Dermatologists always advise people to apply sunscreen before stepping out in the sun, but the results of a small clinical trial by researchers at Food and Drug Administration in the US have indicated that the UV-blocking chemicals in sunscreens seep into the blood cells. Though, there’s no evidence as to what the molecules do inside the body, it is understood to have serious repercussions for sunscreen manufacturers going forward, and may change the options found in drugstore shelves.
“Everyone had always thought that because these are intended to work on the surface of the skin that they wouldn’t be absorbed, but they are,” mentioned Theresa Michele, director of the FDA’s division of nonprescription drug products, and co-author on the FDA-funded study. Her team found that it took only a few hours after the application of sunscreen for the photoprotective chemicals to infiltrate the bloodstream.
The results, published in the journal JAMA, document that the researchers saw the same patterns in all 24 of the volunteers they recruited —12 men and 12 women, who were randomly assigned to apply one of four available sunscreens: two sprays, a lotion, and a cream.
The participants applied their potions four times a day for four days to 75 percent of their bodies, roughly the skin visible in a bathing suit. For those four days, and three days after, researchers collected blood every few hours to be analysed for the presence of avobenzone, oxybenzone, octocrylene, and ecamsule which made for 30 samples in all.
They discovered that while it took only a few hours for the UV-blocking chemicals to spike over the target, for three of the four formulations, those levels remained elevated through the end of the study, three days after participants had ceased spraying and smearing. Only the cream users saw their chemical concentrations tail off sooner.
The fact that these sun-filtering molecules do penetrate into the circulation system does not on its own mean that such ingredients are unsafe. “There might be nothing, and that would be great,” said Kanade Shinkai, a dermatologist at UC San Francisco and editor in chief of JAMA Dermatology.
“But the problem is that we just don’t know.” The bottom line, she said, is that although the evidence is irrefutable that the sun causes skin cancer, scientists know a lot less about sunscreen chemicals’ relative risks and benefits.
Like other over-the-counter drugs, the FDA are trying to study sunscreens to make sure they don’t mess up people’s hormones, affect their reproductive systems, or cause cancer. Such safety testing has never been done on the active ingredients in sunscreen, because those chemicals were approved decades ago, before anyone suspected they could be absorbed into the body. But now, thy suspect that it could be a problem if they do seep into the bloodstream.
However, it is understood that the effects on internal tissues would require more research in the long-term exposure and absorption of such chemicals in children and infants with their smaller ratio of body surface to overall size.
The research team also pointed out that it is required that the research move out of humidity-controlled confines to real-world environments, for example, a hot, sandy beach.
Similar research in India has suggested for a long time that sunscreens are more a luxury than a conscious need.
“It is important to have stringent safety assessment of their potential to produce local toxicity, such as irritation, sensitisation, phototoxicity, acute toxicity, dermal absorption/penetration, sub-chronic toxicity, genetic toxicity, carcinogenicity and photo-carcinogenicity etc. for the sunscreen chemicals in this country,” said a 2013 paper ‘Safety and regulatory issues on sunscreen products in India’ by Sujit Kumar and Roop Narayan Gupta from the Department of Pharmaceutical Sciences, Birla Institute of Technology, Mesra, Ranchi, Jharkhand.
They also stated that SPF rating for cosmetic products and drugs needs to be fixed and guidelines for label claims on these products should be developed.
Meanwhile, results of another study from 2008 titled ‘Efficacy Study of Sunscreens Containing Various Herbs for Protecting Skin from UVA and UVB Sunrays’ said, “scientifically verified that herbs are having enough potential to protect skin from harmful sun rays and it is worthwhile for consumers to use herbal sunscreens”.
The research by Shweta Kapoor and Swarnlata Saraf from the Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur studied 28 volunteers in the ages of 23-29 years. The volunteers were equally distributed in two groups for subjective evaluation for testing sunscreens efficacy (SPF In-vitro determination) and safety (sensitivity test). Back of the forearm was the chosen spot for the study.