Unprotected sun overexposure, not sunscreen or sunglasses, causes sunburn and skin cancer

In mid-July 2024, a Facebook reel with almost half a million views claimed there is “a direct correlation” between the introduction of sunscreen use and skin cancer. It added that wearing sunglasses reduces natural protection against sunburn.

The claims were made by influencer Joy Van Wyngarden in an episode of the podcast Barn Talk. The podcast, hosted by a father-son duo, has almost 150,000 followers on Facebook and over 200,000 subscribers to its YouTube channel.

In the last few years, dangerous anti-sunscreen narratives claiming that sunscreen causes cancer or deprives people of vitamin D have ramped up on TikTok. Dermatologists warn that these claims are incorrect and put people at a higher risk of skin cancer. Two recent surveys suggest that this type of misinformation is already impacting younger generations.

Between January and February 2024, the American Academy of Dermatology conducted an online survey on sun protection in over 1,000 adults in the U.S. The results revealed that more than half of Generation Z (Gen Z, born from 1997 to 2012) adults were unaware that sunburn causes premature aging and increases the risk of developing skin cancer. Moreover, 37% said “they use sunscreen only when nagged by other people”, compared to 27% in the overall population. Finally, 28% of Gen Z adults said that “getting a tan was more important to them than preventing skin cancer”.

In March 2024, the Orlando Health Cancer Institute conducted another online survey of roughly 1,000 U.S. adults aged 18 and older. The survey found that 14% of adults under 35 think “daily sunscreen use is more harmful to the skin than direct sun exposure”.

The claims in the Facebook reel form part of the same anti-sunscreen narrative and are just as incorrect. Below we discuss these common myths in detail.

Substantial evidence shows overexposure to the sun causes skin cancer

Along with visible light, the sun emits other forms of energy, including ultraviolet (UV) radiation. Although the atmosphere absorbs part of this radiation, most UVA and some UVB rays still reach the Earth’s surface.

In 2009, the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) classified both solar and artificial (tanning beds and lamps) UV radiation as agents proven to cause cancer in humans (Group 1 carcinogens)^[1].

Indeed, numerous epidemiological studies show a causal association between exposure to UV radiation and all major types of skin cancer^[2-4]. Australia, which has some of the highest levels of UV radiation in the world, also has the highest rate of skin cancer. According to the Australian governmental agency Cancer Australia, sun overexposure is responsible for an estimated 95% of melanoma and 99% of non-melanoma skin cancers in some regions.

Both UVA and UVB radiation contribute to increasing the risk of skin cancer, but in different ways. UVA rays penetrate deeply into the skin, causing premature skin aging. UVB radiation typically reaches only the outer skin layers and is the main culprit for sunburn and skin cancer (Figure 1).

Figure 1 – Skin damage caused by solar UV radiation. UVA radiation damages the collagen and elastin fibers in deeper skin layers (dermis), causing premature skin aging. UVB rays hit the outer skin layers (epidermis), causing DNA mutations that can eventually lead to skin cancer. Source: MD Anderson Cancer Center.

UVB rays damage the structure of the DNA in skin cells, which continues for hours after the exposure ends^[5]. The skin cells have effective mechanisms to repair this damage. However, prolonged or repeated exposure to UV radiation causes damaged cells to accumulate. When these cells divide and make copies of their DNA, the structural changes caused by UVB radiation result in mutations that can eventually cause damaged cells to develop into a tumor.

Sunscreen use reduces, not increases, the risk of skin cancer

No evidence suggests that sunscreen ingredients increase the risk of developing skin cancer, as previously explained by Science Feedback and other fact-checking organizations. Conversely, there is strong evidence that using sunscreen regularly reduces premature skin aging^[6] and lowers the risk of developing skin cancer^[7-10].

Skin cancers have risen globally since the 1980s, when sunscreen use became widespread. According to IARC estimates, skin cancers were the most common group of cancers diagnosed worldwide in 2022, with more than 1.5 million new estimated cases. Some epidemiological studies even found that people who used more sunscreen seemed to have higher rates of skin cancer^[11,12]. This apparent correlation has been the basis for claims that sunscreen causes or increases the risk of cancer, like in the Facebook reel. However, such claims result from an incorrect interpretation of an effect known as the “sunscreen paradox”.

An article by McGill University explained how this paradoxical effect came about, pointing out that people who use sunscreen also tend to spend more time sunbathing^[13]. In other words, the observed increase in skin cancer rates among sunscreen users is still related to sun overexposure. This excessive exposure directly results from a false sense of security from sunscreen use. This emphasizes the need to exercise caution when exposing oneself to the sun, even when using sunscreen.

The American Society of Dermatology recommends using a water-resistant, broad-spectrum (protects against both UVA and UVB rays) sunscreen with a solar protection factor (SPF) 30 or higher when outdoors. Additionally, it recommends other protective measures, including seeking shade and wearing sun-protective clothing and sunglasses.

Short periods of sunlight exposure produce enough vitamin D

Many social media posts, like this Instagram reel, cite concerns about vitamin D deficiency as a reason for avoiding sunscreen use. The basis for this claim is that sunscreen works by blocking the same radiation that triggers vitamin D production in the body.

Vitamin D is both a vitamin and a hormone that our bodies produce naturally. It is essential for regulating calcium and phosphorus levels in the body, which keeps bones and teeth healthy. In addition, vitamin D plays a role in muscle, nerve, and immune function.

Most of the vitamin D in our bodies is produced in the skin, triggered by solar UVB radiation. Without exposure to natural sunlight, vitamin D levels can drop below the body’s needs, resulting in muscle and bone weakness and other chronic health defects.

However, observational and epidemiological studies show that sunscreen use isn’t associated with vitamin D deficiency^[14,15]. Therefore, while sunscreen may theoretically reduce vitamin D production, this effect doesn’t seem to translate into the real world.

One possible explanation is that sunscreen blocks most but not all UVB radiation and some UVB rays still reach the skin. Furthermore, people tend to apply much less sunscreen than they should, which further reduces protection^[13,16].

In reality, we don’t need much sun exposure to produce enough amounts of vitamin D. According to the WHO, “5 to 15 minutes of casual sun exposure of hands, face and arms two to three times a week during the summer months is sufficient to keep your vitamin D levels high”. These times are even shorter in places closer to the equator, with higher UV levels.

In contrast, the American Academy of Dermatology holds there is no safe level of sun UV that meets vitamin D requirements without increasing skin cancer risk. Based on this, it “does not recommend getting vitamin D from sun exposure or indoor tanning” but from the diet.

While the sun is the primary source of vitamin D, it isn’t the only one. Fish liver oil and fatty fish such as salmon, mackerel, sardines, and tuna are a good source of vitamin D. Low amounts are also present in egg yolk, beef liver, and cheese. Additionally, foods fortified with vitamin D and vitamin D supplements are also available for people who don’t get enough vitamin D from the sun and their diet or have higher requirements.

Sunglasses don’t increase the risk of burning nor reduce vitamin D levels

The Facebook reel claimed that wearing sunglasses increases the risk of sunburn because they block UV rays perceived by the eyes. This, in turn, supposedly prevents the body from producing melanin. The claim is also widespread on TikTok. However, it is also incorrect, as this article by Full Fact explained.

It is not the eyes but the skin that senses UV radiation and activates a protective response against sunburn. UV rays stimulate skin cells to produce a dark pigment called melanin, which causes tanning. An increase in melanin is already a sign of damage and its role is to protect the cells from further harm. The eyes have no role in this process. Skin exposed to UV radiation will produce melanin regardless of whether the person wears sunglasses.

For the same reason, wearing sunglasses will also not prevent the skin from producing vitamin D. We already explained that vitamin D synthesis occurs in the skin, stimulated by solar UVB radiation. Because this process also doesn’t involve the eyes, wearing sunglasses doesn’t interfere with it.

In brief, wearing sunglasses doesn’t increase the risk of sunburn and vitamin D deficiency but can help prevent other health problems instead. Overexposure to solar and artificial UV radiation can harm the eyes in the same way it harms the skin. The American Academy of Ophthalmology explains that too much exposure to UV light increases the risk of eye problems, including cataracts and eye cancers. To minimize these risks, the association recommends “wearing UV-blocking sunglasses” that provide 100% protection against both UVA and UVB rays.

Conclusion

Current evidence doesn’t indicate that sunscreen and sunglasses use cause skin cancer or any other harmful effects. In fact, there is ample evidence that these protective measures help reduce the risk of skin cancer and eye problems that can result from sun overexposure.

REFERENCES

• 1 – El Ghissassi et al. (2009) A review of human carcinogens—Part D: radiation. The Lancet Oncology.
• 2 – Whiteman et al. (2011) The melanomas: a synthesis of epidemiological, clinical, histopathological, genetic, and biological aspects, supporting distinct subtypes, causal pathways, and cells of origin. Pigment Cell and Melanoma Research.
• 3 – International Agency for Research on Cancer Working Group on artificial ultraviolet (UV) light and skin cancer. (2006) The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: A systematic review. International Journal of Cancer.
• 4 – Arnold et al. (2018) Global burden of cutaneous melanoma attributable to ultraviolet radiation in 2012. International Journal of Cancer.
• 5 – Premi et al. (2015) Chemiexcitation of Melanin Derivatives Induces DNA Photoproducts Long after UV Exposure. Science.
• 6 – Guan et al. (2021) Sunscreens and Photoaging: A Review of Current Literature. American Journal of Clinical Dermatology.
• 7 – Watts et al. (2018) Sunscreen Use and Melanoma Risk Among Young Australian Adults. JAMA Dermatology.
• 8 – Gordon et al. (2020) Prevention versus early detection for long-term control of melanoma and keratinocyte carcinomas: a cost-effectiveness modelling study. BMJ Open.
• 9 – Green et al. (1999) Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. The Lancet.
• 10 – Thompson et al. (1993) Reduction of Solar Keratoses by Regular Sunscreen Use. New England Journal of Medicine.
• 11 – Jeremian et al. (2023) Gene-environment analyses in a UK Biobank skin cancer cohort identifies important SNPs in DNA repair genes that may help prognosticate disease risk. Cancer, Epidemiology, Biomarkers and Prevention.
• 12 – Alli et al. (2023) Understanding the Perceived Relationship between Sun Exposure and Melanoma in Atlantic Canada: A Consensual Qualitative Study Highlighting a “Sunscreen Paradox”. Cancers.
• 13 – Autier et al. (1999) Sunscreen Use and Duration of Sun Exposure: a Double-Blind, Randomized Trial. Journal of the National Cancer Institute.
• 14 – Neale et al. (2019) The effect of sunscreen on vitamin D: a review Get access Arrow. British Journal of Dermatology.
• 15 – Young et al. (2019) Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. British Journal of Dermatology.
• 16 – Heerfordt et al. (2018) Sunscreen use optimized by two consecutive applications. PLOS One.