Vanadium – An element both essential and toxic to plants, animals and humans?

Abstract

Vanadium was discovered in 1802/1803 by the Spanish mineralogist A. M. del Río in Mexico. Vanadium are present in the earth’s crust at an average concentration of 110 mg/kg. Vanadium is concentrated mainly in mafic rocks (basalt 200-250 mg/kg) and shales (100-130 mg/kg), lowest concentrations were found in limestones and dolomites (10-45 mg/kg). The average vanadium content of soils worldwide have been calculated to vary from 18 (peat) and 115 mg/kg (Rotliegende weathering soils). Burning of fossil fuels caused about 110000 t V/a to enter the atmosphere globally. With help of indicator plants (wheat, rye, red clover) the local plant bioavailable vanadium offer is to investigate.

All foodstuffs, rich in starch and sugar and of animals are poor in vanadium (540 µg V/kg dry matter, dm); mushrooms and leafy vegetable contain higher levels of vanadium (100 to > 1000 µg V/kg dm). Beer and wine (30 to 45 µg/l deliver much vanadium. In Germany and Mexico women with mixed diet take in 10 to 20 µg V/ day and men 20 to > 35 µg V/day. The high intake results from the higher beer consumption of men. Vegetarians take in significantly more vanadium. The vanadium concentration of organs and milk is not homeostatically regulated. Most tissues of the fauna reflect the vanadium status.

Faecal excretion of the nutritional vanadium intake amounts to 96% in men and non lactating women and to 79 in lactating women. On an average, adults of both sexes and with either form of diet eliminate 4% of the vanadium intake renally. Lactating women secret 17% of the vanadium intake into the milk.

Vanadium is essential for several species of green algae, fungi and nitrogenfixing microorganisms. The inactive apoenzymes of bromoperoxidase, iodoperoxidase and chloroperoxidase can be reconstituted by vanadium to active haloenzymes. The normative vanadium requirement for animals is with < 10 µg/kg feed dry matter or < 10 µg V/day of man small. Intrauterine vanadium depleted goats developed poorly, their conception rate were significant by reduced, they exhibited a higher rate of spontaneous abortion, increased ratio of female to male kids born and a higher mortality. Vanadium deficient kids suffered of skeletal deformations in the forelegs. The size of their pancreas, thymus and thyroid were insignificantly increased. Vanadium may well be found essential for some halogenperoxidases, perhaps one, that is involved in thyroid metabolism.

It is to distinguish between nutritional (µg/day), pharmacological (mg/day) and toxic (mg/kg food dry matter) of vanadium.

Vanadium phytotoxicity (chlorosis and dwarfing) under field conditions is extremely rare. Intake of feed with 10 to 300 mg V/kg feed dry matter animals induced black diarrhoea, weakness, spontaneous abortions, decreased milk production and high mortality in animals.

Vanadium inhibits the Na+ – K+ ATPase and open the potassium-channels of the erythrocyte membrane. In humans, the threshold level for vanadium toxicity is > 3 mg/day. Higher doses can induces diarrhea, green tongues, haematological changes and lowered cysteine content in hair and nails.

Keywords: Vanadium.— Food chain.— Essentiality.— Pharmacological effects.— Toxicity.

Resumen

El vanadio fue descubierto por el mineralogista español A. M. del Río, en México, en los años de 1802/1803. La corteza terrestre de 16 km de espesor contiene 110 mg de vanadio por kg. A través de los combustibles fósiles se difunden anualmente en el medio ambiente 110.000 toneladas de vanadio. Con ayuda de plantas indicadoras se puede determinar la oferta local de vanadio.

El vanadio es esencial para varias especies de algas, hongos y bacterias fijadoras de nitrógeno. La apoenzima de la peroxidasa de bromo, yodo y cloro necesita el vanadio para la formación de la holoenzima.

La necesidad normativa de vanadio relativa al ser humano asciende a > 10 µg/ día y el de la fauna a 10 µg/kg de la materia seca del forraje.

Hay que distinguir entre los efectos farmacológicos, nutritivos y tóxicos del vanadio. Son raras las intoxicaciones por el vanadio. El vanadio frena la ATP-asa de Na+ – K+ y abre los canales de potasio de la membrana de los eritrocitos. Los 10-20 mg/día se consideran como valor límite del consumo de vanadio. Mayores dosis provocan trastornos gastrointestinales e implican con frecuencia tinciones verdes de las mucosas (por ejemplo, de la lengua), alteraciones hematológicas y concentraciones reducidas de la cisteína en los pelos y en las uñas.

Palabras clave: Vanadio.— Cadena alimentaria.— Esencialidad.— Efecto farmacológico.— Toxicidad.