Use of cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27 in the periodic table of chemistry. Cobalt is currently mainly used in lithium-ion batteries, rechargeable batteries and in the manufacture of magnetic, wear-resistant and high-strength alloys. This alloy is used, for example, for turbine blades for gas turbines and aircraft engines. Some alloys are used for prothetisch to (artificial) parts (hip and knee prostheses). Since the arrival of electric cars, the use of cobalt has increased sharply and is expected to increase even more in the coming years.
In addition, there are the compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) that impart a distinctive deep blue color to glass, ceramics, inks, paints and varnishes.
Cobalt-containing smalt (a type of glass) is also finely ground and used as the ultramarine dye. Johannes Vermeer used this color, among other things, for the headscarf of the girl with a pearl earring. Ultramarine was also used in bluing that used to be used to make whites look even whiter. Today it is in detergent for white laundry.
Risk of cobalt in the workplace
Just like about others heavy metals there are concerns about the health risks of exposure to cobalt in the workplace. Cobalt could affect the heart and lungs, among other things. A Finnish dissertation has recently been published (and is publicly available) in which a series of studies have been carried out on workers in cobalt production. The focus of the studies was on the heart and lungs.
Purpose of this study
The aim of the Finnish study was to investigate the effects of long-term exposure to cobalt and cobalt compounds on the lungs and airways and on the heart.
Lungs
The part of the study that focuses on lungs and airways consists of two parts. The epidemiological study looked at the relationship between exposure and respiratory complaints, lung function and possible disorders. The research group consists of employees in cobalt production who have been exposed for at least ten years now or in the past. This concerns 110 men. They have been compared with 140 unexposed workers. The participants completed a questionnaire and a chest x-ray (X-ray of the chest) was taken. Lung function has been tested in various ways and the Clara cell protein has been determined.
* Clara cells: the last branches of the bronchioles, the terminal bronchioles, are lined with a cuboidal epithelium, in which clara cells ('club cells') are present. These cells secrete a variant of the surfactant ('surface active agent') and through their secretion contribute to the immune defense.
Hart
The studies on the effect on the heart were conducted between 2000 and 2006. The first was a cross-sectional study of workers who had worked in cobalt production for at least one year (203). They were compared with an unexposed control group (94). Questionnaires, laboratory tests, blood pressure measurement and ECGs were used in this study. In addition, an echocardiogram was made of the 122 cumulatively highly exposed cobalt workers and an age-matched group of 60 non-exposed control subjects.
In the follow-up study, the employees who continued to work in cobalt production after the year 2000 and who had had an echocardiogram were further investigated (93), as were the unexposed control subjects who had undergone an ultrasound (49). They underwent the same examinations as mentioned above, supplemented with Doppler examination and a long-term ECG recording (Holter).
Results
Cobalt asthma
In case study, 22 workers were diagnosed with occupational cobalt asthma using a specific bronchial provocation test at the Finnish Institute of Occupational Health (FIOH). In the answers to the questionnaires, exposed workers were more likely to report asthma symptoms than non-exposed workers. One new case of cobalt asthma was found but no cases of hard metal disease or fibrosing alveolitis. The incidence of cobalt asthma was highest in the departments with the highest exposure levels.
Irritating fumes and smoking
All cases of cobalt asthma were found in the wards where irritating gases and vapors were present in the ambient air in addition to cobalt exposure. Six months after diagnosis, nonspecific hyperresponsiveness was generally at the same level or slightly increased. The flow values MEF50 (maximum expiratory flow at 50% of expiration (FVC)) and MEF25 (maximum expiratory flow at the time when 25% of the FVC has yet to be exhaled). These values, which reflect the smaller airways, are significantly lower in exposed smokers than in non-exposed smokers. On the provocation tests, cobalt asthma patients mainly show late or double asthmatic reactions.
Ultrasound and EKG
In the first study of the influence of cobalt on the heart, a number of ultrasound parameters were related to cobalt exposure. It involved early diastole, isovolumic relaxation time (IVRT) of the left ventricle and decrease in the rate of early filling. These findings that may indicate a change in left ventricular function were really not found in the follow-up study. In that study, no differences were found between those exposed and those not exposed on ultrasound, ECG and Holter or in the laboratory values.
Conclusions
In this series of studies no chronic lung or respiratory diseases were found, except asthma. Exposure and smoking reinforce each other in their negative effect on lung function. Cobalt asthma seems to develop mainly in situations where workers are exposed to high concentrations of cobalt as well as to irritating gases and vapours. The clinical picture that emerges in the studies is consistent with an IgE-dependent mechanism in the development of cobalt asthma.
It is possible that the findings from the first heart study in the follow-up study six years later were masked by the influence of normal aging and influence of lifestyle factors on the heart. However, other studies also show that healthy people can tolerate high cobalt concentrations in the blood and that the development of a clinical cobalt cardiomyopathy is very unlikely under normal working conditions.
Source
Linna, A. (2023). Effects of Cobalt Exposure on the Respiratory System and the Heart Among Cobalt Production Workers. ACADEMIC DISSERTATION To be presented, with the permission of the Faculty of Medicine and Health Technology of Tampere University, for public discussion on 31 March 2023.