New Concerns about well-known Sunscreen Ingredients after a Recent Clinical Study

A few months ago, I launched a mineral sunscreen in New Zealand that came out of my research lab and is manufactured at a facility that holds an FDA drug-manufacturing license. SPF test results and other information can be found here. Surprisingly, even given the high skin cancer rates in New Zealand, sunscreen manufacture is not regulated here …

Ours was a small and organic product launch targeted at my patients and local community. “Why a mineral sunscreen?”, people asked … and also, “What’s so different about a mineral sunscreen?”

Mineral sunscreens in general use minerals (zinc and titanium) to create a film on skin and keep harmful rays out but contain no chemicals that get absorbed into skin and into our blood streams. Chemicals such as oxybenzone, used as filters in sunscreens, can cause hormone or endocrine disruption, meaning they may interfere with the body’s hormone systems causing developmental or neurological effects. Such chemicals, if they enter the sea while swimming, can also damage coral reefs.

As a skin researcher and MD, I have been concerned about many of these chemicals in sunscreens – especially as many animal and human studies have shown adverse effects on hormones and the link below summarises them. This report is from the widely respected Environmental Working Group (EWG). However, most sunscreen-makers continue to use these chemicals – the defence being that these are hardly absorbed into our blood. The other argument has been -- as sunscreens are not taken in a specific dose as a pill, it is difficult to study them in a clinical trial.

However, a new clinical study from the JAMA, one of the highest-ranked medical journals in the world, looked at whether the active ingredients (avobenzone, oxybenzone, octocrylene, and ecamsule) of 4 commercially available sunscreens are absorbed into blood circulation. The answer: Unfortunately, a resounding YES.

This was an open-label, randomized, 4-group parallel study conducted at a clinical pharmacology department in the United States. All 4 sunscreen active ingredients tested resulted in exposures exceeding 0.5 ng/mL. The clinical effect of plasma concentrations exceeding 0.5 ng/mL is unknown, and needs further research say the study authors. That’s why I have stayed clear of any UV-absorbing chemicals and now only formulate mineral sunscreens.

We know oxybenzone and octocrylene have been found in human breast milk in studies. The reason the JAMA study used 0.5-ng/mL as the testing threshold is because it is the level below which the cancer-causing risk of any unknown compound would be less than 1 in 100 000 after a single dose. All these 4 ingredients exceeded this easily! In this preliminary study involving healthy volunteers, application of 4 commercially available sunscreens under maximal use conditions resulted in plasma/blood concentrations that exceeded the threshold established by the FDA (beyond which toxicity studies are mandatory). The authors are planning another study … but meanwhile I advise people to be safe in the sun by using a good mineral sunscreen.

At present my lab’s sunscreen is only available in New Zealand but watch this space …