In 2015, the EPA sought independent expert advice from the NAS to address scientific issues and provide guidance on the conduct of our controlled human exposure studies. NAS established the Committee on Assessing Toxicologic Risks to Human Subjects Used in Controlled Exposure Studies of Environmental Pollutants. The committee released its final report Controlled Human Inhalation-Exposure Studies at EPA on March 28, 2017.

The committee reviewed contributions to EPA’s Integrated Science Assessments for ozone and particulate NAAQS, IRB applications, consent forms, peer-reviewed publications, adverse event reports, and the presentations and materials provided by EPA and other interested parties. The committee report was peer-reviewed according to the procedures used by the NAS.

The committee report indicated that:

• EPA studies have provided unique and critical contributions to the science base supporting NAAQS decisions.
• Risks of serious adverse events posed to study subjects are unlikely to be large enough to warrant concern, but it is never possible to conclude there is no risk.  Study exposures add very little to cumulative lifetime pollutant exposures and any increase in chronic disease risk, such as lung cancer, resulting from experimental exposures is vanishingly small.
• Controlled human inhalation-exposure studies should continue to be undertaken cautiously when a study is expected to provide additional policy-relevant knowledge that cannot be obtained by other means, and it is reasonably foreseeable that study subjects’ risks will not exceed transient and reversible responses.
• The committee report provided additional recommendations to EPA in the prioritization and conduct of future studies.

The EPA thanks the members of the committee and the NAS on the completion of the report. The report is available to the public at:

• NAS ReportEXIT