Halogenated aromatic hydrocarbon , toxic

Commercial PCBs Toxic and Biochemical Effects. PCBs and related halogenated aromatic hydrocarbons ehcit a diverse spectmm of toxic and biochemical responses in laboratory animals dependent on a number of factors including age, sex, species, and strain of the test animal and the dosing regimen (single or multiple) (27—32). In Bobwhite and Japanese quad, the LC q dose for several different commercial PCB preparations ranged from 600 to 30,000 ppm in the diet the LC q values for mink that were fed Aroclors 1242 and 1254 were 8.6 and 6.7 ppm in the diet, respectively (8,28,33). The... 

Poland, A., and J. C. Knutson. 1982. 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Related Halogenated Aromatic Hydrocarbons Examination of the Mechanism of Toxicity. Ann. Rev. Pharmacol. Toxicol. 22, 517. 

Poland, A., Knutson, J.C. 2,3,7,8-tetrachlorodibenzo-p-dioxin and related halogenated aromatic hydrocarbons examination of the mechanism of toxicity, Ann. Rev.Pharm. Toxicol., 22, 517, 1989. 

As observed in mammalian models, the immune system of fishes is a sensitive target organ system to evaluate toxicity. For a more thorough review of environmental immunotoxicology in fishes, with reference to specific classes of xenobiotics, readers are referred to several reviews that deal with the subject over a span of nearly three decades [45-47, 54-57], While fish in the environment may be exposed to a variety of xenobiotics, the most frequently investigated xenobiotics are the polycyclic aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons (HAHs) due to the presence and activation of the aryl hydrocarbon receptor (AhR) in fish, and heavy metals due to their ubiquitous environmental distribution. 

Halogen acid furnaces, 13 179 Halogenated alkyl phosphates/ phosphonates, 11 489-496 Halogenated aromatic hydrocarbons (HAHs), 13 135 toxic responses to, 13 138 Halogenated aryloxyacetic acids,... 

For halogenated aromatic hydrocarbons like polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and polychlorinated dibenzo-p-dioxins (PCDDs) the binding to the aryl hydrocarbon (Ah) receptor regulates their toxicity [89]. The Ah receptor controls the induction of one of the cytochrome P450 enzymes in the liver. Toxic responses such as thymic atrophy, iveight loss, immu-notoxicity and acute lethality are associated ivith the relative affinity of PCBs, PCDFs and PCDDs for the Ah receptor [89]. The quantitative structure-activity relationship (QSAR) models predicting the affinity of the halogenated aromatic hydrocarbons ivith the Ah receptor describe the electron acceptor capability as well as the hydrophobicity and polarizability of the chemicals [89[. 

Gardinali, PR., Sericano, J.L., Wade, T.L. (2004) Uptake and depuration of toxic halogenated aromatic hydrocarbons by the American oyster (Crassostrea virginica) a field study. Chemosphere 54, 61-70. 

Comparison of Body Burden Effects Levels Among Humans and Animals 2-11 Toxicity Equivalency Factors (TEFs) for Halogenated Aromatic Hydrocarbons 2-12 Updated Toxic Equivalency Factors (TEFs) for Halogenated Hydrocarbons 2-13 Estimated Body Burdens of 2,3,7,8-TCDD That Correspond to MRLs 2-14 Health Effects in Animals Following Lactation-Only Exposure to 2,3,7,8-TCDD 2-15 Health Effects in Humans Associated with CDD and CDF Levels in Breast Milk 2-16 Genotoxicity of 2,3,7,8-TCDD In Vivo 2-17 Genotoxicity of 2,3,7,8-TCDD In Vitro... 

These genetic data strongly support the role of the Ah receptor in mediating the toxicity of 2,3,7,8-TCDD and related halogenated aromatic hydrocarbons. However, it has become clear that a comparison of the properties of the Ah receptor across species and tissues indicates that it is difficult to account for the species-specific sensitivity and diversity of the biological effects of 2,3,7,8-TCDD by characteristics of... 

Extensive evidence suggests that the immune system is a sensitive target for toxicity of 2,3,7,8-TCDD and structurally related halogenated aromatic hydrocarbons (Kerkvliet 1995). Exposure to 2,3,7,8-TCDD can increase susceptibility to bacterial (Thigpen et al. 1975 Thomas and Hinsdill 1979 White et al. 1986), viral (Clark et al. 1983 House et al. 1990), parasitic (Tucker et al. 1986), and neoplastic disease (Luster et al. 1980). However, the specific immunological functions affected by 2,3,7,8-TCDD in most of the host-resistance models have not been fully defined. Thymic involution is characteristic of exposure to 2,3,7,8-TCDD and structurally related chemicals in all species examined. There is experimental evidence showing that immune suppression in rodents occurs at lower doses of... 

Toxic Equivalency Factors (TEFs) and Toxic Equivalents (TEQs). Humans are exposed to complex mixtures of CDDs and other halogenated aromatic hydrocarbons such as CDFs and PCBs which... 

Table 2-11. Toxicity Equivalency Factors (TEFs) for Halogenated Aromatic Hydrocarbons... 

In the context of elaborating a degradation method for hazardous and toxic halogenated aromatic hydrocarbons, Varma and coworkers reported on... 

Halogenated aromatic hydrocarbons (HAH) cause common toxic and biochemical responses and their mechanism of action is also common [79],but the toxicology of PCDEs is not well known [4,40,46]. Weight loss, hepatic porphyria, chloroacne, and impairment of liver function are typical symptoms caused by HAHs [79]. Toxic effects of higher chlorinated PCDEs may appear as chloroacne and liver damage [12]. 

Most of the research on xenobiotic receptors has been conducted in mammalian systems. These studies have identified three families of proteins as having important roles in regulating the response to xenobiotic chemicals (Table 1). The aryl hydrocarbon receptor (AHR), a member of the basic helix-loop-helix Per-ARNT-Sim (bHLH-PAS) family of transcription factors, is well known for its role in the altered gene expression and toxicity elicited by chlorinated dioxins and related planar halogenated aromatic hydrocarbons (PHAHs) as well as certain polynuclear aromatic hydrocarbons (PAHs)114 188 244. Several members of the nuclear/steroid... 

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