Skin cancer affects more than three million people in the United States each year, with a rate of 22.7 per 100,000 people in Oakland County, Michigan. While sunscreen is key to protection from the sun's harmful ultraviolet rays, new research on sunscreen ingredients has numerous consumers and advocacy groups concerned that some products may be affecting health and the environment.
Slathering on a layer of sunscreen for a day outside has been normal operating procedure for sun worshippers and responsible parents for the last several decades, and the advent of lighter and more effective sunscreens has increased the number of products available to consumers, as well as their use. However, recent testing has shown that many of the most popular sunscreens on the market contain ingredients that are absorbed by the skin and enter the bloodstream.
In May, researchers with the U.S. Food and Drug Administration (FDA) presented its own data showing that four of the most widely used sunscreen ingredients do in fact enter the bloodstream through absorption into the skin.
The tests follow a proposed rule introduced by the FDA in February of this year that would update its sunscreen rulebook, including active ingredient safety, dosage forms, sun protection factor (SPF) ratings and broad-spectrum requirements. At the heart of the proposed rule is the FDA's longstanding goal to gather additional safety data, including studies to determine whether ingredients that penetrate the skin can cause endocrine disruption, cancer or other harms.
Whether or not the tested sunscreen ingredients have negative impacts on human health isn't yet known with certainty. However, there is evidence that some sunscreen ingredients that are taken up by humans may be responsible for a loss of coral reef habitats. Additional research suggests those same ingredients may act as endocrine disruptors on some aquatic life. Environmental concerns alone have led to bans on the sale of some sunscreens in all or part of two states.
Weighing in on the issue has been the consumer advocacy organization Environmental Working Group (EWG), which has mounted its own campaign raising concerns about sunscreen ingredients, as well as releasing its own guide to sunscreens.
According to the EWG, many studies in animals and cells have shown sunscreen ingredients to affect reproduction and thyroid hormones. Further, the group claims some sunscreen additives may speed the development of skin cancer, and questions the overall effectiveness of sunscreen in light of potential risks.
With the FDA's final rule not expected to be complete before the end of this year, health experts are urging consumers to continue their current use of sunscreens as a measure against skin cancer, sunburn and other harmful effects caused by the sun.
Associate Professor and Assistant Chair for Medical Education with the University of Michigan's Department of Dermatology Frank Wang said sunscreen use is vital to lowering the risk of skin cancer.
"I couldn't agree more," he said regarding the continued use of sunscreen. "We are seeing an epidemic of skin cancer, including more deadly forms, like melanoma, in younger individuals. And it's one of the most preventable cancers. There are no doubt benefits from sunscreens."
In terms of risks associated with absorption of sunscreens, Wang said more research needs to be done. However, he said the known benefits of sunscreen outweigh the known risks – at least at this time.
"I still recommend sunscreen until more is known," he said. "I usually tell patients that (sunscreen) is just one part of their sun protection regimen. Staying out of the sun in the middle of the day, wearing sun protective clothing, hats and glasses all should be done in combination of sunscreen.
"If you personally have some concerns, stick with something that we know is safe, like physical sunscreens like zinc oxide or titanium dioxide."
Both zinc oxide and titanium dioxide have been characterized as Generally Recognized as Safe and Effective (GRASE) in the FDA's proposed rule. The two ingredients are considered mineral or physical sunscreens. Mineral sunscreens sit on top of the skin and provide protection from the sun by reflecting rays away from the user. Chemical sunscreens, however, work by being absorbed into the skin and creating a chemical reaction with ultraviolet rays, converting the rays into heat and then releasing that heat from the skin.
The FDA also proposes listing two specific chemical sunscreen ingredients as not GRASE, or not considered safe for use: PABA and trolamine salicylate — which aren't currently marketed in products for sale in the United States.
Another dozen chemical UV-filters already widely used in the United States are now under consideration by the FDA, which said there is insufficient evidence to determine whether the ingredients are GRASE, or safe for use. Those ingredients include: cinoxate, dioxybenzone, ensulizole, homosalate, meradimate, octinoxate, octisalate, octocrylene, padimate O, sulisobenzone, oxybenzone and avobenzone. Four of those chemicals – avobenzone, oxybenzone, octocrylene and ecamsule – were found by FDA researchers in May to enter the bloodstream through the skin.
"The FDA has been working on sunscreen for a very long time, and the science and use of sunscreen have been evolving," said Theresa Michele, director of the FDA's Non-prescription Drug Products. "Sunscreen is regulated in the FDA's OTC monograph, which is like a rulebook. If manufacturers follow the rulebook, they can bring products to market with FDA approval. That started back in the 1970s, when people didn't use sunscreen very much. Then science evolved and we started learning more about UV radiation and the damaging effects on the skin, and we realized sun protection is critical to prevent cancer and premature aging."
Drawing on the FDA's study that found some of the ingredients are absorbed into the skin, the FDA is requiring additional information from manufacturers to determine safety and effectiveness.
"For example, the available literature includes studies indicating oxybenzone is absorbed through the skin to a greater extent than previously understood and can lead to significant systematic exposure, as well as data showing the presence of oxybenzone in human breast milk, amniotic fluid, urine and blood plasma," the FDA said in its proposed rule. "The significant systemic availability of oxybenzone, coupled with a lack of data evaluating its full absorption potential is a concern, among other reasons, because of questions raised in the published literature regarding the potential for endocrine activity in connection with systemic oxybenzone exposure. Nearly all of these sunscreen active ingredients also have limited or no data characterizing their absorption."
In addition to evaluating sunscreen ingredients for safety, the FDA's proposed rule would consider sunscreen dosages in spray, oils, lotions, creams, gels, butters, pastes, ointments and sticks as GRASE. Powder forms are being considered, but additional data is requested. However, wipes, towelettes, body washes, shampoos and other dosage forms are proposed to be new drugs because the FDA hasn't received data showing they are eligible to be included in the monograph.
The proposed rules would also cap the maximum SPF value on labels at SPF 60+, and to require sunscreens with an SPF higher than 15 to also provide broad spectrum protection. Additionally, for broad spectrum products, as SPF increases, the magnitude of protection against UVA radiation also increases. "Broad spectrum" protection refers to protection against both UVA and UVB rays, as all sunscreen products don't automatically protect against both.
The proposed rule would also require new product label requirements to assist consumers to more easily identify key information, including the addition of active ingredients on the front label; a notification alert for sunscreens that don't prevent skin cancer, and revised formats for SPF, broad spectrum and water statements.
Finally, the proposed rule would consider all products that combine sunscreen with insect repellents as not generally recommended as safe and effective.
"This proposed rule is quite comprehensive," the FDA's Michele said. "It is an update for most sunscreens available in the United States to better ensure consumers have access to safe and effective sunscreens that are in line with the latest science."
The first update to sunscreen regulations came in the late 1990s, when the FDA added new rules regarding SPF ratings and the use of "broad spectrum" sunscreen, or those that protect from both UVA and UVB radiation. In the early 2000s, the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health put out information that some sunscreen ingredients may be absorbed through the skin.
In 2014, Congress passed the Sunscreen Innovation Act to expedite the review and approval process for over-the-counter sunscreens, giving the agency new tools to review ingredients. While the FDA at that time sought input on ingredients and possible health effects, a formal request for additional data wasn't made until February of 2019, when the agency proposed new regulations.
Michele said the agency typically reviews and evaluates data rather than conducting its own research. In general, the FDA relies on manufacturers to provide data on active sunscreen ingredients needed to establish safety and effectiveness. However, she said the FDA was able to use part of its small research budget to look into absorption of sunscreen ingredients.
"This is one of the first studies done, for any drug, of looking at how much is absorbed into the body," Michele said. "We used to think the skin was like an impermeable barrier, but now we know things can go through the skin and can actually change the drug as it goes through the skin. We have nicotine packets and estrogen packets, and arthritis medication that people rub on. There are all kinds of drugs we give people intentionally through the skin. ... This was the first time someone had looked at absorption in the way that sunscreens are regularly used."
The study, "Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients," was published in May in the Journal of the American Medical Association (JAMA). The study included a randomized clinical trial involving 24 health participants who applied four commercially available sunscreens containing the ingredients avobenzone, oxybenzone, octocrylene and ecamsule. Sunscreen was applied to 75 percent of each participant's body, four times a day for four days, with 30 blood samples collected over a week from each person.
Researchers found plasma concentrations in participants exceeded the FDA's threshold set to require toxicity assessments on drugs to see whether use may result in cancer, birth defects or other health problems.
The Environmental Working Group, which has issued its own guide to sunscreens, has said oxybenzone – one of the most widely used UV-filters – is particularly worrisome. The organization failed to respond to multiple requests by Downtown newsmazine to comment for this article.
"Researcher shows that oxybenzone is an allergen that is absorbed into the skin and can be detected in the bodies of nearly every American," EWG stated on its website. "It is also a potential hormone disruptor still used in 60 percent of non-mineral sunscreens. ... In another study, American adolescent boys with higher concentrations of oxybenzone in their bodies had lower levels of testosterone."
The EWG also cites Danish researchers who found eight of 13 sunscreen ingredients allowed in the United States affected calcium signaling of male sperm cells in laboratory tests, which the researchers suggest could reduce male fertility.
Marya Ghazipura, a doctoral researcher with New York University's Marron Institute, is one of the researchers cited by the EWG. Ghazipura's work has included a systematic review of oxybenzone studies involving humans and animals. The review included pooling together combined results from multiple studies.
"The data is really lacking, not only in the United States, but all over," she said. "But studies are finding high urinary concentrations of UV filters. We've also found humans absorb a lot of UV filters, at a rate of up to two percent."
Ghazipura said the findings are concerning because many of the chemicals, such as oxybenzone and avobenzone, have similar structures to BPA, an industrial chemical used in some plastic containers that have been found to leach into food and pose potential issues to fetuses, infants and children, including brain and prostate gland issues, as well as increased blood pressure.
"It's theorized it can pass through the placenta, but no evidence has been found," she said "But it is entering our system. We see it in our urine. And there are higher amounts in men after they shave, and in women after shaving their legs. By making micro-abrasions then applying these products, it can absorb at a higher rate."
Still Ghazipura said there remains a lack of research to determine if the chemicals are harmful to humans.
"There is a lot of evidence in animal studies, but you can't necessarily extrapolate that for humans," she said. "When considering doses in animals, a typical human would have to apply a half ounce over 25 percent of their body every day for 200 years, so it's not easy to extrapolate those findings."
While mineral sunscreens have been deemed safe by the FDA, Ghazipura said those products tend to be less popular, particularly among users with darker skin tones.
"They tend to be white and thick when applied, so a lot of people, especially people with darker skin, aren't comfortable using them," she said. "That means use goes down, so you see a lot of people that won't gravitate toward those products. Many tend to gravitate toward the chemical sunscreens."
In addition to applications to the skin, Ghazipura said exposure to sunscreen chemicals is expanding in other ways.
"A lot of studies on humans are looking at dermal applications, but as we keep using it, it's getting into our water. The route of exposure is expanding," she said. "We are orally consuming these chemicals, and we don't have enough evidence to see if these concentrations start accumulating. If there's bioaccumulation, we may not see harmful effects until 40 years from now. That may be worth considering.
"It's impacting coral reefs, and we know that. We need to take a step back and consider that."
In 2018, Hawaii was the first state to ban sunscreens believed to be harmful to coral reefs. The law, which goes into effect in 2021, will ban the sale or distribution of sunscreens containing oxybenzone and octinoxate.
A study published in 2015 by Haereticus Environmental Laboratory, a non-profit scientific organization based in Virginia, found the chemicals cause bleaching, deformitites in DNA damage and death in coral.
"In a health environment, ecosystems can take a hit and recover, but when persistently stressed by localized pollution – that's when they don't come back," said Craig Downs, executive director of Haereticus Environmental Laboratory. "The Florida Keys have lost nearly 90 percent of their coral reefs, and they aren't coming back. The same is happening in the Caribbean, where they have lost 80 percent of coral reefs, and they haven't come back. That's the real danger. Not coming back means you're starting to get decertification. You can spend $48 million to do coral reef restoration and it will produce nothing."
Downs' research into sunscreens started when the lab was given the task by the federal government to look into coral reef loss in Trunk Bay, in the U.S. Virgin Islands. That research, he said, began by looking for sources of pollution that could be impacting the water and coral.
"There was only one house there that belonged to Kenny Chesney that was on top of the mountain. We were trying to find out what was killing the reefs and we couldn't find anything," he said. "We ended up in a grocery store, a bunch of scientists arguing and stress eating, when a Rastafarian guy there overheard us and said, 'You're so stupid. It's the tourists.'
Downs said the bay is a major tourist stop, averaging between 3,000 and 6,000 people each day. Their grocery store acquaintance suggested they go to the bay at sunset and observe the water.
"We went down before sunset, and it was beautiful because the sunscreen on the top of the water was iridescent. You could notice it once everyone got out of the water," Downs said. "We went back to the grocery store and started looking at sunscreens, and all the chemicals in them. Oxybenzone was a hit, and in high concentrations."
Downs said the chemicals can bioaccumulate in aquatic life, such as turtles, which nest on beaches. One study found 80 percent abortion rates among turtles, while a nearby beach had an 80 percent hatch rate. Scientists traced the issue to sunscreen in the eggs. Another study out of Spain showed dolphins pass the chemicals on to their young when pregnant.
"We think it's everywhere," he said. "The Chinese are really leading the way on research in the area, but it's been found from Alaska to the north Pacific. In Europe, it's been found in Alpine lakes, and it's because of swimmers and sewage. It's not just in oceans – it's in rivers and can impact mayflies, crayfish and other things that trout feed on."
Downs said the impact of sunscreens on freshwater systems hasn't been an area of focus, but it could impact areas like Michigan, based on the reported loss of trout in the Cowichan River in British Columbia believed to be linked to sunscreens.
"Freshwater science and monitoring of sunscreen chemicals is pretty much absent in the U.S.," he said. "There are a couple of science papers for studies in Europe (Alpine lakes, the Rhine, etc.,) but almost nothing in the North America. The closest story was a Blue Ribbon trout river that has been 'dying' ever since river tubing became so popular."
The CBC reported last summer that the tubing business has since partnered with a company to provide those using the river with titanium dioxide sunscreen.
Earlier this year, Key West city commissioners voted to approve a ban on the sale of sunscreen containing oxybenzone and octinoxate. That ban will take effect in 2021.
Despite mounting evidence that some sunscreen ingredients may be impacting aquatic life, the consumer Healthcare Products Association has rejected laboratory findings, calling the bans irresponsible and based on weak evidence.
"Banning oxybenzone and octinoxate – key ingredients in effective sunscreens on the market – will drastically and unnecessarily reduce the selection of safe and effective sunscreen products available to residents and visitors," the association said in 2018. "Oxybenzone and octinoxate, found in the majority of sunscreens, are safe and effective over-the-counter active ingredients recognized by the Food and Drug Administration as important aides in decreasing the risk of developing skin cancer, the most common cancer in the U.S.
"The ban also avoids the real causes of coral decline according to scientists in Hawaii and around the world: global warming, agricultural runoff, sewage and overfishing."
The statement was made prior to the FDA's proposed rule that is holding the chemicals from GRASE classification until additional data is provided.
Mike Tringale, spokesman for the Consumer Healthcare Products Association, said a response to the proposed rule is being formed.
"We believe the industry will provide or plan to provide what the FDA is seeking," Tringale said. "We are mostly concerned about misunderstanding of the proposed rule. They aren't saying these ingredients are unsafe. They have said they don't want people to stop using sunscreen."
Tringale takes issue with efforts to ban sunscreen.
"We believe the evidence is on our side, not the ban side," he said. "No public policy should be based on one or two studies. That's what happened in Hawaii and Key West. They set these bans on extremely limited evidence. They are all lab-based, not done in the real world. We want policy to be based on a larger body of evidence."
Downs said his research has led to major lobbying efforts by the sun care product industry. It's also led to attempts to scare and discredit him.
"I'm getting death threats now. I had to disconnect my landline," he said. "I get random calls, pick it up and someone says, 'I'm going to kill you and I know where your children are.' We are still moving on with research."
Based on his own research and that of others, Downs said he believes sunscreen manufacturers could be the focus of litigation in the future.
"The industry is looking at trillions in litigation," he said. "Oxybenzone can also cause a proliferation in breast cancer cells, and there's really good research on it that shows oxybenzone causes these types of diseases. That's why the FDA did what they did. There's no choice. Pretty soon, you'll see these lawsuits, like you're seeing with Bayer and glyphosate. Ninety-seven percent of the population in the United States has oxybenzone in their body – the smoking gun is the product. It will be much bigger than Round-up because everyone is exposed to it."
Attorney and associate professor of law Nick Schroeck, who serves as director of clinical programs at the University of Detroit Mercy Law School, said a causal link between sunscreens and harmful impacts to the environment or human health could open up sunscreen manufacturers to litigation.
"If you were showing actual impacts to human health, that's when you get these huge judgements, like with glyphosate," he said. "You can put a dollar value on the environment, but it's typically lower than human health impacts. If they determine coral reefs are lost in major tourists areas, that could be a huge economic hit."
In Michigan, a loss of trout could result in economic disaster for some areas that rely on recreational fishing.
"It will be interesting to see how it shakes out," Schroeck said. "It all comes down to causation and being able to show that even in small quantities it can harm coral, and it's not being caused by other stressors. It's one thing to show it in the lab, but it's another to then show it in the ocean."
Even without the current threat of litigation, some manufacturers are already taking steps to offer consumers more products that are known to be healthy and environment friendly.
Edgewell Personal Care, which makes Banana Boat and Hawaiian Tropic sunscreens, said it supports the efforts of the FDA and will work with the agency as the final rule, with an expectation that additional testing will be be needed.
"It's important to know that we continually evaluate our current and pipeline sunscreen products to ensure we are providing consumers with a variety of safe, high quality and innovative options that respond to their preferences," Edgewell said. "Most recently, our customers have expressed an interest in products without oxybenzone and octinoxate, and we have minimized our use of these ingredients in favor of other readily available and approved UV-filters that provide the same safe and effective production."
Overall, the sun care product market is expected to grow from about $14.8 billion in 2015 to $24.9 billion by 2024.
The interest in different sun care products is expected to be a trend across the entire sunscreen market as consumers and manufacturers work through changes at the regulatory level, said market analyst Larissa Jensen, with The NPD Group.
"As the FDA continues to evaluate traditional sunscreen ingredients and issue laws, we expect the proliferation of more natural-based sunscreens (using zinc oxide and titanium dioxide) to accelerate in sales," she said. "Also of interest are current laws under evaluation (California) or being passed (Hawaii) with regards to sunscreen chemicals that harm oceans. Brands focused on sun safety are already reacting by marking products as 'reef safe' so that consumers can shop easily if they live in or are traveling to those destinations."
Jensen said in-sun product launches, or those products used in the sun, are up triple digits for the first quarter of 2019.
"One of the top launches this year is a mineral/zinc oxide-based product that offers sun, broad spectrum and blue light protection, already adhering to proposed new FDA regulations."
Bayer, which makes Coppertone products, said its product testing already exceeds industry norms and includes additional tests that serve to support safety and overall performance. Meanwhile, the company is in the process of selling its Coppertone line to German-based Beirsdorf AG, makers of Nivea, Eucerin and other skincare products. The sale comes as Monsanto, which was acquired by Bayer in 2018, has become the target of litigation in connection to the use of the herbicide glyphosate (Round-up) and cancer.
Bayer said the sale of Coppertone was a strategic choice to leverage its science and marketing capabilities in five core over-the-counter categories.
"While we have made significant progress in revitalizing the Coppertone brand over the past years, it falls outside of these core OTC categories and requires significant long-term investments to continue the positive momentum and grow the brand to sustainable levels," Bayer said in a statement to Downtown. "The exit from Coppertone recognizes that it's a better strategic fit for another company to invest in at a level where it can continue to grow and thrive.
"We believe that we have found the right partner in Beirsdorf to continue to invest in and grow the Coppertone brand."
The FDA's public comment period on the proposed rule was scheduled to end on June 26; however, sunscreen manufacturers may file a request for a waiver extension to allow for added time to submit data requested by the FDA.
"It may not be possible for the industry to conduct all of the studies we asked for on the 12 ingredients. Rather than pulling them from use, if the manufacturer asks for a deferral for a particular ingredient because they have committed to providing all the data in a reasonable time frame, then we will defer that while the data is being developed," the FDA's Michele said. "In the meantime, we will approve the rest of the rule."
Michele said on June 10 that no manufacturer had yet filed such a request.
Despite potential impacts of sunscreen ingredients, the FDA has been quick to point out that the fact an ingredient is absorbed through the skin and into the body doesn't mean the ingredient is unsafe. Instead, the data calls for further testing to determine the safety. Such measures are part of the typical pre-market safety evaluation process of most chronically administered drugs with systemic absorption.
"Just because it's absorbed doesn't make it unsafe. That's the next step. When things are absorbed, we ask the next question, and that's where we are at right now," Michele said. "The most important thing you can tell consumers is that sunscreens are one of the best ways to protect yourself from the sun, and need to be used in conjunction with other sun protective measures."
Health experts echo the FDA's recommendations on sunscreen use, including local dermatologists following regulations on sunscreen.
"Just because you can detect something doesn't mean there's any danger to health or safety," said Bloomfield Hills dermatologist Linda Honet M.D., who owns and operates Honet Dermatology and Cosmetic. Honet said the use of sunscreen is vital to skin protection, particularly as skin cancer becomes more common among younger patients.
"It used to be a condition of more elderly people. People over 60 or 65. Now, we see it more commonly in younger people. My youngest patient with melanoma is 19," she said.
Overall, about one in five Americans will develop skin cancer in their lifetime, with one dying from skin cancer every hour, according to the National Cancer Institute, a division of the National Institutes of Health. Yet unprotected exposure to UV radiation is the most preventable risk factor for skin cancer.
The most serious form of skin cancer is melanoma, which is the most common cancer among children and young adults, ages 15 to 29. Although melanoma accounts for about three percent of skin cancer cases, it causes more than 75 percent of skin cancer deaths. While not all melanomas are sun-related, UV exposure and sunburns, particularly during childhood, are risk factors.
Non-melanoma skin cancers, while less deadly, can spread if left untreated, possibly leading to disfigurement and other serious health problems.
Basal cell carcinoma is the most common type of skin cancer tumors. Usually appearing as small, fleshy bumps, tumors are most common on the head and neck but can appear anywhere. As it grows, it rarely spreads to other parts of the body nor penetrates to the bone.
Squamous cell carcinomas are tumors that may appear as nodules or red, scaly patches on the skin. It may develop into larger masses and can spread to other parts of the body.
"The number one thing is genetics," Honet said about the risk factors for skin cancer. "They are genetically linked and there's usually a trigger, and that's usually sun or UV radiation.
"Tanning booths have come into the commercial market, and that's been one of the biggest carcinogens. The World Health Organization deemed them to be a carcinogen equal to tobacco, with tanning more implicated in melanoma than other skin cancers. Tanning booths have been a big deal for dermatologists, who have tried to ban them in other countries. In this country, being a free-market society, we haven't banned them."
Outside of genetics, Honet said sun exposure and ozone are other key factors in skin cancer risk.
"I think environmentally, the sun that hits the earth and skin today is more potent than in the 1930s or even the 1980s," she said. "The sun exposure may have a more potent impact. We do see a huge generational difference."
While there are other factors that can increase the risk of skin cancer, such as cigarette smoking, genetics and sun exposure are the main contributors.
When it comes to sun exposure, UV rays, and sunscreens, there are several differences and levels of protection.
Ultraviolet radiation is part of the electromagnetic light spectrum that reaches earth from the sun. Because UV radiation has wavelengths shorter than visible light, it can't be seen by the naked eye. Wavelengths are classified into three categories, depending on length.
For instance, UVA includes the longest waves and are considered aging rays which can cause premature aging of skin, wrinkles and spots. Ultraviolet A rays can pass through most window glass and clouds. UVA accounts for roughly 95 percent of the UV radiation reaching the earth's surface. UVA is less intense than UVB rays, but are 30 to 50 times more prevalent, according to the Skin Cancer Foundation. Further, research within the past two decades show that UVA may initiate the development of skin cancers.
The Skin Cancer Foundation states that UVA is the dominant tanning ray, with tanning booths primarily emitting UVA rays at rates as much as 12 times that of the sun, giving people who use tanning salons a 2.5 times higher chance to develop squamous cell carcinoma and 1.5 times more likely to develop basal cell carcinoma. Overall, the Skin Cancer Foundation say the first exposure to tanning beds in youth increases melanoma risk by 75 percent.
UVB rays are shorter than UVA, and are considered "burning" rays, which cause sunburn and are typically blocked by window glass. Even shorter UVC rays are usually absorbed by the ozone layer and don't reach the earth.
The main cause of sunburn is from UVB radiation, which also plays a key role in the development of skin cancer. Intensity of UVB rays varies by season, location and time of day. The most significant amount of UVB hits the US between 10 a.m. and 4 p.m., from April to October. Still, UVB rays can damage skin year-round.
"Even small doses of sun without protection can be harmful," Honet said. "It's common for farmers or truck drivers to develop problems on the left arm or the left side of the face in the United States – maybe that's different in England. Even an office worker who is inside most of the time, driving back and forth, can still get a lot of UVA radiation through the side window glass. The windshield blocks quite a bit of UVA and UVB rays, but the sides are less effective and allow UVA rays to penetrate the vehicle."
Honet's belief that UV rays have become more intense holds up when reviewing UV Index records maintained by the Environmental Protection Agency and recorded by the National Weather Service. As ozone depletion and seasonal and weather changes lead to different amounts of UV radiation reaching the earth, the National Weather Service uses the index to indicate the risk of overexposure. The Index ranges from 0 (low risk) to 11 or more (extremely high). The index is calculated using a computer model that relates the ground-level strength of UV radiation to forecasted stratospheric ozone concentrations, forecasted cloud coverage and ground elevation.
Low UV Index (0-2) indicates little or no protection is needed. A moderate to high index (3-7) means people should seek shade in the late morning and mid-afternoon, and apply broad-spectrum, SPF 15 or higher sunscreen, wear protective clothing and a wide-brimmed hat and glasses when outside; a very high to extreme index (8 or higher) means extra protection is needed. Additionally, experts recommend seeking shade on high UV Index days when your shadow is shorter than yourself.
UV Index records from 1995 to 2017 for the metro Detroit area list the number of days each year that the UV Index reached low, moderate, high, very high and extreme levels. While the low, moderate and extreme UV Index days have remained consistent overall, the average number of "very high" index days per year was 66.2 from 1995 to 2005, with the number of "high" index days averaged 73 for the same period. However, the average number of "very high" index days per year increased to 91.6 days from 2006 to 2017, while "high" index days decreased to an average of 64 for the same years.
As UV protection remains a top concern for those spending time in the sun, health experts say it's important to remember that there are safe sunscreen options, and that they should be used in conjunction with other ways of staying out of the sun.
"Everyone wants to make sense out of this," said Bloomfield Township dermatologist Steven Grekin D.O., founder of the Grekin Skin Institute. "You have the EWG that says its terrible and you shouldn't use it. Then you have the dermatologists that say you should use it."
Grekin said many hats and clothing are specifically designed to provide protection from UV rays. Such measures should always be used when spending time in the sun. In terms of mineral sunscreens versus chemical filters, he said mineral sunscreens have come a long way since the heavy pastes used prior to the proliferation of chemical filters.
"It's not your grandma's zinc oxide. It's different, and that's a very good point," he said. "If you ask me, I use physical sunscreens and have for years."
Grekin said people using zinc oxide-based sunscreens tend to have fewer allergic reactions, which are common. He also pointed to environmental concerns.
"It's absolutely proven that chemical sunscreens are the ones that are hurting the environment," he said.