 This is caused by the traditional Eskimo practice of allowing animal products such as whole fish, fish heads, walrus, sea lion, and whale flippers, beaver tails, seal oil, and birds, to ferment for an extended period of time before being consumed.The risk is exacerbated when a plastic container is used for this purpose instead of the old-fashioned, traditional method, a grass-lined hole, as the "Clostridium botulinum" bacteria thrive in the anaerobic conditions created by the air-tight enclosure in plastic.The World Health Organization has classified pickled foods as possibly carcinogenic, based on epidemiological studies.