Fish halogenated aromatics

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. 

M Hahn Boston University Utilize fish to investigate the mechanisms of animal sensitivity and resistance to 2,3,7,8-TCDD and related planar halogenated aromatic hydrocarbons (PHAH), especially the resistance which develops after long-term (multi-generation) exposure associated with hazardous waste sites ... 

Diverse chemicals have been reported to affect measured endpoints of fish thyroidal status. These chemicals include aromatic hydrocarbons, planar halogenated aromatic hydrocarbons (dioxans, furans, coplanar PCBs), organochlorine, organophosphorus and carbamate pesticides, chlorinated paraffins, cyanide compounds, methyl bromide, phenol, ammonia, metals (aluminum, arsenic, cadmium, lead and mercury), low pH conditions, environmental steroids and a variety of pharmaceutical agents. For the following reasons their modes of action appear complex and are poorly understood16. 

Another study assessed immunological effects in juvenile C57B1/6 mice that were fed diets containing no fish or 33% coho salmon from Lake Ontario or the Pacific Ocean for 2-A months (Cleland et al. 1989). Intakes of persistent toxic substances were not reported although the halogenated aromatic hydrocarbons with the highest concentrations in the control chow. Pacific salmon diet, and Lake Ontario salmon diet were total PCBs (0.4, 20, and 2,900 ppb, respectively) and p,p-DT)C (0.1, 10, and 670 ppb, respectively). Levels of PCDDs and PCDFs, mercury, tin compounds, and other metals were not examined. 

Newsted JL University of The Evaluation of Halogenated Massachusetts Forestry Aromatic Hydrocarbons in Fish from and Wildlife Management the Connecticut River Basin, MA Amherst, MA U.S. Department of Agriculture... 

Polychlorinated dibenzo-y>-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are chemically classified as halogen-ated (polychlorinated) aromatic hydrocarbons (PHAH). Dioxins are formed as a by-product of chemical processes, whereas PCBs are synthesized by direct chlorination of biphenyls. Due to their lipophilic character, they are concentrated in the food chain and both humans and wildhfe are exposed to them. The major source of human exposure is through the diet, as these substances are concentrated in fatty tissues of beef, poultry, pork and fish, and through cigarette smoking. Moreover, maternal milk contains considerable amounts of PCBs and dioxins. 

Table 5,3 Examples of QSAR models for estimating toxicity to fish of non-polar non-specific toxicants (e.g. alkanes, alkenes, saturated and unsaturated halogenated aliphatic hydrocarbons, basic ethers, cyclic ethers, ketones, amides, secondary and tertiary aliphatic and aromatic amines, alkylbenzenes, halogenated benzenes, piperazines, pyrimidines, polychlorinated hydrocarbon pesticides) log LC50 correlations with various parameters. 

This study was undertaken to test the ability of our previous molecular connectivity models to accurately predict the soil sorption coefficients, bioconcentration factors, and acute toxicities in fish of polycyclic aromatic hydrocarbons (PAHs), alkylbenzenes, alkenylbenzenes, chlorobenzenes, polychlorinated biphenyls, chlorinated alkanes and alkenes, heterocyclic arid substituted PAHs, and halogenated phenols. Tests performed on large groups of such compounds clearly demonstrate that these simple nonempirical models accurately predict the soil sorption coefficients, bioconcentration factors, and acute toxicities in fish of the above compounds. Moreover, they outperform traditional empirical models based on 1-octanol/ water partition coefficients or water solubilities in accuracy, speed, and range of applicability. These results show that the molecular connectivity models are a very accurate predictive tool for the soil sorption coefficients, bioconcentration factors, and acute toxicities in fish of a wide range of organic chemicals and that it can be confidently used to rank potentially hazardous chemicals and thus to create a priority testing list. ... 

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