French fries.

• Position: LIFE-CYCLE STUDIES

Raw Materials

The potatoes are grown on monoculture farms using a single variety for uniformity. The oil for deep-frying comes mainly from soybeans. In the United States, six midwestern states account for 80 percent of the country's cooking oil, the largest share of which is used to make fries. Other oils used for fries come from corn and cottonseed. McDonald's used to cook its fries in the U.S. in beef tallow, but switched to vegetable oils due to health concerns. In New Zealand, McDonald's still fries its "chips" in tallow.

Disposal

Waste fat from homes and restaurants has become a major disposal problem. It blocks drains and pipes, as well as arteries. In London, half of all sewer blockages are caused by fat. In 2001, the U.S. Environmental Protection Agency sued the city of Los Angeles for 2,000 sewer spills over five years, of which 40 percent were caused by fat--most of it from fast-food chains pouring waste deep-fry fat into drains.

A short-term strategy for reducing the disposal problem is to recycle used fat--with its heavy caloric content--as an energy source. A few small companies are collecting fat from restaurants and turning it into fuel for cars. (The concept isn't new; in fact, one of the first diesel engines ever made, in 1900, used peanut oil as a fuel.) The long-term solution, however, is to cut back on fries and stop producing such gargantuan amounts of waste fat to begin with.

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Processing

The oil is partially hydrogenated, which makes the fries crispy but also increases the trans-fat content--a factor in heart disease. Hydrogenation, which hardens liquid oils, was originally developed by Procter & Gamble as a means of hardening cottonseed oil to make candles. (Think of the substance building up in your arteries over decades of eating fries as candle wax.)...