Entire world polluted, Canadian scientists report

By Jeffrey Jones, Reuters, [14 October 1998]

CALGARY—Pesticides and other toxic chemicals used in agriculture and industry are polluting every place on Earth, even the most frigid, uninhabited polar regions, according to a team of Canadian scientists.

In a study of snow in remote areas of the Canadian Rocky Mountains published in the scientific journal Nature on Thursday, researchers from the University of Alberta found high levels of the harsh chemicals, even though samples were taken far from any pesticide use or industrial activity.

The chemicals, known as organochlorine compounds, travelled through the atmosphere from where they were used and fell on to the mountains with rain and snow as the air became cooler, said research team member David Schindler, a biological science professor at the university, located in Edmonton.

All of these compounds tend to evaporate at temperatures in summer at low elevation environments, then are carried through the atmosphere in vapour phase, and in some cases in dust that might be swept up by the wind, Schindler said. They reach the high-elevation, cold sites and condense on the surface.

Previous studies, including those conducted by researchers from his own university, have found detectable levels of contaminants in rain and snow—and high levels in fish and marine mammals—throughout the Canadian Arctic as well.

People in Iceland, Sweden and even the (former) Soviet Union have found the same thing, said Schindler.

The pollutants discovered in the Rocky Mountain snow from the study area between Canada’s Banff and Jasper national parks included the agricultural pesticide DDT, which has been banned for years in many parts of the world.

The scientists also discovered that the concentration of pollutants increased at higher elevations—up to 100-fold between mountain elevations of 770 and 3,300 metres (2,500 and 10,800 feet).

Schindler said he had no evidence concentrations of the chemicals were high enough to be harmful to humans. But some major cities in warmer parts of the globe that draw their drinking water from reservoirs located high above sea level should be monitored, he said, adding that at least three studies into that were spawned by team’s work.

He cited Mexico City and Denver, Colo., as cities in the western hemisphere with nearby heavy industry and agriculture that also have water reservoirs and fisheries at high elevations.

The worst of all would be an area like the Himalayas, where we have elevations up to twice the range than we’ve seen and where some of the areas of most intensive pesticide use are really close by, he said.

Schindler said the good news was that levels of DDT and other harsh and banned chemicals, like polychlorinated biphenyls (PCBs), which were once used in electrical transformers, had dropped by about half from when they were in full use. But they took years to dissipate.

Based on the records we’ve seen, these things continued to increase for eight or 10 years after we controlled them, and that’s probably because we had a lot of contaminated soils which were re-emitting the things to the atmosphere.