Why you shouldn’t rely on SPF for your complete sun protection?

The SPF number printed on a sunscreen bottle — meant to tell you how much protection you’re getting — doesn’t always match what’s inside, a new CBC finds. Market Investigation has found. This means Canadians who rely on sunscreen to protect themselves from the sun may be suffering a false sense of security.

Market Sent the best-selling sunscreen labeled SPF 50 to five different accredited laboratories in Canada and the US to test the product inside the bottle. We got a roller coaster of results and an inside look at a test system with almost no oversight.

Laboratories perform the same testing that a manufacturer does to determine what SPF number to put on the label. all five told Market The product had a different SPF: 34, 50, 60, 44 and 15.

The CBC is not identifying the product tested because the process of determining the SPF was the focus of the investigation, not the product. similar study Shows that variability is surprisingly common in the sunscreen testing field.

“The results are actually quite worrying, aren’t they?” said Brian Diffie, professor emeritus of photobiology at Newcastle University in England, who has spent his career studying sunscreen and how people apply it.

He raised the question, he said: “Which one was right?”

Health Canada, which is responsible for regulating sunscreen in CanadaNo comment on MarketTest results of.

What is SPF?

There are two types of rays coming from the sun which can cause great harm to the skin. UVA rays, or ultraviolet A, penetrate deeply into the skin and can cause premature aging. Meanwhile, UVB rays penetrate closer to the skin’s surface and can cause irritation. Both types of rays can damage DNA and cause skin cancer.

Any sunscreen labeled “broad spectrum” protects against both rays. But that familiar SPF number on the bottle only refers to protection against UVB rays.

SPF, which stands for sun protection factor, is calculated by measuring how long the skin can remain exposed to UV radiation without burning without using sunscreen in a controlled laboratory setting. An SPF of 30 means it would take about 30 times longer for skin to burn in the lab than without sunscreen. Theoretically, the higher the SPF number, the greater the protection against UVB rays.

SPFs 50, 30, and 15 absorb or reflect about 98 percent, 97 percent, and 93 percent of UVB rays from sunscreen, respectively.

The difference may seem small, but dermatologist Dr. Julia Carroll says it’s the percentage we should pay attention to.

“It’s two percent every minute, every second, it’s like a bucket dripping,” she said. “I would prefer to have less UV radiation in my bucket at the end of the day, no matter what.”

How do they test SPF?

The Health Canada- and U.S. Food and Drug Administration (FDA)-approved method of SPF testing is performed on a panel of human volunteers. Manufacturers give the laboratory the estimated SPF value of their product, and the laboratory calculates the minimum amount of simulated sunlight needed to slightly burn a volunteer’s skin. SPF testing is only performed on volunteers with light skin that fits within part of the Fitzpatrick skin type scale, so that it is easier for laboratory technicians to see sunburn.

Then, using a solar light simulator, three areas of the volunteer’s lower back are exposed: one without sunscreen, one with control sunscreen and one with the sunscreen being tested.

Approximately 24 hours later, the level of redness of the volunteer’s back is assessed by a laboratory technician, and an SPF value is calculated. This is repeated on 10 volunteers, and the final SPF number is the average between them, with a calculated margin of error.

There are new testing techniques that do not require burning human participants, but they have not yet been accepted in Canada or the US.

Several factors influence the final SPF number, including how a volunteer’s skin absorbs the sunscreen, how the skin reacts to UV light, the type of pressure used when applying the product, and the lab technician’s interpretation of the redness of the burn.

“Because of that variability, (the test) is very out of date because you’re causing a burning sensation, which is an inflammatory response, and that’s a very variable thing,” said Michael Troud, who runs all the human trials at a consumer product testing company in New Jersey. The company bills itself as the global leader in sun protection testing.

The testing method has different steps to limit variability: Two milligrams of sunscreen is applied per square centimeter of skin to try to create a smooth, consistent application.

Yet studies show that consumers generally apply much less than that amount. This means that they are getting less security.

“SPF is really a crude indicator of how well a product protects you,” said Diffie, Emeritus Professor at Newcastle. “Don’t read anything into the actual numbers. It’s meaningless when you’re talking about the perception you’re getting on the day you choose to apply sunscreen.”

He That said, Diffie and other experts agree that SUnscreen is still important, and is better than not having a weak product. Finding one that feels good and keeps you from burning means you’re more likely to apply it liberally.

“I think you don’t take any product that says it protects your health at face value,” Troudt said. “It requires people to be a little more diligent and not blindly trust the product. You have to pay attention to it.”

Carroll said use sunscreen, but it should be your last line of defense: Shade, covering up and avoiding peak sunlight hours all work together to help protect your skin.

Fraud in the Sunscreen Testing Industry

Manufacturers are only required to test their product in a laboratory on 10 human panelists to gain approval in Canada. Retesting is only required if a product’s formula changes significantly, so older formulas may rely on testing from decades ago. Companies are also not required to submit proof of efficacy. Instead, they certify that their products have been tested and are safe, and only provide lab reports if Health Canada requests them.

There has been fraud in the sunscreen industry. From 1987 to April 2017, the owner and other employees of New York-based AMA Laboratories were found to have defrauded customers, including sunscreen companies, of more than US$46 million by underpaying tests on panelists, as well as fabricating test results. AMA owner Gabriel Letizia Jr. was sentenced to 60 months in prison in 2022. The company has since ceased operations.

In response, Australia’s Department of Health, Disability and Aging ordered any approved sunscreens tested by AMA laboratories to provide additional testing to prove the effectiveness or reliability of their products. Given high rates of skin cancer, Australia is widely considered a leader in sun protection.

According to the World Health Organization, Canada has one of the countries with the highest rates of skin cancer. However, Health Canada did not issue any public response to the AMA scandal.

Brian Ecclefield worked as a sales representative at AMA Labs for nearly nine years, leaving his job in 2017 after the FDA first raided the lab. He said the lab attracted major customers because it was faster, cheaper and provided more favorable results than others.

“I think when any number of those things are true at the same time, people should question it,” he said.

Health Canada confirmed Market There are sunscreens for sale in Canada that are subject to the AMA’s testing, approved before and after 2017, although it does not specify which brands. The department declined multiple interview requests, instead sending a statement that sunscreen companies are required to notify the regulator of any problems, and that it had received no indication of issues related to the AMA controversy to date.

Eckelfield is asking Health Canada to inform Canadians about the fraud, and is asking manufacturers to re-test their products if they rely on the AMA to do so.

“It’s never too late. The greater consumer awareness, the better.”

In February 2025, Market filed an access-to-information request with Health Canada to determine which sunscreens sold in Canada relied on data from a U.S. company. At the time of publication, the request was still under review.

In the meantime, Market Contacted manufacturers directly to ask for lab reports proving the efficacy of the products they had for sale on Canadian shelves, how often they tested them, and whether they relied on the AMA for testing.

While some said they did not use AMA, none would share their lab reports, saying it was proprietary information. All said they follow Health Canada’s rules.

Published by Diffie on January 15, 2000 An article in the British Medical Journal Arguing that we should move away from SPF numbers. Instead, Diffie proposed labeling bottles with high, medium or low security rather than using an exact number derived from a random process.

“It avoids this pretense that … somehow everyone will get higher protections, which some may get and many may not.”

Twenty-six years later, his message is still the same. The most important thing with sunscreen is to feel comfortable enough to use it frequently and apply it liberally, Diffie said.

“Don’t get fooled by the SPF number,” he said. “The most important thing about sunscreen is to use it.”