Letters from the July 2, 2005, issue of Science News

Chlorine’s fate?

“Special Treatment: Tiny technology tackles mega messes” (SN: 4/23/05, p. 266), on the reaction of nanoparticles of iron with trichloroethane (TCE) contaminating an aquifer, states that the TCE is converted “into ethane.” What happens to the chlorine stripped off the TCE? Is it converted into insoluble inorganic compounds or is it available to react with another aquifer contaminant to possibly form another toxic substance?

Charles McChesney
Mars, Pa

The chlorine atoms stripped from TCE are converted into harmless chloride ions that float freely in the groundwater.—A. Goho

On the sunny side

It boggles my mind that someone paid for a study of the benefits of petroleum-based fuel in Africa (“Change of fuel could extend lives in Africa,” SN: 5/7/05, p. 301) when a superior, lower-cost solution is already available. For the cost of the study, solar cookers might have been provided to several thousand families, protecting the health of those families and saving them the time and expense of gathering fuel, not to mention protecting the environment from smoke. The world is currently experiencing a shortage of petroleum-based fuels. It is unlikely that most African families could afford the better fuels—nor can we afford to be encouraging more people to use them.

Anne Barschall
Tarrytown, N.Y.

You can’t get good help

“In Its Own Image: Simple robot replicates itself block by block” (SN: 5/14/05, p. 310) makes the common claim that self-replicating robots could be a boon for clearing minefields. In truth, a complex electronic device simply does not last long in the field. When it breaks and you are 3 days from the nearest town, where do you get a spare part or battery? Tools for removing land mines need to be affordable, simple to manufacture and repair in a mined area, and 100 percent accurate under highly variable conditions. What robot meets these criteria?

Andrew Heafitz

Massachusetts Institute of Technology
Cambridge, Mass.

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