Toxic metals biological effects

One of the most important tasks in Analytical chemistry is the effective and express microquantity determination of toxic metals and biologically active organic materials in different objects of environment, raw materials and products of food technology and biotechnology. 

Variation of the content of impurities in the different CNT preparations [21] offers additional challenges in the accurate and consistent assessment of CNT toxicity. As-produced CNTs generally contain high amounts of catalytic metal particles, such as iron and nickel, used as precursors in their synthesis. The cytotoxicity of high concentrations of these metals is well known [35, 36], mainly due to oxidative stress and induction of inflammatory processes generated by catalytic reactions at the metal particle surface [37]. Another very important contaminant is amorphous carbon, which exhibits comparable biological effects to carbon black or relevant ambient air particles. 

Harr, J.R. 1978. Biological effects of selenium. Pages 393-426 in F.W. Oehme (ed.). Toxicity of Heavy Metals in the Environment. Part l. Marcel Dekker, New York. 

No carrier is completely specific for a given trace metal metals of similar ionic radii and coordination geometry are also susceptible to being adsorbed at the same site. The binding of a competing metal to an uptake site will inhibit adsorption as a function of the respective concentrations and equilibrium constants (or kinetic rate constants, see below) of the metals. Indeed, this is one of the possible mechanisms by which toxic trace metals may enter cells using transport systems meant for nutrient metals. The reduced flux of a nutrient metal or the displacement of a nutrient metal from a metabolic site can often explain biological effects [92]. 

Most of our knowledge of the biological effects of petrolemn pollution is based on studying the acute effects of major spills or heavily contaminated sediments. These effects tend to be directly lethal. Acute toxicity has been foimd to be largely related to water solubility, with cmnulative toxicity reflecting the smn of the effects of each individual hydrocarbon. Relatively little is known about the effects of chronic exposures at lower concentrations, especially in the presence of other stressors, such as heavy metals. Effects of chronic inputs from land-based sources on populations, communities, and ecosystem structure and function are also not sufficiently known. 

While some metals are nutritionally important, there is another group with no beneficial biological effects and in some cases serious toxic effects. Our complex relationship with metals is well illustrated by lead, which we have used for a variety of purposes since ancient times. In the last hundred years, lead was extensively used in paint and as a gasoline fuel additive. In the last 30 years, it was recognized... 

It has been observed that quite generally the toxic effects of organometallic compounds are stronger than those of the underlying metal ions. This is particularly true for the antimicrobial effects. The metal tin shows this phenomenon in a rather dramatic way. Whereas scarcely any pronounced biological effect is known for tin, either in the stannous or the stannic form, certain trialkyltin compounds belong to the most active fungicides known at present. 

The severity of the air pollution problem becomes obvious as we learn to recognize the effects of aerial toxicants upon biological systems. The aesthetic degradation of the air by a pall of smoke is obvious, but the toxic subtleties of S02, heavy metal, or ozone are not as easy to recognize and evaluate. Establishing repeatable cause/effect data in regard to air pollution effects has been a principal problem in the area of human health effects. Fortunately, cause and effect data are obtainable in plant investigations, and even with our current limitations on symptom-... 

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