Vanadium pentoxide

authors determined vanadium concentrations in the urine of a subgroup of workers (Hauser

et al., 1998; see Table 2).

In another study of boilermakers overhauling an oil-fired boiler in the USA, lower

exposures to PM

10

particulates and to respirable vanadium-containing dust were reported

(median, 0.6 mg/m

3

and 12.7 

µg/m

3

, respectively) (Woodin et al., 1999).

The National Institute of Occupational Safety and Health in the USA conducted

surveys on exposure to vanadium pentoxide in the industry. The National Occupational

Hazard Survey, conducted in 1972–74, estimated that 2562 workers in 333 plants were

potentially exposed to vanadium pentoxide in 1970. The largest number of workers

exposed worked in the stone, clay and glass products industries, and the second largest

group was involved with electric, gas and sanitary services (National Institute for Occu-

pational Safety and Health, 1976). The National Occupational Exposure Survey, con-

ducted in 1980–83, reported that approximately 5319 workers in 151 plants were poten-

tially exposed to vanadium in 1980. Among them, 84% were exposed specifically to vana-

dium pentoxide. The largest number of workers were exposed in the chemical and allied

products industry (National Institute for Occupational Safety and Health, 1984). 

Workers in the manufacture of vanadium-containing pigments for the ceramics

industry may be exposed to vanadium compounds. Exposure is controlled by the use of

local exhaust ventilation, and data indicate that vanadium concentrations in air are

normally below 0.2 mg/m

3

(total inhalable fraction) (WHO, 2001).

Other reports of occupational exposures to vanadium have been reviewed (Zenz,

1994).

1.3.3

Environmental exposure

(a)

Air

(i)

Natural sources

Natural sources of atmospheric vanadium include continental dust, marine aerosols

(sea salt sprays) and volcanic emissions. The quantities entering the atmosphere from each

of these sources are uncertain; however, continental dust is believed to account for the

largest portion of naturally-emitted atmospheric vanadium; contributions from volcanic

emissions are believed to be small (Zoller et al., 1973; Byerrum et al., 1974). Atmospheric

emissions of vanadium from natural sources had been estimated at 70 000 to 80 000 tonnes

per year. However, more recent estimates report much lower values (1.6–54.2 tonnes per

year) and suggest that fluxes from natural sources were overestimated by earlier workers

(Mamane & Pirrone, 1998; Nriagu & Pirrone, 1998).

Concentrations of vanadium in the atmosphere in unpopulated areas such as Antarctica

have been found to range from 0.0006 to 0.0024 ng/m

3

(Zoller et al., 1974). Measurements

taken over the eastern Pacific Ocean averaged 0.17 ng/m

3

(range of means, 

≤ 0.02–

0.8 ng/m

3

) (Hoffman et al., 1969). Measurements over rural north-western Canada and

Puerto Rico were one order of magnitude higher (0.2–1.9 ng/m

3

) (Martens et al., 1973;

Zoller et al., 1973).

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(ii)

Anthropogenic sources

Estimates of global anthropogenic emissions of vanadium into the atmosphere over the

last decade range from 70 000 tonnes to 210 000 tonnes per year (Hope, 1994; Mamane &

Pirrone, 1998; Nriagu & Pirrone, 1998). 

The major point sources are metallurgical works (30 kg vanadium/tonne vanadium

produced), and coal and residual oil burning (0.2–2 kg vanadium/1000 tonnes and

30–300 kg/10

6

L burnt, respectively) (Zoller et al., 1973; Lagerkvist et al., 1986). Crude

oils have an average vanadium content of 50 mg/kg (see above). [Residual fuel oils (heavy

fuel oils) are petroleum refining residues remaining after distillation or cracking, and

blends of these residues with distillates. They are used primarily in industrial burners and

boilers as sources of heat and power (IARC, 1989). During refining and distillation, the

vanadium remains in the residual oil because of its low volatility, and as a result becomes

more concentrated than in the original crude.] During combustion, most of the vanadium

in residual oils is released into the atmosphere in the form of vanadium pentoxide as part

of fly ash particulates. Vanadium concentrations in coal fly ash range from 0.1 to 1 mg/g,

and in residual oil from 10 to 50 mg/g (Mamane & Pirrone, 1998). 

Vanadium was found in 87% of all air samples taken in the vicinity of large metallur-

gical plants at concentrations in the range of 0.98–1.49 

µg/m

3

, and in 11% of the samples

exceeded 2 

µg/m

3

(Pazhynich, 1967). At a steel plant in the USA in 1967, concentrations

of vanadium in ambient air ranged from 40 to 107 ng/m

3

and averaged 72 ng/m

3

(WHO,

1988). Concentrations as high as 1000 ng/m

3

vanadium pentoxide were found in air by

Pazhynich (1967) in the former Soviet Union at a site 1500 m from areas of extensive

metallurgical activity unconnected with vanadium production. In the same country, near

a plant producing technical vanadium pentoxide, 24-h mean concentrations of vanadium

pentoxide of 4–12, 1–6, and 1–4 

µg/m

3

in air were recorded at distances of 500, 1000 and

2000 m from the source, respectively (WHO, 1988).

According to the US Toxic Release Inventory (TRI, 1987–2001), the amount of vana-

dium released into the atmosphere from manufacturing and processing facilities in the

USA fluctuated between 5–9 tonnes between 1987 and 1997 and had dramatically

increased to over 100 tonnes by 2001. However, this estimate is believed to be limited

because the largest anthropogenic releases of vanadium to the atmosphere are attributed

to the combustion of residual fuel oils and coal, which are probably not included.

Vanadium-containing particulates emitted from anthropogenic sources into the atmos-

phere are simple or complex oxides (Byerrum et al., 1974) or may be associated with

sulfates (Mamane & Pirrone, 1998). Generally, lower oxides formed during combustion of

coal and residual fuel oils, such as vanadium trioxide, undergo further oxidation to the pen-

toxide form before leaving the stacks (Environmental Protection Agency, 1985).

Concentrations of vanadium measured in ambient air vary widely between rural and

urban locations; in general, these are higher in urban than in rural areas. Earlier reports

suggested concentrations of 1–40 ng/m

3

(van Zinderen Bakker & Jaworski, 1980) or

0.2–75 ng/m

3

(Environmental Protection Agency, 1977) in air in rural sites, although the

annual average was below 1 ng/m

3

. This was attributed to the local burning of fuel oils with

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