IDUKKI, India — Spices grown in the mist-shrouded Western Ghats here have fueled wars, fortunes and even the discovery of continents, and for thousands of years farmers harvested them in the same traditional ways. Until now.

Science has revealed what ancient kings and sultans never knew: instead of improving health, spices sometimes make people very sick, so Indian government officials are quietly pushing some of the most far-reaching changes ever in the way farmers here pick, dry and thresh their rich bounty.

The United States Food and Drug Administration will soon release a comprehensive analysis that pinpoints imported spices, found in just about every kitchen in the Western world, as a surprisingly potent source of salmonella poisoning.

In a study of more than 20,000 food shipments, the food agency found that nearly 7 percent of spice lots were contaminated with salmonella, twice the average of all other imported foods. Some 15 percent of coriander and 12 percent of oregano and basil shipments were contaminated, with high contamination levels also found in sesame seeds, curry powder and cumin. Four percent of black pepper shipments were contaminated.