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Sunblock products cause harm to corals

Green Country Vol. 113 (Apr 2015)

As April arrives, the weather becomes warmer and the UV index rises. Records of the Hong Kong Observatory show that on half the days in April, the UV index reach “Very High” or above. Ultraviolet light can cause sunburn, skin aging and even skin cancer. There are all kinds of sunblock lotion and sunblock body mist in the market for the protection of skin and our health. However, these products may be polluting our oceans.

As early as 2007, scientists estimated that each year about 4,000 to 6,000 tonnes of sunblock products enter the oceans from swimmers and surfers, threatening the health of some 10% of corals worldwide. Sunblock products can be classified into chemical and physical types; the former are more frequently used in Hong Kong. These chemical products make use of benzophenone to absorb UV and are more popular as they have smooth texture, and leave no visible trace when used. However, researchers have found that even at extremely low concentrations, these chemicals may increase the chances of viruses infecting corals, leading to their death.

The physical products, on the other hand, reflect or block UV while leaving a layer of white traces on the skin. In the past it was believed that these products caused less harm to the environment. Yet last year some studies revealed that if nano titanium oxide and nano zinc oxide are used as the main ingredients, hydrogen peroxide will be released in water under sunlight, which will affect zooxanthellae in corals, and in turn lead to bleaching.

To protect our skin and health while minimising harm to corals, we can choose biodegradable sunblock products which are available in other countries at present. Or more simply, don't enter the water for at least half an hour after applying chemical sunblock, so that it is more fully absorbed by the body instead of being washed off into the sea. The best way to achieve zero pollution is of course to stop using all sunblock products, and put on sun-blocking clothing for water activities.

Text | Peggy Chung

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