Every day as snorkelers and divers head to the sea they lather up with tons of UV blocking skin creams, adding up to about 16,000 – 25,000 tons of sunscreen used in the tropics each year. This liberal use of sunscreen has coral reef researchers worried, as about 25% ends up washing off the skin into the sea water. Studies have shown that only 1 part per thousand of the stuff in an aquarium will induce corals to bleach, and increase their ‘viral load’ by a factor of 15 (Danovaro et al. 2008). Estimates based on these studies calculate that up to 10% of the world’s reefs are directly threatened due to sunscreen related pollutants.
Modern day sunscreens were first developed in the late 1970’s, and have since been improved to be longer lasting, more powerful, water-resistant, and full spectrum. These developments have come through the innovation of novel chemicals to produce the desired properties, with the average bottle today containing around 20 chemicals. Many of these chemicals are ‘lypophilic’, meaning that they accumulate in fat cells, and will thus bioaccumulate in top predators through the food chain. Furthermore, many of them undergo photodegredation, and break down into toxic by-products in sunlight and UV radiation.
Some of the more dangerous chemicals in sunscreen include:
- Benzophenone-2: genotoxicant, photo-toxicant, induces bleaching (Downs et al. 2013)
- Paraben Preseratives and UV absorbers: Estropogenic
- Ethylhexylmethoycinnamate (OMC)
- Ocotocrylene (OCT)
- Ethylhexlsalicylate (EHS)
- 4-methylbenzylidene camphor
Although the chemicals above have been proven to have negative health and environmental effects, many of the chemicals contained in suncreens did not exist in the known universe just 20-40 years ago, and their effect on humans and other animals is unknown. Although sunscreens have undeniably helped to reduce the risk of painful sunburns or life threatening skin cancers, they should be used minimally and wisely.
Here are some ways that you can reduce your sunscreen use during your diving holiday to protect the coral reefs while still protecting your health:
- Avoid exposure to the sun during peak hours (11am – 1pm) – stay in the covered area of the boat, wear a hat/shirt, use a rash guard or wetsuit while snorkeling.
- Apply sunscreen sparingly and only to exposed areas, and at least 45 minutes before entering the water, to reduce the amount washed off.
- Choose ‘Reef Safe’ sunscreens, or zinc-based sunscreens which tend to contain fewer chemicals
- Help spread awareness to other divers you see lathering up on the boat