Abstract Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic blood disorder that precedes multiple myeloma, and its etiology remains incompletely understood. Risk factors described in the literature include advanced age, male sex, Black race, a family history of plasma cell disorders, and the presence of chronic inflammatory or autoimmune conditions. Furthermore, direct exposure to pesticides has been proposed as a potentially modifiable risk factor. Accordingly, this study aimed to synthesize and evaluate the available evidence on MGUS prevalence and its possible relationship with occupational pesticide exposure among rural workers and pesticide applicators, including prevalence data when reported. A systematic review with meta-analysis was conducted according to Cochrane recommendations. Literature searches were conducted in October 2024 using the Medline (PubMed), Scopus, and Cochrane Library databases to identify relevant primary studies. Four eligible observational studies evaluating MGUS in participants directly exposed to pesticides were included. The studies reported positive associations between specific pesticides, such as aldrin, dieldrin, a carbon tetrachloride/carbon disulfide mixture, chlorothalonil, petroleum-derived products, and permethrin, and the occurrence of MGUS among rural workers. These findings were analyzed qualitatively due to methodological heterogeneity that precluded pooling of risk estimates. The meta-analysis, restricted to prevalence outcomes, showed that MGUS prevalence increases with age, suggesting age as an important risk factor. The scarcity of published studies and methodological heterogeneity highlight the need for further investigations to better characterize environmental and occupational risks associated with MGUS, which may inform future preventive strategies in higher-risk populations.
Oliota et al. (Wed,) studied this question.