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Family Health

What Is the Best Sunscreen?

BY JENNIFER CHEN June 17, 2019

Yale Medicine doctors weigh in on concerns sparked by latest sunscreen study.

The warm-weather shopping list includes lightweight clothing, sandals and, of course, sunscreen. The ubiquitous skin cancer-fighting lotion can be found in every beach tote, behind every stroller, and in every hiking backpack. 

Recently, however, some types of sunscreens have come under scrutiny. In May of this year, a randomized clinical trial conducted by the FDA asked 24 healthy participants to apply four commercially available sunscreen formulations on their skin. Participants were then tested to see which of those four active ingredients, if any, were found in the bloodstream.

The results of the study showed that all four active ingredients tested (avobenzone, oxybenzone, octocrylene, and ecamsule) entered the bloodstream in just one day at levels high enough to warrant further investigation. Three of the ingredients remained in the bloodstream even after seven days, according to the FDA.

The study follows at the heels of others that suggest that some of these chemicals can penetrate the skin and either mimic critical hormones in the body or disrupt them.

While the results are concerning, dermatologists caution people not to jump to conclusions. “At present, we do not know if there are any harmful effects from the absorption of these chemicals in our bloodstream, and to date there are no studies showing that sunscreen causes harmful effects on our health,” says Yale Medicine dermatologist Jonathan Leventhal, MD. “Bottom line, further investigations are required."

But it doesn’t mean you shouldn’t take precautions. Michael Girardi, MD, another Yale Medicine dermatologist, recommends that people may want to use mineral sunscreens, which do not contain the chemicals in the FDA study, until we know more.

Mineral sunscreens: The safer option?

Many people don’t know that there are actually two types of sunscreens: mineral and chemical. Mineral sunscreens (also known as sunblock or physical-blocker sunscreens) use minerals, including zinc oxide and titanium dioxide, to reflect UV-A and UV-B rays from the sun; valuable protection, since both of these may elevate your risk for skin cancer. The molecules of these substances in sunblock are large enough that they shouldn’t be absorbed into the skin.

On the other hand, instead of reflecting the sun’s rays, chemical-based sunscreens absorb both types of UV rays. The molecules of these chemicals are smaller and more likely to penetrate the skin and enter the bloodstream.

So, if sunblock doesn’t have chemicals in it and isn't absorbed into the bloodstream, why doesn’t everyone use it?

It’s important to note that the phrase “chemical sunscreens” is a misnomer, as both types of sunscreens contain chemicals, says Dr. Girardi. Also, the science isn’t entirely clear on the safety of sunblock. There have been limited animal studies that show that sunblock doesn’t penetrate the skin, but few have tested it on humans. “There is a risk that physical-blocker sunscreens may be absorbed in the bloodstream as well,” says Sean Christensen, MD, a Yale Medicine dermatologist.

Another concern: Zinc oxide and titanium dioxide have been shown to be a carcinogen when inhaled in large amounts in rat studies. It’s currently not considered an issue for sunscreens, however, and more studies may be needed in the future to determine what levels are safe.

Mineral sunscreen vs. chemical sunscreen: A popularity contest

Mineral sunscreens haven’t been as popular among the public because they tend to leave a whitish or purplish sheen on top of the skin. They can also be thicker and harder to spread, which means that it takes more time to make sure you get it evenly on your skin. People also often choose chemical sunscreens because they contain SPF ratings of up to 80 or 100, whereas sunblock lingers around 60. However, at a certain point, a higher SPF rating does not necessarily mean better sun protection. The latest FDA proposal for guidelines on sunscreens puts a limit on SPF ratings at 60 because there has been no evidence that sunscreens with higher ratings show significantly better sun protection.

Regardless of which sunscreen you choose to use, it should not be your only method of sun protection, says Dr. Girardi. People should also make sure they wear hats, stay in the shade, and avoid going out when the sun is strongest (between the hours of 10 a.m. and 4 p.m.).

To spray or not to spray?

For both mineral and chemical sunscreens, there are lotion and spray options. Sprays may seem like an easy alternative, especially when you don’t have the time to rub sunscreen lotion into your skin, but Dr. Girardi prefers lotions. “It’s harder to apply sprays evenly and the risks of getting it in your eye and inhaling it are greater,” he says. 

Should you DIY?

Recently, natural DIY recipes for sunscreens have cropped up on the internet. These are made of natural oils, such as coconut oil, olive oil, or jojoba oil. However, studies have shown that these natural oils and juices don’t offer enough protection against UV rays to be a safe sunscreen. So dermatologists advise against relying on those for adequate protection against the sun.   

Whether you opt for mineral or chemical sunscreens, the bottom line is that some type of sunscreen is still better than none.

“We've been using them for more than 20 years and they have a very good track record for decreasing the risk for skin cancer,” says Dr. Christensen. “Until we know more, the most important thing is that patients protect their skin.”

To learn more about Yale Medicine Dermatology, click here.