SUMMER has returned to the northern hemisphere, and many will be reminded to slather on the sunscreen to keep sunburn at bay. But after recent developments, some may hesitate, wondering if sunscreen is totally safe.
In the past five months, the US body that regulates sunscreen has declared that 12 active ingredients used in sunscreens . And in聽a , the organisation found that four of these ingredients enter the bloodstream through the skin.
The revelations have come from the US at least partly because sunscreens there are, unusually, regulated as over-the-counter drugs. But similar products are sold around the world. And sunscreens may be only the tip of the iceberg, with general cosmetics starting to come under scrutiny too.
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There is no need to drastically change your behaviour just yet as none of the commonly used ingredients have been decidedly declared unsafe, but questions remain. Why are these concerns only coming now? And how worried should we be about the stuff we put on our skin?
In most countries, sunscreens are classified as cosmetic products. In the European Union, they are subject to rules on which ingredients can be used, and must pass tests for skin and eye irritation, for example.
In the US, however, sunscreens, including cosmetics marketed with a sun protection factor, are regulated like drugs because they make specific health claims: to reduce the chances of sunburn, skin ageing and skin cancers. The US Food and Drug Administration (FDA) issues rules for industry to follow and new drugs must undergo rigorous clinical trials in people, but because sunscreens were already marketed before these rules took effect, their safety has been reviewed after the fact.
Although the first sunscreens came onto the market in the 1920s, it took the FDA 50 years to issue any regulations. In 1978, it finally issued a tentative set of rules and updated them in 1999, listing 16 active ingredients as safe. However, these ingredients are now coming under scrutiny.
鈥淥nly two of the original 16 鈥榮afe鈥� ingredients can actually be considered safe and effective鈥�
Take oxybenzone, for example, which is widely used in sunscreens. In 2008, the US Centers for Disease Control and Prevention found traces of it in the urine of . Other studies have .
鈥淭here is some evidence that oxybenzone may be a hormone disruptor, and act as a very weak oestrogen,鈥� says Kim Harley at the University of California, Berkeley. Some cancers have an oestrogen component. 鈥淭he issue is that there鈥檚 so much we don鈥檛 know,鈥� she says.
Similar questions have been raised about the other ingredients.
The FDA issued in February this year, saying that only two of the original 16 鈥渟afe鈥� ingredients can actually be considered safe and effective: zinc oxide and titanium dioxide. Of the remaining ingredients, two will be banned, while the rest, including oxybenzone, have big question marks over them.
Then, in May, the FDA published a study looking at four of these ingredients, again including oxybenzone. Researchers including Theresa Michele, who directs the organisation鈥檚 Division of Nonprescription Drugs, applied one of four sunscreen products to 24 volunteers, following the products鈥� instructions for maximal use, four times a day for four days. They then looked for traces of the chemicals in the volunteers鈥� blood.
Not only did all four chemicals turn up in the blood, they did so at levels that demand further research to make sure they aren鈥檛 causing cancer, says Michele.
Dermatologist Kanade Shinkai, based at the University of California San Francisco Medical Center, says she thought sunscreen would pass through the skin. But what was a surprise was that it was absorbed after the first application and that it persists for days, she says.
So, is it time to throw out your sun protection? Not so fast. 鈥淚 think sunscreen is important because we know the sun causes cancer,鈥� says Harley. 鈥淏ut these compounds are getting into our bodies, and what鈥檚 concerning is that there鈥檚 a real lack of information on what the consequences could be.鈥�
Manufacturers can point to the fact that all these ingredients were deemed safe by the FDA and we have been using sunscreen for decades without seeing detrimental effects.
鈥淏ack in the 70s, we thought that anything you put on the skin just stayed there,鈥� says Michele. 鈥淲e never thought that things could be absorbed by the skin.鈥�
Similar concerns are now being raised about the chemicals in cosmetics too. They face little regulation in the US and have had the same level of scrutiny as sunscreen in the EU. This means that few studies have been done about which chemicals in cosmetics can enter the bloodstream and what their effects may be.
Part of the problem comes from complaints falling through the cracks. If someone in the US complains of an adverse drug effect to its manufacturer, then the company has to report it to the FDA. But this isn鈥檛 the case for cosmetics, meaning issues can go unnoticed.
Take the case of hair product WEN by Chaz Dean Cleansing Conditioners. In 2014, the FDA began investigating the product after it received 127 complaints directly from consumers. It later discovered that, by this point, the company had already received 21,000 complaints of hair loss and scalp irritation. The FDA hasn鈥檛 yet announced an end to its investigation, but its options are limited. The product is still on sale.
In the European Union, people are expected to report issues to their national authorities.
Problems persist with other cosmetic products too. Despite this, Steve Xu at Northwestern University in Chicago and his colleagues found that, between 2004 and 2016, .
Cosmetic issues
鈥淲hat we saw was very low,鈥� says Xu, who, as a dermatologist, says he sees patients with skin irritation resulting from personal care products on a daily basis. 鈥淭hat tells me people are not going to the FDA, they鈥檙e going to the manufacturer, and the manufacturer is a black hole.鈥�
There have been attempts to tighten regulation of cosmetics in the US, but without much success.
In the meantime, researchers aren鈥檛 saying that cosmetics are unsafe. Just that their full effects are unknown.
As for sunscreen, while the recent FDA rules are due to be finalised by November, it is unlikely we will have the final word on the 12 ingredients still under investigation then. Michele says the industry has asked for eight of the ingredients to be left off the list to allow for extra data to be collected. 鈥淭his is a proposed rule, so it鈥檚 not final yet,鈥� she says. 鈥淲e鈥檙e currently reviewing comments.鈥�
In the meantime, if you are worried about sunscreens, one option is to stick to products that use zinc oxide or titanium dioxide as an active ingredient. These are 鈥済enerally recognised as safe and effective鈥� by the FDA. And taking other sun protection measures, such as covering up and seeking shade in peak hours, is also vital.
More Insight online Your guide to a rapidly changing world www.newscientist.com/insight
Toxic for reefs
As of January next year, visitors to Palau, an island country in the western Pacific, will be prohibited from buying or using a range of sunscreens. The country has classified products containing any of 10 commonly used sun filters and preservatives as 鈥渞eef-toxic鈥�, as they are thought to harm coral reefs. Other places have followed suit, and similar bans will come into effect in 2021 in Hawaii and in Key West, Florida.
Craig Downs at Haereticus Environmental Laboratory in Virginia and his colleagues ran laboratory experiments to assess the problem. They found that immature corals exposed to oxybenzone (see main article), an ingredient that is commonly used in sunscreens, die.
The corals became deformed and pale in colour, and were unable to eat, as depicted in the images above. 鈥淭heir mouths just opened, and it looked like a horror movie scream,鈥� says Downs. 鈥淭hey were as good as dead in the first 8 hours.鈥�
Sunscreen manufacturers have said that lab-based experiments can鈥檛 tell us what happens in the real world, but more bans are likely. 鈥淲e have one reef, and we have to do one small thing to protect that,鈥� Teri Johnston, mayor of Key West, was quoted as saying before the city鈥檚 vote on sunscreen. 鈥淚t鈥檚 our obligation.鈥�
