Toxins in Milk Cartons, 100 Million Trees for North Dakota, and Distress Calls from Thirsty Plants

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The bleaching process in papermaking produces dioxin, a proven carcinogen and one of the world's most toxic compounds.

Papermakers produce bright, white paper by bleaching brown pulp with chlorine-based chemicals. One by-product, unfortunately, is dioxin, a proven carcinogen and one of the world’s most toxic compounds. According to an EPA study, fish downstream from many U.S. paper mills are contaminated with high levels of dioxin. Also, the toxin apparently exists in the paper products themselves–and can pass into food. A study of bleached-paper milk cartons by Canada’s Health and Welfare Branch has shown that dioxin from the cartons migrates into the milk. Greenpeace U.S.A. has petitioned the USDA, which subsidizes this country’s school lunch program, to drop bleached milk cartons from the program. “Dioxin is so incredibly toxic,” says Greenpeace spokesperson Shelley Stewart, “that no amount, no matter how small, can be considered safe.” Several European countries are tackling the problem by leaving cartons unbleached or by switching to a safer oxygen-bleaching process.

North Dakotans will celebrate their state’s 100th anniversary this year by launching a program to plant 1 million trees for each year since the territory declared statehood–100 million trees, in other words–by the year 2000. That figures out to 10 million trees every year for the next 10 years. According to American Forests magazine, North Dakota, though one of the least-forested states in the nation, leads the country in the planting of trees for shelterbelts and windbreaks.

Scientists at the U.S. Forest Service’s North Central Forest Experimental Station in East Lansing, Michigan, have found that thirsty plants emit high-pitched noises inaudible to the human ear but meaningful to insects. Trees and plants produce these “acoustic emissions” when their moisture-conducting tissue–xylem–begins to break down from lack of water; the more the plant deteriorates, the more frequent the sounds become. The “distress calls” may be the plants’ undoing; the researchers theorize that insects use the sounds to locate weakened plants, which they use for food or breeding grounds.