LAS VEGAS (AP) — University of Nevada, Las Vegas researchers have found that several hot sauce brands sold in the U.S. contain dangerous levels of lead.

Researchers examined 25 bottles of hot sauce imported from Mexico and South America and purchased from local ethnic markets, grocery stores, and a swap meet in what the university described as a first-of-its-kind study.

They found that four of the bottles, or 16 percent of the sample, exceeded Food and Drug Administration standard for safe levels of lead.

The results were published in the Journal of Environmental Science and Health earlier this year and publicized last week by the university.

Lead poisoning can affect every organ in the body and can cause learning disabilities and behavioral problems in young children. Researchers acknowledged that many children probably steer clear of hot sauce, but said that it is a staple of some ethnic diets.

UNLV researcher Shawn Gerstenberger said his results point to the need for better screening of hot sauce and other products imported from Mexico.

“The results indicate the need for more rigorous screening protocols for products imported in Mexico, including an applicable standard for hot sauce. Without enforceable standards for hot sauces and condiments, manufacturers will not be encouraged to improve quality control measures designed to reduce the amounts of lead and other toxic elements before exporting,” he said in a statement.

He added that states might choose to reject imported hot sauces found to contain detectable concentrations of lead.

Researchers tested the lead content of packaging as well as the sauce itself because lead in packaging has been known to leech into food.

In 2006, UNLV researchers discovered that Mexican-style candies containing chili peppers and salt also contained dangerous levels of lead. That study helped bring about the removal of some imported candies from grocery store shelves.