A laboratory sweep at the U.S. National Institutes of Health (NIH) has turned up forgotten stores of the toxin ricin and four pathogens, according to a 5 September agency memo.

The agency undertook the search after discovering improperly stored vials of deadly smallpox virus in a refrigerator at its Bethesda, Maryland, campus in July. That news came just weeks after the U.S. Centers for Disease Control and Prevention (CDC) said that employees at one of its Atlanta labs were potentially exposed to anthrax because they did not follow established safety guidelines. And in March, CDC employees shipped samples of the dangerous H5N1 influenza virus to another government laboratory without taking proper precautions.

The NIH says that its lab-safety sweeps revealed small amounts of improperly stored ricin and pathogens that cause tularemia, the plague, botulism and the tropical disease meloidosis. All five substances are classified as ‘select agents’ — pathogens and toxins that the U.S. government considers to pose a severe threat to public health and safety.

The ricin was discovered in a historical sample collection dating from 1914 and may be 85-100 years old, the agency memo says.

“All of the agents were found in sealed and intact containers and there were no personnel exposures associated with the storage or discovery of these vials or samples,” NIH director Francis Collins said in the memo. Collins added that the agents were reported to the CDC and destroyed.

Meanwhile, the U.S. Food and Drug Administration said on 5 September that it had found improperly stored samples of Staphylococcus enterotoxin, a pathogen that can cause food poisoning. The discovery was first reported by the Associated Press.

This article is reprinted with permission and was first published on September 6, 2014.