How many chemical in cigarettes are known or suspected to cause cancer a) more than 10 b) more than 20 c) more than 50 d) more than 100

Investigator a has biological specimens that are coded and linked to identifiers of the source individuals. investigator a provides the specimens to investigator b but does not provide the individual identifiers. investigator b agrees not to re-identify the source individuals. is investigator b's research using the biospecimens human subjects research according to the definition of human subjects research in the federal regulations?