Impact of Pesticide Exposure on the Prevalence of Monoclonal Gammopathy of Undetermined Significance (MGUS) Among Residents of South of Brazil Region: An Epidemiological Case-Control Study
Authors: Cunha Ademar Dantas , Saini Kamal Veer , Boixader Laura Vidal , Oliota Ana Flavia Redolfi , Borsa Mayara Pryscila , Rizzotto Maria Lucia Frizon , Brandalise Patricia , Hamilton Brian 
Published: December 2024

Background: Monoclonal gammopathy of undetermined significance (MGUS) is marked by the asymptomatic proliferation of monoclonal plasma cells, which sometimes precedes multiple myeloma (MM), a bone marrow malignancy primarily affecting individuals over 50 years old and accounting for 10% of hematological cancers globally. While the etiology of MGUS remains largely unclear, there is evidence suggesting that pesticide exposure may contribute to the development of this condition, especially among rural workers due to their frequent exposure to such substances. The prevalence of MGUS varies globally, estimated at 3-4% in individuals over 50, but higher in agricultural areas due to pesticide exposure. The western region of Parana is one of the main areas for pesticide use in Brazil. In 2017, the state of Paraná accounted for 16% of the total pesticide usage in the country, making it the third-largest national consumer. In Brazil, pesticide use reached 10.9 kg per hectare, significantly higher than the 2.85 kg/ha in the USA and 1.9 kg/ha in China. These data highlight the intensity of pesticide use in Parana's agriculture compared to the rest of Brazil and the world. This study focuses on the western macro-region of Parana State, Brazil, known for intensive agriculture and significant pesticide use, contributing 23% to the state's agricultural production value in 2018.

Trial design: This epidemiological, observational, case-control study aims to assess the prevalence and the association between direct pesticide exposure and the presence of MGUS, emphasizing the identification of key risk factors. The study population includes men over the age of 50, divided into two groups: the case group, consisting of individuals with a history of occupational pesticide exposure (pesticide applicators), and the control group (non-pesticide applicators), representing the general community population. The study aims to enroll 480 participants, with 240 in each group. Ethical approval was granted by the Human Research Ethics Committee (number 5.794.378), data is being collected from September 2023 up to September 2025. Laboratory tests, including protein electrophoresis, immunofixation, and freelite assays, serve as primary endpoints. A regression analysis will evaluate factors related to MGUS risk, considering independent variables such as age, race, weight, health history, comorbidities, medications, family health history, and detailed pesticide exposure information (type, duration, specific pesticides used, crops treated, and PPE use). The analysis adopts a 95% confidence level and a two-sided significance level of 5%. By comparing the odd risk of exposed individuals to a control group, the study seeks to provide valuable insights into the potential risks associated MGUS with pesticide exposure.