Effects of occupational cobalt exposure on the heart in the production of cobalt and cobalt compounds: a 6-year follow-up.

OBJECTIVE: It has been suspected that cobalt is toxic to the heart. It can cause cardiotoxicity in heavily exposed humans and in experimental systems. The issue of interest for this study is whether cobalt also affects the myocardium at occupational exposure levels. METHODS: To study the effect of occupational cobalt exposure on the heart, we conducted a follow-up of workers at a cobalt production plant. The workers' hearts had been examined by echocardiography in 1999-2000. Altogether 93 exposed and 49 non-exposed workers examined in 1999-2000 were re-examined in 2006. Occupational history and health data were collected with a questionnaire. Blood pressure was measured, and electrocardiography (ECG), laboratory tests, Holter registration, and echocardiography were conducted for all participants. Analysis of covariance (ANCOVA) was used to analyse the data. RESULTS: No differences were found between the exposed and unexposed groups for any of the echocardiographic parameters in 2006. There were no differences in the laboratory values, the ECG parameters, or the results of the Holter registration of the exposed and unexposed workers. CONCLUSIONS: Although the previous results in 2000 suggested an association between cumulative exposure to cobalt and echocardiographic findings, the results of this new cross-sectional study with a tissue Doppler 6 years later did not confirm the association in the present cohort. If cobalt exposure affects heart muscle functions at this exposure level, the effects are smaller than those caused by physiological changes due to ageing, medication, and traditional cardiovascular risk factors, such as elevated blood pressure.

Cobalt asthma--a case series from a cobalt plant.

BACKGROUND: Cobalt has been shown to induce mainly asthma, allergic contact dermatitis and hard metal disease. The data on cobalt asthma are mainly based on case reports. AIMS: To characterize all the cases of occupational cobalt asthma encountered in a cobalt plant at the time of diagnosis and 6 months later. We also evaluated the incidence of cobalt asthma in different departments on the basis of data on occupational exposures. METHODS: We identified cases of cobalt asthma confirmed with specific bronchial challenge tests in the Kokkola cobalt plant in Finland where exposure levels have been regularly monitored. RESULTS: Between 1967 and 2003, a total of 22 cases of cobalt asthma were diagnosed in the cobalt plant. On challenge tests, mostly late or dual asthmatic reactions were observed. The incidence of cobalt asthma was the highest in the departments with the highest cobalt exposure levels. All cases of cobalt asthma were encountered in departments where irritant gases were present in the ambient air in addition to cobalt. At the time of the follow-up examination 6 months later, non-specific hyperreactivity had mostly remained at the same level or increased. CONCLUSIONS: The incidence of cobalt asthma correlated with the exposure levels of cobalt in corresponding departments. An irritating effect of gaseous compounds may enhance the risk of cobalt asthma and even the smallest amounts of cobalt may be harmful to susceptible workers. Symptoms of asthma may continue despite the fact that occupational exposure to cobalt has ceased.

Does organisational justice protect from sickness absence following a major life event? A Finnish public sector study.

BACKGROUND: It has been shown that fairness perceptions have a strong impact on health, especially under conditions of great work stress. The aim of this study was to extend previous research in studying whether working in high justice workplace would protect from health effects following environmental stressors outside work. METHODS: Using a prospective longitudinal design, the relationships between organisational justice and sickness-related absences both before and after a major life event among 25 459 public sector employees working in 2551 work units were studied. Sickness absences covered the period from 36 months before the event until 30 months after the event. RESULTS: The increase in sickness absences after the event was larger and stayed at a higher level even 30 months after the event, among those who perceived the management practices in their work unit to be relatively unfair. Similar patterns were found for each of the distributive, procedural and interactional dimensions of organisational justice. CONCLUSIONS: Fair organisational and managerial procedures may buffer the negative health effects of psychosocial health risks outside work.

Long hours in paid and domestic work and subsequent sickness absence: does control over daily working hours matter?

OBJECTIVES: To explore the associations of working hours (paid, domestic, commuting, and total) with sickness absence, and to examine whether these associations vary according to the level of employee control over daily working hours. METHODS: Prospective cohort study among 25 703 full-time public sector employees in 10 towns in Finland. A survey of working hours and control over working hours was carried out in 2000-01. The survey responses were linked with register data on the number of self-certified (< or =3 days) and medically certified (>3 days) sickness absences until the end of 2003. Poisson regression analyses with generalised estimating equations were used to take into account the fact that the employees were nested within work units. Adjustments were made for work and family characteristics and health behaviour. The mean follow-up period was 28.1 (SD 8.1) months. RESULTS: Long domestic and total working hours were associated with higher rates of medically certified sickness absences among both genders. In contrast, long paid working hours were associated with lower rates of subsequent self-certified sickness absences. Long commuting hours were related to increased rates of sickness absence of both types. Low control over daily working hours predicted medically certified sickness absences for both the women and men and self-certified absences for the men. In combinations, high control over working hours reduced the adverse associations of long domestic and total working hours with medically certified absences. CONCLUSIONS: Employee control over daily working hours may protect health and help workers successfully combine a full-time job with the demands of domestic work.

Effort/reward imbalance and sedentary lifestyle: an observational study in a large occupational cohort.

OBJECTIVES: To investigate the association between effort/reward imbalance (ERI) at work and sedentary lifestyle. METHODS: Cross sectional data from the ongoing Finnish Public Sector Study related to 30,433 women and 7718 men aged 17-64 were used (n = 35,918 after exclusion of participants with missing values in covariates). From the responses to a questionnaire, an aggregated mean score for ERI in a work unit was assigned to each participant. The outcome was sedentary lifestyle defined as <2.00 metabolic equivalent task (MET) hours/day. Logistic regression with generalised estimating equations was used as an analysis method to include both individual and work unit level predictors in the models. Adjustments were made for age, marital status, occupational status, job contract, smoking, and heavy drinking. RESULTS: Twenty five per cent of women and 27% of men had a sedentary lifestyle. High individual level ERI was associated with a higher likelihood of sedentary lifestyle both among women (odds ratio (OR) = 1.08, 95% CI 1.01 to 1.16) and men (OR = 1.17, 95% CI 1.02 to 1.33). These associations were not explained by relevant confounders and they were also independent of work unit level job strain measured as a ratio of job demands and control. CONCLUSIONS: A mismatch between high occupational effort spent and low reward received in turn seems to be associated with an increased risk of sedentary lifestyle, although this association is relatively weak.

Exposure to cobalt in the production of cobalt and cobalt compounds and its effect on the heart.

AIMS: To investigate whether exposure to cobalt in cobalt plants has any measurable effect on the cardiovascular system. METHODS: Occupational, cross sectional study, using a self administered questionnaire, blood pressure measurement, electrocardiography, and laboratory tests in which 203 male workers with at least one year of exposure to cobalt and 94 unexposed controls participated. Echocardiography was performed on a subset of 122 most highly exposed cobalt workers, of which 109 were analysed, and on 60 controls, of which 57 were analysed. Analysis of covariance and a multiple regression analysis were used to evaluate the data. RESULTS: Two of the echocardiography parameters measured were associated with cobalt exposure. In the higher exposure group the left ventricular isovolumic relaxation time (mean 53.3, 49.1, and 49.7 ms in the high exposure, low exposure, and control groups respectively) and the deceleration time of the velocity of the early rapid filling wave (mean 194.3, 180.5, and 171.7 ms for those in the high exposure, low exposure, and control groups respectively) were prolonged, indicating altered left ventricular relaxation and early filling. CONCLUSION: Cumulative exposure to cobalt was found to be associated with the results of Doppler echocardiography measurements, indicating altered diastole. This finding supports the hypothesis that cobalt accumulation in the myocardium could affect myocardial function. Whether this finding has clinical implications remains to be evaluated.

In vivo evaluation of matrix granules containing microcrystalline chitosan as a gel-forming excipient.

Interest in drug delivery to the gastrointestinal tract by means of chitosan has been increasing. In the study reported, the biopharmaceutical properties of granules containing microcrystalline chitosan (MCCh; molecular weight 150 kDa, degree of deacetylation 75%) were evaluated via bioavailability tests in human volunteers. Ibuprofen and furosemide were used as model drugs. With ibuprofen, granules containing 40% of MCCh behaved as a slow-release formulation (t(max) 2.9 h). With furosemide, the most marked difference between a conventional dosage form and granules containing 40% MCCh was a marked lag time (0.5 h) before absorption from the latter. This difference was reflected in t(max) values for furosemide. Despite the lag time, AUC values for furosemide were high, indicating that the granules containing MCCh had remained in the stomach and that drug release had taken place in the stomach rather than in the intestine. The results of the bioavailability studies indicate that MCCh matrix granules allow a simple preparation of slow-release and perhaps stomach-specific dosage forms. Use of model drugs differing in relation to sites of absorption in the gastrointestinal tract aided identification of sites of absorption of drugs from the granules. Further studies, including gamma-scintigraphic evaluations, will be performed on how the granules behave in the stomach.

Dissecting amazonian biodiversity.

Biogeographical and biodiversity studies in Iowland Amazonian rain forests typically refer to observed or postulated distribution barriers such as past unfavorable climates, mountains, rivers, and river floodplains that divide the uniform tierra firme (noninundated) forest. Present-day ecological heterogeneity within tierra firme has hardly been discussed in this context, although edaphic differences are known to affect species distribution patterns in both inundated areas and tierra firme. Quantification of landscape heterogeneity in Peruvian Iowland Amazonia (500,000 kilometers squared), based on field studies and satellite image analysis, shows that Peruvian Amazonia is considerably more heterogeneous than previously reported. These observations have implications for the research, management, and conservation of Amazonian biodiversity.

Late miocene tidal deposits in the amazonian foreland basin.

Late Miocene tidal sediments of Acre, Brazilian Amazonia, were deposited in an embayment or interior seaway located in the sub-Andean zone. This late Tertiary embayment system may once have connected the Caribbean with the South Atlantic. The tidal coasts of the embayment-seaway have provided an avenue for the earliest waif (over water) dispersal phases of the great American biotic interchange in the late Miocene. The subsequent change from semimarine to terrestrial environments is of value in assessing the importance of earlier hypotheses on the evolution of the westem Amazonian landscape and gives insight into the formation of several observed biogeographic patterns, especially of aquatic biota.