Date:  August 8, 2014



Formaldehyde Confirmed as Known Human Carcinogen


A new report from the National Research Council has upheld the listing of formaldehyde as “known to be a human carcinogen” in the National Toxicology Program 12th Report on Carcinogens (RoC).  The committee that wrote the Research Council report found that the listing is supported by sufficient evidence from human studies that indicate a causal relationship between exposure to the chemical and at least one type of human cancer.  The committee reached the same conclusion after conducting both a peer review of the RoC and an independent assessment of the formaldehyde literature.


The NTP is an interagency program that produces the RoC.  Formaldehyde is a substance of interest for the RoC because many people in the United States are exposed, either through environmental sources such as combustion processes and tobacco smoke, or in occupational settings that include the furniture, textile, and construction industries.  Formaldehyde is also produced naturally by human cells.  It was first listed by NTP as “reasonably anticipated to be a human carcinogen” in 1981 before being upgraded to “known carcinogen” in the 2011 RoC.


Based on RoC listing criteria, a substance can be classified as known to be a human carcinogen if there is sufficient evidence of carcinogenicity from studies in humans that indicate a causal relationship between exposure to the substance and human cancer.  In its peer review of the RoC, the Research Council committee found that NTP described the strengths and weaknesses of relevant studies in a way that was consistent and balanced, but noted that it would be more complete if it also discussed why weaker evidence did not alter the conclusion.


In addition, NTP did not include a description of its interpretation of “limited” and “sufficient” evidence for human studies, which factors into whether a chemical is listed as reasonably anticipated to be or known to be a human carcinogen.  The Research Council committee defined “limited evidence” in humans to be two or more studies of varied design that suggest an association between formaldehyde and a specific type of cancer but that cannot exclude alternative explanations such as chance, bias, or confounding factors.  Evidence was deemed to be “sufficient” if those alternative explanations could be ruled out with confidence.  On this basis, the committee agreed that there is sufficient evidence to support an association between formaldehyde and cancer in humans.


In its independent assessment, the committee considered human, animal, and mechanistic studies published through November 8, 2013 that focused on nasopharyngeal cancer, sinonasal cancer, and myeloid leukemia.  It found sufficient evidence of carcinogenicity in human and animal studies and “convincing relevant information” that formaldehyde induces mechanistic events associated with the development of cancer in humans.  Based on these findings, the committee concluded that formaldehyde should be listed in the RoC as “known to be a human carcinogen.”



Lauren Rugani, Media Officer

Christina Anderson, Media Assistant

Office of News and Public Information

202-334-2138; e-mail


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Pre-publication copies of Review of the Formaldehyde Assessment in the National Toxicology Program 12th Report on Carcinogens available from the National Academies Press on the Internet at or by calling 202-334-3313 or 1-800-624-6242.  Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).



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Division on Earth and Life Studies

Board on Environmental Studies and Toxicology


Committee to Review the Formaldehyde Assessment in the

National Toxicology Program 12th Report on Carcinogens


Alfred O. Berg* (chair)

Professor and Chair Emeritus

Department of Family Medicine

University of Washington



John C. Bailar III*

Professor Emeritus

University of Chicago

Mitchellville, Md.


A. Jay Gandolfi

Professor Emeritus

College of Pharmacy

University of Arizona



David Kriebel


Lowell Center for Sustainable Production; and


Department of Work Environment

University of Massachusetts



John B. Morris

Board of Trustees Distinguished Professor;

Professor of Pharmacology and Toxicology

Department of Pharmaceutical Sciences; and

Interim Dean

University of Connecticut School of Pharmacy



Kent E. Pinkerton


Center for Health and the Environment;


Department of Pediatrics

School of Medicine; and


Department of Anatomy, Physiology, and Cell Biology

School of Veterinary Medicine

University of California



Ivan Rusyn


Department of Environmental Sciences and Engineering;


Laboratory of Environmental Genomics; and


Carolina Center for Computational Toxicology

Gillings School of Global Public Health

University of North Carolina

Chapel Hill


Toshihiro Shioda

Associate Professor of Medicine

Harvard Medical School; and


Molecular Profiling Laboratory

Massachusetts General Hospital Cancer Center



Thomas J. Smith

Professor Emeritus

Department of Environmental Health

Environmental Science and Engineering Program

Harvard School of Public Health



Meir Wetzler


Division of Leukemia

Department of Medicine

Roswell Park Cancer Institute; and

Professor of Medicine

School of Medicine and Biomedical Sciences

University at Buffalo

State University of New York



Lauren Zeise

Deputy Director for Scientific Affairs

Office of Environmental Health Hazard Assessment

California  Environmental Protection Agency



Patrick Zweidler-McKay

Section Chief

Pediatric Leukemia and Lymphoma; and

Associate Professor

Department of Medicine

Division of Pediatrics

The Children’s Cancer Hospital

The University of Texas M.D. Anderson Cancer Center





Heidi Murray-Smith

Study Director



*Member, Institute of Medicine