Swimmers,hoppers and fliers:

Even hundreds of miles from the nearest industrial or agricultural activity, the sea ice, ocean, and Arctic plants and animals regularly yield evidence of elemental and synthetic chemical contamination. This contamination includes not only herbicides, fungicides, and pesticides—chemicals that are used in open air, may have washed directly into rivers or are released from factories—but also metals, among them mercury as well as flame retardants and water repellants, among other substances that are, at least in theory, incorporated into the materials of the products they’re designed to enhance.

Among the errant compounds now found regularly in the Arctic, for example, are brominated flame retardants, including those known as PBDEs (polybrominated diphenyl ethers) used widely in upholstery foam, textiles, and plastics. Also routinely recorded in the far north—some at remarkably high levels—are perfluorinated compounds (PFCs) used as stain repellants, waterproofing agents, and industrial surfactants (think Scotch-guard, Teflon, Gore-Tex, and the slick coating on paper used in food packaging such as pizza boxes, candy wrappers, and microwave popcorn bags).

These same compounds are now being detected in animals and people all over the world. A network of more than forty sampling sites has found evidence of synthetic chemicals that do not break down into nontoxic components—a mix of pesticides, fossil-fuel emissions, and industrial compounds—virtually everywhere it looked, from Antarctica, North America, Australia, and Africa to Iceland. A recent five-year study conducted in U.S. national parks across the American West and Alaska found these same contaminants in the majority of its snow, soil, water, plant, and fish samples.

It’s not known when the first persistent synthetic chemical contaminants arrived in the Arctic, but this kind of pollution has been detected there on a regular basis since the 1960s. “Everyone thought the Arctic was pristine, so we were taken aback to find such high contaminant levels in top predators,” says Gary Stern, a senior scientist with Canada’s Department of Fisheries and Oceans. But “anything released in the mid-latitudes travels rapidly north.”

Long-lasting synthetic chemicals are often referred to as “persistent organic pollutants,” or POPs for short. Used in this way, “organic” means that the chemical compound contains one or more carbon atoms and not all organic compounds are toxic or persistent.

Public awareness of POPs such as DDT, PCBs, and dioxins has been growing. By 2001 concern about the environmental and health impacts of POPs had risen sufficiently to prompt the United Nations Environment Programme to formulate a treaty called the Stockholm Convention aimed at curtailing the use and release of these chemicals. “Exposure to Persistent Organic Pollutants (POPs) can lead to serious health effects,” writes the organization that administers the Stockholm Convention, “including certain cancers, birth defects, dysfunctional immune and reproductive systems, greater susceptibility to disease, and even diminished intelligence.” (The United States has signed, but as of 2009 had not yet ratified, the Stockholm Convention—so it has not been a full participant in its meetings and decision making, and its use of chemicals is not yet formally bound by the Convention’s regulations.)

By taking samples at numerous study sites over extended periods of time, scientists have discovered that some contaminants travel entirely by air—these are what Frank Wania of the University of Toronto calls fliers. Some—the swimmers—stay in the water, circulating with ocean currents. Most are hoppers, though; they make their way north in what’s been dubbed the grasshopper effect, a series of air- and waterborne hops, moving toward the Arctic with cyclical and seasonal patterns of evaporation and condensation.