Letters from the March 31, 2007, issue of Science News

On the hoof

Do cows and other domestic-herd animals really emit more methane than bison and other wild-herd animals emitted before people came along? Do grass, alfalfa, and other pasture plants remove less carbon dioxide than do forests? There were open grasslands before pastures replaced some forests. I hope the people who are researching these things (“Big footprints,” SN: 1/13/07, p. 30) take such issues into consideration before trying to frighten everyone into becoming vegetarians.

Anne Bevier
Monterey, Calif.

Nanotechnicalities

Not only is the finding that nanotubes “remained in particular in the liver and spleen” of concern (“Tracking nanotubes in mice,” SN: 1/27/07, p. 61), but there is no indication made or concern expressed over what happens after excretion. What biological activity do these structures have in the open environment, and for how long? Can they become airborne? Do they get removed in sewage-treatment plants? After all, these things have never existed before.

William Belknap
Boulder City, Nev.

Fuels’ gold?

No mention is made in “Gas tanks could guzzle half of U.S. corn yields” (SN: 2/3/07, p. 78) of the huge amount of petrochemical inputs required both for large-scale farming of corn and for the distilling process required to produce ethanol. When these and other environmental costs are factored in, the promotion of corn-based ethanol as fuel will ultimately be exposed as an environmentally disastrous policy.

C. Greenwood
Sacramento, Calif.

The article begs the question: Are biofuels well suited to provide a significant portion of our nation’s energy pie? I think the answer is yes, but another approach is needed. We would do well to look to New Zealand, South Africa, and parts of the United States, where the extraction of biofuels from algae grown on wastewater streams is being pioneered. Extremely prolific and among the highest oil-yielding plants on earth, algae can, without competition for arable land, feed off wastewater from cities, farms, and other provenances and serve as raw material for fuel.

Thomas Sullivan
Vineyard Haven, Mass.