Giannina Satta

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.

Environmental and lifestyle factors affect benzene uptake biomonitoring of residents near a petrochemical plant

BACKGROUND We monitored urinary benzene excretion to examine factors affecting benzene uptake in a sample of the general population living near a petrochemical plant. METHODS Our study population included 143 subjects: 33 petrochemical plant workers (W) with low level occupational benzene exposure; 30 residents in a small town 2 km from the plant (2kmR); 26 residents in a second small town located 2 to 4 km from the plant (4kmR); and 54 urban residents 25km from the plant (25kmR). Exposure to benzene was evaluated by personal air sampling during one work-shift for the W group, and from 8.00 to 20:00 for general population subgroups, and by urinary benzene (BEN-U). RESULTS Median airborne benzene exposure was 25, 9, 7 and 6 μg/m(3) benzene among the W, 2kmR, 4kmR, and 25kmR subgroups, respectively; the highest level was found among the workers, while there was no significant difference among the other groups. Median BEN-U was 2 to 14-fold higher in smokers compared to non-smokers; among non-smokers BEN-U was the highest in W (median 236 ng/L), and lower in the 2kmR (48 ng/L) and 4kmR (63 ng/L) subgroups than in the 25kmR (120 ng/L) subgroup. A multiple linear regression analysis, explaining up to 73% of BEN-U variability, confirmed that active smoking and airborne benzene most strongly affected BEN-U. Among the non-smoking, non-occupationally exposed study subjects, a positive association was found between BEN-U and the distance of residence from the plant. This association was explained by increased exposure to urban traffic emissions in the study group residing at a greater distance from the plant. Environmental tobacco smoke had a marginally positive role. CONCLUSION Among factors affecting benzene uptake in non-occupationally exposed individuals, urban residence contributes to benzene exposure more than residing in close proximity to a petrochemical plant.

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.

Male fertility following occupational exposure to dichlorodiphenyltrichloroethane (DDT)

BACKGROUND The inconsistent epidemiological results of the endocrine disrupting effects of DDT fuel a harsh debate on its global ban. OBJECTIVES We tested the hypothesis that occupational exposure to dichloro-diphenyl-trichloroethane (DDT) causes impairment in male fertility in a cohort of DDT exposed workers, in Sardinia, Italy. METHODS We accessed official records on date of marriage and date of birth of the first child to estimate time to pregnancy (TTP) in the spouses of 1223 workers employed in a 1946-1950 anti-malarial campaign. The TTP calculation was censored at the 13th month after date of marriage. We used a modified Coxs proportional hazard model to calculate the fecundability ratio (FR) by job, by cumulative exposure to DDT, and by time window in relation to the anti-malarial operations, adjusting by paternal age at marriage. RESULTS Among the spouses of DDT applicators, fecundability did not vary during DDT use (FR=1.22, 95% CI 0.84-1.77) nor in the following decade (FR=1.01, 95% CI 0.67-1.50) with reference to the prior years. A significant increase occurred among the unexposed and the less exposed sub-cohorts, which generated a non-significantly reduced FR among the DDT applicator sub-cohort with reference to the unexposed following exposure. CONCLUSION We did not find evidence of an impairment in male fertility following heavy occupational exposure to DDT. However, although fecundability was highest among the spouses of the DDT applicators in the years prior to the anti-malarial campaign, we cannot exclude that DDT exposure prevented an increase parallel to that observed among the unexposed and the less exposed sub-cohorts.

Occupational Exposure to Ethylene Oxide and Risk of Lymphoma

Background: Ethylene oxide, a high-volume commodity, is an established human carcinogen, although the relevant epidemiologic evidence is limited. Methods: We explored the association between occupational exposure to ethylene oxide and risk of lymphoma in a case-control study, including 2347 lymphoma cases first diagnosed in 1998–2004 and 2463 controls, from 6 European countries. The diagnosis of lymphoma was based on the 2001 World Health Organization Classification of lymphoma. Occupational exposure to ethylene oxide was retrospectively assessed by industrial hygienists and occupational physicians based on detailed self-reported information. We modeled risk of lymphoma with unconditional logistic regression analysis as a function of various exposure measures, adjusting for age, sex, and participating center. Results: Thirty-one cases and 27 controls (1.2% of the total study population) were defined as ever having been exposed to ethylene oxide (odds ratio = 1.3 [95% confidence interval [CI] = 0.7–2.1]). Lymphoma risk showed a 4.3-fold increase associated with medium-high frequency of exposure to ethylene oxide (95% CI = 1.4–13). Among major subtypes, chronic lymphocytic leukemia was consistently associated with ethylene oxide exposure, related in a dose-response manner to probability, frequency, and duration of exposure, as well as to cumulative exposure and (less definitively) with exposure intensity. Conclusions: Our results add to the evidence that ethylene oxide is a human carcinogen.

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

1633d Agricultural risk factors for lymphoma – contact with livestock and exposure to organic dust

Introduction Farming occupations have been reported at risk of developing non Hodgkin lymphoma. Within the EPILYMPH multicentre European case-control study on the aetiology of lymphoma, we explored the association of risk of the major lymphoma subtypes with exposure to specific classes of pesticides, contact with livestock, and exposure to organic dust. Methods In 1998–2003, 2348 cases of lymphoma (all subtypes), and 2462 controls participated in the EPILYMPH case-control study in several centres six European countries. A detailed occupational history was collected in cases and controls. Information on contact with breeding animals, exposure to five organic dusts, and to specific classes of pesticides was obtained through personal interviews. Local agronomists and occupational experts assessed likelihood, frequency and intensity of specific exposures based on the questionnaire information. Risk of the major lymphoma subtypes associated with contact with the most frequently represented species of livestock, organic dusts, and classes of pesticides was calculated with unconditional logistic regression analysis adjusting by age, gender, education, and centre. Result Exposure to organophosphate insecticides was significantly associated with an increase in risk of chronic lymphocytic leukaemia; risk of 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 to 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. We did not find an association with exposure to any of the organic dust exposures. Discussion Agricultural exposures are numerous, and difficult to disentangle; also, the use of agrochemicals varies with time, type of crop, and location. Some exposures might be etiologically relevant, others might protect against lymphomas depending on age at first exposure, possibly in relation to the different type of immune response elicited.

0484 Exposure to ionising radiation and risk of lymphoma subtypes: analysis of the epilymph results

Introduction The association between ionising radiation and risk of solid tumours and leukaemia is well established; however, the role of low dose radiation exposure in the aetiology of lymphoma is still uncertain. We investigated the role of occupational exposure to internal and external ionising radiation in the aetiology of lymphoma and its major subtypes. Methods Between 1998 and 2004, 2348 cases and 2465 controls from six different European countries participated in the multicentre EpiLymph case-control study. A detailed occupational history was collected by questionnaire in all participants a coded using the ISCO68 occupational and NACE industrial coding systems. Based on the same coding systems, we developed a Job Exposure Matrix (JEM) to assess probability and intensity of exposure to internal and external ionising radiation. We used unconditional logistic regression to calculate Odds Ratios and their 95% Confidence Intervals for lymphoma and its major subtypes associated with the ionising radiation exposure metrics, adjusting by age, gender, education and country. Results Risk of lymphoma overall did not show an association with exposure to radiation either internal or external. Risk of Diffuse Large B-Cell Lymphoma (DLBCL) was elevated and did show an upward trend with intensity of exposure to external radiation (Low Intensity OR=2.1, 95%CI=0.97–4.46 and High Intensity OR=2.5, 95%CI=1.21–5.08). We did not observe any risk increase associated with internal exposure to ionising radiation. Conclusions Our results provide limited support to the relation between external sources of ionising radiation and risk of DLBCL. We cannot exclude the possibility of bias due to the multiple comparisons we made.