Yard Waste: Garbage Into Gold?

TAKING out the trash is a household chore that has acquired global implications. We now carefully separate items that can be recycled to keep from burying ourselves in an ever-growing solid-waste stream that, according to an Environmental Protection Agency projection, could reach 190 million tons a year for the United States alone by this decade's end.

One of the biggest components (18 percent) of the municipal solid-waste stream - second only to paper (40 percent) - is yard waste, grass clippings, old leaves, and other household cleanup debris. Here is an eminently recyclable discard. A fast-growing number of municipalities are diverting it from landfills and onto compost heaps. There, through the "magic" of biological decay, it transforms into a soil enhancer.

If that old slogan "garbage into gold" ever had any validity, it would surely seem to apply here. But is yard-waste composting really safe? How much pesticide and toxic-metal contamination does it contain and what happens to it? Does it put undesirable amounts of nitrates into ground water?

Environmental chemists David A. Kovacic and Thomas J. Bicki of the University of Illinois at Urbana-Champaign and Richard A. Cahill of the Illinois State Geological Survey at Champaign have looked at this issue and find they can't answer such key questions. They report in the American Chemical Society journal Environmental Science & Technology that "environmental monitoring at composting operations or facilities is lacking, and currently published research on the environmental fate of composted yard wast e constituents is extremely limited." They warn that "in the rush to reduce volume in landfills, federal and state agencies have prescribed composting as a primary solution without evaluating potential environmental problems."

Commenting on their study in a telephone interview, Dr. Kovacic said he and his colleagues "are not against composting." It's a potentially valuable way to deal with yard waste. What the Illinois chemists are urging is adequate research to ensure that composting is done in an environmentally safe way.

There is more to consider than what toxic substances yard waste may bring with it. Scientists need to learn how specific substances degrade in a compost heap, how they leach into soil and water, and where they end up.

Organic acids may dissolve aluminum, iron, or manganese, which could poison aquatic ecosystems. Large municipal compost heaps could put tons of nitrogen in the soil and contaminate ground water, ponds, and rivers.

Kovacic says "there really isn't a good quantitative study" on such effects. He adds that "when you start to analyze [available research] in a rigorous manner, there's not much there." He further notes that the kind of rigorous research he wants would help control toxic contamination by identifying which pesticides do safely degrade in compost heaps and which do not. That could help in regulating pesticide use in the yards that generate the waste.

The Illinois chemists estimate that an adequate program of such research for the US would likely cost only "several million dollars." That's a modest expense to gain knowledge that's badly needed to put the fast-developing composting industry on an environmentally sound basis.

Congress now is considering legislation - the National Waste Reduction, Recycling, and Management Act - that would encourage composting as part of the national recycling effort. It should include funding for this necessary environmental research. After all, the slogan is garbage into gold not into fool's gold.