Frogs have been found in bags of vegetables -- and they weren't always dead.

The Washington Post says researchers have published the first known review of wild animals customers discovered in prepackaged produce.

The newspaper says that while more than half the incidents involved amphibians, "rodents, snakes, lizards, birds and even a bat found their way into bagged lettuces, spinach and cut green beans."

Researchers recently published their findings online. They say 40 such situations have been reported since 2003, and 38 of those happened between 2008 and 2018. Most of the time, the creatures were found in conventional produce, as opposed to organic leafy green packages.

According to the research published by ScienceDirect, some of the animals were alive when they were found. At least one lizard and nine frogs were still breathing when they were discovered by customers.

"This is the first review quantifying incidents of vertebrates found by customers in prepackaged produce, yet it remains unclear whether these occurrences indicate a food-safety crisis or a complaint against food quality," the study said.

According to The Post, the researchers' methodology involved combing through online media reports. And, while that means the study isn't necessarily comprehensive, the researchers hope that by drawing attention to the matter, food industry leaders can help reduce animal contamination.

As for how the wildlife may have gotten into the food, The Washington Post suggested mechanical farming techniques that involve less human handling of the products could play a factor.

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