Academic journal article Iranian Journal of Public Health

Evaluation of Occupational Exposure of Glazers of a Ceramic Industry to Cobalt Blue Dye

Academic journal article Iranian Journal of Public Health

Evaluation of Occupational Exposure of Glazers of a Ceramic Industry to Cobalt Blue Dye

Article excerpt


Background: Cobalt is one of the most important constituent present in ceramic industries. Glazers are the relevant workers when they are producing blue colored ceramic, causing occupational exposure to such metal. Through this study, urinary cobalt was determined in glazers in a ceramic industry when they were producing blue-colored ceramic glazes.

Methods: In this case-control study, spot urine samples were collected from 49 glazers at the start and end of work shifts (totally 98 samples) in 2011. Control group were well matched for age, height, and weight. A solid phase extrac-tion system was used for separation and preconcentration of samples followed by analysis by inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

All participants filled out a self administered questionnaire comprises questions about duration of exposure, work shift, use of mask, skin dermatitis, kind of job, ventilation system, overtime work, age, weight, and height. The lung function tests were performed on each control and cobalt exposed subjects. Analysis of covariance (ANCOVA) was used to evaluate the obtained results.

Results: Urinary levels of cobalt were significantly higher in the glazers compared to the control group. There were significant differences at urinary concentration of cobalt at the start and end of the work shiftin glazers. Spirometric parameters were significantly lower in the glazers compared to the control group. Among the variables used in ques-tionnaire the significant variables were dermatitis skin, mask, ventilation, and overtime work.

Conclusion: This study verified existence of cobalt in the urine glazers, showing lower amount than the ACGIH standard.

Keywords: Urine cobalt, Glaze, Spirometry, Inductively coupled plasma-atomic emission, Spectroscopy


Production of blue colored ceramic in glaze industry is of important concern for structuring of floors and walls. Cobalt ion plays a main role to produce blue color in ceramic industries. This is because cobalt has mobile 3d electrons in its atomic structure (1). The main component, such as silica, present in ceramic are similar to glass, causing both favorite melting point and color (2, 3). Water is added to glaze for producing a cream suspension solution. This solution then is applied to a day body at increasing temperature up to 1300°C. Therefore, an interface layer is made up by glaze and clay body interaction, then, glaze is adhered to the clay (2, 3). Finally, color is occurred on glaze in result of high temperature reaction. In such process, cobalt toxicity is taken place when glazers are exposed to the cobalt in powder form. To prevent adverse effect of cobalt, such as, gamut of respiratory disorders, asthma, and also lung cancer, occupational exposures are of great concern in the ceramic industries (2, 3).

Cobalt is not a cumulative toxicant and is mainly excreted in urine to a lesser extent via faces. Cobalt in blood and urine mainly shows the exposure already occurred. The two main target organs are the skin and the respiratory tract (4). Cobalt is the critical toxic component causing hard metal lung disease (5) that is a rare form of occupational lung disease that can occur in workers engaged in the manufacture, utilization, or maintenance of tools hard metal. Cobalt may cause allergic dermatitis (6-9), cardiomyopathy (10, 11) and asthma (7,1215). Exposure to cobalt leads to severe alterations in capillaries, edema and hemorrhage of lung in experimental animals (16).

In hard metal industries such as cobalt, occupational asthma is characterized by wheezing cough, and contact dermatitis characterized by erythematous papules. The International Agency for Research on Cancer (IARC) recently has classified cobalt and cobalt compounds as possibly carcinogenic to humans (Class 2B) (17).

The objectives of this study were to determine the cobalt level in urine of glazers of a ceramic industry and also to find out whether a relationship exists between factors including duration of exposure, work shift breathing masks, skin dermatitis, overtime work, ventilation, age, weight, height, and the urinary concentration of cobalt. …

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