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A lab found a carcinogen in dozens of sunscreens. Here’s what those findings really mean.


When independent laboratory Valisure announced it had found the known carcinogen benzene — a compound linked to blood cancers such as leukemia — in 78 sunscreens and after-sun products, the news prompted a flurry of alarming headlines and articles. But some experts are raising questions about how the study was conducted, and dermatologists are emphasizing that the news does not mean sunscreen is unsafe.

 Valisure CEO David Light defended the methodology used in the testing of 294 batches of products from 69 different companies. He also said the company did not intend “for anything to be misconstrued, and we’ve stated many times that we want to make sure that people understand this particular problem doesn’t appear to be an issue directly with sunscreen.”

Still, dermatologist Ranella Hirsch, a self-described “myth debunker” on Instagram, said she was deluged with questions after the study was released, such as, “Does this mean I shouldn’t wear sunscreen?” and, “Is benzene listed in the ingredients on the back of the bottle?”

What consumers need to understand, the Cambridge, Mass.-based Hirsch said, is that this isn’t a sunscreen problem, it’s a contamination problem. “Contaminations happen and mechanisms exist for this very thing. An individual make and car can have a part recalled, but you aren’t likely to stop driving.”

Hirsch posted a cheat sheet on Instagram to try to quell confusion. Bottom line, she wrote: “Sunscreen ingredients are safe and should be used to protect from the known and established risk of skin cancer.”

According to the Skin Cancer Foundation, more people are diagnosed with skin cancer every year in the United States than all the other cancers combined, and regular use of broad-spectrum sunscreen with at least an SPF of 15 can decrease your risk of skin cancer and skin precancers.

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Benzene, the contaminant Valisure detected in the 78 products, is a component of gasoline and a frequently used solvent for rubber and waxes. It is also used in the extraction of oils from seeds and nuts, and in the manufacturing of detergents and pharmaceuticals. The chemical is found in the air from emissions from burning coal and oil, tobacco smoking, gas stations, and vehicle exhaust.

 Martyn Smith, a professor of toxicology and the Kenneth Howard and Marjorie Witherspoon Kaiser Endowed Chair in Cancer Epidemiology at University of California at Berkeley, said he wasn’t surprised by Valisure’s findings, because benzene is difficult to avoid. “It’s the building block for many chemicals in our world, including many drugs like aspirin and other things. It’s also found in all fossil fuels, and anytime you burn anything — from a wood-burning fire to a candle — you are exposed to benzene.”

Chemistry professor Joe Schwarcz, director of the Office for Science and Society at McGill University in Montreal, agreed.

“Because of our analytical capabilities, you can find contaminants in everything,” he said. “If you look for it, you will find it.” The presence of a chemical does not equal the presence of risk, Schwarcz added.

Smith said he compared the highest level of benzene contamination mentioned in Valisure’s report to urban air breathing for 24 hours, and estimated that applying 10 ml of the contaminated sunscreen (approximately one application) could — in the worst-case scenario — result in absorbing about half the amount of benzene one gets from breathing city air in for a day. 

He also noted that 16 of the 20 most contaminated products according to the Valisure report were sunscreen sprays. Despite their high contamination levels, Smith said the risk of exposure would be very low. “You would have to cover yourself in spray” to get to a dangerous level, he said.  “And the level would be diluted by the same stuff that propels the spray.”

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Another issue with the study, according to Schwarcz, is that it’s not clear how much benzene in contaminated sunscreen would get into a person’s blood.

“Benzene is a very volatile compound that evaporates quickly so when you put it on your skin, I suspect most of it will evaporate before it has a chance of being absorbed,” he said. “You would probably find some [benzene] because you would probably find it in everyone's blood, whether or not they have used the contaminated sunscreen or not.”

Other concerns about the Valisure report raised by scientists were that it relied on oral exposure levels although sunscreen is applied topically, and it used the chemical compound NDMA as a comparable benchmark in its testing, although toxicity levels and other aspects of benzene and NDMA are not the same.

Michelle Wong, a science educator and beauty blogger with a PhD in chemistry who is based in Sydney, said she was frustrated that so many dermatologists and scientists posted about Valisure’s study without looking into the issue. “They clearly only read the news release, because if they read the petition, they would have noticed that Valisure used NDMA as a comparison benchmark. If you have any sort of background in toxicology you would ask yourself why they would make this nonsensical comparison.”

 In responding to these points, Light, who is also Valisure’s founder, said the company used oral exposure to NDMA as a regulatory comparison. “We’re not saying that it has to be exactly the same, but the point is that these are regulatory limits by the [Food and Drug Administration] and sunscreen is a drug product,” he said. “So, the amount of NDMA is limited by both a concentration and an exposure limit. And this is broadly across all drug products, so we can debate the clinical impact of absorption and various absorption routes, but the FDA does not make a distinction.”

When Valisure announced its findings, it also released a citizen petition to the FDA asking for a recall of the contaminated products. It also asks for changes in regulations including the creation of “rules or administrative orders requiring robust independent chemical batch level testing and verification of the chemical content of batches of drugs and other regulated consumer products and, while these are pending, issue guidance requesting such testing and verification” and support for independent drug quality testing programs. 

Light said one of the “core values” of the company is consumer advocacy.

“I spent most of my time in the biotech industry, and for that reason I care about public health,” he said.

When asked whether Valisure could benefit if the FDA implemented more regulation of drug and consumer products, Light said, “We certainly want companies to have additional quality assurance — that is our whole business.” He added: “We hope that there are many independent laboratories that can help, because these are serious quality problems that exist in drugs, and the overall creation of independent analysis we think is incredibly important.”

A representative from the FDA said in an emailed statement that the agency is evaluating the petition. “The FDA takes seriously any safety concerns raised about products we regulate, including sunscreen,” the statement said. “While the agency evaluates the submitted citizen petition, we will continue to monitor the sunscreen marketplace and manufacturing efforts to help ensure the availability of safe sunscreens for U.S. consumers.”

 The statement added that the FDA would both respond directly to Valisure and post its response on

 The experts said that while there is value in the sort of consumer testing Valisure does, independent labs should be careful with their rhetoric and mindful of how their research may be construed by the public. “I don't usually like downplaying public health risks,” Smith said, “but I also don’t like scaring the public unnecessarily when there’s no need no need for that.”

If you want to check whether a sunscreen was tested by Valisure, the list starts on page 12 of its petition.  

Janna Mandell is a San Francisco-based journalist covering the beauty industry.

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