9 months ago

AD 2016 Q1


DIVE SLATE 16 SUNSCREEN POLLUTION | 19 TWENTY-TWO ANCIENT SHIPWRECKS FOUND IN GREECE | 23 TRINIDAD’S LEATHERBACKS | 26 DAN MEMBER PROFILE 28 CALENDAR OF EVENTS, EDUCATION SPOTLIGHT | 29 TRAVEL SMARTER SUNSCREEN POLLUTION A SERIOUS AND INCREASINGLY CLEAR THREAT TO CORAL By Craig Downs, Ph.D. Some effects of marine pollution are visible, such as the plastic garbage that often litters reefs and beaches. Other effects are similarly obvious, such as the brimstone stench of a nearshore dead zone caused by sewage and fertilizer runoff. Unfortunately, marine pollution goes even further than most people can easily witness, and these less-apparent aspects of pollution have elusive but far-reaching consequences. I first came to understand the significance of sunscreen lotion in marine pollution during an investigation into declining coral reefs in the U.S. Virgin Islands. A local resident complained to my investigative team about an oily, iridescent sheen on the surface of the water that lingered after the mass of tourists had gone home; it was supposedly caused by sunscreen washing off the swimmers. “Swimmer pollution” threatens coral reefs across the world, from the Gulf of Aqaba in the Red Sea to the shores of Playa Hermosa, Costa Rica, and almost everywhere in the Caribbean. Anywhere humans get into the water on or near a reef is a potential avenue for contamination. Besides washing off swimmers’ skin and into the water, sunscreen can get into the sea by other means. Many sunscreen ingredients are readily absorbed through the skin. Oxybenzone, one of the most common ultraviolet-blocking chemicals in sunscreen, for example, can be detected in urine within 30 minutes of application. When you flush the toilet or wash off sunscreen in the shower, chemicals from the lotion enter the sewer. For towns near coral reefs and without sophisticated sewage treatment and management systems, this pollution is rather inevitable. (There is an etymological argument that the word “sewer” comes from the old English word “sea ward,” in which household and municipal waste was channeled out of villages and towns toward the sea or other bodies of water.) Any coral reef near significant human habitation is potentially vulnerable to a plume of pollution. Sunscreen lotions do not threaten every single coral reef in the world. Sunscreen and other personal care products, however, do threaten the coral reefs that are most important to people — those that are focal points of tourism as well as fringing reefs that are critical for protecting coasts from erosion. And they threaten the capacity of local subsistence fisherman to access the abundance of food that healthy nearshore reefs once provided. Not only does intense sunscreen pollution threaten the survival of these reefs, but it also can prevent the recovery and restoration of alreadydegraded reefs. STEPHEN FRINK ECOTOXICOLOGY OF SUNSCREEN LOTIONS AND THEIR INGREDIENTS In October 2015 my colleagues and I examined the toxicological effects of oxybenzone on coral larvae. 1 We found that oxybenzone induces coral bleaching by lowering the temperature at which corals will 16 | WINTER 2016

leach when exposed to prolonged heat stress. We also showed that oxybenzone is genotoxic, meaning that it damages coral DNA as well as induces severe and lethal deformities. Most alarming, we determined that oxybenzone also acts as an endocrine disruptor, causing the coral larvae to inappropriately encase itself in its own stony skeleton — at a time in its development when it should not even have a skeleton. Our research demonstrated that these pathologies can occur at concentrations as low as 62 parts per trillion. For perspective, beaches in Hawaii have oxybenzone levels higher than 700 parts per trillion early in the morning before swimmers even arrive. Other emerging research is showing that oxybenzone concentrations on nearshore reefs around the world are commonly between 100 parts per trillion and 100 parts per billion — well within the range of being a significant environmental threat. Oxybenzone is toxic to more than just corals. It’s toxic to algae, sea urchins, fish and mammals. It inhibits embryonic development in sea urchins. It can result in gender shifts in fish, in which male fish take on female attributes, while females have reduced egg production and embryo hatchings. In mammals it has been demonstrated to be a potential mutagen and to exhibit procarcinogenic activity. Studies in both mice and rats showed that exposure to oxybenzone increases liver and kidney weights, reduces immunity, increases uterine weights in juveniles and reduces fertility. In recent studies, human couples whose urine contained higher concentrations of benzophenones had a harder time getting pregnant, while men with higher concentrations had higher levels of diseased sperm. Both dolphin and human mothers can transfer oxybenzone to their infants via breastmilk. There are a host of other chemicals in sunscreen that are potentially toxic to coral reefs, some of which — including methoxycinnamate and camphors — are on the International Chemical Secretariat’s Oxybenzone and many other common sunscreen ingredients are now known to damage corals, even in extremely low concentrations. Opposite: Fortunately, demand by concerned consumers is leading to increased availability of less harmful sunscreens. SIN (Substitute it Now) list based on their activity as endocrine disruptors to humans and wildlife. Noncoated nanoparticles (less than 35 nanometers in diameter) of zinc oxide and titanium dioxide (referred to as “mineral-based” sunscreens) can be toxic to corals, fish and other reef organisms. Their toxicity arises from both their miniscule size and their interaction with cells, as well as the fact that they cause oxidative stress in sunlight (i.e., they too can cause coral bleaching). Non-nanotized (commercial designation above 150 nanometers in diameter) coated zinc oxide and titanium dioxide don’t readily exhibit acute toxicities. Nanoplastic ultraviolet (UV) absorbers, which commonly have diameters of around 350 nanometers, are also not necessarily toxic to the marine environment, though their nanotized property may be a cause for concern. An “organic” certification doesn’t mean a sunscreen is safe for the environment. A number of plant-based oils can be toxic to reef organisms, especially arthropods. For example, neem, eucalyptus and lavender oils, which are used in some organic sunscreens, also have applications as insect repellents or insecticides, suggesting they may also have increased relative toxicity to invertebrates. Other ingredients such as beeswax can be contaminated with a variety of industrial fungicides and insecticides. Organic ingredients, or any ingredient in a product, should be subjected to toxicological testing. Silicone polymers, cyclic siloxanes (e.g., octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane) and other alternatives to oils warrant some concern. These organosilicon compounds are not biodegradable and can bioaccumulate in aquatic and marine organisms, including edible fish. STEPHEN FRINK ALERTDIVER.COM | 17

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