Screening for monoclonal gammopathies of undetermined significance: A prospective study.

Abstract

Background: Several studies have reported an increase in the incidence of multiple myeloma among farmers following pesticide use.

Aim: This study aimed to seek an association between pesticide exposure and monoclonal gammopathy of undetermined significance (MGUS) in young pesticide applicators.

Setting: The setting for this study was the Souss Massa region of the Kingdom of Morocco.

Methods: We conducted a case-control study among 239 young male pesticide applicators with known exposure to pesticides (male pesticide applicators = exposed group) and 157 males with no direct exposure to pesticides (unexposed group). Serum protein electrophoresis was performed on all sera, and when monoclonal proteins were detected, they were characterised by serum protein immunofixation electrophoresis.

Results: We found that the prevalence of MGUS was significantly higher in the exposed group older than 40 years 4.03% (95% confidence interval [CI]: 1.49-9.62) compared with the control group 0.91% (95% CI: 0.16-4.97), with no cases reported before this age. However, the odds ratio did not reach statistical significance 3.33 (95% CI: 0.39-28.78), which can be explained by the size of the population and the mean age ± s.d. of the pesticide applicators of 39.54 ± 11.51. In contrast, the international studies found the same results with all recruited patients over 50 years. This selection was made at the beginning of the study. Monoclonal proteins in the exposed group were characterised as follows: immunoglobulin Gλ 3 (1.25%), IgGκ 1 (0.41%) and biclonal IgGκ + IgGκ 1 (0.41%).

Conclusion: We recommend mandatory screening for monoclonal gammopathy in pesticide applicators over the age of 40 years. Further studies are needed to investigate the association between pesticide molecules and MGUS.

Contribution: The results of this study can be used by the Ministry of Health and the Ministry of Agriculture to provide baseline data to help develop appropriate prevention measures and awareness programmes against the misuse of pesticides.