Vanadium - Toxicology of Metals - page 890

of 4-140 ng V/g in hair and 4-625 ng/g for nails were
listed by the U.S. Environmental Protection Agency
(EPA, 1979). Kucera et al . (1992) did not fi nd a correla-
tion between vanadium concentrations in blood (0.042
ng V/mL) and hair (98 ng/g dry wt) in 17 nonexposed
children. On the basis of their results, a level of 30-100
µ

respiratory irritation and sporadic coughing that
started 5 hours after the challenge, became persistent
after approximately 12 hours, and lasted for 8 days
(Zenz and Berg, 1967). Exposure to a lower concentra-
tion (0.2 mg V/m 3 , 98% particles <5

m; for 8 hours,
5 subjects) had the same effect, but the induction time
for the persistent cough was longer (about 20 hours).
The highest concentration of vanadium in the urine
(0.13 mg V/L) and feces (0.3 mg/kg) of the subjects
was found after 3 days. Vanadium was not detected in
their blood. Concentrations of 0.1 mg V/m 3 caused no
irritation during 8 hours of exposure (two volunteers
not previously exposed), but the formation of mucus
was increased 24 hours later, increased further on the
second day, and disappeared after 4 days. There were
no alterations in pulmonary function tests or chest
X-ray; on re-exposure, respiratory irritation occurred
at this concentration. It was not possible to identify a
no observed adverse effect level (NOAEL) for bron-
chial effects in this study. The potential for vanadium
to produce skin irritation on direct contact is unclear.
No skin irritation was noted in 100 human volunteers
after skin patch testing with 10% V 2 O 5 in petrolatum
(HSE, 2002).

µ

g V/kg was suggested as the most typical value for
vanadium in hair. However, these authors proposed
that the vanadium hair level was not the best indica-
tor of environmental exposure to vanadium, because
vanadium may be leached out from the hair matrix
during washing. For reviews on reference values in
serum and tissue levels, the reader is referred to Byrne
and Kosta (1978), Nechay (1984), Cornelis et al . (1994),
and Sabbioni et al . (1996).

7 EFFECTS AND DOSE-RESPONSE
RELATIONSHIPS

Vanadium is essential for certain bacteria, marine
microalgae, lichen, and fungus (IPCS, 2001). In the 1970s,
vanadium was reported to be an essential trace element
for chicken and rats. These fi ndings have subsequently
been questioned, because the diets were unbalanced,
and the control diets contained small amounts of vana-
dium (Sabbioni et al ., 1996). However, other reports
have suggested that vanadium is essential for higher
animals (Arnold et al ., 1993). These studies showed
abnormalities in the bone structure in goat kids born
by females who had a long-term exposure to vana-
dium-defi cient diets. Anke (2004) recently published
a review on studies dealing with the essentiality of
vanadium.
Several vanadium-dependent enzymes have been
found in lower organisms; in mammals, a specifi c bio-
chemical function for vanadium has yet to be identifi ed.
The possibility has been considered that vanadium
might play a role in the regulation of Na + /K + exchang-
ing ATPase, phosphoryl-transfer enzymes, adenylate
cyclase, and protein kinases. The possible role of the
vanadyl ion in hormone, glucose, lipid, bone and tooth
metabolism has also been discussed (see IPCS, 2001;
Nechay, 1984; Rehder and Jantzen, 1998; WHO, 1996).

7.1.2.2 Occupational Exposure
Acute local effects of occupational exposure to
airborne vanadium compounds include irritation of
the respiratory tract and the eyes, and occasionally
skin manifestations. Mild effects are characterized by
sneezing, rhinitis, sore throat, dry or productive per-
sistent cough, chest pain, and conjunctivitis (Roshchin,
1968; Sjöberg, 1950). The signs and symptoms disap-
pear within 2-5 days. No quantitative data on the eye
irritation threshold for vanadium pentoxide dust are
available. However, exposure to a concentration of
0.018 mg/m 3 of V 2 O 5 is known to cause eye irritation.
Workers exposed to 1-5 mg/m 3 of V 2 O 5 developed der-
matitis, as well as conjunctivitis and tracheobronchitis
(OSHA, 1999). There was usually a latent period of 1-6
days before the effects; commonly, mucus formation
and persistent cough appeared (Roshchin, 1968; Wil-
liams, 1952). According to Lewis (1959b), acute effects
may occur at concentrations of V 2 O 5 as low as 0.1-1.0
mg/m 3 . In more severe cases, at concentrations of air-
borne vanadium up to > 10 mg/m 3 , bronchospasm
and bronchitis accompanied by wheezing and dysp-
nea, which also were reversible, were observed (Lewis,
1959b; Zenz et al ., 1962). Bronchopneumonia may result
from very high exposures (Roshchin, 1968; Sjöberg,
1950). In some cases, the severity of respiratory effects
increased with repeated exposure of shorter duration
and lower intensity, indicating a sensitization reaction

7.1 Local Effects and Dose-Response
Relationships
7.1.1 Human Studies

7.1.2.1 Experimental Exposure
Exposure of two healthy volunteers to vana-
dium pentoxide dust (1 mg/m 3 , 8 hours) produced