This story was originally published in May 2017.

If you’re spending hours in the sun this summer, sunscreen is a must. But according to a 2017 report, nearly three quarters of all sunscreen products on the market don’t actually work or could potentially cause more harm.

For their 11th annual sunscreen guide, researchers at the nonprofit Environmental Working Group evaluated the UV-ray protections, toxic ingredients and other health hazards in approximately 900 sunscreens, 500 SPF-labeled moisturizers and more than 100 lip products.

The group found 73% of the 880 tested sunscreens either contained “worrisome” ingredients or didn’t work as well as advertised.

Two toxic ingredients, oxybenzone (a hormone disruptor) and retinyl palmitate (a form of Vitamin D with the potential to increase skin cancer risk), were among the chemicals found.

A young woman places suncream on her friend while the sunbath on the beach during a heatwave August 6, 2003 in Eastbourne, England.

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"Sunscreens are really mismarketed, and as a result, people who depend on them think they are far more powerful than they really are," the group’s lead scientist, Sonya Lunder, said.

Another study by Consumer Reports found nearly half of the sunscreen products analysts examined don't meet the SPF listed on their labels.

Still, according to the EWG report, nearly all reviewed sunscreens filtered harmful UVA rays, a nearly 20% increase since 2007.

According to Newsweek, the Sunscreen Innovation Act of 2014, a law signed by former President Barack Obama allowing more efficient FDA review of sunscreen ingredients, helped drive the positive changes.

But researchers say the FDA Broad Spectrum Testing standards are still too weak and more work needs to be done.

Here are some tips from EWG when picking out the best sunscreen for you:

A higher SPF level doesn’t always mean it’s a better product.

According to EWG researchers, high-SPF products contain more sun-filtering chemicals than others. This could lead to other types of sun damage (like melanoma risk) and health risks such as allergic reactions, tissue damage, hormone disruption and more.

But that doesn’t mean you should aim for products with low SPF. The American Academy of Dermatology standards require an SPF of 30 or higher.

Consider mineral sunscreens.

Mineral sunscreens contain nanoparticles, which help reduce the white, chalky tint other sunscreens leave on the skin.

Though the Consumer Reports study earlier this year said mineral-based sunscreens performed worse than chemical ones in terms of SPF, EWG researchers offered favorable ratings to the mineral ingredients, because the zinc oxide and titanium oxide in the products offer good protection from UVA rays.

Avoid spray-on sunscreens.

Sunscreen sprays are considerably popular with consumers, but EWG researchers caution against using spray products due to possible inhalation risk. The group is also concerned the spray doesn’t provide as thick and even coating of protection.

European sunscreens have better UVA protection.

According to EWG, Europeans not only have more sunscreen products to choose from, but their products also meet high standards for UVA protection, unlike most American products.

This is because European manufacturers can choose from seven different ingredients, some of which are notably advantageous compared to the chemicals approved by the FDA.

In fact, only two of the FDA-approved sunscreen ingredients filter UVA rays, according to the EWG report.

More tips from EWG.