The U.S. Food and Drug Administration (FDA) has conducted a study into the prevalence of salmonella in imported spices, following widespread concerns that spices might be a source of foodborne diseases. The research confirms that some spices available on the U.S. market are contaminated with salmonella, with most of the affected production coming from India and Mexico, the New York Times reported.

Researchers looked at more than 20,000 food shipments over a period of three years. After analyzing the samples gathered by the FDA, the agency found that almost seven percent of the spice lots were contaminated with the pathogen. In comparison to other imported food products, this rate is nearly twice as high.

Details from the study show that as much as 15 percent of coriander and 12 percent of oregano and basil imports were contaminated with salmonella. Other spices with high rates of contamination were cumin, curry powder and sesame seeds. Shipments of one of the most commonly used spices — black pepper — were also contaminated, with four percent of imported lots having salmonella, the New York Times said.

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Overall, 14 percent of all spices imported from Mexico and nine percent of those from India were contaminated. However, since imports from the Asian country are almost four times higher than those from Mexico, the problem with Indian spices seems more serious.

Results from the FDA study were published in the journal Food Microbiology but the whole study will be made available to the public soon, officials from the agency told the New York Times.