Vanadium pentoxide

a high vanadium content. Recent data from rural areas show concentrations ranging from

0.3 to about 5 ng/m

3

, with annual averages frequently below 1 ng/m

3

, which can be

regarded as the natural background concentration in rural areas (Mamane & Pirrone, 1998).

Annual average concentrations of vanadium in air in large cities may often be in the

range of 50–200 ng/m

3

, although concentrations exceeding 200–300 ng/m

3

have been

recorded, and the maximum 24-h average may exceed 2000 ng/m

3

(WHO, 1988). In the

USA, cities can be divided into two groups based on the concentrations of vanadium

present in their ambient air. The first group consists of cities widely distributed throughout

the USA and characterized by vanadium concentrations in ambient air that range from 3

to 22 ng/m

3

, with an average of 11 ng/m

3

. Cities in the second group, primarily located in

the north-eastern USA, have mean concentrations of vanadium that range from 150 to

1400 ng/m

3

, with an average of about 600 ng/m

3

. The difference is attributed to the use of

large quantities of residual fuel oil in cities in the second group for the generation of heat

and electricity, particularly during winter months (Zoller et al., 1973; WHO, 2000). Vana-

dium concentrations in ambient urban air vary extensively with the season. However,

there are indications that vanadium concentrations in urban locations in 1998 were lower

than those reported in the 1960s and 1970s (Mamane & Pirrone, 1998).

Hence, the general population may be exposed to airborne vanadium through inha-

lation, particularly in areas where use of residual fuel oils for energy production is high

(Zoller et al., 1973). For instance, assuming vanadium concentrations in air of approxi-

mately 50 ng/m

3

, Byrne and Kosta (1978b) estimated a daily intake of 1 

µg vanadium by

inhalation.

(b)

Water

Vanadium dissolved in water is present almost exclusively in the pentavalent form. Its

concentration ranges from approximately 0.1 to 220 

µg/L in fresh water and from 0.3 to

29 

µg/L in seawater. The highest concentrations in fresh waters were recorded in the vici-

nity of metallurgical plants or downstream of large cities (WHO, 1988; Bauer et al.,

2003). Anthropogenic sources account for only a small percentage of the dissolved vana-

dium reaching the oceans (Hope, 1994).

(c)

Food

Vanadium intake from food has been reasonably well established, based on the ana-

lysis of dietary items (Myron et al., 1977; Byrne & Kosta, 1978b; Minoia et al., 1994) and

total diets (Myron et al., 1978; Byrne & Kucera, 1991a). Considering consumption of

about 500 g (dry mass) total diet, daily dietary vanadium intake in the general population

has been estimated at 10–30 

µg per person per day, although it can reach 70 µg per day

in some countries (Byrne & Kucera, 1991a).

An increased daily intake of vanadium may result from the consumption of some

wild-growing mushrooms (Byrne & Kosta, 1978b) and some beverages (Minoia et al.,

1994), especially beer. Contamination of the marine environment with oil in the Gulf War

resulted in increased concentrations of vanadium in certain seafood (WHO, 2001).

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Considering the poor absorption of vanadium from the gastrointestinal tract, dietary

habits can be expected to have only a minor influence on vanadium concentrations in

body fluids (WHO, 1988; Sabbioni et al., 1996) (see Section 4.1).

1.4

Regulations and guidelines

Occupational exposure limits and guidelines for vanadium pentoxide in workplace air

are presented in Table 3.

ACGIH Worldwide

®

(2003) recommends a semi-quantitative BEI for vanadium in

urine of 50 

µg/g creatinine. ACGIH recommends monitoring vanadium in urine collected

at the end of the last shift of the work week as an indicator of recent exposure to vanadium

pentoxide. Germany recommends a biological tolerance value for occupational exposure

for vanadium in urine of 70 

µg/g creatinine. Germany also recommends monitoring vana-

dium in urine collected at the end of the exposure, for example at the end of the shift or,

for long-term exposures, after several shifts (Deutsche Forschungsgemeinschaft, 2002).

2.

Studies of Cancer in Humans

No data were available to the Working Group.

3.

Studies of Cancer in Experimental Animals

3.1

Inhalation exposure

3.1.1

Mouse

In a study undertaken by the National Toxicology Program (2002), groups of 50 male

and 50 female B6C3F

1

mice, 6–7 weeks of age, were exposed to vanadium pentoxide

particulate (light orange, crystalline solid; purity, 

≈ 99%; MMAD, 1.2–1.3 µm; GSD,

1.9

µm) at concentrations of 0, 1, 2 or 4 mg/m

3

by inhalation for 6 h per day on 5 days per

week for 104 weeks. Survival was significantly decreased in males exposed to 4 mg/m

3

compared with chamber controls (survival rates: 39/50 (control), 33/50 (low concen-

tration), 36/50 (mid concentration) or 27/50 (high concentration) in males and 38/50,

32/50 30/50 or 32/50 in females, respectively; mean survival times, 710, 692, 704 or 668

days in males and 692, 655, 653 or 688 days in females, respectively). Mean body weights

were decreased in females exposed to 

≥ 1 mg/m

3

and in males exposed to 

≥ 2 mg/m

3

.

Exposure to vanadium pentoxide caused an increase in the incidence of alveolar/

bronchiolar neoplasms, but did not cause an increased incidence of neoplasms in other

tissues. The incidence of neoplasms and non-neoplastic lesions of the respiratory system

VANADIUM PENTOXIDE

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