Multiple Myeloma and Environmental Exposure to Pesticides in the French West Indies: A Population Based Case-control Study.

Overview

Multiple myeloma (MM) is a malignancy of plasma cells engaging in monoclonal immunoglobulin production. A strong presumption was established between exposure to pesticides and the risk of MM. The French West Indies departments of Guadeloupe and Martinique are characterized by a wide use of pesticides related to bananas plantation, particularly chlordecone which has been classified by IARC as possibly carcinogenic and has recognized hormonal properties (endocrine disruptor). The objective of this study is to measure the association between exposure to pesticide and other environmental factors in the occurrence of MM in Guadeloupe and Martinique and to estimate the proportion of cases of MM attributable to pesticide exposure. Genetic susceptibility markers and their links to environmental factors will be subsequently studies from blood samples collection.

Multiple Myeloma (MM) is a mature B-cell lymphoma characterized by monoclonal proliferation of tumor plasma cells invading the bone marrow. It is the second malignant hemopathy among Non-Hodgkin's Lymphomas. Etiology of the disease is poorly understood. Its higher incidence in black subjects suggests the existence of genetic factors. Numerous studies have evoked the role of exposure to environmental and occupational factors in the occurrence of MM such as exposure to pesticides, solvents, in particular benzene, and other petroleum derivatives, as well as work in an agricultural environment, in hairdressing and in the metallurgical and textile industries. According to the Collective Inserm expertise "Pesticides and Health", a strong presumption (++) has been established between exposure to pesticides and the risk of occurrence of MM. In the French West Indies (Guadeloupe, Martinique), the incidence of MM is higher than in France. These 2 departments are characterized by a major use of pesticides in connection with the banana culture developed intensively from the 1950s. These cultures successively used organochlorine insecticides, mainly β-hexachlorocyclohexane (β-HCH), technical HCH (mixture of α, β, and γ isomers of HCH), and especially chlordecone (CLD). CLD was used from 1972 to 1993 under the trade names of Kepone® (1972-1978) and then Curlone® (1982-1993) with a CLD rate of 5%. The absence of biotic and abiotic degradation of CLD has resulted in persistent soil pollution, still present today, contamination of surface and deep waters, many plant and animal products, terrestrial and marine, and then the population. CLD is a proven carcinogen in rodents, classified as a possible carcinogen by the International Agency for Research on Cancer (IARC) and has recognized hormonal properties (endocrine disruptor). CLD has been associated with an increased risk of prostate cancer in Guadeloupe. In Martinique, a geographic correlation study has shown a high incidence of MM in individuals residing on soils polluted by CLD. Studies on the impact of pesticides on health come up against numerous limits, in the foreground of which is the great diversity of products (more than 900 active ingredients were approved one day in France and marketed in more than 9000 different products) and the difficulty in reconstructing retrospectively and objectively the exposures of individuals due to the multiplicity of sources of exposure (leisure, gardening, domestic use). Mode of action of pesticides is still insufficiently documented, but some are classified as genotoxic, immunotoxic, tumor promoters or endocrine disruptors. Data available in the literature mainly relate to case-control or cohort studies on the occupational exposure of agricultural workers in industrialized countries. Measurement of this exposure is mainly made from self-administered questionnaires. The investigators propose to assess feasibility of a case-control study on role of exposure to pesticides, in particular to CLD and persistent pollutants, as well as other occupational exposures in the occurrence of MM in the West Indies. This study is part of the recommendations of the Inserm-InVs Chlordecone Scientific Council and action 18 of the National Interministerial Chlordecone Plan "initiate work on the link between myelomas and exposure to chlordecone".