Increased Risk of Multiple Myeloma Identified in Female Agricultural Workers

A study published in Environment International reported an elevated risk of multiple myeloma (MM) among female agricultural workers compared to the general population.

“Agricultural work can expose workers to potentially hazardous agents including known and suspected carcinogens,” wrote the study authors. “This study aimed to evaluate cancer incidence in male and female agricultural workers in an international consortium, AGRICOH, relative to their respective general populations.”

The researchers compiled data from eight international cohorts linked to their respective cancer registries: France (AGRICAN: n = 128,101), the US (AHS: n = 51,165, MESA: n = 2,177), Norway (CNAP: n = 43,834), Australia (Australian Pesticide Exposed Workers: n = 12,215, Victorian Grain Farmers: n = 919), Republic of Korea (KMCC: n = 8,432), and Denmark (SUS: n = 1,899). Standardized incidence ratios (SIR) were calculated for specific and combined cancer risks. National and regional rates were used as a reference and combined by random-effects meta-analysis.

Over nearly 2,800,000 person-years, 23,188 total cancers were observed among agriculture workers. An elevated risk for MM was identified in women in four cohorts (meta-SIR=1.27, 95% confidence interval [CI] 1.04-1.54) compared to the general population. However, this relationship was not identified in male agricultural workers (meta-SIR=1.08, 95% CI 0.88–1.32).

“Although the number of MM cases in women was small in most of the existing studies, the data overall are suggestive of an excess of multiple myeloma in female agricultural workers, particularly farmers,” wrote the authors. “Our analysis showed a significant excess only in the AGRICAN cohort for both men and women, which could indicate higher levels of exposure to certain risk factors for MM in the French agricultural setting. … Further analyses accounting for multiple occupational exposures among farmers and other possible risk factors, such as obesity are warranted.”

Other cancers with elevated risk among agriculture workers included melanoma in women (3 cohorts, meta-SIR=1.18) and prostate cancer in males (6 cohorts, meta-SIR=1.06). There was a reduced risk of several cancers noted, including bladder, breast, colorectum, esophagus, larynx, lung, and pancreas. The researchers noted large between-cohort variations in risk of liver and lung cancers in men and women and stomach, colorectum, and skin cancers in men.

In conclusion, the authors wrote, “The results suggest that agricultural workers have a lower risk of various cancers and an elevated risk of prostate cancer, multiple myeloma (female), and melanoma of skin (female) compared to the general population. Those differences and the between-cohort variations may be due to underlying differences in risk factors and warrant further investigation of agricultural exposures.”