Occupation as a blue collars and exposure to solvents as risk factors of diffuse large B-cell lymphoma (DLBCL)

Introduction
The association between NHL (Non Hodgkin Lymphoma), solvents and occupation are reported in several studies. Our italian national case-control study was inserted within the INTERLYMPH consortium for the GWAS protocol and to examine new etiological hypothesis of NHL, studying the role of genetic polymorphisms (SNPs), occupational and personal factors such as diet, location of house, smoke. The study is ongoing.

Methods
109 cases of lymphoma and 43 healthy controls were recruited in a research unit of Bari and Taranto within an, since 2007. Cases and controls were invited to blood sample drowning for serum measurement of xenobiotic and DNA analysis of SNPs and to administration of a questionnaire. In this phase we only produce a description of different subtypes of lymphoma recruited in our research unit and to carry out a preliminary assessment of the role of occupational factors using CAREX job exposure matrix, for the lack of haematic and genetics data

Results
The found subtypes of lymphoma, according the fifth level WHO 2008 classification, among blue collars, showed an higher proportion of NHL, mainly represented by Diffuse Large B- subtype (DLBCL) and Follicular lymphoma (FL). In the multivariate analysis an higher risk of lymphoma was reported among the blue collars [OR=4,06 (1,03-15.96)]. Moreover, the exposure to some carcinogenic solvents (Benzene, carbone tetrachloride, ethylene dichromate, dibromoethane), adjusted by several variables in a multiple unconditional regression model, resulted associated to lymphoma [OR=3,29 (1,36-7,94)].

Discussion
Benzene is a carcinogenic to humans (group 1, IARC); trichloroethylene is classified as probably carcinogenic to humans (group 2b); carbon tetrachloride, used as a solvent, is related to an excess risk for NHL for women; dibromoethane is considered as a carcinogen by the IARC (Class 2). In scientific literature the associations between these carcinogenic solvents and NHL are still weak and unknown, because of the different subtypes distribution.