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Exposure related observations in humans: other data

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Endpoint:
exposure-related observations in humans: other data
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2004-2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study had high or direct relevance to the Hazard or Risk Assessment of Ni Metal, and medium quality of exposure data. A detailed description of the scoring criteria and results can be found attached to IUCLID Section 7.10.5 – Exposure related observations in humans: other data.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Characterization and assessment of dermal and inhalable nickel exposures in nickel production and primary user industries.
Author:
Hughson GW, Galea KS, Heim KE
Year:
2010
Bibliographic source:
Ann. Occup. Hyg. 54(1):8-22.

Materials and methods

Type of study / information:
Occupational dermal and inhalation exposure data as measured by personal monitoring.
Endpoint addressed:
not applicable
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Workplace surveys were carried out in five different European workplaces, including three nickel refineries, a stainless steel plant, and a powder metallurgy plant. Personal samples of dust were collected to determine the corresponding dermal and inhalable nickel exposures. The wipe and air samples were analyzed for total inhalable dust and then for soluble, sulfidic, metallic, and oxidic nickel species.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Ethical approval:
not specified
Details on study design:
Sampling: Exposure measurements were collected for several areas/tasks in each of 5 workplaces: three nickel refineries, one stainless steel plant, and one powder metallurgy facility that produced AlNiCo magnets. Most refinery tasks were highly automated and, in many instances, supervised or operated by a small number of individuals. Some manual tasks were undertaken, for example, cleaning, mechanical repairs to the production equipment, transferring products, and removing and tying bags during powder filling tasks. The electro-winning task at Refinery 1 involved significant manual involvement during removal of cathodes from the electrolysis tanks. A variety of ventilation, respiratory protective equipment (RPE) and personal protective equipment (PPE), and hygiene measures were used at the sites visited. In general, these were considered to be adequate, but there were instances where the operators did not always use the recommended RPE and PPE, including gloves. Due to the high level of automation and the small number of workers available for sampling, it was necessary to collect repeat samples from some workers over consecutive days to obtain more measurements for each task. Since the purpose of the study was to obtain measurements for specific process-task categories, the data were first grouped into seven specific categories, based on the type of process and the nickel-containing material being used.
Exposure assessment:
measured
Details on exposure:
TYPE OF EXPOSURE: dermal and inhalation

TYPE OF EXPOSURE MEASUREMENT: Personal sampling

Dermal Sampling Method: Dermal exposure measurements were obtained using a removal method, i.e. samples were collected from the skin contaminant layer at predetermined anatomical locations. The dermal exposure samples were collected using commercial moist wipes using a template with an open aperture of 25 cm2 pressed onto the skin. Each area of skin was wiped with three sequential wipes and a clean template was used on each occasion. For each subject, samples were collected on three separate occasions during the working day, i.e. before break times and at the end of the shift. Workers were instructed not to wash their hands until after the sampling was done. For each of these three sampling periods, the palms and backs of both hands and both forearms were sampled. At the last sampling period, additional samples were collected from the neck, face (perioral region), and chest. It was not possible to use the template for sampling the perioral region, but this area was estimated to be equivalent to 25 cm2. A total of 12 individual dermal samples and one field blank sample were collected for each worker per shift. The field blank was collected to check for adventitious contamination and comprised three wipes that were handled in the same way as the exposure samples but were not wiped over the workers' skin.

Analysis of Dermal Samples: All wipe samples were transferred to the laboratory in 250-ml wide-neck glass jars. The wipes contained in each sample jar were analysed to determine the soluble and insoluble nickel content. Firstly, the samples were treated with 0.1 M ammonium citrate to dissolve any soluble nickel species. The wipes in each sample container were covered with the ammonium citrate and left to soak for 3 h. The resultant solution was vacuum filtered through a 1-μm membrane filter and then made up to 100 ml using deionized water in a volumetric flask. The filtrate was therefore assumed to contain the soluble nickel fraction. Secondly, the filter and remainder of the wipes were covered with 10% nitric acid, heated to near boiling point for 3 h, cooled, vacuum filtered, rinsed and then made up to 100 ml volume. This portion was assumed to comprise the insoluble nickel fraction. It should be noted henceforth that the terms 'soluble' and 'insoluble' nickel refer to their solubility in 0.1 M ammonium citrate solution and solubility tests in other liquids may of course produce different results.

All dermal exposure samples were analysed for nickel by the Institute of Occupational Medicine (IOM) using inductively coupled plasma atomic emission spectroscopy in accordance with a documented in-house method, based on Occupational Safety and Health Administration (OSHA) method 121. All sample masses were blank corrected by subtracting any nickel detected on laboratory blanks and field blanks. The analytical recovery was checked by analysing blank wipe samples spiked with known masses of nickel for each batch of samples analysed. A correction was therefore applied to exposures sample measurements to adjust for incomplete analytical recovery. All dermal exposure results are expressed as a skin surface loading (μg/cm2 for both soluble and total nickel content). The total nickel content was derived from the sum of the soluble and insoluble nickel measurements. The skin surface loading for each sample was calculated and an average of each set of three was calculated as an estimate of average daily exposure. A skin surface loading for the combined surfaces of the hands and forearms was also calculated for comparison with predicted exposures obtained from the EASE model, using the mean surface areas for hands (840 cm2) and the forearms (1140 cm2). These surface areas were used in preference to the corresponding European Centre for Ecotoxicology and Toxicology of Chemicals values because they corresponded to the surface areas previously used in the EU risk assessment and Technical Guidance Document.

Sampling and Analysis of Inhalable Dust and Nickel Compounds: Inhalable dust sampling was carried out using personal sampling apparatus in accordance with Health and Safety Executive method MDHS 14/3. This involved using an IOM inhalable dust sampler loaded with a pre-weighed cassette containing a 25-mm quartz fiber filter. The quartz fiber filters used for the air sampling were chosen for compatibility with the analytical procedure. The sampling apparatus was fitted to the worker near the start of the working shift and left running for the majority of the working day so that the inhalation exposures could be considered to be representative of average full-shift exposures.

After sampling, the IOM cassettes were reweighed to determine the total inhalable dust concentration and the samples were then shipped to INCO Technical Services, Ltd, Mississauga, Ontario, Canada, for analysis of soluble/insoluble nickel species. The speciation method is based on sequential leaching of the dust sample with reagents of increasing chemical power to release nickel ions into solution. Three selective leaches, utilizing in order of increasing power, ammonium citrate/citric acid solution, hydrogen peroxide-ammonium citrate, and bromine-methanol solutions, were followed by decomposition of the final leach residue with nitric and perchloric acids. The resulting four solutions were then analyzed using atomic absorption spectrometry, providing measurements of four different nickel species: soluble nickel, sulfidic, metallic, and oxidic nickel, respectively. This enabled airborne measurements for each of the different nickel species to be obtained. Measurement of total airborne nickel exposure was calculated for each sample by taking the sum of the masses of the different nickel species.

EXPOSURE PERIOD: 8 h work day

DESCRIPTION / DELINEATION OF EXPOSURE GROUPS / CATEGORIES:
1. Front-end refinery processes (raw material handling/ leaching)
2. Electro-winning/electrolysis (nickel in solution)
3. Packing solid nickel metal products (cutting nickel cathodes and packing nickel briquettes)
4. Packing nickel compounds (soluble nickel salts)
5. Packing nickel metal powders (insoluble nickel powder)
6. Powder metallurgy (magnet production)
7. Stainless steel production

Statistical Analysis: Since the purpose of the survey was to identify exposure levels for certain job types and production processes, the exposure data were firstly grouped into specific process-task categories based on the type of nickel product being used and the industry sector being considered. The soluble and total nickel dermal exposure data for each process-task category were summarized in terms of the number of measurements (n), median, geometric mean (GM), geometric standard deviation (GSD), and the range (maximum and minimum values). The inhalation exposure data for each category were also summarized in this manner for total inhalable dust and total inhalable nickel. The data were tested for normality and log transformed where appropriate. Summary statistics were obtained using Microsoft Excel 2003 and box-whisker plots were produced using SigmaPlot version 11. Correlations between log-transformed dermal exposure and inhalable dust concentrations were investigated by calculating the Pearson correlation coefficient using SigmaPlot version 11. To aid the statistical analysis of the data, sample results that were below the limit of detection (LOD) were set to half the LOD.

Results and discussion

Results:
1. Dermal Soluble Nickel Exposures (n, median, GM, GSD, Range) (μm/cm2)

Front-end refinery:
Hands and forearms – 6, 0.24, 0.24, 1.5, 0.14-0.48
Neck – 6, 0.21, 0.14, 4.4, <0.02-0.61
Face – 6, 0.62, 0.7, 1.5, 0.47-1.51
Chest – 6, 0.24, 0.15, 4.1, <0.02-0.44

Electro-winning/electrolysis:
Hands and forearms – 12, 0.31, 0.34, 2.2, 0.12-1.78
Neck – 12, 0.17, 0.16, 4.7, <0.02-1.39
Face – 12, 0.49, 0.24, 5.6, <0.02-1.54
Chest – 12, 0.05, 0.04, 3.4, <0.02-0.21

Packing nickel metal products:
Hands and forearms – 7, 0.26, 0.27, 1.9, 0.10-0.94
Neck – 7, 0.33, 0.24, 2.3, 0.09-0.83
Face – 7, 0.7, 0.55, 1.9, 0.24-1.18
Chest – 7, 0.04, 0.05, 5.4, <0.02-0.4

Packing nickel compounds:
Hands and forearms – 14, 0.54, 0.61, 3.0, 0.08-3.52
Neck – 14, 0.49, 0.27, 3.9, <0.02-1.92
Face – 14, 0.75, 0.47, 5.9, <0.02-2.55
Chest – 14, 0.24, 0.14, 7.0, <0.02-5.77

Packing nickel powder:
Hands and forearms – 7, 2.61, 2.59, 1.6, 1.12-4.72
Neck – 6, 2.18, 2.03, 1.9, 0.69-4.27
Face – 6, 4.17, 3.29, 2.0, 1.28-7.29
Chest – 6, 0.77, 1.05, 2.4, 0.44-3.37

Powder metallurgy (magnet production):
Hands and forearms – 8, 0.12, 0.08, 3.4, <0.02-0.32
Neck – 8, 0.17, 0.08, 6.5, <0.02-1.39
Face – 8, 0.17, 0.18, 8.1, <0.02-2.15
Chest – 8, 0.1, 0.08, 4.6, <0.02-0.67

Stainless steel production:
Hands and forearms – 13, 0.01, 0.02, 1.8, <0.02-0.05
Neck – 13, 0.04, 0.03, 3.8, <0.02-0.37
Face – 13, 0.03, 0.03, 3.3, <0.02-0.2
Chest – 13, 0.01, 0.02, 3.0, <0.02-0.18

2. Dermal Total Nickel Exposures (n, median, GM, GSD, Range) (μm/cm2)

Front-end refinery:
Hands and forearms – 6, 0.61, 0.75, 2.4, 0.29-2.55
Neck – 6, 0.48, 0.43, 1.9, 0.16-0.97
Face – 6, 1.57, 1.83, 3.0, 0.48-6.91
Chest – 6, 0.41, 0.54, 2.3, 0.24-1.6

Electro-winning/electrolysis:
Hands and forearms – 12, 0.63, 0.56, 2.5, 0.16-3.19
Neck – 12, 0.26, 0.25, 4.3, <0.02-2.21
Face – 12, 0.58, 0.39, 5.4, <0.02-4.32
Chest – 12, 0.06, 0.06, 2.9, <0.02-0.24

Packing nickel metal products:
Hands and forearms – 7, 0.85, 1.17, 2.6, 0.62-9.12
Neck – 7, 1.65, 1.18, 4.0, 0.1-5.39
Face – 7, 2.47, 2.99, 3.2, 0.55-16.2
Chest – 7,0.63, 0.28, 8.3, <0.02-2.87

Packing nickel compounds:
Hands and forearms – 14, 0.85, 1.17, 4.0, 0.11-13.43
Neck – 14, 0.74, 0.49, 2.7, 0.08-2.43
Face – 14, 1.08, 0.73, 4.9, <0.01-3.12
Chest – 14, 0.35, 0.27, 5.2, <0.02-6.23

Packing nickel powder:
Hands and forearms – 7, 8.4, 8.73, 1.8, 3.1-17.49
Neck – 6, 6.16, 6.2, 1.5, 3.67-10.23
Face – 6, 17.41, 15.16, 2.3, 3.87-44.51
Chest – 6, 1.37, 1.56, 2.3, 0.51-4.49

Powder metallurgy (magnet production):
Hands and forearms – 8, 1.87, 1.69, 5.2, 0.1-25.33
Neck – 8, 0.65, 0.38, 6.8, <0.02-4.34
Face – 8, 1.82, 1.54, 7.4, 0.13-33.23
Chest – 8, 0.28, 0.4, 7.1, <0.02-4.56

Stainless steel production:
Hands and forearms – 13, 0.08, 0.11, 2.7, <0.02-0.84
Neck – 13, 0.14, 0.13, 3.2, <0.02-0.66
Face – 13, 0.22, 0.14, 3.5, <0.02-0.84
Chest – 13, 0.12, 0.10, 3.8, <0.02-1.33

Inhalable total nickel exposures (n, median, GM, GSD, Range) (mg/m3):

Front-end refinery – 6, 0.16, 0.13, 2.3, 0.05-0.4
Electro-winning/electrolysis – 12, 0.04, 0.04, 3.0, 0.01-0.18
Packing nickel metal products – 7, 0.1, 0.08, 3.3, 0.01-0.34
Packing nickel compounds – 12, 0.02, 0.02, 2.6, 0.01-0.1
Packing nickel powders – 7, 0.81, 0.77, 3.0, 0.13-2.81
Powder metallurgy (magnet production) – 8, 0.03, 0.5, 3.9, 0.01-0.36
Stainless steel production – 10, 0.04, 0.03, 2.3, 0.01-0.12

Airborne nickel species - soluble, sulfidic, metallic, oxidic [GM (GSD)]

Front-end refinery (n=6)– 25 (1.6), 44 (1.5), 3 (6.8), 13 (3.1)
Electro-winning/electrolysis (n=12) – 82 (1.5), 1 (8.7), <1 (6.3), 1 (9.5)
Packing nickel metal products (n=7) – 21 (1.5), 1 (7.0), 30 (1.2), 41 (1.4)
Packing nickel compounds (n=12) – 76 (1.3), 2 (12), <1 (1.0), 3 (12)
Packing nickel powders (n=7) – 2 (2.3), 1 (2.1), 33 (1.5), 60 (1.3)
Powder metallurgy (magnet production) (n=8) – 1 (10), 3 (6.3), 42 (2.1), 35 (1.4)
Stainless steel production (n=10) – 1 (10), 1 (8.8), <1 (7.2), 89 (1.1)

Any other information on results incl. tables

Not applicable.

Applicant's summary and conclusion

Conclusions:
The authors concluded that the nickel powder packers and all the workers in the powder metallurgy plant were exposed mainly to metallic and other relatively insoluble nickel-containing species (e.g. oxidic nickel and nickel alloys). Workers involved with packing solid nickel metal products (cathode cutting operators and nickel briquette workers) were also exposed mainly to metallic and oxidic nickel species but also had some soluble nickel present.
Executive summary:

Study rated by an independent reviewer.