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Vanadium and Compounds Toxicology


Compounds

The monoxide and dioxide, trioxide, pentoxide, chlorides, dioxichloride, trioxichloride, fluorides, iodide, sulphate, trisulphide, ammonium metavanadate, sodium metavanadate, sodium orthovanadate and sodium pyrovanadate.
It is the pentoxide that may be used by ceramists as a coloring material in glazes.

Uses

Most of the vanadium produced in the world is in the form of pentoxide (V2O5) which is used for producing alloys:
  • ferrovanadium containing from 30% to 95% vanadium,
  • special steels with vanadium carbide,
  • hard alloys with chromium, nickel, manganese, boron, titanium, tungsten,
  • etc.
Mineral compounds are used as hot catalysts:
  • in petrochemistry,
  • for the production of sulphuric acid,
  • for the production of phtalic anhydride,
  • in the oxidation of ethanol.
They also enter the composition of pigments used:
  • in dyeing,
  • in glassmaking,
  • in ceramics
Moreover they are used :
  • as developers in photography,
  • in the manufacture of inks and luminescent materials.

Exposure

1. Non-professional exposure: General population exposure comes above all from air pollution in the vicinity of thermoelectric power stations. Tobacco smoke contains of 1-8 ppm vanadium. Food provides some too; in general vanadium is undetectable in water. 2. Professional exposure: Fume is recognized as being generally more toxic than dust considering their smaller particulate dimension which allows a more complete penetration the level of the small airways of the lungs.

There is metallurgy:

  • ore precessing,
  • refining of the pentoxide,
  • manufacture of alloys.

Catalysts handling in petrochemistry (cleaning of tanks and reactors).

Activities exposing to soots and ashes from fuel and mineral oils.

Cleaning and/or repairing of boilers burners as well as tanks in refineries and on ships, work in stove-building/boilermaking are important sources of workers' contamination.

The contamination of workers results from inhalation of dust and fume, generally in the form of pentavalent derivatives. 25% of the inhaled dose is absorbed, whereas absorbtion by ingestion is less than 1%. In vitro, on human skin, radioctive vanadium does not penetrate skin.

Toxicity

Experimentally, the most toxic are the pentavalent, and also the most soluble compounds.

1. Iatrogenic intoxications:

Sodium metavanadate was used in the 1920s and 1930s in the treatment of several diseases at doses between 50 to 150 mg/day, and no particular undesirable effect was observed.

On the other hand, vanadium and ammonium tartrate, in amounts varying between 50 and 150 mg/day caused:

  • tiredness,
  • greenish colored tongue,
  • abdominal pains,
  • soft stools.

Because of supposed anabolic properties, vanadyl sulphate is used by athletes and body-builders in doses reaching 60 mg/day.

However, a clinical trial carried out in 1995 in New Zealand at a dose of 0.5mg/kg/day for 12 weeks did not show any effect on several blood parameters such as blood count, blood viscosity, proteins, lipids, creatinine, bilirubin, liver transaminases, etc.

2. Acute intoxication by ingestion: There are only two cases described in the world medical literature following vanadium salts ingestion.

In the 1st case that occurred in Poland, the amount of pentoxide ingested is unknown and the clinical picture included :

  • severe hemorrhagic gastroenteritis,
  • hypovolemia,
  • electrolytes disorders (hypokaliemia and hyponatremia).

No visceral effect occurred.

In the 2nd case, the amount ingested was 10 with 15g. of sodium metavanadate and the clinical picture included :

  • nausea, vomiting, diarrhoea,
  • greenish colored tongue and gums,
  • erosive gastritis,
  • neurological disorders,
  • reduction in prothrombin time, platelets and fibrinogen.

3. Professional intoxications:

a-Acute intoxication:

-By projection:

Accidental projection on the skin and/or in the eye of a concentrated solution of chlorides or oxides of vanadium causes chemical burns of nonspecific aspect, of variable intensity according to the precocity of decontamination.

Treatment is symptomatic, particularly abundant fluhing with tap water.

-By inhalation:

Inhalation of vapor, fume or dust of vanadium oxides causes respiratory accidents ranging from simple rhinopharyngeal and tracheal irritation to chemical broncho-pneumonopathy.

Signs may be delayed from several hours to several days.

In the absence of adequate individual protection, one may find:

  • surperficial conjunctivitis,
  • rhinitis with epistaxis,
  • violent dry cough.
  • sputum, occasionally greenish,
  • thoracic pain,
  • exertional shortness of breath,
  • rales and wheezing as signs of a bronchospasm which may last up to several weeks.

In the case of massive inhalation, respiratory disorders may be accompanied by nonspecific general signs:

  • tiredness,
  • intense frontal headache,
  • ebrious sensation,
  • nausea,
  • metallic taste,
  • pruriginous erythema.

Respiratory function testing shows a fall in the Forced Expiratory Volume 1.0 second(FEV1.0), and also sometimes a nonspecific bronchial hyperreactivity.

Persistence of Reactive Airways Dysfonction Syndrome (RADS, Brooks'syndrome) is suggested in an Australian publication. In practice, the presence of a Brooks' syndrome must be systematically searched for after the event.

Laboratory tests usually show very high blood and/or urinary vanadium levels; according to reported cases, urinary concentrations may vary from 280 µg/L to 4 mg/L, whereas the normal level varies from 0.1 to 0.2 µg/L.

Treatment is symptomatic:

    -oxygen, -bronchodilators(ß-adrenergic agonists), -no chelating treatment has proved to be effective.

b- Chronic intoxication :

Local effects:

- Digestive effects :

A metal taste and a greenish colored tongue represent characteristic signs of massive dust contamination of the workplace and inefficient individual protection gears.

Swallowing of inhaled particles can be responsible for minor digestive symptomd like :

-heart burns -loose stools quickly reversible at the end of exposure.

- Skin effects :

Cases of exzema-like dermatitis were reported in a Swedish study, around respiratory protection masks, hands, wrists and forearms, but only one worker tested positive to 2% sodium metavanadate in water skin test. No other publication reports confirmed allergy to vanadium, the sensitizing capacity of the metal appears improbable.

-Respiratory effects :

Repeated exposure to dust and fume can cause airways irritation and asthma-like symptoms and signs.

E.N.T. pathologies may be :

-rhinitis -pharyngitis and/or laryngitis.

Biopsies of the nasal mucous membrane showed a nonspecific inflammatory process.

Respiratory disorders may include :

-cough -thoracic wheezing or -delayed dyspneic (shortness of breath) crises -long term nonspecific bronchial hyperreactivity which corresponds to the definition of asthma caused by repeated exposure to peaked concentrations of irritating vapors or fumes, or Reactive Airways Dysfonction Syndrome (RADS).

Systemic effects :

All of the well controlled studies which attempted to demonstrate neurological, cardiovascular or other effects, proved to be negative.

Genotoxicity and carcinogenesis :

Experimentally :

Vanadium and compounds do not appear genotoxic; they are not mutagen nor cancerogenic.

In man :

No surmortality due to cancer, in particular bronchial, has been observed in the industrial setting.

Reproduction :

Experimentally :

Reproduction toxicity studies in the rat and the mouse are negative when the amounts used are nontoxic to the mother. As for sodium metavanadate, maternal toxicity is observed following a dose of 7.5 mg/kg/day, while embryofoetotoxicity is observed with doses greater than 15mg/kg/jour.

In man :

In man, there is no indication that vanadium can influence reproduction unfavourably.

Exposure :

The VEMP for vanadium pentoxide is 0.05 mg/m3 expressed as V2O5, for fume and respirable dust, in Quebec.

Prevention :

So good house keeping of your studio is very important; to do so you may, among other things, use wet processes, or even a vacuum system whose air is exhausted outside of the workshop.

Avoidance of processes generating unnecessary dust is also importan. To this, we may add work in closed systems and improvement of the general ventilation.

Adequate equipment of respiratory protection should be worn during handling of vanadium compounds, and during cleaning of equipment which burns coal or mineral oils as in power stations.

Workers in confined places, as in boilers , must wear acid-proof clothing well fitted to the wrists and ankles, with adequate gloves and rubber boots. Good personal hygiene is necessary and double lockers should be available to separate working clothes from personal clothing.

Medical surveillance :

Clinical monitoring of exposed workers may include periodical spirometric measurements.

It may also include urinary biometrology which reflects the exposure that occurred in the previous 2 or 3 days.

The biological exposure index used in France is 50µg/g of creatinine.

Some authors propose the use of skin testing to screen those who would be sensitized to vanadium compounds, but this possibility seems very rare according to french authors.

References :

1-Occupational Medicine, Carl Zenz, last edition. 2-Occupational & Environmental Medicine, Joseph LaDou, last edition. 3-Chemical Hazards of the Workplace, Proctor & Hughes, last edition. 4-Sax's Dangerous Properties of Industrial Materials, Lewis C., last edition. 5-Clinical Environmental Health and Toxic Exposures, Sullivan & Krieger, 2001 5-Industrial Chemical Exposure, Lauwerys & Hoet, last edition. 7-Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys R.,1999 8-Encyclopedie Medico-Chirurgicale- Toxicologie-Pathologie Professionnelle Paris, Testud F.; septembre 2001.

Out Bound Links

In Bound Links




Edouard Bastarache M.D.
Occupational & Environmental Medicine
Author of "Substitutions for Raw Ceramic Materials"
Tracy, Québec, CANADA

edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/




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