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Toxicological information

Health surveillance data

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Administrative data

Endpoint:
health surveillance data
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Reliability:
other: Human investigations associated with toxicokinetic issues are briefly summarised below. Reliability scores were not assigned, since these are strictly not considered applicable to human information.
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The references contained in this summary entry represent monitoring data of the occupational population with very limited value for risk assessment purposes, due to the following reasons. Urinary biomonitoring has been used in several cobalt producing or processing industries. However, the correlation between inhalation exposure and urinary excretion is not straightforward. This is likely due to several factors, among them differences in bioavailability of the particular cobalt substance handled, as well as variance in personal hygiene management between individual workers, for example involving inadvertent oral exposure from hand-to-mouth transfer. Nevertheless, based on the toxicokinetic profile of cobalt, urinary biomonitoring appears to be a valuable tool in the assessment of systemic exposure.

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Absorption and excretion of cobalt in the hard metal industry
Author:
Scansetti, G. et al.
Year:
1994
Bibliographic source:
Sci. Total Environ. 150, 141-144
Reference Type:
publication
Title:
Urinary cobalt excretion in short time occupational exposure to cobalt powders
Author:
Apostoli, P. et al.
Year:
1994
Bibliographic source:
Sci. Total Environ. 150, 129-132
Reference Type:
publication
Title:
Urinary cobalt as a measure of exposure in the wet sharpening of hard metal and stellite blades
Author:
Linnainmaa, M.; Kiilunen, M.
Year:
1996
Bibliographic source:
Int. Arch. Occup. Environ. Health 69, 193-200
Reference Type:
publication
Title:
Accumulation of metals in the tissues of occupationally exposed workers
Author:
Hewitt, P.J.
Year:
1988
Bibliographic source:
Environ. Geochem. Health 10, 113–116
Reference Type:
publication
Title:
Cobalt concentration in whole blood and urine from pottery plate painters exposed to cobalt paint
Author:
Christensen, J.; Mikkelsen, S.
Year:
1985
Bibliographic source:
Int. Conf. Heavy Metals in the Environment, 86-89
Reference Type:
publication
Title:
Chromium, cobalt and lanthanum in lung, liver and kidney tissue from decreased smelter workers
Author:
Gerhardsson, L. et al.
Year:
1984
Bibliographic source:
Sci. Total Environ. 37, 233-246
Reference Type:
publication
Title:
Studies on exposure to cobalt in different branches of industry (in German)
Author:
Hartung, M. et al.
Year:
1983
Bibliographic source:
Arbeitsmed. Sozialmed. Praventivmed. 4, 73-75
Reference Type:
publication
Title:
Distribution of 24 elements in the internal organs of normal males and the metallic workers in Japan
Author:
Teraoka, H.
Year:
1981
Bibliographic source:
Arch. Environ. Health 36, 155–165

Materials and methods

Endpoint addressed:
basic toxicokinetics
Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
STUDY 1: Urine biomonitoring was implemented in hard metal workers.STUDY 2: Urine biomonitoring was implemented of workers which were involved in cobalt sintering operations (tool manufacturing).STUDY 3: Urine biomonitoring was implemented in workers manufacturing and maintaining hard metal tools.STUDY 4: Post-mortem tissue analysis (lung) for cobalt and other metals was implemented in metal refining workers.STUDY 5: Blood and urine biomonitoring was implemented of pottery plate painters.STUDY 6: Post-mortem cobalt tissue levels (lung, liver, kidney) were analysed in smelter workers.STUDY 7: Urinary biomonitoring was implemented in workers (n=94) from five different industrial sectors (hard metal, dental laboratories, porcelain manufacture, chemical production, cobalt metal production).STUDY 8: Cobalt levels in post-mortem tissue samples from healthy individuals (n=12) were compared with those of metal workers (n=7) involved in chrome plating, chromate refining, painting or stonemason operations.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Type of population:
occupational
Details on study design:
STUDY 1: Absorption and excretion of cobalt in the hard metal industry was investigated by means of ambient air and urine measurements in three factories with high levels of environmental cobalt pollution.STUDY 2: Urine samples of workers in two different plants were analysed for cobalt concentration.STUDY 3: The concentration of urinary cobalt as an estimator of exposure to airborne cobalt was analysed from workers which were exposed to hard metal dust.STUDY 4: Lung samples and other tissues from workers and control subjects were analysed post-mortem to assess the accumulation of metals. STUDY 5: Concentration of cobalt in urine samples of two different group of workers which are exposed to cobalt and one control group were analysed with atomic absorption spectrophotometry.STUDY 6: The concentration of cobalt in samples of different tissues were analysed after autopsies of 66 deceased copper smelter workers and compared with 14 controls.STUDY 7: Urine samples were collected from workers from five different industrial sectors were collected and analysed with atomic absorption spectrophotometry.STUDY 8: Concentration of 24 elements in the internal organs from metallic workers and control subjects were analysed with spectrographic method after post-mortem autopsies.

Results and discussion

Results:
STUDY 1:The relationship between workplace air monitoring and urine biomonitoring was not straightforward; dermal exposure and inadvertent oral intake are discussed as “confounding” factors.STUDY 2: The aim of the study was not to examine the relationship between workplace air monitoring and urine biomonitoring but to evaluate problems encountered in biological monitoring. It could however be shown that cobalt in urine rapidly increased after exposure and decreased in the following days, but the pattern was independent of the degree of exposure. A relationship between the level of inhalation exposure and cobalt in urine was not established in the study.STUDY 3:The authors conclude that urinary cobalt can be used to assess workers’ exposure to airborne cobalt when wet-tip grinding processes are used. The coefficient of correlation was 0.753. It was stated that smoking and personal hygiene affected urinary cobalt concentration and that high concentrations of cobalt were found in coolants contaminating workers’ skin. Cobalt in air measurements during grinding (wet process) of hard metal or stellite blades seem to be relatively low (results only provided graphically, all values seem to be below 100 µg/m³). The correlation coefficient in this study is different compared to other studies and dermal exposure and inadvertent oral intake from contaminated skin in this study is very likely. In addition, there was a statistically significant difference shown in urinary cobalt concentrations between smokers and non-smokers, indicating defects in personal hygiene and oral intake from contaminated skin.STUDY 4: It is shown that tissue concentrations of cobalt (in freeze dried lung tissue) from South Wales miners are above the concentration ranges in controls. However, information on exposure levels, use of personal protective equipment, etc. is not provided in the study.STUDY 5: Pottery painters exposed to soluble cobalt paint, slightly soluble cobalt paint and controls without cobalt exposure were studied. A linear relationship between blood cobalt and creatinine corrected urine cobalt was found (r=0.82, p<0.001) when handling soluble cobalt paint. Improvement of exhaustion only slightly reduced urinary and blood cobalt levels in this case although levels in air decreased from 0.07 8.61 mg/m³ to about 0.05 mg/m³. When handling slightly soluble cobalt paints, cobalt concentrations were only slightly increased demonstrating the importance of the chemical composition.STUDY 6: Tissue from deceased copper smelter workers was examined, showing twofold increase of cobalt in lung tissues compared to controls. The authors state that the concentration of cobalt in lung tissues did not decline with time after exposure had ended, indicating a long biological half-time. The concentration of cobalt in lung tissue did not differ between workers with lung cancer compared to other workers. The cobalt concentrations in liver and kidney did not differ significantly between workers and controls.STUDY 7: The use of specific techniques in the industry sectors (grinding under wet or dry conditions, powder handling, spraying of solutions, mixing of pastes) lead to different cobalt exposure levels via inhalation. Although external cobalt exposure levels are detectable in all 5 examined industry sectors, these lead to relevant internal cobalt exposure levels in only 3 sectors. A relationship between external and internal cobalt exposure could not be shown and the authors assume that this is caused by the quality of dust and bioavailability of cobalt in dust.Hard metal grinding is conducted under wet conditions, accumulating cobalt in grinding water and in aerosols. In dental laboratories, grinding of cobalt containing dental prostheses is conducted under dry conditions. Spraying of cobalt-containing solutions and mixing of cobalt containing materials and pastes is done in porcelain manufacture. During chemical production exposure to cobalt dust may occur and during cobalt metal production, hot-metallurgical processes are also relevant.STUDY 8: In the study, higher cobalt concentrations are exclusively mentioned for the lung tissue in airplane painters. Information on external cobalt levels, cobalt content in handled paints, etc. is not provided.

Applicant's summary and conclusion