Research recommendations for selected IARC-classified agents.
OBJECTIVE
There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were 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.


METHODS
For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent.


METHODS
Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches.


RESULTS
Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation.


CONCLUSIONS
Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.
Ward
Elizabeth M
EM
Epidemiology and Surveillance Research, American Cancer Society, Atlanta Georgia 30303, USA. elizabeth.ward@cancer.org
Schulte
Paul A
PA
Straif
Kurt
K
Hopf
Nancy B
NB
Caldwell
Jane C
JC
Carreón
Tania
T
DeMarini
David M
DM
Fowler
Bruce A
BA
Goldstein
Bernard D
BD
Hemminki
Kari
K
Hines
Cynthia J
CJ
Pursiainen
Kirsti Husgafvel
KH
Kuempel
Eileen
E
Lewtas
Joellen
J
Lunn
Ruth M
RM
Lynge
Elsebeth
E
McElvenny
Damien M
DM
Muhle
Hartwig
H
Nakajima
Tamie
T
Robertson
Larry W
LW
Rothman
Nathaniel
N
Ruder
Avima M
AM
Schubauer-Berigan
Mary K
MK
Siemiatycki
Jack
J
Silverman
Debra
D
Smith
Martyn T
MT
Sorahan
Tom
T
Steenland
Kyle
K
Stevens
Richard G
RG
Vineis
Paolo
P
Zahm
Shelia Hoar
SH
Zeise
Lauren
L
Cogliano
Vincent J
VJ
D000818:Animals; D015197:Carcinogenicity Tests; D019317:Evidence-Based Medicine; D006801:Humans