Context October 29, 2014, the Interregional epidemiology Unit (CIRE) in region Centre-Val de Loire (France) received a referral from the manager of a research centre on 4 cases of Non-Hodgkin lymphoma (NHL).4 cases have the particularity to do the same profession and live near the research institute but especially in the same area. CIRE must study the feasibility to carry out an epidemiological investigation in order to identify common risk factors among 4 cases related with the observed pathology.

Method CIRE requested the Groupe d’Alerte en Santé Travail (GAST), composed of experts in professional risks and responsible for organising the response to reports of inhabitual events in occupational health and referring also to the InVS guide for the investigation of cancer cluster in the workplace.

Results Three cases of NHL were identified, all diagnosed in 2014. The 4th case had another location. These 3 cases are aged 57–66 years and living in the same area located within the centre for 10 to 30 years. These cases are working in the research centre for at least 30 years. 3 NHL have different histological types. Two of three cases exercised as animal technician and have been in direct contact with sheep and cattle.The 3rd working as a tractor driver. During their career, all cases have been regularly exposed to a multitude of products including veterinary products and pesticides.

Conclusion Validation of health and exposure data of 3 cases of NHL with a detailed questionnaire is more appropriate to have arguments about the existence of prolonged exposure to toxics including pesticides, which have been linked with increased risk of NHL. This cluster show the specificity of exposures in research centres: populations concerned with a small number and a large variety of products.