Current evidence does not indicate that sunscreen ingredients increase cancer risk; it shows that exposure to the sun without protection

COMPLAINT

“Sunscreens cause cancer, not the sun”; sunscreens and sunless tanning products contain carcinogenic ingredients

DETAILS

Non supported: There is no evidence that sunscreen ingredients increase the risk of any type of cancer. On the contrary, plenty of evidence shows that using sunscreen reduces the risk of skin cancer.
Inaccurate: Overexposure to the sun is the leading cause of skin cancer, contrary to claims on social media.
Lack of context: Benzene is not an ingredient in sunscreen. The presence of minute levels of benzene in the sunscreens was probably due to the contamination of certain batches of the product.

KEY TO GO

Skin cancer is the most common type of cancer in the United States and its main cause is overexposure to the sun’s ultraviolet rays. Medical associations and public health authorities recommend people minimize the risk of skin cancer by avoiding overexposure to the sun and using sunscreen outdoors.

COMPLETE CLAIM: “Sunscreens cause cancer, not the sun”; “tan sprays and self-tanning lotions/serums change your DNA”; sunscreen products were ‘recalled for having benzene, a known carcinogen which experts say could potentially increase the risk of cancer’

REVIEW

Skin cancer is the most common type of cancer in the United States. It is estimated that as many as one in five Americans will develop skin cancer in their lifetime.[1], primarily associated with overexposure to ultraviolet (UV) radiation from the sun. Therefore, the best way to prevent skin cancer is to protect the skin from UV rays.

The American Academy of Dermatology recommends seeking shade during peak hours, wearing protective clothing and sunglasses, and always using sunscreen when outdoors. However, myths and misconceptions about skin cancer, sun exposure and prevention are still prevalent and contribute to hesitancy to follow these simple protective measures.

In early April 2022, posts claiming that sunscreens cause cancer (see examples here, here and here) circulated on social media platforms. These posts received a total of more than 13,000 interactions on Facebook and Instagram.

As we will explain below, the claim that sunscreen increases the risk of cancer or has harmful effects in humans is not supported by currently available scientific evidence. On the contrary, data from several studies indicate that regular use of sunscreen is safe and prevents sunburn, long-term skin damage and skin cancer.

This review explains where this claim might have come from and what the state of current scientific evidence is regarding sun exposure, skin cancer and sunscreen safety.

UV radiation from the sun is a known carcinogen

Messages claiming that the sun does not cause cancer are inaccurate, as Health Feedback explained earlier in this review. The sun emits not only visible light, but also invisible UV rays. Thus, our skin also receives UV rays. Overexposure to the sun can damage the skin through two different types of UV. UVA rays are primarily associated with long-term damage and premature aging (wrinkles and age spots). UVB rays have a higher amount of energy than UVA rays and are the main cause of sunburn and skin cancer, but both UVA and UVB rays increase the risk of skin cancer[2].

Epidemiological studies show a causal association between exposure to solar and artificial UV rays, such as tanning beds and sunlamps, and all major types of skin cancer[3,4]. UV radiation is a proven cause of basal cell carcinoma and squamous cell carcinoma (SCC), and is also associated with an increased risk of developing melanoma[5]. This is because UV rays can penetrate skin cells and damage their genetic material. Cells can only partially repair this damage, which accumulates over time and can eventually impair cell function and lead to skin cancer.

In 2009, the International Agency for Research on Cancer (IARC) classified the sun and artificial UV radiation as group 1 carcinogens, i.e. agents that have been shown to cause cancer. cancer in man.[6].

Concerns About Sunscreen Ingredients

Sunscreen products are regulated as over-the-counter drugs by the United States Food and Drug Administration (FDA). This means that the active ingredients they contain must be proven safe and effective before these products enter the market.

Several studies, including randomized controlled clinical trials that have evaluated the use of sunscreens for more than ten years, indicate that regular use of sunscreens is safe and reduces the risk of skin cancer[7-9]. Based on this evidence, the American Academy of Dermatology and the American Cancer Society recommend everyone use sunscreen outdoors. The most adequate sunscreen would be one that offers broad-spectrum protection, i.e. a sunscreen that protects against both UVA and UVB rays, has a sun protection factor (SPF) of at least 30 and water resistant.

Initially, it was assumed that the active ingredients in sunscreens remained on the surface of the skin. In 2019 and 2020, the FDA published two clinical trials showing this was not the case, and several common active ingredients, including oxybenzone, octinoxate, and octocrylene, were absorbed into the bloodstream.[10,11]. These findings prompted the FDA to update the sunscreen marketing requirements and to request additional safety data to fill data gaps resulting from this new evidence.

While the FDA’s findings don’t mean the sunscreen ingredients are unsafe, some social media users have misinterpreted the findings to mean the ingredients were harmful. Some of them cited previous studies showing that high concentrations of some of these active ingredients caused cancers and hormonal disorders in laboratory animals and cell cultures.[12,13].

However, animals and cells are very different from humans, and the results of these studies cannot be directly extrapolated to humans. Moreover, these studies generally used concentrations of active ingredients much higher than those present in sunscreens.[12-14]. Some of these studies also used a different route of administration, such as feeding the animals foods containing chemical UV filters rather than applying the chemicals to the skin.

In other words, while these preliminary results deserve further investigation, they don’t provide evidence that sunscreens harm people’s health. In fact, the US National Academies of Sciences, Engineering, and Medicine state that “sunscreen use is not linked to higher rates of any type of cancer.” This means that the known risk of developing skin cancer from unprotected sun exposure far outweighs any potential risk from sunscreen ingredients.

Concerns about the presence of benzene in sunscreen products

Some posts like this have specifically linked cancer risk to the presence of benzene, a chemical that the IARC says causes cancer in humans with long-term exposure. In 2021, an analysis by the independent laboratory Valisure reported traces of benzene in 78 unique batches of sunscreen products out of the 294 analyzed (27%). One of the affected companies, Johnson & Johnson, has issued a voluntary recall of the affected products and lots as a precautionary measure.

However, it is important to note that benzene is not a true sunscreen ingredient. The authors of the report therefore assumed that its presence was due to the contamination of certain batches during the manufacturing process. The report also states that the trace amounts detected do not indicate a safety issue with sunscreens in general, as most batches tested did not contain detectable levels of benzene.

The United States Centers for Disease Control and Prevention (CDC) explains that people are exposed daily to low levels of benzene from tobacco smoke, gas stations, motor vehicle exhaust and industrial emissions. Based on Environmental Protection Agency (EPA) guidelines, Johnson & Johnson stated that “daily exposure to the benzene in these aerosol sunscreens at the levels detected in our testing is not expected to adversely affect health”.

David Leffell, chief of dermatological surgery and cutaneous oncology at the Yale School of Medicine, explained in an email to Health Feedback:

“Benzene has been found in some sunscreens, possibly due to the manufacturing process. But any cancer risk, which has not been specifically documented, is outweighed by the known risk of developing skin cancer from the sun.

Concerns about the presence of dihydroxyacetone in self-tanning lotions

Sunless tanning lotions and sprays have also been subject to claims of allegedly harmful effects in humans. For example, this Facebook post claimed that these products “change your DNA.”

The post cited a 2004 study showing that dihydroxyacetone (DHA), the active ingredient in suntan lotions, damaged DNA in cells grown in the lab. But as with sunscreen ingredients, the results of this study do not imply that DHA is harmful to humans for external use at the concentrations found in tanning products.

The US FDA considers DHA levels in suntan lotions and sprays safe for external use. There are no data regarding its safety when applied to the eyes, lips or other mucous membranes, or when ingested or inhaled, and the agency recommends avoiding such exposure.

Conclusion

There is no conclusive evidence that the ingredients in sunscreens and tanning lotions and sprays are unsafe, contrary to claims on social media. Conversely, several studies show that the use of sunscreen reduces the risk of skin damage caused by UV rays, which are a well-known carcinogen. For this reason, the US CDC and the American Academy of Dermatology recommend using sunscreen outdoors in conjunction with other protective measures, including wearing protective clothing and sunglasses, and limitation of exposure during periods of maximum sunshine.

FEEDBACK FROM SCIENTISTS

David J Leffell, Professor of Dermatology and Professor of Surgery, Yale School of Medicine, Yale University:
DHA, commonly used in self-tanners, has not been shown to cause cancer in humans.
Benzene has been found in some sunscreens, possibly due to the manufacturing process. But any cancer risk, which has not been specifically documented, is outweighed by the known risk of developing skin cancer from the sun.

REFERENCES

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