THE Love Canal study in New York forced the then American president, Jimmy Carter, to declare an emergency in the vicinity and cleared the way for relocating about 2,500 residents. The study revealed that there was a significant excess in the incidence of low birth weight among new-born infants from 1940 to 1953 -- a period when chemicals were being dumped indiscriminately near the Love Canal area. It was found that the accumulation of more than 200 chemicals in the groundwater forced up chemical wastes to the topsoil layer, thus facilitating "lateral migration": this slowly overflowing bathtub effect resulted in the spreading of dangerous waste to adjacent backyards and basements.

Another epidemiological study in Kerala pointed to the link between background radiation from monazite deposits in beach sands and a high incidence of congenital diseases. Nearly half the people living in these areas received a dose of 500 millirad annually, the maximum permissible limit. A similar study in Jaipur on the incidence of asthma has shown that allergic disorders -- especially among housewives -- caused mostly by house dust, might be the cause.

In the '80s, about 20,000 people in Spain were affected by a new disease called "toxic allergic syndrome". In the first 4 months alone, 13,000 people were treated in hospitals. The disease baffled doctors till an epidemiological investigation identified the cause as the ingestion of olive oil adulterated with contaminated rapeseed oil.