Ever been seaside, smoothing on your SPF 40 and wondered how suntan lotion affects the ocean? You're probably aware that some of it rinses off every time you dive in, but can such a small amount, diluted into something as large as the whole ocean, really cause any harm? The truth is, there are two ways that that little blob of sunscreen is having a major impact on the oceanic ecosystems.
The first, and perhaps most pressing, way that suntan lotion is affecting the ocean is in the destruction of coral reefs. These colorful conglomerations are negatively impacted by the chemicals in sunscreen. The ultra-violet (UV) filters, which protect our skin from the sun, cause what's known as "bleaching" in corals. Bleaching is the loss, by death or expulsion, of the single-celled protozoa which live within the coral. (The beautiful array of colors found in coral are actually contained within these protozoa.) The coral and the protozoa have a symbiotic relationship. When the protozoa leave, die, or lose their pigment, the whole coral community struggles. Suntan lotion is only one of many factors that can cause bleaching, but a recent study indicated that up to ten percent of the world's reefs are at risk from exposure to suntan lotion.
The second, and somewhat bizarre, impact that suntan lotion has had on the ocean (and other bodies of water) is the gender change in certain species of fish. For example, the males of both the hornyhead turbot and English sole, which feed off the Californian coast, are becoming a lot more feminine. Both species are growing ovary tissue in their testes. The culprit in this case is a specific chemical in sunscreen: oxybenzone. Oxybenzone is found in many sunscreens, as it does a good job at absorbing ultraviolet rays. However, there are draw backs. When oxybenzone is washed down the drain, it survives fairly intact. When you add it to other waste water contaminates containing estrogen, you are looking at a soon-dwindling fish population. And what affects the fish, soon affects the entire food chain.
While it is still recommended that you use sunscreen for protection, we may see changes in its makeup in the future. You may also find more and more places becoming off-limits, to protect other species. The impact that sunscreen is having on the ocean is also a warning sign. The earth's water is all recycled. What ocean life lives in, we eventually drink. The next species impacted may be our own.