The RNV3P collects data from two complementary samples: 30 university hospital centres (workers or former workers) and an occupational health service (current workers). This dual approach is useful for surveillance and for hypothesis generation on new emerging disease-exposure associations.

Surveillance of work-related diseases and associated exposures is a major issue of public health, in particular for identifying and preventing new threats for health. In the occupational health context, the French national occupational disease surveillance and prevention network (RNV3P) have constructed a growing database that records every year all Occupational Health Problems (OHPs) diagnosed by a network of physician specialists. The network aims to provide and develop an expertise on the disease-exposure relationships, and uses the RNV3P database for developing the surveillance of OHPs and for the detection of emerging associations between diseases and occupational exposures. In this paper, we have developed the theoretical framework of the occupational exposome, defined as a network of OHPs linked by similar occupational exposures, as a novel approach which allows to characterize and to analyze the disease-exposure associations reported in the RNV3P database in the form of a relational network. Next, the occupational exposome is structured in terms of occupational exposure groups which constitute informative sub-sets of hazards considered as the backbone tree spectrum of the occupational exposures potentially related to a disease. To illustrate the wide possibilities of this method, the exposome approach is applied to the RNV3P database's sample of Non-Hodgkin Lymphomas (NHLs). As a result, we found that the NHL occupational exposome could be described in terms of 86 embedded exposure groups, defined as a set of OHPs sharing at least one component of the occupational multi-exposure. For example, "organic solvents and thinners" is the most represented hazards related to NHLs, but is also co-associated to "benzene", "ionizing radiations" or "agricultural products". From the knowledge stored in the database by physician experts, the occupational exposome constitutes a decisive step towards the evolving monitoring of multi-exposure associated to a given disease.

Surveillance of both diseases and associated exposures is a major issue of public health, in particular for identifying and preventing new threats for health. Indeed, environmental exposure – health associations remain poorly understood and sometimes not elucidated due to the lack of exploitation of data and global view of population exposures including critical periods of exposure or during exposed occupations. In the occupational health context, we used the observational database of the Occupational Health Problems (OHPs) from the RNV3P network (French National Network of Surveillance and Prevention of Occupational Diseases) to investigate the relationship structure of OHPs with occupational (multi)-exposures. And, to improve our understanding and capability of analysing occupational environment – health associations, we employed the newly developed Observational Surveillance method, based on the Occupational Exposome approach, for an optimal exploitation of the RNV3P database (of about 200 000 OHPs). The method involves structuring the data in terms of an occupational exposome, i.e., a relational network of significant occupational exposures associated with OHPs. It allows the identification of significant associations (disease related exposures and/or sectors) and the study of the spectrosome, i.e., the dynamical and structured spectrum of exposures associated to OHPs.To illustrate, we considered the non-Hodgkin lymphoma (NHL) representing 90% of lymphomas and which the incidence was found increasing from 1970s until the end of the 20th century and starting to level off in the last few years. Causes of the increase and associated risk factors remain largely unknown. Exposures to solvents or agricultural products have been suggested, but the very widespread multi-exposure at the workplace prevents to conclude from epidemiological studies.The spectrosome analyses of NHL from the RNV3P allowed to highlight new occupational (multi)-exposures, in addition to those already known, and to study the dynamic structure of occupational exposures and NHL relationship in specific workplace.

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