Nickel - Toxicology of Metals - page 729

agents include nickel, as well as other metals (arsenic,
cadmium, chromium, and beryllium) and organic
chemicals (benzene, 2-naphthyl-amine, vinyl chloride,
and 4-aminobiphenyl). Metals, including nickel, can
be accurately measured in tobacco by use of reverse-
phase HPLC with detection limits as low as 8 ng Ni/L
tobacco (Li et al ., 2002). The nickel content in cigarettes
and tobacco is reported to be high, 2.32-4.20 mg/kg
and 2.20-4.91 mg/kg, respectively, regardless of the
kind and the origin of tobacco (Stojanovic et al ., 2004).
Agricultural practices, soil characteristics such as
pH, and rainfall can infl uence metal accumulation in
tobacco and other plant leaves. In cigarette smoke, the
amount of nickel varies from 0-0.51

were exposed to concentrations in the range of 0.15-
1.2 mg/m 3 . In this factory, the levels of water-soluble
nickel were about the same for workers in the smelt-
ing, roasting, and electrolyte purifi cation departments.
In a recent evaluation of changes over time in exposure
to nickel aerosols in the nickel-producing and nickel-
using industries, signifi cantly negative linear trends for
total nickel exposures in the mining (−7%/year), smelt-
ing (−9%/year), and refi ning (−7%/year) sectors, but
not in total milling activities (+4%/year), were reported
(Symanski et al ., 2000).
Nickel fumes can also be released into industrial
atmospheres by stainless steel welding and welding
of high-nickel alloys. Metal inert gas (MIG) welding of
stainless steel produces fumes with 3-6.5% Ni and par-
ticle sizes less than 0.1

g/cigarette. How-
ever, atomic absorption analysis of nickel recovered on
fi lters from mainstream cigarette smoke showed only
1.1% of the nickel was found in the smoke, whereas
most of the tobacco nickel was recovered in the ash
(Torjussen et al ., 2003).

µ

m, whereas manual metal arch
(MMA) welding produces fumes with less nickel, 0.4- 1%,
and larger particle sizes >0.1

µ

m (Sunderman et al ., 1986).
However, MMA welding methods can generate 3-4 times
the volume of fumes than MIG methods.
The American Conference of Governmental and
Industrial Hygienists (ACGIH) threshold limit value
time-weighted average, TLV-TWA, for exposure to
nickel compounds is 1.5 mg/m 3 for elemental nickel,
0.1 mg/m 3 for soluble inorganic nickel compounds and
nickel subsulfi de, 0.2 mg/m 3 for insoluble inorganic
compounds, and 0.05 ppm for nickel carbonyl, although
nickel carbonyl is listed “understated” by ACGIH as of
January, 2005. The US Occupational Safety and Health
Administration (OSHA) permissible exposure limit
time-weighted averages, PEL-TWA, is set at 1 mg Ni/m 3
for soluble nickel compounds and 1 mg Ni/m 3 for metal-
lic nickel and insoluble nickel compounds (NIOSH,
2005a). The NIOSH recommended exposure limit (REL)
for elemental nickel and all nickel compounds exclud-
ing nickel carbonyl is much lower, 0.015 mg/m 3 . For
nickel carbonyl, the OSHA PEL-TWA and the NIOSH
REL are both set at 0.001 ppm (0.007 mg/m 3 ) (NIOSH,
2005b). This occupational exposure limit for nickel car-
bonyl has been adopted by numerous countries world-
wide, including, but not limited to, Sweden, Denmark,
Finland, the Philippines, Russia, and Japan (NIOSH,
2005c). International exposure limits for other nickel
compounds vary. For nickel carbonyl exposure to 2 ppm
is considered by NIOSH to be “immediately dangerous
to life and health.” For all other nickel compounds expo-
sure levels at 10 mg/m 3 are similarly hazardous.

µ

4.2 Working Environment
Occupational exposures to nickel occur in mines,
refi neries, smelters, factories and chemical plants, with
an estimated 0.2% of the workforce being exposed to
appreciable amounts of nickel (Grandjean, 1984). In
addition, workers can be exposed to nickel by han-
dling various nickel-plated tools, such as cutting tools.
In mining operations, the miners can be exposed to
high concentrations of respirable particles (<10 m)

at concentrations of 5 mg Ni/m 3 , with time-weighted
total nickel exposure from ambient air averaging 25 mg
Ni/m 3 (Warner et al ., 1984).
In the past, it was estimated that workers in the
nickel refi nery industry were exposed by inhalation to
concentrations of approximately 1 mg/m 3 of mixtures
of specifi c soluble and insoluble nickel compounds
(Morgan and Rouge, 1984), leading to the bodily
retention of perhaps up to 100

µ

g nickel/day (Grand-
jean, 1984). Actual levels of airborne nickel (stationary
sampling) in a Finnish refi nery were less, measured at
230-800

µ

g/m 3
since then (Kiilunen et al ., 1997). Inside the protective
masks used by some workers, the nickel concentrations
were even lower, 0.9-2.4

µ g/m 3 from 1966-1988 and at 170-460 µ

g/m 3 . In tasks where masks
were not used, the nickel concentrations in the breath-
ing zone were 1.3-21

µ

g/m 3 . In a recent evaluation of
occupational exposures of Norwegian nickel refi nery
workers on the basis of personal monitoring from 1973
to 1994 (Grimsrud et al ., 2000), the average concentra-
tion of nickel in breathing zones for all workers after
1978 was

µ

5 METABOLISM

5.1 Essentiality
Nickel is thought to be essential to animals
(reviewed in Anke et al ., 1984) in that low nickel

0.7 mg/m 3 . Before 1970, the exposure levels
for smelter and roaster day workers were 2-6 mg/m 3 ,
whereas electrolysis and electrolyte purifi cation workers

≤