SCIENCE NEWS

Junk food addiction

You knew those Ding Dongs, candy bars and strips of bacon weren't good for you. But now comes a study suggesting that junk food may be addictive in the same way as heroin or cocaine.

Researchers at Scripps Research Institute in Florida found that rats given unlimited access to the kind of high-fat, high-calorie food available in convenience stores -- such as Ho Hos, candy bars and sausage -- became compulsive overeaters as the pleasure pathways in their brains became less and less responsive, forcing them to consume more to get the same amount of pleasure. These rats also went for the junk food even when they had to endure a slight shock to their foot to get at the food. These behaviors, according to the researchers, are classic hallmarks of addiction.

"Not only did we find that the animals' brain reward circuits became less responsive at they continued to overeat and become obese," Paul Kenny, an associate professor of molecular therapeutics at Scripps, reported at the annual meeting of the Society for Neuroscience, "but that decrease in responsiveness was similar to what our laboratory has seen previously in rats as they become addicted to cocaine or heroin."

When, after 40 days of unrestricted access to the junk foods, the rats were then deprived of it and fed a more nutritious food pellet, the animals refused to eat, even though they were clearly starving.

Globalization of air pollution

Globalization applies to air pollution, too. Satellite observation, airplane sensors and data from various observatories have found that air pollution produced in Asia wafts over the United States, while U.S.-made pollution blows across the Atlantic to Europe. According to the National Research Council, which collected and analyzed the data from various sources, soot, ozone, mercury and organic pollutants such as the pesticide DDT were found in plumes of harmful pollutants that traveled from one continent to another, affecting air quality thousands of miles from their original sources.

The report notes that it can be hard to distinguish on the ground between domestic and foreign pollutants but that satellite observation and meteorological and chemical analysis can do it. For instance, the report describes an incident from 2004 when a polluted air mass was detected at Mount Bachelor Observatory in Oregon eight days after it left East Asia.

The health effects of pollutants vary: Ozone and particulate matter can cause respiratory problems that "are most worrisome from a health point of view," said Charles Kolb, chairman of an NRC committee that studied the data and recently released a report on it. Mercury and persistent organic pollutants such as DDT can gradually build up in farmland or watershed areas and make their way into the food chain.

-- Margaret Shapiro