Toxicity vanadium

Probably the vanadium compound to which people are most likely to be exposed is vanadium pentoxide, V205. Exposure normally occurs via the respiratory route, and the pulmonary system is the most likely to suffer from vanadium toxicity. Bronchitis and bronchial pneumonia are the most common pathological effects of exposure skin and eye irritation may also occur. Severe exposure can also adversely affect the gastrointestinal tract, kidneys, and nervous system. 

Reproductive Effects. Autopsy data have not provided detectable levels of vanadium in human reproductive organs. It is unlikely that the reproductive system is a sensitive indicator for vanadium toxicity in humans. Only one animal study was located that specifically tests the effects of vanadium on reproduction. In this well-conducted rat study, no adverse effects on fertility, reproduction, or parturition were noted when male and female rats were exposed to sodium metavanadate and then mated. 

Reproductive Toxicity. No data exist on reproductive effects on humans from exposure to vanadium by any exposure route. One animal study shows that vanadium did not affect reproductive parameters in rats following oral exposure (Domingo et al. 1986). Since vanadium is poorly absorbed from the gastrointestinal tract (Conklin et al. 1982 Roschin et al. 1980) and skin (WHO 1988), exposure by these routes is unlikely to be a health risk in humans. Toxicokinetic studies in humans (Schroeder et al. 1963) and reliable studies in animals (Edel and Sabbioni 1988) do not indicate that the reproductive system accumulates vanadium. Humans are most likely to be exposed to vanadium in the air, but the reproductive system does not appear to be a sensitive target of vanadium toxicity. Further studies would not appear to be particularly useful. 

Johnson J, Rajagopalan KV, Cohen HJ. 1973. Studies on vanadium toxicity in the rat. Environ Health Perspect 4 102. 

Roshchin AV, Ordzhonikidze EK, Shalganova IV. 1980. [Vanadium-toxicity, metabolism, carrier state.] J Hyg Epidemiol Microbiol Immunol 24 377-383. (Russian)... 

In humans, the threshold level for vanadium toxicity is approximately 10-20 mg per day. Schroeder et al. (1963) administered... 

Bartov (1977) studied the effect of ascorbic acid or ascorbyl palmitate supplementation in a diet containing soybean oil and butylated hydroxytol-uene on the oxidative stability of broiler fat and muscle. Ascorbyl palmitate is a fat-soluble form of ascorbic acid. The authors found no effects by the dietary supplements. Tsai et al. (1978) reported a similar lack of effect for ascorbic acid on lipid stability of pork obtained from supplemented pigs. In laying hens, ascorbic acid supplementation was shown to protect against loss in egg albumen quality associated with vanadium toxicity (Benabdeljelil and Jensen, 1990). 

Vanadium and its compounds are toxic and should be handled with care. The maximum allowable concentrahon of V2O5 dust in air is about 0.05 (8-hour hme-weighted average -40-hour week). 

Under unusual circumstances, toxicity may arise from ingestion of excess amounts of minerals. This is uncommon except in the cases of fluorine, molybdenum, selenium, copper, iron, vanadium, and arsenic. Toxicosis may also result from exposure to industrial compounds containing various chemical forms of some of the minerals. Aspects of toxicity of essential elements have been pubhshed (161). 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

The a—and P-aHoys are used where higher strengths are required, such as in shafts, oil and gas weUs, and medical implants. Again, Pd and Ru variations of the basic alloys are available where improved corrosion resistance is needed. Several of the Hsted P-aHoys were developed for implants. These alloys were designed to be free of aluminum and vanadium, which have created some concern related to potential toxicity when used in implants (50). 

Vanadium compounds, including those which may be involved in the production, processing, and use of vanadium and vanadium alloys, are irritants chiefly to the conjuctivae and respiratory tract. Prolonged exposure may lead to pulmonary compHcations. However, responses are acute, never chronic. Toxic effects vary with the vanadium compound involved. For example, LD q (oral) of vanadium pentoxide dust in rats is 23 mg/kg of body weight (24). 

The toxicity of vanadium alloys may depend on other components in the alloy. For example, the V Ga alloy requires precautions related to both vanadium and gaUium, and gallium is highly toxic. Similarly, alloys with chromium may require precautions associated with that metal. 

The ammonium salts of vanadic acid and vanadium pentoxide have been Hsted as toxic constituents in soHd wastes under the Resource Conservation and Recovery Act (27). 

Vanadium Va Oxides and chlorides have a high toxicity... 

One-electron reduction or oxidation of organic compounds provides a useful method for the generation of anion radicals or cation radicals, respectively. These methods are used as key processes in radical reactions. Redox properties of transition metals can be utilized for the efficient one-electron reduction or oxidation (Scheme 1). In particular, the redox function of early transition metals including titanium, vanadium, and manganese has been of synthetic potential from this point of view [1-8]. The synthetic limitation exists in the use of a stoichiometric or excess amount of metallic reductants or oxidants to complete the reaction. Generally, the construction of a catalytic redox cycle for one-electron reduction is difficult to achieve. A catalytic system should be constructed to avoid the use of such amounts of expensive and/or toxic metallic reagents. 

Presently the catalytic selective NOx reduction by ammonia is efficient and widespread through the world for stationary sources. The remarkable beneficial effect of 02 for the complete reduction of NO into nitrogen is usually observed between 200 and 400°C. However, such a technology is not applicable for mobile sources due to the toxicity of ammonia and vanadium, which composes the active phase in vanadia-titania-based catalysts. Main drawbacks related to storing and handling of ammonia as well as changes in the load composition with subsequent ammonia slip considerably affect the reliability of such a process. On the other hand, the use of urea for heavy-duty vehicles is of interest with the in situ formation of ammonia. 

The replacement of vanadia-based catalysts in the reduction of NOx with ammonia is of interest due to the toxicity of vanadium. Tentative investigations on the use of noble metals in the NO + NH3 reaction have been nicely reviewed by Bosch and Janssen [85], More recently, Seker et al. [86] did not completely succeed on Pt/Al203 with a significant formation of N20 according to the temperature and the water composition. Moreover, 25 ppm S02 has a detrimental effect on the selectivity with selectivity towards the oxidation of NH3 into NO enhanced above 300°C. Supported copper-based catalysts have shown to exhibit excellent activity for NOx abatement. Recently Suarez et al and Blanco et al. [87,88] reported high performances of Cu0/Ni0-Al203 monolithic catalysts with NO/NOz = 1 at low temperature. Different oxidic copper species have been previously identified in those catalytic systems with Cu2+, copper aluminate and CuO species [89], Subsequent additions of Ni2+ in octahedral sites of subsurface layers induce a redistribution of Cu2+ with a surface copper enrichment. Such redistribution... 

The conventional selective reduction of NOx for car passengers still competes but the efficient SCR with ammonia on V205/Ti02 for stationary sources is not available for mobile sources due to the toxicity of vanadium and its lower intrinsic activity than that of noble metals, which may imply higher amount of active phase for compensation. As illustrated in Figure 10.9, such a solution does not seem relevant because a subsequent increase in vanadium enhances the formation of undesirable nitrous oxide at low temperature. Presently, various attempts for the replacement of vanadium did not succeed regarding the complete conversion of NO into N2 at low temperature. Suarez et al. [87] who investigated the reduction of NO with NH3 on CuO-supported monolithic catalysts... 

Chromium has proved effective in counteracting the deleterious effects of cadmium in rats and of vanadium in chickens. High mortality rates and testicular atrophy occurred in rats subjected to an intraperitoneal injection of cadmium salts however, pretreatment with chromium ameliorated these effects (Stacey et al. 1983). The Cr-Cd relationship is not simple. In some cases, cadmium is known to suppress adverse effects induced in Chinese hamster (Cricetus spp.) ovary cells by Cr (Shimada et al. 1998). In southwestern Sweden, there was an 80% decline in chromium burdens in liver of the moose (Alces alces) between 1982 and 1992 from 0.21 to 0.07 mg Cr/kg FW (Frank et al. 1994). During this same period in this locale, moose experienced an unknown disease caused by a secondary copper deficiency due to elevated molybdenum levels as well as chromium deficiency and trace element imbalance (Frank et al. 1994). In chickens (Gallus sp.), 10 mg/kg of dietary chromium counteracted adverse effects on albumin metabolism and egg shell quality induced by 10 mg/kg of vanadium salts (Jensen and Maurice 1980). Additional research on the beneficial aspects of chromium in living resources appears warranted, especially where the organism is subjected to complex mixtures containing chromium and other potentially toxic heavy metals. 

Taylor, D., B.G. Maddock, and G. Mance. 1985. The acute toxicity of nine grey list metals (arsenic, boron, chromium, copper, lead, nickel, tin, vanadium and zinc) to two marine fish species dab (Limanda limanda) and grey mullet (Chelon labrosus). Aquat. Toxicol. 7 135-144. 

High levels of dietary tin increased zinc loss from rats (Greger 1989). Zinc prevented toxic effects of vanadium (10 mg/kg BW) on bone metabolism of weanling rats (Yamaguchi et al. 1989). 

Yamaguchi, M., H. Oishi, and Y. Suketa. 1989. Effect of vanadium on bone metabolism in weanling rats zinc prevents the toxic effect of vanadium. Res. Exper. Medic. 189 47-53. 

Boisson, F., M. Gnassia-Barelli, and M. Romeo. 1995. Toxicity and accumulation of selenite and selenate in the unicellular marine algae Cricosphaera elongata. Arch. Environ. Contamin. Toxicol. 28 497-493. Bovee, E.C. and T.L. O Brien. 1982. Some effects of selenium, vanadium and zirconium on the swimming rate of Tetrahymena pyriformis a bioassay study. Univ. Kans. Sci. Bull. 52 (4) 39 44. 

It was discovered nearly 20 years ago that V(V) as vanadate and V(IV) as vanadyl can mimic some of the effects of insulin (stimulate glucose uptake and oxidation and glycogen synthesis) (512, 513). Vanadate is an effective insulin mimetic in the diabetic rat (514), but has proved to be too toxic for human use. Vanadyl, as VOS04, is also unsuitable because high doses are needed on account of its poor oral absorption. Vanadium complexes with organic ligands have proved to be less toxic and can have improved aqueous solubility and lipophil-icity. 

It was reported in 1980 that vanadate showed insulin activity (415) at about the same time it was demonstrated that vanadate is reduced to vanadium(IV) in vivo (416,417). Subsequently it was found that orally administered vanadate restored blood glucose levels and cardiac function to normal in rats (418). Vanadyl sulfate, less toxic than vanadate, also lowers blood sugar levels and ameliorates cardiac... 

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