Pesticide Exposures And The Risk Of Multiple Myeloma In Men: An Analysis Of The North American Pooled Project (NAPP)

Shelley HARRIS, Dalla Lana School of Public Health, University of Toronto, Canada
PRESUTTI R. 1,2 , KACHURI L. 1,2,3,4 , SPINELLI J. 5 , PAHWA M. 1,2 , BLAIR A. 6 , HOAR ZAHM S. 6 , CANTOR K. 6 , WEISENBURGER D. 7 , PAHWA P. 8 , MCLAUGHLIN J. 1,3,4,9 , DOSMAN J. 8 , BEANE FREEMAN L. 6

1 Occupational Cancer Research Centre, Cancer Care Ontario, Toronto, ON, Canada
2 Prevention and Cancer Control, Cancer Care Ontario, Toronto, ON, Canada
3 Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
4 Lunenfeld-Tanenbaum Research Institute, Toronto, ON, Canada
5 British Columbia Cancer Agency Research Centre, University of British Columbia, Vancouver, BC, Canada
6 U.S. National Cancer Institute, Bethesda, MD, USA
7 Department of Pathology, City of Hope Medical Center, Duarte, CA, USA
8 University of Saskatchewan, Saskatoon, SK, Canada
9 Public Health Ontario, Toronto, ON, Canada

Purpose: Multiple myeloma (MM) has been linked to agricultural activities, including pesticide exposures.  Three case-control studies of haematological cancers were harmonized to form the North American Pooled Project (NAPP). The objective of this work was to evaluate associations between pesticide use and MM risk.  

Methods: The NAPP included 547 cases and 2700 controls. Pesticide use was evaluated using different exposure metrics:  ever/never; duration of use (years); and cumulative lifetime days (LD) (days/year × years of use). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression adjusting for age, residence, use of proxy respondents, and medical conditions.

Results: Increased MM risk was observed for use of carbaryl (OR=2.02, 95% CI=1.28-3.21), captan (OR=1.98, 95% CI=1.04-3.77), and DDT (OR=1.44, 95% CI=1.05-1.97). Using the Canadian subset of data, we observed a more than 3-fold increase in MM risk (OR=3.18, 95% CI=1.40-7.23) for ≤10 LD of carbaryl use. The association was attenuated for >10 LD of carbaryl use (OR=2.44; 95% CI=1.05-5.64; ptrend=0.01). For captan, ≤17.5 LD of exposure was associated with a more than 3-fold increase in risk (OR=3.52, 95% CI=1.32-9.34), but this association was attenuated in the highest category of >17.5 LD (OR=2.29, 95% CI=0.81-6.43; ptrend=0.01). An increasing trend (ptrend=0.04) was observed for LD of DDT use (LD>22; OR=1.92, 95% CI=0.95-3.88).
 
Conclusions: We observed significant increases in MM risk for use of carbaryl, captan and DDT. IARC has classified DDT as probably carcinogenic to humans, and carbaryl was classified as likely carcinogenic in humans by the US EPA. IARC revised the classification of captan from a ‘probable human carcinogen’ to ‘not likely carcinogenic’ in 2004.   This work will inform future hazard re-assessments by these agencies.

Funding: Canadian Cancer Society Research Institute Grant # 703055 and the U.S. National Institutes of Health Intramural Research Program of the National Cancer Institute.