Chlorinated hydrocarbons chemical classes

Chemical/Pharmaceutical/Other Class Chlorinated hydrocarbon Chemical Formula C16H14CI2O3... 

Synonyms Chlorinated hydrochloric ether Ethyli-dene chloride Ethylidine dichloride Chemical/Pharmaceutical/Other Class Chlorinated hydrocarbon Chemical Structure ... 

Some companies have decided to avoid certain classes of compounds in their investigations simply because of the possibility that they will be plagued by regulatory problems due to the general character of their molecular structures (e.g. chlorinated hydrocarbons). One company has abandoned about 100 commercially interesting compounds since they have appeared on lists of suspected chemicals. Another company is backing off on all uses of chemicals which bring the chemicals in close proximity to food... 

Chlorinated hydrocarbons 1. Chemicals containing only chlorine, carbon, and hydrogen. These include a class of persistent, broad-spectrum insecticides that linger in the environment and accumulate in the food chain. Among them... 

To a first approximation, bioconcentration can be considered as the partitioning of a chemical between an organism and the surrounding aqueous milieu. It is therefore not surprising that many studies have been made of the relationship between BCF and the partition coefficient. Some such studies have involved specific chemical classes such as chlorinated polycyclic hydrocarbons (Schiiiirmann and Klein, 1988) and anilines (Zok et al., 1991), but a good number have involved diverse chemicals. There is considerable divergence in the correlations reported, which probably reflects differences in test conditions as mentioned (vide ultra) by Nendza (1998). Nendza (1991) cited six QSARs of the form ... 

The most important analytical parameters for the description of water quality and some randomly selected examples are presented in Tab. 5-1. These parameters are usually subdivided into global, group and specific parameters and into bacteriological and toxicological qualities. Global parameters (or sum parameters) of water quality are not substrate specific. Group parameters are related to defined classes of compounds such as chlorinated hydrocarbons, PAHs, phenols, whereas specific parameters indicate the concentrations of single chemicals present in... 

These findings are highly significant. The fact that domestic usage of the chlorinated hydrocarbon insecticides has reached a peak and is on the decline can only mean that the maximum amounts of this class of pesticide chemicals in the environment have already been reached and can only decline in the future. It stands to reason, therefore, that the residue levels of these compounds have reached a peak in the fatty tissues of humans, wildlife, and domestic animals that have had access to residues of these pesticide chemicals in the environment and are probably declining. From the standpoint of public health, there is not one shred of evidence that the traces of these compounds in the body fat have any detrimental effect. Of course, it cannot be stated absolutely that some effect will not be discovered in the future. However, by the same token, it cannot be stated absolutely that this effect will not be beneficial ... 

The development of resistance by certain insect species to chlorinated hydrocarbon insecticides aroused research into alternative chemical classes of compounds. This research led to the development of the carbamates as useful broad-spectrum insecticides. The best known of this class is carbaryl (Sevin), which has emerged as one of the most extensively used insecticides. 

Chlorinated hydrocarbons (1) Chemical substances containing only chlorine, carbon, and hydrogen. These include a class of persistent, broad-spectrum insecticides that linger in the environment and accumulate in the food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride, and toxaphene. Other examples include TCE, which is used as an industrial solvent. (2) Any chlorinated organic compounds, including chlorinated solvents such as dichloromethane, trichloromethylene, and chloroform... 

Chemical/Pharmaceutical/Other Class Polycyclic chlorinated hydrocarbon... 

Chemical/Pharmaceutical/Other Class Halogen-ated aromatic hydrocarbon Chemical Structure There are 74 chlorinated dibenzo-p-dioxin congeners. The basic structure for unsubstituted dibenzo-p-dioxin (showing the carbon numbering scheme that is used to name specific congeners) and the structure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (one of 22 tetrachlo-rinated dibenzo-p-dioxins) are shown below... 

Synonyms Hexachloro-1,3-butadiene Hexachloro-buta-1,3-diene (HCBD) Perchlorobutadiene Chemical/Pharmaceutical/Other Class Chlorinated hydrocarbon... 

Synonyms 1,2,3,4,5,5-JJexachloro-l,3-cyclopen-tadiene 1,3-Cyclopentadiene, 1,2,3,4,5,5-hexa-chloropentadine Perchlorocyclopentadiene Perchloro-l,3-cyclopentadiene Chemical/Pharmaceutical/Other Class Chlorinated cyclic hydrocarbon Chemical Formula CfClg Chemical Structure ... 

Synonyms Trichloroethene 1,1,2-Trichloroe-thene TCE TRI Trichlor Acetylene trichloride Ethylene, trichloro Ethylene trichloride Triclene Chemical/Pharmaceutical/Other Class Chlorinated olefinic hydrocarbon Chemical Eormula C2HCI3... 

Indeed, the promise of IA has led to workable enzyme-linked immunosorbent assays (ELISAs) for a variety of pesticides, including thiolcarbamates, triazoles and triazines, substituted ureas and sulfonylureas, bipyridilium compounds, and other groups of chemicals(2) (Table I). Additionally, radioimmunoassay (RIA) methods exist for chlorinated hydrocarbons, organophosphates, phenoxy adds and other chemical classes. 

Of the several classes of synthetic insecticides, the chlorinated hydrocarbon (CH) and organophosphate (OP) insecticides have the greatest psychiatric significance [Pesticides and Neurological Diseases 1982 Ecobichon 1996). The CH insecticides, also called organochlorine insecticides, include three chemical classes di-chlorodiphenyltrichloroethane (DDT), cyclodienes (aldrin, dieldrin, heptachlor, chlordane, endosulfan), and chlorinated benzene and cyclohexanes (lindane) (Ecobichon 1996). Their ban in the United States and Europe resulted from their high chemical stability and lipid solubility that allowed environmental persistence and magnification in the food chain (Ecobichon 1996 Kaloyanova and El Batawi 1991). 

Biotransformation of certain chlorinated hydrocarbon insecticides results in their conversion to metabolites which are less polar than the parent chemical. Heptachlor and aldrin are converted to the more lipophilic compounds heptachlor epoxide and dieldrin, respectively, whereas DDT is converted to DDE. The primary residue of DDT, which persists to the present day in animals and humans after exposure over a decade ago, is DDE. Following biotransformation, these compounds distribute to tissues which are higher in neutral lipid content than are the major organs of metabolism and excretion, the liver and kidney. These lipid-rich tissues are relatively, deficient in the so-called mixed-function oxidase (MFO) enzyme systems necessary for biotransformation of the halogenated hydrocarbons to more polar and thus more easily excreted compounds. As a result, these lipophilic chemicals remain unchanged in adipose tissue with only limited amounts returning to the circulation for possible metabolism and excretion. Paradoxically, aldrin and heptachlor metabolism results in an increased rather than reduced body load. This is opposite of the pattern seen for most other pesticide classes. 

The classic prototype chlorinated hydrocarbon pesticide is DDT (dichloro-diphenyltrichloroethane), a chemical which earned its discoverer, Dr. Paul Muller, a Nobel Prize in 1948. This honor was an event that partly reflected the tremendous beneficial impact that this class of compounds had on disease prevention and food production. Although this compound is not used any longer in the United States (see Chapter 3), it is still widely used throughout the world where the risk/benefit ratio favors continued pesticide use. This is because of its efficacy in agriculture and its ability to kill insect vectors of important human diseases such as malaria. It is thus monitored in the FDA food surveillance programs. 

The chlorinated hydrocarbons can be classified into four distinct chemical classes ... 

As a class the silicone fluids have no color or odor, have low volatility, and are nontoxic. The fluids have reasonable chemical resistance but are attacked by concentrated mineral acids and alkalis. They are soluble in aliphatic, aromatic, and chlorinated hydrocarbons. 

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