Chemical Sunscreen Concerns and Sunscreen Doping
There are a large number of animal studies showing the endocrine system can be disrupted by the chemical UV-filters in sunscreens, but human studies have not confirmed these findings. To help minimize the risk of possible side effects, the FDA limits on how much of these ingredients can be used in a formulation of sunscreen. The current chemical sunscreens regulated in the US include azobenzene, octisalate, octocrylene, oxybenzone, and octinoxate. Concerns reported with each of these ingredients are outlined below.
Benzophenone derivatives (e.g. Oxybenzone, Avobenzone, Benzophenone): These chemicals are often used in sunscreens to absorb UV radiation. Some research suggests that benzophenone derivatives may have hormone-disrupting effects, particularly on thyroid hormone activity. There is also concern it is contributing to the bleaching of coral reefs
Octinoxate (Ethylhexyl methoxycinnamate): Another common ingredient in sunscreens, octinoxate has been found to have estrogenic activity in some studies, raising concerns about its potential impact on hormonal balance and possibly contributing to the bleaching of coral reefs
Octocrylene has been found to accumulate in our blood, urine and breast milk. In animal studies, it showed neurotoxicity and progesterone mimicking effects.
Octisalate has been identified as an endocrine disruptor in studies on human sperm cells.
Here is a snippet from a recent review article in the International Journal of Dermatology on the topic:
Recent evidence of high systemic absorption of sunscreen ingredients has raised concerns regarding the safety of sunscreen products. Oxybenzone (BP-3) and octinoxate (OMC), two common sunscreens. Their impact on human health requires a careful assessment.
There are 29 studies that address the impact of these ingredients on human health. Studies show that elevated systemic level of BP-3 has no adverse effect on male and female fertility, female reproductive hormone level, adiposity, fetal growth, child’s neurodevelopment and sexual maturation. However, the association of BP-3 level on thyroid hormone, testosterone level, kidney function and pubertal timing has been reported and prompts further investigations to validate a true association. The systemic absorption of OMC has no reported effect on thyroid and reproductive hormone levels.
My take way: the risk is low from using chemical sunscreens, but I still choose to use mineral based sunscreens.
Recent Controversy Regarding “Doping” Mineral Sunscreens
Historically, both types of UV blockers (chemical and physical) were highlighted on the active ingredient list, but more recently, a somewhat controversial step of sunscreen "doping" is happening where chemical blockers are being included in mineral sunscreens that are nearly identical to the regulated chemical filters but are not being disclosed because they are not regulated in the US and do not have to be highlighted as an active ingredient. On most occasions, it allows lower percentages of mineral UV blockers (zinc and titanium) to be in the formulation, which has the appeal of making them more cosmetically elegant while still being marketed under the guise as a 100% mineral sunscreen. Many of these chemical ingredients are nearly identical to ones that are classified as chemical UV filters in chemical sunscreens. Many are also being regulated in the EU, but not the US.
In addition to being sneaky, this behavior could increase the risks associated with sunscreen because the amount of these chemical UV blockers being used is not regulated. For example, as of June 2022 the FDA only allowed octisalate to be present at 5% in a chemical sunscreen. However, the chemical butyloctyl salicylate, which is nearly identical, can be used at whatever percentage because it isn’t regulated.
The most common ingredients to look for in this ‘doping’ process include butyloctyl salicylate (nearly identical to octisalate), ethyl ferulate (similar to octocrylene), diethylhexyl syringylidenemalonate (similar to octinoxate) and tridecyl salicylate (similar to octisalate).
The take home point is that if you are trying to avoid chemical sunscreens, you have to read the labels and look for these ingredients even if the sunscreen says it is 100% mineral! Mineral sunscreens are safe during pregnancy but also for rosacea patients and those with sensitive skin. Zinc is anti-inflammatory and a natural skin protectant so it often helps with these conditions.
You can read more on “sunscreen doping” at Lab Muffin Beauty Science.
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