What could the data tell us about the size of a potentially exposed population?
Researchers prioritized data sets that indicated that a large portion of the population could have been exposed to contaminants. • Were the data actual measures of contaminants in the environment or reported emissions or chemical releases? Researchers were more confident in measured levels of contaminants in the environment than in data that reported industrial emissions or chemicals released to the environment. • Do the data suggest that people actually could have had contact with the contaminant? Exposure is contact with a contaminant. Without exposure there can be no health effect, regardless of the level of contamination found in the environment. In every case, researchers used data about levels of contaminants to estimate exposure. • Did the data represent a time period that could have been related to breast cancer incidence between 1993 and 1997? Scientists estimate that breast cancer could occur somewhere between 5 and 40 years after a person is exposed to risk factors that migh
