Letters from the December 1, 2007, issue of Science News

Bed nets and insecticides

Kenyan researchers report that insecticide-treated bed nets can reduce malaria-related deaths in children (“Keep Out: Treated mosquito nets limit child deaths,” SN: 9/29/07, p. 195). While these nets appear to provide preventive measures against malaria, my only concern is the toxicity of the insecticides. The World Health Organization lists two of the insecticides used on the nets, bifenthrin and permethrin, as possible human carcinogens. Deltamethrin and cyfluhrin can have harmful effects on the nervous and endocrine systems. Is it ethical to prevent one disease now, but possibly foster the development of other diseases in the future?

Loren Babirak
Orono, Maine

WHO calls insecticide-treated bed nets “one of the most effective prevention measures for malaria.” WHO recommends nets that are treated with permethrin, etofenprox, or a pyrethroid. Katherine Macintyre of Tulane University says these insecticides pose a health risk “only if you swallow them.” Studies over the past 20 years show little public health danger from them. “Next to malaria, it’s nothing,” Macintyre says.—N. Seppa

Fat vibrations

It would be interesting to some way check fat versus muscle cells in airline pilots and crew; ship crews; anyone who rides the subways to work or the passengers and crew of any commuter train; taxicab drivers; or any construction worker who drives a vehicle or handles a vibrating piece of equipment, and then compare the findings with an equal sampling of sedentary subjects (“Good Buzz: Tiny vibrations may limit fat-cell formation,” SN: 10/27/07, p. 260). Even if that could not be done and we relied only on visual evidence, I think the results would show that living a life with more than 15 minutes of vibration a day has no effect on the problem of obesity.

Ted Blinder
Havertown, Pa.

CO2 and biodegradability

Soil water picks up carbon dioxide generated when soil organic matter decomposes, and this then escapes to the atmosphere (“Groundwater use adds CO2 to the air,” SN: 11/10/07, p. 301). This study should give pause to those who insist that man-made materials be biodegradable. When biodegradable materials decompose they add CO2 back into the atmosphere more quickly than otherwise. Nonbiodegradable materials serve to keep organic carbon buried and hence keep CO2 from rapidly escaping back into our atmosphere.

Kenneth M. Towe
Eatonton, Ga.