EXPERT REACTION: Sunscreen chemicals may be leaching into our blood

Australian skin cancer prevention advocates recommend the use of sunscreens as one component of a person’s personal sun protection package. They have done this on the assumption that using sunscreens as recommended would not have harmful consequences. This assumption is challenged by these new finding that blood concentrations of the active ingredients of some sunscreens in routine use exceed levels at which the US Food and Drug Administration (FDA) has indicated more comprehensive evaluations of their safety are needed. While this finding does not mean sunscreen use is unsafe, more evidence is needed about effects these sunscreen chemicals have on the human body if we are to be sure that they are not unsafe at present levels of use.

It's no surprise to find that fat-soluble substances can pass through the skin and appear in the bloodstream.  We all know about nicotine skin patches, and things like liniments for sore muscles, and anti-inflammatories like Voltaren. We apply them deliberately to our skin so they can be absorbed.

Sunscreen chemicals are not much different to the active ingredients of those medications. What matters is what they do when they get inside us. That is determined by their intrinsic toxicity (probably not known), by how much gets through the skin, where they concentrate in the body, and how long they stay there before bodily processes eliminate them. And, you need to wonder ... are their effects any worse than getting severe sunburn?

I agree with the authors that further studies are needed to determine the clinical significance of their findings.

The widespread use of sunscreens and the introduction of sunscreen into regular cosmetics has led to significant benefits in terms of skin cancer prevention.  However, there are a number of complex issues that need to be resolved.  Sunscreens have already been implicated in loss of eyebrow and scalp hair and now this toxicology data is a concern.  Fortunately no-one I know is using sunscreen four times daily as in this study protocol.  We need to see this study repeated with standard amounts of sunscreen being used. 

This small study had significant limitations and shouldn’t stop Australians from using sunscreen to protect themselves from potentially deadly UV rays.

It’s important to put this study in context -  the sample size was only 24 people, which is very small for any type of scientific research. The study also didn’t replicate real world conditions, for instance the sunscreen wasn’t used outdoors where we would expect the UV radiation would breakdown some of the active ingredients. The authors acknowledge that these results do not indicate that individuals should refrain from the use of sunscreen.

Even if the sunscreen chemicals were absorbed, there is limited evidence to suggest that this would cause harm, but we do know that excess UV causes skin cancer and that sunscreen helps prevent skin cancer.

In Australia, the Therapeutic Goods Administration (TGA) regulates all sunscreens ensuring that only approved ingredients, which have been assessed for quality and safety, are used in each product and at certain quantities. The TGA regularly reviews the evidence and ensures that sunscreen ingredients are safe, and effective.

It’s important that Australians continue to use sunscreen as one method of sun protection. Cancer Council recommends using an SPF30 or higher sunscreen that is broad spectrum, water resistant and TGA approved.

Sunscreen isn’t a suit of armour, and should only be used as the last line of defence. Whenever the UV level is three or above, the Cancer Council also recommends slipping on protective clothing, slapping on a broadbrim hat, slopping on sunscreen, seeking shade and sliding on sunglasses.

Melanoma Institute Australia cautions against using results of a small overseas study, based on atypical application and use of sunscreen, to undermine community confidence in sunscreen.
 
All sunscreens on the Australian market are highly regulated, and there is indisputable scientific evidence that sunscreen helps protect against UV damage, the greatest risk factor for developing melanoma which kills one Australian every five hours.
 
MIA recommends all Australians follow the five sun-safe rules – seek shade, cover up with protective clothing, wear a broad-brimmed hat, wear sunglasses, and use SPF 50+ sunscreen – to reduce their melanoma risk.

The final statement in the study says 'These results do not indicate that individuals should refrain from using sunscreen'.  That is the most important immediate take out message.

This is a small and preliminary study, involving 24 people, 14 of whom have strong natural sun protection through their skin type being dark (Fitzpatrick 5 – 6)

There remains no evidence of 'clinical significance'.  That means we still have no evidence that any such absorption has any adverse effects on any individual.

The amount of sunscreen used in the study of 24 people was far in excess of what most people use.  While they followed the recommended application levels, consistent evidence suggests most people use half or less of the recommended amount of sunscreen and many do not reapply once, let alone four times.

As we move into the dry season in the northern part of Australia, people need to understand sunscreen remains a safe and effective means of protecting against the proven damage caused by excessive sun exposure.

Further studies are needed to determine what this preliminary finding means for the health of Australians who rely on sunscreen as an effective way of protecting against the sun.