Olivine, cobalt silicate blue

Epidemiological data

Administrative data

Endpoint:

epidemiological data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

other: Any kind of reliability rating is not considered to be applicable, since human epidemiological studies, field studies and case reports are not conducted/reported according to standardised guidelines

Rationale for reliability incl. deficiencies:

other: Reasonably well-documented publication.

Data source

Reference

Reference Type:

publication

Title:

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

Author:

Linna, A.; et al.

Year:

2004

Bibliographic source:

Occup. Environ. Med. 61, 877-885

Materials and methods

Study type:

cross sectional study

Endpoint addressed:

repeated dose toxicity: inhalation

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

A cross-sectional study on the effects of cobalt exposure in the Kokkola cobalt plant on the cardiovascular system of workers was conducted with 203 male workers with at least one year of exposure to cobalt.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

cobalt and cobalt compounds

IUPAC Name:

cobalt and cobalt compounds

Details on test material:

The exact test item was not decribed in the publication. On the other hand, it was stated that between 1966 and 1987 cobalt powder was produced from pyrite ore concentrate. Thereafter cobalt powder, inorganic cobalt, and nickel compounds have been produced using by-products of the metallurgic industry as raw material.

Method

Type of population:

occupational

Ethical approval:

confirmed, but no further information available

Details on study design:

METHOD OF DATA COLLECTION- Type: Questionnaire / Clinical tests:- Details: Data on working history in the plant and earlier possible exposure to cobalt, lead, carbon disulphide, and arsenic were requested in the self administered questionnaire. The reasons for changing work tasks or jobs and workplaces were also requested. There were also questions regarding physical exercise, smoking, alcohol consumption, cardiovascular and pulmonary diseases, and diabetes. STUDY PERIOD: Exposure to most dusts and gases in the process has been regularly monitored several times every year since 1966 until the end of 1999. SETTING: The cobalt plant of this study is located in Kokkola on the western coast of Finland.STUDY POPULATION- Total number of subjects participating in study: 203 - Sex/age: male/ mean age of 42 +/- 10.5 years- Smoker/nonsmoker: 66.5% of the exposed group were ex-smokers or smokers, while 33.5% were nonsmokers - Consumption of alcohol: 4.8 +/- 4.5 drinks per week were consumed by workers from the exposed group.COMPARISON POPULATION- Type: Control or reference group- Details: The control group consisted of an age-stratified sample of 94 male workers in a zinc plant that had not been exposed to cobalt, arsenic or lead. The zinc exposure level was 0.1-0.2 mg/m³ for four fifths of the workers, and for one fifth it was about 1 mg/m³.- Sex/age: male/ mean age of 42.2 +/- 10.6 years- Smoker/nonsmoker: 67.4% of the control group were ex-smokers or smokers, while 32.6% were nonsmokers - Consumption of alcohol: 5.6 +/- 4.8 drinks per week were consumed by workers from the control group.HEALTH EFFECTS STUDIEDEffects of cobalt exposure on the cardiovascular system were investigated. Echocardiography was performed on a subset of 122 cumulatively most exposed workers, of which 109 was analysed, and 60 controls with same age distribution, of which 57 were analysed.

Exposure assessment:

measured

Details on exposure:

TYPE OF EXPOSURE: uptake of cobalt occurs through the lungs TYPE OF EXPOSURE MEASUREMENT: Area air sampling / Personal sampling:Air samples have been collected by an authorised hygienist both at stationary points and with personal samplers in the workers’ breathing zones.EXPOSURE LEVELS: A mean cumulative exposure to cobalt of 0.40 mg/year (median 0.18 mg/year, range 0.02-2.52) was determined for workers investigated for effects on the cardiovascular system. And a a mean exposure to cobalt of 0.58 mg/year (median 0.47 mg/year, range 0.03-2.52) was determined for workers investigated by echocardiography. EXPOSURE PERIOD: The average exposure time was 15 years for workers investigated for effects on the cardiovascular system. The average exposure time was 21.2 years for workers investigated by echocardiography.POSTEXPOSURE PERIOD: no data DESCRIPTION / DELINEATION OF EXPOSURE GROUPS / CATEGORIES: no data

Statistical methods:

The echocardiographic data were studied using a regression analysis and an analysis of covariance (ANCOVA).In the final analyses high and low exposure was determined on the basis of being above or below the median mg/years of cobalt exposure.

Results and discussion

Results:

EXPOSURENo further details are given. FINDINGSNo significant differences in the electrocardiography findings and conduction parameters, heart rate, blood pressure and laboratory tests (inter alia serum T4 and TSH levels) were found between the cobalt exposed and control workers. There were no significant differences between the exposed group and the control group in the prevalence of reported cardiovascular diseases, diabetes mellitus, or pulmonary diseases, except asthma, diagnosed by a physician.Two of the echocardiography parameters measured was 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 (>0.47 mg-year), low exposure (<0.47 mg-year), 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. Minor increases in the left ventricular wall thickness concurred with these observations. No signs of systolic cardiac dysfunction were found. The ejection fraction, fractional shortening, and the left ventricular end diastolic diameter were similar in the exposed and control groups. STATISTICAL RESULTSNo further details.

Confounding factors:

no details

Strengths and weaknesses:

no data

Applicant's summary and conclusion

Conclusions:

In summary, no clinically significant cardiac dysfunction due to cobalt exposure was found. Two echocardiography parameters (isovolumic relaxation time, deceleration time) which were considered to be the most important outcome variables because of their ability to reflect the earliest changes in the cardiac function were significantly changed due to cumulative exposure to cobalt. The clinical significance of these changes, however, remains to be evaluated.