Aaron Blair, Ph.D., M.P.H.
|Organization:||National Cancer InstituteDivision of Cancer Epidemiology & Genetics, Occupational and Environmental Epidemiology Branch|
|Address:||Executive Plaza South Room 8008|
Dr. Blair received a Ph.D. in genetics from North Carolina State University and an M.P.H. in epidemiology from the University of North Carolina. He joined the NCI as a Staff Fellow in 1976, and was appointed to head the Occupational Studies Section in 1978. Dr. Blair was appointed Chief of the group when it became a branch in 1996. He has received the NIH Director's Award, the PHS Special Recognition Award, NIH Merit Award, the DHHS Quality of Work Life Award, the University of North Carolina H.A. Tyroler Distinguished Alumni Award, the John Goldsmith Award for Outstanding Contributions to Environmental Epidemiology from the International Society for Environmental Epidemiology, and The Harriet Barr Distinguished Alumnus Award from the Public Health Alumnus Association of the University of North Carolina and the NIH Director's Award for the Deepwater Horizon Gulf Oil Spill Study. Dr. Blair has authored more than 400 publications on occupational and environmental causes of cancer.
My research focuses on evaluating cancer and other disease risks associated with agricultural exposures, chemicals in the workplace and the general environment, physical activity and disease, methodologic issues in occupational epidemiology, and studies of under-investigated populations.
A number of pesticides are carcinogenic in laboratory animals. The widespread use of these agents raises questions about their carcinogenicity in humans. Several studies have focused on farmers since they have heavier and more frequent exposures than the general population and are able to identify their pesticide usage. Despite an overall lower mortality than the general population, farmers have excess cancers of the lip, stomach, brain, prostate, skin, and the lymphatic and hematopoietic system, as well as non malignant chronic diseases. Ongoing studies are designed to identify risk factors that account for these excesses.
Our studies found evidence for possible links between pesticides and pancreatic cancer in a case control study in China, and certain carbamate and organophosphate insecticides and risk of non-Hodgkin lymphoma. Studies of non-Hodgkin lymphoma and multiple myeloma in Canada found links with several pesticides. Although previous studies associated non Hodgkin lymphoma with potential exposure to the herbicide 2,4 D, possible mechanisms of action are unclear. In a biomarker study among herbicide applicators, we found an association between urinary levels of 2,4 D and increased lymphocyte replication, the level after exposure being greater than before. Another study found higher exposure levels among farmers who did not follow careful work practices while applying insecticides to animals. A major prospective investigation of farmers and their families, the Agricultural Health Study (AHS) in Iowa and North Carolina, is gathering detailed information on pesticide use and collecting biologic specimens to evaluate gene environment interactions of pesticides and other agricultural exposures. Use of fungicides among orchardists in the cohort was associated with retinal degeneration. Because investigators are often dependent upon information from interviews to assess pesticide exposures among farmers, a methodologic study that obtained interview information from the same farmers a year apart found that they could reliably provide considerable detail on pesticide use. A study in AHS found that the insecticides paraquat, rotenone and dieldrin were associated with Parkinson disease. A case-control study of non-Hodgkin lymphoma and multiple myeloma in Canada found risks for these cancers rose with increasing numbers of pesticides used that were possible or probable carcinogens.
A study of members of a dry cleaning union exposed to solvents found excesses of esophageal and possible elevations for other cancers. An extended follow up of the mortality experience of a large cohort of workers exposed to formaldehyde found a continued excess of cancer of the nasopharynx and an excess of leukemia that rose with peak and average exposure. A cohort of people involved in the clean-up of the Gulf oil spill is being assembled to evaluate possible disease risks from exposure to crude oil and dispersants.