Aresearcher wants to conduct a secondary analysis using a centers for disease control and prevention (cdc) database that was collected by the agency solely for surveillance purposes from 1996-2006. the researcher did not participate in the initial collection of the data. the database is publicly available. the database does not include any identifiers. the irb makes a determination that the individuals whose records will be reviewed do not meet the federal definition of human subjects. which of the following considerations was relevant to the irb's determination that this activity does not constitute research with human subjects?