Cardiac Autonomic Control and Neural Arousal as Indexes of Fatigue in Professional Bus Drivers.

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

Indexes of cardiac autonomic profile detected with short term Holter ECG in health care shift workers: a cross sectional study.

BACKGROUND: The assessment of early effect of shift work-related circadian rhythms desynchronization and work-related stress in health care workers has gained a primary role among the duties of the occupational physician. OBJECTIVES: Aim of our study was to assess the cardiac autonomic modulation through quantification of sinus rhythm variability, as an index of the adaptability to shift work of the cardiovascular system in healthcare shift workers. METHODS: We measured Heart Rate Variability (HRV) by short-term (60 minutes) Holter Electrocardiography (ECG) during the regular duties in the respective department of 42 healthcare workers (31 nurses and 11 physicians) of an Italian Hospital (12 male and 30 females, aged 24-58 years), working on 3 shifts with a forward fast rotation with rest at the end of the night shift (7 am - 2 pm; 2 pm - 10 pm; 10 pm - 7 am) or in a fixed daytime shift (8 am - 2 pm). Measurements were all performed between 9 am and 12 am for fixed day workers and between 9 am and 12 pm or between 10 pm and 1 am for shift workers. The following HRV parameters were compared between the subgroups of shift workers and daytime workers: mean heart rate (HR), standard deviation of all normal RR (NN) intervals (SDNN), standard deviation of the averages of NN intervals in all 5-minute segments of a recording (SDaNN) and the triangular index (the integral of the density distribution divided by the maximum of the density distribution). We used parametric tests for independent series to compare HRV parameters by subgroups within the study subjects. We also tested correlation between the variables of interest and the association between HRV and shift work modality, along with other covariates, by means of a multiple linear regression analysis. RESULTS: We found significantly lower values of SDaNN in shift workers compared with workers engaged solely on day shifts (50.80 ms vs 66.71 ms; p=0,014). The mean heart rate did not show any significant difference between day workers and shift workers (85.78 bmp vs 85.53 bpm respectively). Multivariate analysis showed a significant association between SDNN and female gender and age, while no significant associations were found between HRV and shift work. DISCUSSION: The autonomic control of the heart rhythm could be disrupted by desynchronization of the biological rhythm secondary to the organization of shift work and night work. Shift work is an important factor of social and biological distress, influencing the adaptability of the cardiovascular system to stimuli and demands of work organization.

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.

Analysis of potential influence factors on background urinary benzene concentration among a non-smoking, non-occupationally exposed general population sample.

OBJECTIVES: Analytical difficulties and lack of a biological exposure index and reference values have prevented using unmetabolized urinary benzene (UB) excretion as a biomarker of low-level environmental exposure. To explore what environmental factors beyond active smoking may contribute to environmental exposure to benzene, we monitored UB excretion in a non-smoking, non-occupationally exposed sample of the general population. METHODS: Two spot urine samples were obtained from 86 non-smoking, non-occupationally exposed subjects, selected among a random sample of the general population of the metropolitan area of Cagliari (Sardinia, Italy), at 8:00 a.m. (UBm) and 8:00 p.m. (UBe). UB was measured by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry analysis. Questionnaire information on personal and environmental exposures during the sampling day was gathered with personal interviews. Multivariate analysis of variance and multiple regression model were applied to investigate the role of such variables on the level of UB. RESULTS: The ninety-fifth percentile of UBe in this population was 311.5 ng/L, which is tentatively proposed as the UB guidance value for unexposed populations. UBm and urban residence were the only predictors of a significant increase in UBe excretion. Self-reported residential vehicular traffic will not account for the excess median value among urban residents; commuting time among urban residents showed a suggestive nonsignificant linear correlation with UBe, but the small sample size prevented reliable inference to be drawn. Age, environmental tobacco smoking, employment status and body mass index did not affect UB excretion. CONCLUSIONS: Our findings support the use of unmetabolized UB as a specific and sensitive biomarker of low-level environmental exposure to benzene.

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.

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.

[Urinary benzene in biological monitoring of environmental exposure to low benzene concentrations]. / Il benzene urinario nel monitoraggio biologico dell'esposizione a bassi livelli ambientali.

INTRODUCTION: Conflicting opinions exist about urinary benzene (UB) as a reliable biomarker of exposure. Objective of our study is to evaluate the effect of low-level environmental exposure on UB levels. METHODS: We monitored UB excretion in 74 non-smoking non- occupationally exposed subjects; a questionnaire interview gathered information on relevant exposures during the day of monitoring. RESULTS: UB excretion was related (p < 0.05) to gender, sampling time, residence, and reported vehicular traffic, but not to passive smoking and body mass index. CONCLUSION: Our findings support the use of unmetabolized UB as a specific and sensitive biomarker of low-level exposure to benzene.

Asbestos exposure and malignant lymphoma: a multicenter case-control study in Germany and Italy.

AIMS: To analyze the relationship between asbestos exposure and malignant lymphoma in a multicenter case-control study conducted in Germany and Italy according to a common core protocol. METHODS: Male and female patients with malignant lymphoma (n = 1,034) between 18 and 80 years of age were prospectively recruited in six study areas in Germany (Ludwigshafen/Upper Palatinate, Heidelberg/Rhine-Neckar-County, Würzburg/Lower Frankonia, Hamburg, Bielefeld/East Westphalia, and Munich) and in two study areas in Sardinia, Italy (Cagliari and Nuoro provinces). A total of 1,173 population control subjects were drawn from population registers. In a structured personal interview, we elicited a complete occupational history, including every occupational period that lasted at least 1 year. On the basis of job task-specific supplementary questionnaires, trained experts assessed the exposure to asbestos. As a measure of cumulative asbestos exposure on a time by intensity scale, fiber-years were calculated. 12 cases (1.2%) and 12 control subjects (1.0%) had a cumulative asbestos exposure of more than 2.6 fiber-years (highest exposure category according to the 90th percentile of exposed control subjects). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis adjusted for age, sex and study region. Patients with specific lymphoma sub-entities were additionally compared with the entire control group. RESULTS: We observed no statistically significant association between cumulative asbestos exposure and the risk of any lymphoma subtype. An elevated risk was found for the association between exposure to more than 2.6 fiber-years and multiple myeloma (OR = 6.0; 95% CI 1.4-25.1); however, numbers were small (n = 3 cases, all of them from Italy; n = 12 control subjects). CONCLUSIONS: Our study does not support an association between asbestos exposure and risk of malignant lymphoma.

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 (5.0x10(-4)) than among the wtG6PD subcohort (33.6x10(-4); chi2 = 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.

Effect of urban traffic, individual habits, and genetic polymorphisms on background urinary 1-hydroxypyrene excretion.

PURPOSE: Potential sources of exposure to polycyclic aromatic hydrocarbons (PAHs) and genetic polymorphisms were investigated in relation to their contribution to interindividual variation in baseline levels of urinary 1-hydroxypyrene (1-OHP) excretion in subjects without occupational exposure to PAHs. METHODS: Urinary excretion of 1-OHP was measured in 114 subjects, including 48 women and 66 men. Questionnaire information was collected on possible environmental and individual sources of PAH exposure. A subset of 70 individuals also was evaluated for a single-nucleotide polymorphism (Ex7+295C-->T) in the cytochrome P-450 1A2 (CYP1A2) gene, and 61 of these also were evaluated for the glutathione transferase T1 (GSTT1) gene polymorphism. RESULTS: 1-OHP values did not show a significant seasonal variability and were unaffected by age; education; body mass index; smoking status, including passive smoking; or the C-->T base substitution in position 295 of exon 7 of the CYP1A2 gene. After reciprocal adjustment with logistic regression, living in a heavily trafficked urban area (odds ratio, 4.9; 95% confidence interval, 1.0-24.9), and frequent intake of grilled meat (odds ratio, 6.9; 95% confidence interval, 1.1-43.5) were significant predictors of background urinary 1-OHP levels of 0.50 microg/g creatinine or greater. Elevated risks also were associated with daily alcohol intake greater than 65 g and the nonnull GSTT1 genotype. CONCLUSION: Our study shows that exposure to urban traffic, dietary habits, and the nonnull GSTT1 genotype may contribute to interindividual variation in background levels of 1-OHP urinary excretion in subjects without occupational exposure to PAHs.

Urinary 6-sulfatoxymelatonin excretion in humans during domestic exposure to 50 hertz electromagnetic fields.

OBJECTIVES: Exposure to extremely low frequency electromagnetic fields (ELF-EMF) has been suggested to suppress melatonin secretion, which might result in higher cancer risks because of its missing oncostatic action. We investigated the effects of residential exposure to ELF-EMF on the excretion of urinary 6-sulfatoxymelatonin (6-OHMS), the major melatonin metabolite, as an indicator of nocturnal melatonin secretion. METHODS: 6-OHMS was measured in two spot urine samples, collected at 22.00 h and 08.00 h, in 29 men and 22 women. Spot ELF-EMF measurements were conducted at the centre and the four angles of the living room, the bedroom, and the kitchen of study subjects at low current configuration (all lights and appliances turned off), and they were repeated immediately at high current configuration (all lights and appliances turned on). RESULTS: Risk of a reduced 6-OMHS nocturnal secretion was elevated for daily alcohol intake (OR = 6.4; 95%C.I. 1.4,33.1), and body mass index (BMI) above the median (OR = 2.2; 95%C.I. 0.5,9.6). Risk of disrupted rhythm of 6-OHMS excretion was moderately elevated for domestic ELF-EMF exposure above the upper tertile at low current configuration (OR = 2.6; 95%C.I. 0.4,15.7). CONCLUSION: Alcohol consumption, BMI, and gender seem to affect nocturnal melatonin secretion, while an effect of residential exposure to ELF-EMF is uncertain. Future studies should properly account for the effect of such variables, when addressing the hypothesis of disturbances in melatonin secretion as a plausible explanation for the reported excess risk of several tumoral diseases associated with low level ELF-EMF exposure.

Reproductive outcomes in DDT applicators.

OBJECTIVES: To explore reproductive outcomes in relation to occupational exposure to DDT. METHODS: We inquired into the reproductive history, including total number of children, sex distribution in the offspring, time-to-pregnancy, and number of spontaneous abortions and stillbirths, of the spouses of 105 men first exposed to DDT in a 1946-1950 anti-malarial campaign in Sardinia, Italy. The time-to-pregnancy in months at the first successful conception was estimated from population Registrars. Cumulative DDT exposure during the anti-malarial campaign was retrospectively estimated. RESULTS: The stillbirth rate was elevated and the male/female ratio in the offspring was reversed among DDT-exposed workers, and particularly among DDT applicators, compared to the unexposed subjects. Among DDT applicators, the stillbirth rate increased and the male/female ratio decreased by the tertile of cumulative DDT exposure. The fecundity ratio among spouses of DDT applicators was 0.72 (95% CI, 0.41,1.21) compared to the unexposed. The average number of children and abortion rate were unaffected by DDT exposure. CONCLUSIONS: The low statistical power of our study does not allow definitive conclusions. However, the results prompt further in-depth research into adverse reproductive outcomes and reduced fertility among men heavily exposed to DDT.

Effectiveness of therapy with iloprost in hand-arm vibration syndrome.

AIM: To evaluate the efficacy and tolerance of therapy with iloprost in hand-arm vibration syndrome. METHODS: We describe a clinical case of a male aged 53 years, who was a heavy smoker for 30 years and a mason working with vibrating tools since 1962. He presented with a history of 10 years of attacks of vasospasm, functional impairment and digital ulceration. He was diagnosed as having hand-arm vibration syndrome vascular stage 4 on the Stockholm Workshop 1986 Scale. Besides suspension from work and abstention from smoking, we began intravenous infusion of iloprost for 6 h in cycles of 3-6 consecutive days, arriving at a dose of 1.5-2.0 ng/kg/min. RESULTS: After eight cycles, he reported significant symptomatic and functional improvement. Iloprost was seen to be efficacious: the trophic skin lesions disappeared and his microcirculatory perfusion tests improved. There were no significant side effects. CONCLUSIONS: We suggest that the use of iloprost in the treatment of the most advanced stages of vascular hand-arm vibration syndrome warrants further study