mosquito coils are finally in the dock, after a prolonged deference. Two independent studies indicate that coils commonly used in Asian countries, including India, can be disastrous for human health. While one indicates they contain a cancer-causing substance, the other estimates that a single coil releases particulate matter equal to 75 to 137 cigarettes. The studies are published in the September 2003 issue of Environmental Health Perspectives.

Mosquito coils are one of the four insecticide products popularly used by Asians to protect themselves from disease-carrying mosquitoes. (The other three are aerosols, liquid vapourisers and vapourising mats.) Coils are said to the most inefficient mosquito repellent. However, with an upsurge in diseases such as malaria, their use along with the others is on the rise worldwide. "In developing countries, mosquito coils are regularly used by middle class families which have small houses. Moreover, windows are kept closed during sleeping hours. These factors make people (especially children) more vulnerable to the harmful chemicals,' assert the authors.

Most coils used in the developing world have pyrethroid insecticides, particularly d-allethrin, as the active ingredient. Though d-allethrin itself is not harmful, a chemical compound used as the synergist (called s-2 or octachlorodipropyl ether) is quite dangerous, claim the scientists from the department of entomology at the University of California Riverside (ucr). The synergist is a chemical substance used to boost the potency of the key ingredient, even though it lacks significant insecticidal character on its own.

The ucr team, comprising of Robert Krieger, Travis Dinoff and Xiaofei Zhang, says it is very likely that the coils are exposing users to bischloromethyl ether, also called bcme