Scientists Question Use of NHANES Data for Chemical Exposure Studies
A recent research article focusing on bisphenol A (BPA) has questioned the use of National Health and Nutrition Examination Survey (NHANES) datasets “to draw causal inferences regarding environmental chemical exposures and adverse health outcomes.” Judy LaKind, et al., “Use of NHANES Data to Link Chemical Exposures to Chronic Disease: A Cautionary Tale,” PLoS One, December 2012. Using “consistent a priori selected methods,” researchers analyzed four NHANES datasets to determine whether (i) there was “a consistent association between urinary [BPA] measures and diabetes, coronary heart disease (CHD), and/or heart attacks across surveys”; and (ii) NHANES was “an appropriate dataset for investigating associations between chemicals with short physiologic half-lives such as BPA and chronic disease with multifactorial etiologies.”
The results evidently revealed no significant associations “between urinary BPA and heart disease or diabetes” for any of the NHANES surveys. Based on these findings, the study’s authors opted not to draw “any conclusions regarding whether BPA is a risk factor for these diseases,” but instead cautioned that “using cross-sectional datasets like NHANES to draw such conclusions about short-lived environmental chemicals and chronic complex disease is inappropriate.” In particular, they noted that “the main limitation of cross-sectional studies such as NHANES is the inability to determine the temporal sequence of exposure and outcome, the main property of a cause-and-effect relation.”
“Whether one-time measurements of chemicals with short physiologic
half-lives can or should be used to ascertain chronic exposures must be
carefully explored on a chemical-by-chemical basis,” concluded the authors.
“However, it is clear that for many chemicals we cannot be confident that
one-time measurements represent long-term exposures. … We need to
expend resources on more appropriately designed epidemiologic studies and
toxicological explorations to understand whether these types of chemicals
play a causal role in chronic disease.”
