Swimming can turn your sunscreen toxic! Compound used in the protective lotions becomes deadly when it reacts with chlorine and the sun, increasing risk of cancer

A compound used in the protective lotions turns toxic when it reacts with chlorine and ultraviolet rays, researchers found.

Avobenzone is considered the most popular sun-blocker in the world due to its ability to absorb sunlight at different wave lengths - preventing skin damage. 

But Russian scientists suggest the UV-filtering compound forms cancer-causing toxins when exposed to a mixture of sun and chlorinated water.

Aldehydes, phenols and chlorinated acetyl benzenes were created in experiments simulating swimmers wearing sunscreen.

The latter two are considered extremely toxic and are strongly linked to deadly tumours and infertility, Lomonosov Moscow State University experts say. 

While a study earlier this year hinted that aldehydes can raise the risk of cancer as they interfere with the body's natural repair mechanism.

Lead author Dr Albert Lebedev said: 'On the basis of the experiments one could make a conclusion that a generally safe compound transforms in the water and forms more dangerous products.

'In spite of the fact that there are no precise toxicological profiles for the most established products, it's known that acetyl benzenes and phenols, especially chlorinated ones, are quite toxic.

'Studying the products of transformation of any popular cosmetics is very important as very often they turn out to be much more toxic and dangerous than their predecessors.

'In principle, basing on such researches, one could obtain results, which could restrict or even put under a ban the usage of one or another product and preserve the health of millions of people.'

Sunscreen can render a man infertile by disrupting human sperm cells, a Danish study found last April.

Nearly half of the ingredients commonly used to block out ultra-violet light mimic the effects of the female hormone progesterone.

This stops sperm cells functioning normally, researchers said at the time.

The sunscreen lotion can enter the blood stream by being absorbed through the skin.

Niels Skakkebaek, a professor at the University of Copenhagen said the findings were worrying.

‘These results are of concern and might explain in part why unexplained infertility is so prevalent,' he said.

This technique, on laboratory cells, allows precise analysis of the most complex mixtures of chemical compounds.

For the study, they simulated the real situation when a sunscreen, applied on the skin of a swimmer, comes into contact with pool water.