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Avoid Oxybenzones


How a common chemical in sunscreen is damaging our coral reefs

Tuesday 6 September 2016 Dr Karl Kruszelnicki article link here

People need to avoid skin damage when they go to the beach, but many sunscreens include oxybenzone, and that's bad news for coral. Dr Karl Kruszelnicki explains what makes this chemical so harmful, and what we can do about it.

From the cradle to the grave, Australians are taught to use sunscreen to avoid sunburn and skin cancers. But the universe is complicated, with unexpected links—and so, everything has a cost. In this case, the cost appears to be that one popular sunscreen chemical seems to attack coral.

Oxybenzone has been proven to have harmful effects on coral. In fact, it has four separate bad effects on baby coral.
So let's have a look at this chemical.

It's called oxybenzone, and it's one of the most widely used organic UVA filters. It's also called BP-3, or benzophenone-3. But in addition to blocking UVA, it also absorbs UVB. This means it blocks UV ranging from 270 to 350 nm.

This makes oxybenzone very attractive, because not many organic sunscreens block both UVA and UVB. As a result, oxybenzone is used in hairsprays, cosmetics, nail polishes, and in over 3,500 sunscreen preparations worldwide.

You would prefer that any chemical you slather on your skin stays outside your body. But oxybenzone is very fat-loving (or lipophilic), so it crosses the skin easily. On average, oxybenzone will appear in the urine of over 96 per cent of those who apply it to their skin.

Unfortunately, when oxybenzone acts on humans, it operates as an 'endocrine disruptor'. This sounds bad. Endocrines, also called hormones, are essential for the body to work properly. However, the effects (so far) of oxybenzone on human metabolism seem to be (probably) minor.

Most developed countries allow it to be used at levels up to 5 to 10 per cent. However, the Swedish Research Council deems oxybenzone to be unsuitable for children under the age of two, as these youngsters have not yet developed the enzymes to break it down.

But oxybenzone has been proven to have harmful effects on coral. In fact, it has four separate bad effects on baby coral.

First, it predisposes to coral bleaching at lower temperatures than normal. As global warming kicks in, and the oceans become even hotter than normal, then oxybenzone causes even more coral bleaching.

Second, oxybenzone damages the DNA of coral, in many different ways. This includes 'oxidative damage to the DNA, formation of cyclobutane pyrimidinic dimers, single-strand DNA breaks, cross-linking of DNA to proteins', and so on and so on. The overall result is that coral with damaged DNA are less able to reproduce. In the case of the coral that are able to reproduce, their offspring are likely to be unhealthy. This leads to each generation of coral being less healthy than the one before.

Third, oxybenzone acts as a powerful endocrine (hormone) disruptor in coral. The juvenile coral produce too much calcium carbonate. They end up totally encasing themselves inside their own skeleton. Inevitably, this leads to their death.

Finally, oxybenzone deforms the juvenile coral. They stop swimming, change shape, and their mouths grow five times larger.

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As Paracelsus said some five centuries ago, 'All drugs are poisons, what matters is the dose.' So what's the dangerous dose of oxybenzone?

It turns out that oxybenzone can be toxic to baby coral at levels as low as 62 parts per trillion. In plain English, that's equivalent to one drop in 6.5 Olympic swimming pools. Dr C. Downs surveyed reefs in Hawaii and the US Virgin Islands. His team measured levels as high as 1,400,000 parts per trillion. That's more that 20,000 times higher than the toxic levels.

But on the bright side, there is a solution.

Consider CFCs. When we realised that CFCs were damaging the ozone layer, the initial response by the chemical companies was that effective substitutes were impossible. However, once the governments of the world put pressure on them via the Montreal Protocol, effective substitutes were soon found.

The solution is straightforward. People still need to avoid skin damage (up to skin cancer). Sunscreen is part of that strategy. Each year, about 6,000 to 14,000 tonnes of sunscreen cream (or lotion) enter the oceans. After all, we're told we should slather on generous amounts of sunscreen.

But we know that titanium oxide and zinc oxide are not as harmful to coral as oxybenzone. So we could use these (and other chemicals) which don't harm humans nor ocean creatures—or we could cover up.