Dear EarthTalk: How worried should I be about skin cancer now that summer is approaching and I’ll be spending time in the sun?
—Eva Haley-Locke, Seattle, WA
According to the U.S. Environmental Protection Agency (EPA), incidences of skin cancer in the United States have reached epidemic proportions, with one in five Americans now developing the disease in their lifetime. The National Cancer Institute reports that cases of melanoma, the most serious form of skin cancer, increased faster than any other cancer among Caucasians in the U.S. over a recent 20-year study period. The sometimes-fatal disease now accounts for three percent of cancers diagnosed in the U.S.
Incidences of melanoma in African Americans are much lower than in Caucasians due to the additional melanin, or pigment, in the skin, which offers some sun protection. However, dark skin is no guarantee against melanoma—and once African Americans are diagnosed with melanoma, studies show that their long-term survival is significantly lower than that of Caucasians: 58.8 percent compared to 84.8 percent.
Meanwhile, non-melanoma skin cancers are on the rise, too. Every year, more than a million Americans develop non-melanoma skin cancer, and more than 1,900 die from the disease, according to EPA statistics. But non-melanoma skin cancers have a cure rate as high as 95 percent if detected and treated early.
Skin cancer is triggered by exposure to the sun"s ultraviolet-B (UV-B) radiation. Luckily, the Earth"s ozone layer absorbs most UV-B radiation before it reaches the surface. However, the recent thinning of the ozone layer due to the emission of chlorofluorocarbons (chemicals used to propel aerosol sprays and keep refrigerators and air conditioners cool) may have further increased everyone"s exposure to UV-B radiation.
Fortunately, 183 countries, including all the major industrial powers, have agreed to phase out these chemicals by 2015 according to the terms of a 1987 treaty known as the Montreal Protocol. The signatories to the treaty are optimistic that the phase-out should restore the ozone layer to its normal thickness over the course of several decades.
Interestingly, some researchers don’t believe that current melanoma increases are related to the thinning ozone layer, as the disease can take several decades to develop, whereas ozone depletion is a more recent phenomenon. "Recent increases in rates may just reflect better reporting, or the popularity of suntans in the 60"s and "70"s," says University of Colorado biochemist Robert Parson.
Nevertheless, UV-B exposure remains a risk. People should protect themselves by wearing hats, sunglasses and sunscreen, and avoiding extended sun exposure. Many dermatologists believe there may be a link between childhood sunburns and melanoma later in life; so strong sunscreen (SPF 30 or higher) should be applied to kids before they head off to the beach.
CONTACTS: EPA SunWise Program, www.epa.gov/sunwise ; National Cancer Institute, www.nci.nih.gov ; Montreal Protocol, www.unep.org/ozone/Montreal-Protocol/Montreal-Protocol2000.shtml .
Dear EarthTalk: I recently heard an alarming statement, that every woman on Earth has some trace of a chemical called dioxin in her breast milk. Is this true? And if so, why is it and what are the ramifications? Should I not breast-feed my baby?
—Katya Proctor, Richmond, VA
Unfortunately, it is true that women all around the world have dioxins in their breast milk. In fact, most people—not just women—have detectable levels of dioxin in their tissues, according to the U.S. Environmental Protection Agency (EPA). Dioxins are now widespread in our environment, and tend to remain in the environment for long periods of time, traveling long distances, primarily through air.
Dioxins are typically detected in air, soil, sediments and food and result from a number of industrial activities, including incineration of municipal solid waste and medical waste, vinyl manufacturing, the chlorine bleaching of wood pulp in papermaking, and coal-fired power plants. Other major sources of dioxin include forest fires, residential wood burning and the backyard burning of household waste.
There are 75 forms of dioxin. All are "organochlorine" compounds, that is, organic chemicals to which varying amounts of chlorine have been added. They are potent chemicals known to cause cancer, skin disease, liver problems, birth defects and damage to the brain and central nervous system. The Natural Resources Defense Council (NRDC) says that dioxin is "among the most toxic substances on Earth."
According to the Children"s Health Environmental Coalition (CHEC), kids are exposed to dioxins through food, primarily from the animal fats in meat and dairy products. Also, dioxins can cross the placenta to expose babies in the womb. Breast-fed infants are exposed to dioxins that have accumulated in breast milk. Researchers worry that fetuses and breast-feeding infants may be at particular risk from exposure to dioxins, which may cause harm to the developing brain and immune system.
Despite these risks, the American Academy of Pediatrics still recommends breast milk as "the preferred source of feeding for almost all babies for at least the first year of life," touting its health, nutritional, immunological, developmental and psychological benefits. Besides, dioxins are so prevalent that even infant formulas can contain some.
Eradicating dioxins from the environment is a tall order, says NRDC, as they are unintentional industrial byproducts and their elimination would require fundamental changes in how industry operates. The EPA does report, however, that industrial dioxin emissions in the U.S. have been reduced by more than 90 percent since 1987. Environmental organizations are calling on industries and the EPA to make every effort to eliminate or reduce dioxin formation where possible, and are calling for an end to many forms of incineration and the phase-out of products whose manufacture and disposal produces dioxin.