SAFE USE OF NICKEL IN THE WORKPLACE
Last Revised: 5/1997
3. SOURCES OF EXPOSURE
3.1 OCCUPATIONAL EXPOSURES
3.2 NON-OCCUPATIONAL EXPOSURES
3.3 REFERENCES
Given its many uses and applications, the potential for exposure to nickel, its compounds, and alloys is varied and wide ranging. Of main concern to this document are occupational exposures. Non-occupational exposures are briefly mentioned at the end of this section.
Although exposure to specific forms of nickel differs among using and producing industries, the main exposure routes of toxicological relevance - inhalation and, to a lesser extent, skin contact - are the same in both industries.
The wide range of occupations with direct exposure to nickel via these routes of exposure are summarized below within 12 different industrial sectors. These sectors are: (1) mining, (2) milling, (3) smelting, (4) refining, (5) stainless and alloy steel production, (6) nickel alloy production, (7) welding and hot cutting, (8) nickel plating, (9) production and blending of chemicals, (10) manufacturing of nickel catalysts, (11) manufacturing of nickel/cadmium batteries, and (12) other uses (including coinage, pigments, and powders). The first four sectors correspond to the nickel-producing industry, while the rest belong to the nickel-using industry.
Current exposures for all the industry sectors noted above are summarized in Table 3. Current data-generally acquired over the past 10 to 15 years, but occasionally representing data recorded since the late 1970s-typically represent actual measurements derived from standard procedures of 'total' aerosol sampling (e.g., through methods developed by the UK's Health and Safety Executive or the US' National Institute of Occupational Safety and Health). The data for this table come from a variety of sources including:
- published, peer-reviewed literature,
- company or agency reports which are in general circulation,
- company or agency internal reports which are not in general circulation but are accessible through those organizations,
- company or agency databases and log-books which may be obtained through direct personal contacts, and
- follow-up through direct personal contacts (where appropriate and feasible) to fill gaps in information relevant to the evaluation.
From this table, it can be seen that exposures in the nickel-producing sectors generally tend to be higher than in the using sectors, although there are some exceptions. For example, average exposures in mining tend to be relatively low (less than 0.15 mg Ni/m3), whereas average exposures in chemical blending and nickel catalyst production can sometimes exceed 1.0 mg Ni/m3.
It is also clear from Table 3 and the footnotes to this table that the range of exposures in any given industry sector varies widely (orders of magnitude). Workers employed in some jobs and activities in a sector with generally low exposures could well be exposed for days, weeks, or even years to levels of nickel aerosols well above those of some workers employed in another sector which experiences generally high exposures. Thus, it is unwise to regard occupational exposures within sectors as uniform among jobs, among workers within jobs, or within workers from day to day, without gathering further data on the particular industry sector of concern.
While it is clear that certain forms of nickel tend to predominate in different industry sectors (e.g., soluble nickel in plating), it appears that in no industry sector are workers exposed purely to one form of nickel. Hence, an understanding of the health effects of individual nickel species cannot be obtained from human data alone. Animal and human data, in conjunction with mechanistic studies, need to be considered as part of the weight-of-evidence required for determining species-specific occupational exposure limits. In addition, although little is currently known about the effects of particle size relative to speciation, it should be borne in mind that the size of the nickel particles to which workers are exposed is likely to play an important role in the biological effects of different nickel species. To the extent that such data are available, they are discussed below.
3.2 NON-OCCUPATIONAL EXPOSURES
Nickel is ubiquitous and can be found in ambient air, water, food, and soil. Some of this nickel is naturally occurring; however, some is introduced into the environment as a result of human activity. Human exposure to nickel can also occur through skin contact with nickel-containing articles, such as jewelry, through nickel-containing implants, through the leaching of nickel into dialysate fluids, and through tobacco smoke.
TABLE 3: SUMMARY OF CURRENT NICKEL EXPOSURES IN NICKEL-PRODUCING AND -USING INDUSTRIES
| Industry Sector | Range of Exposure Concentrations(mg Ni/m3) 1 | Range of Mean Aerosol Exposure Concentrations (mg Ni/m3) 1 | Predominant Species2 |
| Mining | 0-<1.0 | 0.003-0.15 | SU, O3 |
| Milling | 0.001-4.0 | 0.01-<0.70 | SU |
| Smelting | 0.001-77.04 | 0.01-<3.0 | SU, O3 |
| Refining | 0.001-20.05 | 0.003-~1.506 | SU, O, M, SO7 |
| Stainless & alloy steels | 0-<1.0 | 0.001-0.10 | O, M |
| Nickel alloy steels | 0.001-9.08 | 0.002-~0.509 | O, M |
| Welding & hot cutting | Trace-7.08 | 0.001-~0.510 | O, M11 |
| Nickel plating | Trace-~3.012 | 0.0004-~0.10 | SO13 |
| Production of chemicals | 0.001-~3.0 | 0.02-~1.50 | SO, O, M |
| Nickel catalysts | 0-26.014 | 0.004-~1.015 | SO, O, M16 |
| Ni-cadmium batteries | 0-~2.0 | 0.005-~0.50 | O, M, SO |
| Others | Trace-14.0 | Trace-0.517 | Mixed |
1 'Total' nickel, unless otherwise indicated.
2 M=metallic nickel, O=oxidic nickel, NC=nickel carbonyl, SU=sulfidic nickel, SO=soluble nickel salts.
3 Dependent upon the type of ore.
4 Upper limits of ranges for most data sources did not exceed 2.0 mg Ni/m3.
5 Upper limits of ranges for most data sources did not exceed 5.0 mg Ni/m3.
6 A few mean aerosol concentrations exceeded 1.5 mg Ni/m3. The highest mean value reported was
4.84 mg Ni/m3.
7 Dependent upon the operation and job.
8 Upper limits of ranges for most data sources did not exceed 1 mg Ni/m3.
9 A few mean aerosol concentrations exceeded 0.5 mg Ni/m3. The highest mean value reported was 3.2
mg Ni/m3.
10 A few mean aerosol concentrations exceeded 0.5 mg Ni/m3. The highest mean value reported was
3.58 mg Ni/m3.
11 In some instances, soluble nickel was noted to be present, although it was not the predominant form of
nickel found.
12 Upper ranges for most data sources did not exceed 1.0 mg Ni/m3.
13 In instances where speciation was conducted, insoluble nickel compounds were noted to be present although
they were not the predominant forms of nickel found.
14 Upper ranges for most data sources did not exceed 4.0 mg Ni/m3.
15 A few mean aerosol concentrations exceeded 1.0 mg Ni/m3. The highest mean value reported was
1.55 mg Ni/m3.
16 In addition to potential exposures to oxidic and/or metallic nickel species, sulfidic nickel is also
believed to be present in the spent nickel catalyst.
17 A few mean aerosol concentrations exceeded 0.5 mg Ni/m3. The highest mean value reported was
4.1 mg Ni/m3.
