Organic chemicals, elements found toxicity

An alkaloid is a complex organic chemical substance found in plants, which characteristically combines nitrogen with other elements, has a bitter taste, and typically has some toxic, stimulant, analgesic effects. There are many different alkaloids, 30 of which are found in the opium plant. While morphine is the most important alkaloid in opium—for its natural narcotic qualities as well as providing the chemical structure for heroin—another alkaloid, codeine, is also sought after for its medicinal attributes. Other alkaloids include papaverine, narcotine, nicotine, atropine, cocaine, and mescaline. While the concentration of morphine in opium varies depending on where and how the plant is cultivated, it typically ranges from 3 percent to 20 percent. 

Thorium is commonly found in combination with other actinide elements, with organic and inorganic chemicals, and with acids and bases during occupational exposure. The health effects of occupational exposures to thorium on humans, therefore, cannot necessarily be attributed to thorium. The daughter products of thorium have unique properties that also add to the radiological toxicity of thorium. For further information, see the toxicological profiles on uranium, radon, and radium. 

Many studies have been concerned with uptake by and effects of trace elements on organisms, sometimes in relation to different chemical species of the element concerned (e.g. Langston and Bryan, 1984). As an example, the extent to which copper is complexes has been found to control its toxicity to organisms (Sunda and Guillard, 1976 Anderson and Morel, 1978 Jackson and Morgan, 1978). 

The term speciation is used to describe any analytical procedure in which the amounts of an element in discrete chemical forms are determined, as opposed to the total amount of an element in the sample. For example, it may be of interest to determine the amounts of Cr3 + and Cr042 in environmental samples, if the two ionic species have different toxicities, rather than the total amount of chromium. In this instance ion exchange may be used to separate the cationic and anionic species.23 Sometimes all the species to be determined may be either cationic or anionic, as in the case of the determination of Fe2+ and Fe3+ or S2, S032-, and S042-. Sometimes inorganic and organically bound forms may be determined, as in the case of arsenic species in natural waters.24 Where flame spectrometric determination has been employed in speciation studies of this type, selected key references may be found in the element-by-element section of Chapter 6. 

This element is a chalcophile, and in unweathered rocks is most commonly found as the mineral cinnabar (HgS). In soil environments, the cationic form, is most common, as the reduced oxidation state (+1) has a limited stability range. Reduction to the metallic elemental form, H, is easily achieved in soils by both biological and chemical reactions. Elemental mercury is somewhat volatile, and the vapor is extremely toxic to organisms. Under anaerobic conditions at least, soil microbes methylate mercury, forming volatile organomercury compounds that are bioavail-able and present a health hazard. At the same time, however, anaerobic conditions can convert Hg into the exceedingly insoluble sulhde, HgS. Some of the more important transformations possible for mercury in soil are summarized in Figure 9.9. 

The search was now on to identify different radicals. Dumas found the methyl radical. Robert Wilhelm Bunsen investigated compounds of the cacodyl radical (a smelly, toxic, sometimes explosive set of compounds containing arsenic) and isolated what appeared to be a free radical. It was actually a compound made of two radicals joined together, but it supported the idea that radicals were stable, isolatable entities, which could be treated like organic elements. Bunsen did not carry this work further because an explosion of cacodyl cyanide cost him an eye and several weeks of illness (and thereafter he steered clear of organic chemistry in general). He did go on to have a successful career in other chemical endeavors, inventing for instance a gas burner called the Bunsen burner, which is still standard laboratory equipment. 

Cadmium is a toxic element (see Chapters 1,14,15) that accumulates especially in kidney and liver [4] being bound preferably to metallothionein (Chapters 6,11). On the other hand, the chemical similarity of Cd " " to Zn " is confirmed by the fact that carbonic anhydrase of marine phytoplankton contains Cd (Chapter 16), whereas the corresponding zinc enzymes are found in organisms from aU kingdoms [5] catalyzing the reversible hydration of carbon dioxide. In marine diatoms cadmium, cobalt, and zinc can functionally substitute for one another to maintain optimal growth [6]. Cadmium-carbonic anhydrase is involved in the acquisition of inorganic carbon for photosynthesis [6]. 

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