- The garbage man
- A UW researcher and colleagues look at what we
throw away - and how we throw it - to figure out
ways to make better recycled products.
Communities across Wisconsin may benefit from UW-Madison research that has literally gone to waste. Agricultural economist John Strasma and his students study garbage, and they're finding ways to help local governments cut the cost of waste disposal and recycling programs. Consider, for example, a recent study of plastic bottle recycling, funded by a grant from the Wisconsin Recycling Market Development Board. Whether they contain milk, soda or detergent, plastic bottles are made of valuable polymers that could easily be melted down and turned into new containers. They could, that is, if not for a common contaminant: their own caps. Plastic bottle caps, rings and even labels are made of different kinds of plastic. Separating them often requires costly manual labor, but failing to do so strips recycled plastic of most of its usefulness and value. "If you have several types of plastic polymers mixed up, then all you can do is make things like low-grade plastic lumber, and since there's lots of raw material for that, it doesn't bring much money," says Strasma. "But if you can single out a particular polymer, then industry is willing and able to pay a great deal for it."The researchers have found that most bottle caps can be made from the same kind of plastic as their bottles. That would require a change in the way the packaging industry produces most tops, but Strasma says the industry is willing to listen. And he says UW-Madison may help coordinate an industry-wide standard for plastic caps. Such small details play a big part in making recycling work, especially for taxpayers. State-mandated municipal recycling programs are never likely to operate in the black, according to Strasma. Their main goal is to keep materials out of landfills. But stronger recycling markets can help underwrite a larger share of the equipment and labor that curbside pickup programs require. "The end purposes are to try to lower the cost of recycling collection and processing and increase the amount of money that municipalities get for running recycling programs by producing a consistent plastic," Strasma says. But in another recent study, Strasma found that Wisconsin municipalities themselves could do more to strengthen recycling markets. State law requires all public offices to purchase paper with a minimum recycled content and strongly encourages efforts to buy other recycled materials. Funded by the Wisconsin Recycling Market Development Board, the study found two-thirds of the government entities surveyed abide by the state law. As for the rest, a small number were unwilling to comply, but most simply had not yet heard about the requirement.
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- Pesticides: Missing the point
- Are our fears about the health effects of pesticides
in our food justified? One UW researcher shows why
the answer may be no.
UW-Madison toxicologist Michael Pariza says the public may have overblown fears about the cancer risks of pesticides. Many scientists are divided on the human health impact of pesticide use. But Pariza, a national expert on food safety, argues that many pesticides, when used properly, present minuscule
"We're not poisoning our food by having a minute
quantity of pesticide in it any more than we're poisoning
our water by adding tiny amounts of chlorine."
health risks and may ultimately protect us from greater risks. An insect called a corn borer illustrates Pariza's point. When it gets into stressed corn crops, it carries the spores that produce aflatoxin, a powerful natural carcinogen - ultimately stronger than the pesticides that control the insect, he says. Virtually all foods contain traces of carcino-genic substances, many of them from natural sources. Although these typically are not health threats to humans, Pariza says they may pose a higher risk in the long run than any traces of pesticide residue on foods.Pariza, director of UW-Madison's Food Research Institute, has argued to lawmakers that comparing risks makes more sense than a total ban of pesticides. "We're not poisoning our food by having a minute quantity of pesticide in it any more than we're poisoning our water by adding tiny amounts of chlorine to protect us from cholera," he says. Pariza favors a rethinking of the federal Delaney Clause, enacted in 1958, which prohibits the use of food additives that cause cancer. That was expanded in 1987 to include pesticides. But Pariza questions the measures used to assess a substance's possible risk. Many of the substances covered by the Delaney Clause are not powerful carcinogens, he says, and only produce cancer in lab animals at levels hundreds of times higher than humans would ever ingest. Instead, Pariza says efforts should focus on other food-safety threats unrelated to natural or synthetic chemicals. An estimated 12.5 million food-associ-ated illnesses occur each year in the United States, at a health cost of $8.5 billion. The vast majority are from infectious agents, like salmonella bacteria, hepatitis A virus, and a variety of parasites - all of which are controllable. Pariza has co-authored treatises on the safety of food enzymes and bio-engineered food products that are models for Food and Drug Administration policies. Most recently, he served on the National Research Council's committee on "Carcinogens and Anti-Carcinogens in the Human Diet."
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