2020)
Also this doesn’t hurt either:
“At the skin level, most studies performed in humans or animals showed that nano-TiO2 did not penetrate beyond the outer layers of stratum corneum to viable cells and did not reach the general circulation, either in healthy or in compromised skin.” (Dréno et al. 2019)
Another thing I found to be interesting while digging all this up was that companies don’t seem to be accurately depicting the lab data in the formulations to what was used in a lab setting. Take a read:
“The most common model used to study sunscreen from 2009 to 2017 was in cell culture model, followed by in vivo model. The examples of sunscreen active (chemical and physical) experimental models were summarized in Table 1. From cell culture studies, when the toxic doses that were reported in papers are compared to FDA approved dose in each active (Fig. 3), it is clear that except benzophenone-3, all the other chemical actives and physical UV filters were tested in much higher concentration that recommended approximate active in 2 mg/cm2 skin area. Although not all paper revealed the number of cells at the time of treatment. Therefore, there was a assumed cell density according to the cell culture plate area.”
So I guess that’s the closest to what we know right now. In the mean time, I think sticking to applying and then double applying may just be the best way to go.
Author & Concept By: Dr Ekta Y.MD MBA MS
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