National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
Address for correspondence: James Huff, Ph.D., Environmental Carcinogenesis, National Institute of Environmental Health Sciences, P.O. Box 12233, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709. Voice: 919-541-3780; fax: 919-541-5002.
huff1{at}niehs.nih.gov
Ann. N.Y. Acad. Sci. 982: 208-230 (2002).
The Ramazzini Foundation (RF) in Bentivoglio, Italy and the
National Toxicology Program (NTP) in Research Triangle Park,
North Carolina have carried out several hundred chemical carcinogenesis
bioassays: 200 by RF and 500 by NTP. Of these, 21 have been
evaluated by both laboratories. The 14 chemicals for which both
laboratories have designed, conducted, and reported bioassay
results are: acrylonitrile, benzene, chlorine, diesel fuel,
ethylbenzene, methylene chloride (dichloromethane), propylene,
styrene, styrene oxide, toluene, trichloroethylene, trichlorofluoromethane,
vinylidene chloride, and xylenes. The other seven chemicals
(two are fibers) were evaluated by both laboratories, but results
have not yet been published. Results of these 14 interlaboratory
studies were compared both to explore consistency of carcinogenic
responses and to identify possible factors that may reveal reasons
for any differences observed. Individual carcinogenesis results
from each laboratory were duplicated and complementary. Of the
14 chemicals compared, 11 (80%) were either carcinogenic (9
chemicals) or noncarcinogenic (2 chemicals) in both studies.
Eight of the paired chemicals had at least one carcinogenic
target site in common. The other three were carcinogenic in
one laboratory but not in the other. Possible explanations for
these differences include dose, method of administration, duration
of follow-up, and whether or not total tumors are counted. The
collaboration between these two pioneering bioassay laboratory
programs contributes greatly to our understanding of chemical
carcinogenesis and results in better protection of workers and
the general population from chemical diseases, especially cancers.
