WASHINGTON — The National Institutes of Health said on Friday that it had uncovered a nearly century-old container of ricin and a handful of other forgotten samples of dangerous pathogens as it combed its laboratories for improperly stored hazardous materials.

The agency began an intensive investigation of all of its facilities in July after a scientist found vials of smallpox dating from the 1950s, along with other contagious viruses and bacteria that had been stored in a lab on the N.I.H.’s campus.

The N.I.H. said it had found small amounts of five improperly stored “select agents,” pathogens that must be registered and kept in highly regulated laboratories. All were found in sealed and intact containers, with no evidence that they posed a safety risk to anyone in the labs or surrounding areas, the agency said in a memo to employees. All of the samples have been destroyed.

They included a bottle of ricin, a highly poisonous toxin, found in a box with microbes dating from 1914 and thought to be 85 to 100 years old, the memo said.