Mariagrazia Zucca

Increased Mitochondrial DNA Copy Number in Occupations Associated with Low-Dose Benzene Exposure

Background: Benzene is an established leukemogen at high exposure levels. Although low-level benzene exposure is widespread and may induce oxidative damage, no mechanistic biomarkers are available to detect biological dysfunction at low doses. Objectives: Our goals were to determine in a large multicenter cross-sectional study whether low-level benzene is associated with increased blood mitochondrial DNA copy number (mtDNAcn, a biological oxidative response to mitochondrial DNA damage and dysfunction) and to explore potential links between mtDNAcn and leukemia-related epigenetic markers. Methods: We measured blood relative mtDNAcn by real-time polymerase chain reaction in 341 individuals selected from various occupational groups with low-level benzene exposures (> 100 times lower than the Occupational Safety and Health Administration/European Union standards) and 178 referents from three Italian cities (Genoa, Milan, Cagliari). Results: In each city, benzene-exposed participants showed higher mtDNAcn than referents: mtDNAcn was 0.90 relative units in Genoa bus drivers and 0.75 in referents (p = 0.019); 0.90 in Milan gas station attendants, 1.10 in police officers, and 0.75 in referents (p-trend = 0.008); 1.63 in Cagliari petrochemical plant workers, 1.25 in referents close to the plant, and 0.90 in referents farther from the plant (p-trend = 0.046). Using covariate-adjusted regression models, we estimated that an interquartile range increase in personal airborne benzene was associated with percent increases in mtDNAcn equal to 10.5% in Genoa (p = 0.014), 8.2% (p = 0.008) in Milan, 7.5% in Cagliari (p = 0.22), and 10.3% in all cities combined (p < 0.001). Using methylation data available for the Milan participants, we found that mtDNAcn was associated with LINE-1 hypomethylation (–2.41%; p = 0.007) and p15 hypermethylation (+15.95%, p = 0.008). Conclusions: Blood MtDNAcn was increased in persons exposed to low benzene levels, potentially reflecting mitochondrial DNA damage and dysfunction.

Lymphoma risk and occupational exposure to pesticides: results of the EPILYMPH study

Objectives We investigated the role of occupational exposure to specific groups of agrochemicals in the aetiology of lymphoma overall, B cell lymphoma and its most prevalent subtypes. Methods In 1998–2003, 2348 incident lymphoma cases and 2462 controls were recruited to the EPILYMPH case-control study in six European countries. A detailed occupational history was collected in cases and controls. Job modules were applied for farm work including specific questions on type of crop, farm size, pests being treated, type and schedule of pesticide use. In each study centre, industrial hygienists and occupational experts assessed exposure to specific groups of pesticides and individual compounds with the aid of agronomists. We calculated the OR and its 95% CI associated with lymphoma and the most prevalent lymphoma subtypes with unconditional logistic regression, adjusting for age, gender, education and centre. Results Risk of lymphoma overall, and B cell lymphoma was not elevated, and risk of chronic lymphocytic leukaemia (CLL) was elevated amongst those ever exposed to inorganic (OR=1.6, 95% CI 1.0 to 2.5) and organic pesticides (OR=1.5, 95% CI 1.0 to 2.1). CLL risk was highest amongst those ever exposed to organophosphates (OR=2.7, 95% CI 1.2 to 6.0). Restricting the analysis to subjects most likely exposed, no association was observed between pesticide use and risk of B cell lymphoma. Conclusions Our results provide limited support to the hypothesis of an increase in risk of specific lymphoma subtypes associated with exposure to pesticides.

Interleukin‐1B (IL1B) and interleukin‐6 (IL6) gene polymorphisms are associated with risk of chronic lymphocytic leukaemia

Common polymorphisms in genes encoding for cytokines implicated in the inflammatory response and Th1/Th2 balance might play a role in the development and prognosis of chronic lymphocytic leukaemia (CLL). To test the hypothesis, we investigated 13 single nucleotide polymorphisms (SNPs) in nine of such genes in a population‐based case‐control study, conducted in the Italian region of Sardinia in 1999–2003. Forty incident CLL cases and 113 population controls were available for study. The following SNPs were selected: IL1A‐889C > T, IL1RN 9589A > T, IL1B‐31C > T, IL1B‐511C > T, IL2‐384T > G, IL6‐174G > C, IL6‐597G > A, IL10‐1082A > G, IL10‐3575T > A, TNF‐308G > A, LTA‐ 91A > C, LTA 252A > G and CARD15 nt1007. After adjusting by age and gender, individuals homozygous for the IL1B‐511T allele run a lower risk of CLL (OR = 0.1, 95% CI 0.0, 0.8, p = 0.032), while risk showed a 4.5‐fold increase associated with the genotype homozygous for the IL6‐174C allele (OR = 4.5; 95% CI 1.1, 19.3, p = 0.041). Individuals homozygous for the IL6‐174C allele and carrying the homozygous IL1B‐511C allele showed an 11‐fold increase in CLL risk (OR = 11.4, 95% CI 1.9, 69.4, p = 0.008). None of the other interleukin SNPs evaluated showed any association with CLL risk. Large multicentre pooled studies are warranted, achieving the statistical power required to confirm whether IL6 and IL1B gene polymorphisms might play a role in CLL development and prognosis, as well as the null associations herein reported. Copyright

Lymphoma risk in livestock farmers: results of the Epilymph study

We explored the risk of lymphoma and its most prevalent subtypes associated with occupational contact with livestock, and whether risk was modified by age at first contact, in 2,348 incident lymphoma cases and 2,462 controls who participated in the EPILYMPH case–control study. A detailed occupational history was collected in cases and controls, including working in a livestock farm, species of livestock, its approximate number and circumstances of contact. For each disease outcome, and each type of livestock, odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated using unconditional logistic regression, adjusting for age, gender, education and center. Lymphoma risk (all subtypes combined) was not increased amongst those exposed to contact with any livestock (OR = 1.0, 95% CI 0.8–1.2). Overall, we did not observe an association between occupational contact with livestock and risk of lymphoma (all types) and B‐cell lymphoma. The risk of diffuse large B cell lyphoma (DLBCL) was significantly lower amongst subjects who started occupational contact with any species of livestock before or at age 12 (OR = 0.5, 95% CI 0.2–0.9), but not at older ages. A significant heterogeneity in risk of B cell lymphoma by age at first contact was detected for contact with cattle, poultry and swine. Early occupational contact with livestock might be associated with a decrease in risk of B cell lymphoma.

Risk of lymphoma subtypes and dietary habits in a Mediterranean area

BACKGROUND Previous studies have suggested that diet might affect risk of lymphoma subtypes. We investigated risk of lymphoma and its major subtypes associated with diet in the Mediterranean island of Sardinia, Italy. METHODS In 1998-2004, 322 incident lymphoma cases and 446 randomly selected population controls participated in a case-control study on lymphoma etiology in central-southern Sardinia. Questionnaire interviews included frequency of intake of 112 food items. Risk associated with individual dietary items and groups thereof was explored by unconditional and polytomous logistic regression analysis, adjusting by age, gender and education. RESULTS We observed an upward trend in risk of lymphoma (all subtypes combined) and B-cell lymphoma with frequency of intake of well done grilled/roasted chicken (p for trend=0.01), and pizza (p for trend=0.047), Neither adherence to Mediterranean diet nor a frequent intake of its individual components conveyed protection. We detected heterogeneity in risk associated with several food items and groups thereof by lymphoma subtypes although we could not rule out chance as responsible for the observed direct or inverse associations. CONCLUSIONS Adherence to a Mediterranean diet does not seem to convey protection against the development of lymphoma. The association with specific food items might vary by lymphoma subtype.

Leukemia in children and youths of the Azuay province, Ecuador: 2000–2010

We mapped leukemia risk among children and youths in the Azuay province, Rio Paute river basin, Ecuador, in 2000–2010, using a Bayesian disease mapping model. We assessed the comprehensiveness of the list of leukemia cases from the Sociedad de Lucha contra el Càncer en el Ecuador (SOLCA) Hospital in Cuenca, the only referral center for oncology in the whole Rio Paute area, by comparison to the Quito cancer registry. Risk of leukemia did not vary significantly by canton within the Azuay province. However, a moderate increase in risk of borderline statistical significance was observed in the city of Cuenca and particularly among males in a heavily industrialized parish, who had an almost eight-fold excess (95% CI 3.03, 20.39, p = 0.01) of AML. Analytical studies are warranted to properly address specific etiological factor of leukemia among children and youths of the Azuay province of Ecuador.

N-acetyltransferase polymorphisms are associated with risk of lymphoma subtypes

Genes encoding for arylamine N‐acetyltransferase 1 and 2 (NAT1 and NAT2) have been investigated with alternate findings in relation to risk of non‐Hodgkin lymphoma (NHL). We tested functional haplotype‐based NAT1 and NAT2 gene polymorphisms in relation to risk of lymphoma overall and its major B cell subtypes, diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL) and chronic lymphocytic leukaemia (CLL). We used allele specific primers and multiplex PCR to detect NAT1 and NAT2 haplotypes in 248 patients with incident lymphoma and 208 population controls. We inferred the NAT1 rapid and slow acetylator and the NAT2 rapid, intermediate or slow acetylator phenotype, based on published functional data on the respective genotypes. Odds ratios and 95% confidence intervals (95% CIs) for lymphoma, B‐NHL, DLBCL, FL, CLL, and other B‐NHL combined associated with the inferred rapid NAT1 acetylator and with the intermediate and slow NAT2 acetylator phenotypes were estimated with unconditional and polytomous logistic regression analysis, adjusting for age, gender and education. NAT1 rapid acetylators showed a 2.8‐fold excess risk (95% CI 1.5–5.2) for lymphoma (all subtypes combined). Risk was highest for CLL and FL, with significant heterogeneity detected across subtypes. Risk also increased with decreasing NAT2 acetylating capacity with no heterogeneity detected across B cell lymphoma subtypes. Risks did not vary by gender. Although poor statistical power was a major limitation in our study, larger studies and pooled analyses are warranted to test whether NAT1 and NAT2 gene polymorphisms might modulate risk of specific lymphoma subtypes through the varying metabolic activity of their products. Copyright

Estimates of Environmental Exposure to Radiofrequency Electromagnetic Fields and Risk of Lymphoma Subtypes

We investigated the association between environmental exposure to radiofrequency electromagnetic fields (RF-EMF) and risk of lymphoma subtypes in a case-control study comprised of 322 patients and 444 individuals serving as controls in Sardinia, Italy in 1998–2004. Questionnaire information included the self-reported distance of the three longest held residential addresses from fixed radio-television transmitters and mobile phone base stations. We georeferenced the residential addresses of all study subjects and obtained the spatial coordinates of mobile phone base stations. For each address within a 500-meter radius from a mobile phone base station, we estimated the RF-EMF intensity using predictions from spatial models, and we performed RF-EMF measurements at the door in the subset of the longest held addresses within a 250-meter radius. We calculated risk of lymphoma and its major subtypes associated with the RF-EMF exposure metrics with unconditional logistic regression, adjusting by age, gender and years of education. In the analysis of self-reported data, risk associated with residence in proximity (within 50 meters) to fixed radio-television transmitters was likewise elevated for lymphoma overall [odds ratio = 2.7, 95% confidence interval = 1.5–4.6], and for the major lymphoma subtypes. With reference to mobile phone base stations, we did not observe an association with either the self-reported, or the geocoded distance from mobile phone base stations. RF-EMF measurements did not vary by case-control status. By comparing the self-reports to the geocoded data, we discovered that the cases tended to underestimate the distance from mobile phone base stations differentially from the controls (P = 0.073). The interpretation of our findings is compromised by the limited study size, particularly in the analysis of the individual lymphoma subtypes, and the unavailability of the spatial coordinates of radio-television transmitters. Nonetheless, our results do not support the hypothesis of a link between environmental exposure to RF-EMF from mobile phone base stations and risk of lymphoma subtypes.

Interaction between Dietary and Lifestyle Risk Factors and N-Acetyltransferase Polymorphisms in B-Cell Lymphoma Etiology

Background: Gene-environment interactions are suggested to play a role in lymphomagenesis. Methods: We tested the interaction between the NAT1/NAT2 phenotype, as inferred by the respective genotypes, and exposure to dietary and lifestyle risk factors, in 199 incident lymphoma cases and 188 population controls. We used unconditional logistic regression to calculate the odds ratio (OR) and its 95% confidence interval for lymphoma (all subtypes combined) and B cell lymphoma, associated to the rapid NAT1 phenotype and to the intermediate and slow NAT2 phenotype, and to the estimated dietary intake of heterocyclic amines and folate, current smoking, coffee, and use of permanent hair dyes, as well as the respective interaction terms. We adjusted the ORs by age, gender, and education, and we used the likelihood ratio test to test the interaction between the NAT1, NAT2 phenotype and the dietary and lifestyle variables. Results: We observed an increase in risk of lymphoma (all subtypes combined) and B-cell lymphoma in particular associated with the estimated above median dietary intake of heterocyclic amines (OR = 4.2, 95%CI 1.2 – 14.8) and folate (OR = 4.1, 95%CI 0.7 – 22.4) among subjects with the NAT1 rapid acetylator phenotype, but not independent on the NAT1 phenotype. The test for interaction was significant for heterocyclic amines, but not for folate (p for interaction = 0.026 and 0.076 respectively). Ever use of permanent hair dyes was associated with an elevated risk independent on the NAT1, NAT2 phenotypes; risk decreased to null among intermediate and slow NAT1 acetylators (p for interaction = 0.010). Conclusions: Our results suggest that NAT1, NAT2 polymorphisms interact with dietary and lifestyle exposures in modulating risk of lymphoma and particularly B-cell lymphoma.

0272 Risk of lymphoma and occupational exposure to organic dust

Objectives A medical history of allergy, and particularly asthma, has been associated with an inverse risk of non-Hodgkin’s lymphoma (NHL). As occupational exposure to specific organic dusts is a risk factor for asthma, we explored risk of lymphoma and its major subtypes in relation to organic dusts. Method In 1999–2004, 324 incident lymphoma cases and 464 population controls, frequency matched to cases by age and gender, were recruited among adult residents in Sardinia, Italy. Expert industrial hygienists assessed exposure to organic dust overall, and specific organic dusts. The odds ratio (OR) for lymphoma (all types) and its major subtypes, and its 95% confidence interval, was calculated using unconditional logistic regression. Results Exposure to organic dust in general was inversely associated with risk of lymphoma (all types) (OR = 0.7, 95% CI 0.4–1.2), with a declining trend by duration and level of exposure. The inverse association was apparently more pronounced for exposure to flour dust and wood dust, but not to natural or artificial textile fibres. A consistent inverse risk was observed for B-cell lymphoma (OR = 0.6, 95% CI 0.3–1.0), and it was likewise for its major subtypes, namely diffuse large cell lymphoma (DLBCL), follicular lymphoma (FL) and chronic lymphocytic leukaemia (CLL). Age <= 18 at first exposure conveyed a further decrease in lymphoma risk (OR = 0.5, 95% CI 0.2–1.2). Conclusions Although with interpretative limitations due to the small study size, our results suggest that exposure to flour dust and wood dust might contribute a reduction in risk of malignant lymphoma.