Editor’s Note: The GAO Mine Safety Report GAO-14-345, “Basis for Proposed Exposure Limit on Respirable Coal Mine Dust and Possible Approaches for Lowering Dust Levels,” found here, assesses MSHA’s decision to “not use NIOSH’s surveillance data as the basis for its proposed new coal mine dust limit…” and instead base their proposal on other available data. GAO’s assessment of the agency’s data selection decision indicates that their auditing standards are consistent with OIRA’s government-wide data quality requirements.

Below is are two excerpts from the GAO report.

Appropriately, MSHA did not use NIOSH’s surveillance data as the basis for its proposed new coal mine dust limit, although the data served to inform MSHA’s decision to take action.


It would not have been appropriate for MSHA to use NIOSH’s surveillance data in developing its proposed exposure limit for coal mine dust because of some important limitations of the data. For example, because the data do not include individual miners’ past exposures to coal mine dust, they cannot be used to estimate disease risk for individual miners. Based on principles of epidemiology and statistical modeling, measures of past exposures to coal mine dust are critical to assessing the relationship between miners’ cumulative coal mine dust exposure and their risk of developing CWP. Also, because there is no active selection of miners by researchers and participation in the surveillance program is voluntary, miners who choose to participate may differ in unknown ways from those who choose not to participate, which could result in an overestimation or underestimation of the prevalence of disease. This methodological limitation is known as participation bias, and there are many ways it could affect the prevalence of disease indicated by the surveillance data.