Exposure to Solvents and Risk of Non-Hodgkin Lymphoma: Clues on Putative Mechanisms

Abstract

Malignant lymphomas are a group of diseases of uncertain etiology. Both environmental factors and genetic susceptibility have been reported as risk factors. We have conducted a population-based case-control study in Italy: all newly diagnosed cases of malignant lymphoma, in males and females ages 20 to 74 years in the 1991 to 1993 period, were identified; the control group was comprised of a random sample of the general population resident in each of the areas under study, stratified by sex and 5-year age groups. Overall, 1,428 non -Hodgkin lymphoma (NHL) cases and 1,530 controls were interviewed. Experts from each geographic area examined questionnaire data and assigned a level of probability and intensity of exposure to a range of chemical groups and individual chemicals. For those in the medium/high level of exposure, there was an increased risk of NHL for exposure to benzene, xylene, and toluene. We have examined the hypothesis that the effect of solvents is related to their immunotoxicity by analyzing the interaction with a previous history of autoimmune disease. We have found an apparent, though not statistically significant, increased risk of NHL in those with both exposure to benzene and a history of autoimmune disease (odds ratio, 16.3; 95% confidence interval, 0.8-321). In addition, an odds ratio of 29.8 (95% confidence interval, 1.4-650.2, based on nine exposed cases) was associated with high-level exposure to benzene in those with a positive family history of malignant hematologic neoplasms. Both hypotheses (i.e., the interaction with autoimmune diseases and with familial predisposition) indirectly suggest that an immunologic mechanism could be involved in lymphomagenesis from solvents. (Cancer Epidemiol Biomarkers Prev 2007;16(3):381 -4)

Occupation/industry and risk of non-Hodgkin’s lymphoma in the United States

“…NHL has been associated with a number of occupations, including farmers, woodworking, rubber manufacture, mechanics, textile workers, janitors, printers, meat processors and hair dressers in epidemiological studies, although inconsistencies exist between studies 33 34. These studies suggest that pesticides, benzene, polychlorinated biphenyls and dyes might contribute to the aetiology of NHL 35 36. Our analysis revealed an increased risk for NHL among subjects in several employment groups.…”

Occupational exposure to solvents and risk of lymphoma subtypes: results from the Epilymph case–control study

“…High-level occupational exposure to benzene among subjects with a familial history of haematological neoplasms was associated with an almost 30-fold excess risk of NHL, and subjects exposed to benzene with a history of immune system diseases ran a 16-fold excess risk 7. Although generated by small numbers, both findings seem to indicate immune system disruption as a mechanism of lymphomagenesis among benzene-exposed workers.…”

I. Epidemiology of adult non-Hodgkin lymphoma

“…Solvents as a general category have been inconsistently associated with NHL [48]. Results from studies of TCE have been heterogeneous, and although some European studies reported positive associations, there was no consistent exposure-response pattern within or across the studies.…”