Biography
Dr. Cantor received a Ph.D. in biophysics from the University of California at Berkeley and an M.P.H. from the Harvard School of Public Health. He began work with the NCI epidemiology group on detail from the Environmental Protection Agency in 1976, and joined the NCI staff in 1981. Dr. Cantor received the NIH Merit Award for his contributions to the study of drinking water contaminants. He has advised several national and international panels on drinking water and health issues.
Research Interests
Our research focuses on general areas of environmental and occupational epidemiology. In the environmental realm, we are investigating the relation between human cancer and exposure to a variety of drinking water contaminants, including chlorination byproducts, nitrate, and arsenic. Other research interests include cancer risks associated with selected occupational exposures, such as pesticides and electromagnetic radiation.
Chlorination Byproducts
Several drinking water contaminants have been identified as potential carcinogens. Prominent among these are byproducts of chlorine disinfection, nitrate, and arsenic. Unintended chemical byproducts resulting from chlorination of drinking water were first discovered in 1974. We have conducted a number of epidemiologic studies to evaluate the carcinogenic risks posed by these byproducts. The first studies were ecologic in design, and pointed to cancers of the bladder, colon, rectum, and certain other sites as candidates for more detailed investigation.
Analyses of data from the National Bladder Cancer Study found an increased risk among persons who had consumed chlorinated surface water (elevated in byproduct levels) for more than 40 years, and who ingested above median amounts of drinking water. Following up on these results, we conducted a case control study of six cancer sites (bladder, colon, rectum, brain, pancreas, and kidney) in Iowa. A dose response relation between duration of chlorinated surface water use and risk of rectal cancer was observed in both men and women, while elevated risks of bladder cancer and brain cancer were noted among men. An excess risk was not detected for cancer of the pancreas or kidney. This research is continuing on several fronts, including developing more precise measures of exposure for participants in the Iowa case control study, initiating biochemical studies to evaluate the biologic plausibility of our observations, and following up on our initial findings, especially for brain and bladder cancers.
Nitrates
The endogenous formation of carcinogenic N nitroso compounds can occur following ingestion of nitrate from drinking water. Nitrate is first reduced in the saliva to nitrite, which can react in the stomach with secondary amines and amides. The epidemiologic data are still quite limited on this issue. An NCI study found a dose response relation between risk of non Hodgkin's lymphoma and exposure to elevated nitrate in drinking water. We are implementing additional studies to evaluate further the importance of drinking water nitrate in the etiology of lymphoma and other cancers.
Arsenic
Arsenic is recognized as a carcinogen in humans. It causes lung cancer after exposure to airborne dust, and skin cancer following ingestion of inorganic arsenic in food or water. Studies from Taiwan, Argentina, and Chile reveal that arsenic in drinking water also causes cancers of the lung and bladder, and possibly kidney and other cancers. Exposures in these studies are in the several hundred microgram/liter range. Additional epidemiologic investigation of arsenic carcinogenesis is a high priority, especially since no acceptable animal model exists. We collaborated on a small case control study that suggested an elevated bladder cancer risk associated with arsenic exposure at relatively low levels in drinking water. We are now pursuing this finding using information from a more recent and larger case control study of bladder cancer in the same region.
Keywords
arsenic, bladder cancer, chlorination byproducts, colon cancer, drinking water contaminants, electromagnetic radiation, nitrate, pesticides, rectal cancer
Selected Publications
- Cantor, K.P., Lynch, C., Hildesheim, M., Dosemeci, M., Lubin, J., Alavanja, M.: "Drinking water source and chlorination byproducts in Iowa: I. Risk of bladder cancer." Epidemiology 1998; 9: 21-28.
- Cantor KP, Silberman W. "Mortality among aerial pesticide applicators and flight instructors: Followup from 1965 through 1988." Am J Ind Med 1999; 36:239-47.
- Cantor, K.P, et al. "Drinking water source and chlorination byproducts in Iowa: III. Risk of glioma." Am J Epidemiol 1999; 150: 552-60.
- Cantor KP. "Invited commentary: Arsenic and cancer of the urinary tract." Am J Epidemiol 2001; 153:419-21.
Collaborators
DCEG Collaborators
- Michael Alavanja, Dr.P.H.; Dalsu Baris, M.D., Ph.D.; Aaron Blair, Ph.D.; Louise Brinton, Ph.D.; Wong Ho Chow, Ph.D.; Joanne Colt, M.P.H.; Mustafa Dosemeci, Ph.D.; Larry Engel, Ph.D.; Michal Freedman, Ph.D.; Gloria Gridly, M.S.; Allan Hildesheim, Ph.D.; Peter Inskip, Sc.D.; Jay H. Lubin, Ph.D.; John Nuckols, Ph.D.; Amy Picard, M.P.H.; Nathaniel Rothman, M.D.; Claudine Samanic, M.S.P.H.; Debra Silverman, Sc.D.; Rashmi Sinha, Ph.D.; Patricia Stewart, Ph.D.; Mary Ward, Ph.D.; Shelia Zahm, Sc.D
Other NCI Collaborators
Other Scientific Collaborators
- John Brock, Ph.D., Michelle Lynberg, Ph.D., Larry Needham, Ph.D., Centers for Disease Control and Prevention, Atlanta, GA
- James Cerhan, Ph.D.; Alexander Parker, Ph.D., Mayo Clinic, Rochester, MN
- Brian Chia, Ph.D., University of Nebraska, Omaha, NE
- Allan Smith, M.D., Ph.D., University of California, Berkeley, CA
- Caterina Wesseling, M.D., National University, San Jose, Costa Rica
- Pierluigi Cocco, M.D., University of Cagliari, Sardinia, Italy
