[Monoclonal gammopathy of uncertain significance (MGUS) and ionizing radiation].

The term monoclonal gammopathy refers to a clinical condition characterized by the presence in serum and/or urine of clonal immunoglobulins, i.e. homogeneous immunoglobulins, structurally identical both as a heavy chain and as a light chain, produced by a B cell clone (1). The prevalence of MGUS is low in young subjects (less than 2% of patients with MGUS are less than 40 years of age, while in the population aged over 50 years it is relatively high (3.2%) and increases considerably with age. Although historically considered to be a benign condition, patients with MGUS are at risk to develop multiple myeloma over time. Therefore, MGUS may be framed as a preneoplastic stage of the plasma cell that precedes the possible development of a multiple myeloma. In a limited percentage of cases, it can be considered the asymptomatic pre-malignant stage preceding multiple myeloma (MM) on a probabilistic basis. Few studies have assessed the prevalence of MGUS in people occupationally exposed to pesticides. Several other studies on atomic bomb survivors in Hiroshima and Nagasaki have revealed a possible association with exposure to ionizing radiation (IR). Routine laboratory tests performed on the subjects exposed to the risk factors studied appear to be indicated for workers from the age of 50 years. The finding of a GMUS in the absence of further laboratory alterations is the most frequent finding and does not require further action, if it is not to plan include blood chemistry tests at least every two years. In this situation, no restrictions appear to be justified on the work activity involving the risk of exposure to IR or pesticides. In case of concurrent presence of alterations that may be indicative or suggestive of an increased risk of evolution in a neoplastic way a close periodicity - every 3-6 months - of haematological checks is recommended. In such cases, it appears justified to move away from activities involving exposure to ionizing radiation for a period of time which should be evaluated on the basis of the evolution of the picture and the progress of laboratory tests during the monitoring period.