Many are advocating for natural sunscreens. Let’s discuss the evidence behind the reported toxicity of the common chemical sunscreen oxybenzone.
Oxybenzone or benzophenone-3e is present in many sunscreens on the market today and has been found in the majority of blood samples taken in studies.
It’s also present frequently in breast milk and has been reported to act like an estrogen in the body, change sperm production, be associated with endometriosis and have high rates of skin allergies.
Given that this chemical is already present in the body of most of us, let’s review the evidence of its reported estrogen-like effects and possible toxicity. To have ill effects on the body, we must first show that its absorbed.
Is oxybenzone really absorbed into the blood stream?
In a 2 week study by Janjua et al, 32 healthy subjects (15 men and 17 women) were assigned daily whole-body sunscreen applications compared to a basic cream foundation without sunscreen. All three sunscreens studies were found to be detectable in the urine. Minor differences were observed in the testosterone levels of the male subjects, but no changes were found in the reproductive hormones FSH and LH.
Janjua et al also published a second article demonstrating the presence of the chemical sunscreen oxybenzone and 2 others in the blood or “plasma” one to two hours after the first application.
So, it would seem that the evidence supports the absorption of these chemical into our blood if we apply them to our skin. However, does this really matter?
Studies on endocrine effects of chemical sunscreens
The results of multiple research studies looking at the possible endocrine disrupting effects of the most common chemical sunscreens used in cosmetics are discussed in a large review paper by Krause, et al from the University of Copenhagen in Denmark.
The theorized effect on the endocrine system by chemical sunscreens is thought to occur through the disturbance of the hypothalamic-pituitary-thyroid axis (HPT). This simply means that the change may come from the central hormone regulating area of the body and effect many hormone systems.
Several studies are described by the Krause, et al paper in which the effects of chemical sunscreen including oxybenzone are examined in vitro (petri dish or outside the body) and in vivo (inside the body or lab animal).
The possible estrogen effect of oxybenzone as well as other chemical sunscreens were studied by exposing female rats and measuring their reproductive organ weight. The group found that female rats exposed to oxybenzone had heavier uteruses. This is notable given that the rats were immature, and were not expected to have uterine growth at that young age.
Schlumpf et al, from the University of Zurich, conducted a study in which cells grown outside the body in the lab (in vitro), chemical sunscreens like oxybenzone were found to have a partial stimulatory effect on breast cancer receptors.
So if you believe that evidence found in the reproductive system in rats and cells grown outside the body apply to humans, then the results of these studies should be considered.
It is certainly biologically plausible that the same disease mechanisms found in rats exist in us, and that these studies should raise concern for the safety of chemical sunscreens.
So what alternatives exist to chemical sunscreens?
More natural sunscreens such as those with zinc oxide and titanium dioxide have far fewer reported health concerns and break down less in the sun. Newer formulations are less chalky and even easier to apply.
However, caution should be used even with natural sunscreens, especially when put in a spray. They should not be inhaled as the International Agency for Research on Carcinogens has even classified titanium dioxide as a possible carcinogen when inhaled in high doses.
Two of our favorite sunscreen brands at our house are All Terrain and Babyganics. They are natural and effective sunscreens, and I have no financial ties to these companies. They are just our family’s personal picks.
Beyond these brands, there are many natural options available at almost every grocery store and online company to choose from.
So, have fun outside. Please just be mindful when choosing your sunscreen.
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In good health,
J Lee Jenkins, MD
J Lee Jenkins, MD, MSc, FACEP is a practicing board-certified emergency physician and researcher in emergency public health. She can also be found on twitter (twitter.com/jleejenkins) and Facebook (J Lee Jenkins MD).
Information on this web site is provided for informational purposes only. This blog is not intended to provide personal medical advice. As always, please consult with your personal doctor prior to making any changes to your health regimen.