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Report Identifies Research Gaps in 20 Suspected Carcinogens

Author: American Cancer Society
Published: 2010/07/15 - Updated: 2026/03/31
Publication Details: Peer-Reviewed, Reports & Proceedings
Category Topic: Cancer - Tumors - Related Publications

Contents: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This report, a collaborative effort by the American Cancer Society, the International Agency for Research on Cancer (IARC), the National Institute for Occupational Safety and Health (NIOSH), the National Institute of Environmental Health Sciences (NIEHS), and the National Cancer Institute (NCI), identifies critical knowledge gaps for 20 agents suspected of causing cancer - including diesel exhaust, PCBs, formaldehyde, and lead compounds - whose carcinogenicity in humans has not yet been conclusively established. Published in the peer-reviewed journal Environmental Health Perspectives, the research outlines specific study needs to help move these agents toward definitive classification, with a particular focus on occupational exposures that affect millions of workers. For people with pre-existing health conditions, the elderly, and those with disabilities who may face heightened vulnerability to environmental and workplace exposures, understanding which substances are under serious scientific scrutiny - and why - is genuinely useful information - Disabled World (DW).

Topic Definition: Suspected Carcinogens

Suspected carcinogens are substances, agents, or exposure circumstances that have shown evidence of potential cancer-causing properties in animal studies or limited human research, but for which the scientific evidence is not yet sufficient to confirm a definitive causal link to human cancer. These agents are typically classified by the International Agency for Research on Cancer (IARC) within Groups 2A (probably carcinogenic to humans), 2B (possibly carcinogenic to humans), or Group 3 (not classifiable as to carcinogenicity), reflecting the current state of incomplete or conflicting data rather than an established verdict of safety or danger. Identifying and studying suspected carcinogens is a critical step in cancer prevention research, as closing knowledge gaps for these agents can ultimately lead to stronger occupational safety standards, better-informed public health policy, and more protective regulations for workers and communities exposed to them on a regular basis.

Introduction

Suspected Cancer Carcinogens Report Outlines Knowledge Gaps

Report outlines knowledge gaps for 20 suspected carcinogens - PCBs, diesel exhaust among agents identified as focus of further research.

A new report from the American Cancer Society and other world-leading health groups identifies gaps in research for 20 suspected carcinogens whose potential to cause cancer is as yet unresolved. The report is designed to prioritize agents for additional research, and to lead to well-planned epidemiologic or mechanistic studies leading to more definitive classification of these agents.

Main Content

The report, "Identification of research needs to resolve the carcinogenicity of high-priority IARC carcinogens," is a concerted effort to identify ways to close existing gaps in knowledge for particular agents classified by the International Agency for Research on Cancer (IARC) by identifying information needs and the research to address them for 20 selected agents.

The agents are generally in IARC Groups 2A, 2B, and 3.

The project originated as part of the National Institute for Occupational Safety and Health's (NIOSH) National Occupational Research Agenda (NORA) to enhance occupational cancer research, and involved collaboration with IARC, the American Cancer Society, the National Institute of Environmental Health Sciences (NIEHS), and the National Cancer Institute (NCI). The effort was co-sponsored by the American Cancer Society.

Agents Needing Additional Study:

  • Acetaldehyde
  • Atrazine
  • Carbon black
  • Chloroform
  • Cobalt with tungsten carbide
  • Di(2-ethylhexyl) phthalate (DEHP)
  • Dichloromethane, methylene chloride (DCM)
  • Diesel exhaust
  • Formaldehyde
  • Indium phosphide
  • Lead and lead compounds
  • Polychlorinated biphenyls (PCBs)
  • Propylene oxide
  • Refractory ceramic fibers
  • Shift work
  • Styrene-7,8-oxide and styrene
  • Tetrachloroethylene (perc, tetra, PCE)
  • Titanium dioxide
  • Trichloroethylene (TCE)
  • Welding fumes

"There is significant concern among the public about substances or exposures in the environment that may cause cancer, and there are some common occupational agents and exposure circumstances where evidence of carcinogenicity is substantial but not yet conclusive for humans," said Elizabeth Ward, Ph. D., vice president, Surveillance and Health Policy Research at the American Cancer Society and lead author of the report.

"The objectives of this report are to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans." Dr. Ward, one of the organizers of the meeting and lead author of a version of the report that appears in the journal Environmental Health Perspectives , added that the report highlights the importance of research in occupational settings for the identification of human carcinogens as well as the need for funding and access to populations for this work to continue.

Article: Ward EM, Schulte PA, Straif K, Hopf NB, Caldwell JC, et al. 2010 Research Recommendations for Selected IARC-Classified Agents. Environ Health Perspect.

Insights, Analysis, and Developments

Editorial Note: The value of this kind of systematic gap analysis should not be underestimated. Knowing that a substance has not been definitively classified as a human carcinogen is not the same as knowing it is safe - and that distinction matters enormously for workers, patients, caregivers, and policymakers alike. By naming specific agents and spelling out exactly what research is still needed, this collaborative effort between some of the world's foremost cancer research institutions gives scientists, regulators, and advocates a clear road map rather than a vague call for more study. The inclusion of everyday occupational exposures like welding fumes, diesel exhaust, and shift work makes this report especially relevant to working-age people and those managing chronic health conditions who deserve to know when the science on something they are regularly exposed to remains genuinely unresolved - Disabled World (DW).

Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by American Cancer Society and published on 2010/07/15, this content may have been edited for style, clarity, or brevity.

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APA: American Cancer Society. (2010, July 15 - Last revised: 2026, March 31). Report Identifies Research Gaps in 20 Suspected Carcinogens. Disabled World (DW). Retrieved April 27, 2026 from www.disabled-world.com/health/cancer/Suspected-Cancer-Carcinogens.php
MLA: American Cancer Society. "Report Identifies Research Gaps in 20 Suspected Carcinogens." Disabled World (DW), 15 Jul. 2010, revised 31 Mar. 2026. Web. 27 Apr. 2026. <www.disabled-world.com/health/cancer/Suspected-Cancer-Carcinogens.php>.
Chicago: American Cancer Society. "Report Identifies Research Gaps in 20 Suspected Carcinogens." Disabled World (DW). Last modified March 31, 2026. www.disabled-world.com/health/cancer/Suspected-Cancer-Carcinogens.php.

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