Toxicity of elements

It is a remarkable contrast that, whereas Zn is biologically one of the most important metals and is apparently necessary to all forms of life,( Cd and Hg have no known beneficial biological role and are amongst the most toxic of elements. 

Solubility in water and body fluids appears to be directly related to toxicity (the low toxicity of elemental arsenic is attributed to its virtual insolubility in water and body fluids, whereas the highly toxic arsenic trioxide, for example, is soluble in water to 12.0 g/L at 0°C, 21.0 g/L at 25°C, and 56.0 g/L at 75°C). 

Bentley RE, Dean JW, Hollister TA, et al. 1978. Laboratory evaluation of the toxicity of elemental phosphorus (P4) to aquatic organisms. EG G, Bionomics, Wareham, MA. DAMD-17-74-C-4101 ADA061785. 

Figure 2 Interdependencies among 30 elements in mammals. An arrow from element A to B indicates that administration of element A may rednce toxicity of element B, low levels of element A may heighten toxicity of element B, or high levels of element B may inhibit salntary effects of element A. (Reprinted from Ref. 2 hy permission of Marcel Dekker, Inc)...

Biomedical analysis analysis of DNA, proteins, quantification of P, Zn, Cu, and Fe levels in Alzheimer s and Parkinson s diseases, toxicity of elements [88, 89]... 

Oral toxicity of elemental nickel is low. Treatment of illness caused by ingestion of nickel salts is usually limited to fluid replacement in cases of severe vomiting and diarrhea. Once sensitization has occurred, contact with nickel should be strictly avoided since reactions may occur after exposure to very low levels. This is particularly important in the workplace where high-level exposures are more likely to occur. 

Svenson, F., Viktor, T. and Remberger, M. (1998) Toxicity of elemental sulfur in sediments. Environ. Tox. Water Qual., 13, 217-224. 

Hall RH, Laskin S, Frank P, et al. 1951. Preliminary observations on toxicity of elemental selenium. AMA Arch Ind Hyg Assoc 4 458-464. 

Iodide and iodate have a low toxicity and high bioavailability, whereas the toxicity of elemental iodine and periodate is high. The bioavailability of organic iodine, especially iodine associated with macromolecules, is low. 

The table summarizes our knowledge about the essentiality, toxicity and isotopes of elements. It can be seen that the toxicity of elements depends on their chemical form. The isotopes of elements are rare cosmogenic nuclides. Nuclear fuel reprocessing, as well as reactor accidents, may release them to the biosphere. The isotopes are used as a radioactive tracer in medical practice. 

An area of research where effort is currently being directed is the study of metal complexation in aqueous solutions and on mineral surfaces (see Hochella and White 1990 and references therein). The reason that research is focusing on details of the molecular structure in this type of system is that scientists have begun to realize that speciation can play a dramatic role in the mobility and toxicity of elements in the environment (see Brown et al. 1999 for a review). Molecular modeling has the potential to make an impact on this field in a variety of ways (see Rosso, Rustad or Sherman, this volume), one of which is in modeling vibrational spectra to help interpret observed spectra. When model vibrational frequencies can be combined with model NMR chemical shifts (see Tossell, this volume) and compared with experimental spectra, complex problems may be more easily understood. 

Toxicity of elemental mercury has been reviewed (Who 1991). Symptoms after acute exposure to mercury vapor include chest pains, dyspnea, coughing, hemoptysis, impairment of pulmonary function, and interstitial pneumonitis leading to death. Subacute exposure to mercury vapor causes psychic reactions characterized by delirium, hallucinations, and suicidal tendencies. 

What is the historic evidence for the toxicity of elemental chlorine in air ... 

Despite its essentiality for marine diatoms [5,6], cadmium is best known for its toxicity to mammals [1,4,15,16] and in this context it is interesting to consider the interdependencies between Cd and other elements. In Figure 2, which may not be complete, the most obvious interdependencies with Cd are shown [17]. An arrow from element A to B, A—>B, indicates that administration of element A may reduce toxicity due to element B. Hence, the toxicity of Cd may be reduced by the ions of Ca, Zn, Cu, Fe, Co, and the metalloid Se. However, low levels of element A, e.g., of Ca ", Zn ", and Cu ", may increase the toxicity of element B (Cd " ), or high levels of element B (Cd " ) may inhibit salutary effects of element A (Zn " ). Such interrelations are common, though not easy to reveal and to understand. 

The toxicity of alumina, lead, arsenic, mereuiy and cadmium are well documented. These studies however often relate to the elements ingested in nutriments. Very few studies have been made on the toxicity of elements associated with implants and in their immediate neighborhood and the standards in vigor are not often based on any experimental data. 

Table 12.2. Toxicity of elements encountered in inorganic biomaterials...

Acute toxicity in humans is rarely seen because of the low toxicity of elemental selenium used in industry [33]. Toxicity in humans causes the same symptoms as in animals pulmonary edema, hemorrhaging and vascular disruption [33]. Estimates of acute levels are lacking, although a level of 0.2 grams of sodium selenate is considered acutely toxic [17]. 

There is some debate associated with the toxicity of elemental Sb, but a considerable toxicity issue associated with its salts, oxides (particularly antimony trioxide), and organometallic compounds. However, these products are typically not formed during standard reflow soldering processes. The standard, IPC-J-STD006, allows solder alloys to contain up to 0.6% Sb to avoid leaching Ag or Cu into ground water [78]. 

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