Michele Meloni

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.

QTc interval and electrocardiographic changes by type of shift work

BACKGROUND We conducted a cross sectional survey of electrocardiographic changes among shift-workers. METHODS We classified the electrocardiogram morphology, and measured the QTc interval in 91 male workers engaged in regular daily work-shifts, 32 in 24 hr work-shift (h24), and 93 in irregular 6 hr work-shift (h6). RESULTS With reference to daily workers, the QTc interval was prolonged among h6 workers (P < 0.001) and h24 workers (P < 0.005). The age- and obesity-adjusted standardized prevalence ratio (SPR) of a borderline/prolonged QTc was 2.2-fold among h6 workers (95% CI 1.2, 4.2); conduction disorders (SPR = 2.6; 95% CI 1.3, 5.2) and repolarization disorders (SPR = 1.9; 95% CI 1.0, 3.5) were also more frequently observed among h6 workers. Excluding 19 subjects with risk factors for prolonged QTc did not change the results. CONCLUSIONS Our study reveals significant changes in the ECG morphology in relation to shift-work, especially in unpredictable and non-standard working hours.

Causes of death among lead smelters in relation to the glucose-6-phosphate dehydrogenase polymorphism

Objective: To assess, by updating a follow-up mortality study of a lead smelters cohort in Sardinia, Italy, the adverse health effects following occupational lead exposure in relation to the glucose-6-phosphate dehydrogenase (G6PD) polymorphism. Method: The 1973–2003 mortality of 1017 male lead smelters were followed-up, divided into two subcohorts according to the G6PD phenotype: whether G6PD deficient (G6PD−) or wild-type (wtG6PD). Deaths observed in the overall cohort and the two subcohorts were compared with those expected, on the basis of the age-, sex- and calendar year-specific mortality in the general male population of the island. Directly standardised mortality rates (sr) in the two subcohorts were also compared. Results: Cardiovascular mortality was strongly reduced among production and maintenance workers, which is most related to the healthy worker effect. However, the sr for cardiovascular diseases was substantially lower among the G6PD− subcohort (5.0×10−4) than among the wtG6PD subcohort (33.6×10−4; χ2 = 1.10; p = NS). Neoplasms of the haemopoietic system exceeded the expectation in the G6PD− subcohort (SMR = 388; 95% CI 111 to 1108). No other cancer sites showed any excess in the overall cohort or in the two subcohorts. No death from haemolytic anaemia occurred in the G6PD− subcohort. Conclusion: With due consideration of the limited statistical power of our study, previous results suggesting that in workplaces where exposure is under careful control, expressing the G6PD− phenotype does not convey increased susceptibility to lead toxicity are confirmed. The observed excess risk of haematopoietic malignancies seems to have most likely resulted from chance.

Work Related Stress, Well-Being and Cardiovascular Risk among Flight Logistic Workers: An Observational Study

Work-related stress is a known occupational hazard, with a putative role on the development of cardiovascular diseases (CVD). Although several investigations have explored the association in various workplace scenarios, none have focused on the airport flight logistic support personnel, a transportation business of crucial importance, potentially exposed to job stress and consequently to an increase in CVD risk. We explored the relationship between work-related stress and cardiovascular risk in 568 healthy workers of a flight logistic support company using the Health and Safety Executive questionnaire, the Framingham Heart Study General Cardiovascular Disease (CVD) Risk Prediction Score, and the WHO general well-being index (WHO-5). We used univariate and multivariate statistical methods to take account of possible confounders. Our results show that a low job support significantly increases the CVD risk score and decreases the WHO well-being index with reference to subjects reporting high support on the job. In addition, the well-being index of workers with high strain jobs appears lower in respect to workers employed in low strain job. The multivariate analysis confirms a protective effect of job support, and shows a detrimental influence on CVD risk by physical inactivity, regular intake of alcohol, and a low educational level. In addition, job control, job support, low strain, and high demand coupled with high control (active job) showed a beneficial effect on psychological well-being. Our results suggest that a combination of general risk factors and organizational factors contributes to increase CVD risk and well-being, representing a crucial target for intervention strategies to promote health in the workplace.

P061 Association between work related stress and qt prolongation in male workers: the role of low job control

Introduction Several studies have shown that high demand and low control jobs are associated with poor physical and mental wellbeing. Aim of our study was to test the association between job strain and the QTc interval on the electrocardiogram, an indicator of autonomic function, blood pressure, body mass index (BMI), and fasting glycaemia level. Methods Overall 280 male workers of a logistic support company for secure communication and intelligence were included in our study population. We measured work-related stress using the HSE indicator tool, general wellbeing using the Well-being Index (WHO5); affectivity was measured by the short version of the positive and negative affect schedule (PANAS); the frequency corrected QT (QTc) interval on the electrocardiogram was measured using the Bazett’s formula; QT index (QTi) value, blood pressure, BMI, and fasting glycaemia were also recorded, as well as medications, lifestyles and comorbidities. Based on the Karasek’s taxonomy, we compared high strain jobs, low strain jobs, active jobs and passive jobs with respect to WHO5, PANAS, QTc, QTi, blood pressure, BMI and glycaemia. Group differences were analysed by means of parametric and non parametric tests. Results Results showed that low strain jobs were associated with a lower frequency of negative affectivity than high strain jobs (Fisher test = 3.63, p < 0.05). Employees with passive jobs (low demand and low control) showed a significantly longer QT index than workers in high-strain jobs (high demand and low control) (F = 3.18, p < 0.05). No significant differences were found among the four groups on the other investigated variables. Conclusions In our study population, we did not observe a reduction in cardiac vagal control, as indicated by a prolonged QTi, among subjects employed in high strain and low control jobs.

Lymphoma risk among animal breeders

Objectives Occupational contact with breeding animals might be implicated in lymphoma aetiology. Methods In 1998–2003, 2337 incident lymphoma cases and 2434 controls participated in the EPILYMPH case-control study in six European countries. A detailed occupational history was collected in cases and controls, including species of breeding animals, their approximate number, and circumstances of contact. We conducted a preliminary analysis on ever exposed to contact with breeding animals, and we stratified the analysis by age at first exposure, whether before or after 12. The OR and its 95% CI was calculated with unconditional logistic regression for all lymphomas, and its major subtypes, adjusting by age, gender, and education. Results Lymphoma risk (all subtypes combined) did not increase among those exposed to contact with breeding animals (OR = 1.0, 95% CI 0.8 to 1.2). Risk of DLBCL was significantly lower among subjects employed in poultry farms (OR = 0.6, 95% CI 0.4 to 1.0). This inverse association was observed among subjects who started exposure before or at age 12 (OR = 0.5, 95% CI 0.2 to 1.1), but not later. Conclusions Early occupational contact with poultry might be associated with a decrease in risk of specific lymphoma subtypes.

Risk of specific lymphoma subtypes is associated to polymorphism in genes implicated in the metabolism of workplace carcinogens

Objectives Exploring lymphoma risk associated with metabolic gene polymorphisms might provide clues on the role of gene-environment interactions in lymphomagenesis. Methods We assessed polymorphisms in genes encoding for the metabolic enzymes CYP1A2, CYP2E1, GSTM1, GSTT1, NAT1, NAT2, NQ01, and PON1 in 255 incident lymphoma cases and 204 population controls. The OR for lymphoma overall, B lymphoma, and the diffuse large B cell lymphoma (DLBCL) and chronic lymphocytic leukaemia (CLL) subtypes, associated to the less frequent allele was calculated along with the respective 95% CI, adjusting by age and gender. Results GSTT1 gene polymorphism significantly increased risk of DLBCL (OR = 5.0, IC 95% 3.0 to 8.3). An excess risk of DLBCL was also related to polymorphisms in the CYP1A2, PON1, NAT1 and NAT2genes. CLL risk was reduced in relation to CYP1A2 polymorphisms, increased in relation to GSTM1 deletion, and strongly associated with NAT1, and NAT2 mutant haplotypes. Conclusions Caution is recommended in interpreting the high risks in our study, due its small size. However, our results suggest that polymorphisms in genes encoding for the metabolic enzymes might affect risk of specific lymphoma subtypes associated with exposure to workplace carcinogens.