Aromatic compounds bioconcentration

Bioconcentration factors of dioxins in fishes are relatively low compared to other chlorinated aromatic compounds because of the low metabolic conversion of dioxins, their low available concentrations in test systems, and their highly variable uptake rates (de Voogt et al. 1990). In general, bioconcentration factors for persistent superlipophilic chemicals, such as OCDD, derived for freshwater fishes from supersaturated solutions may seriously underestimate the true BCF (Geyer... 

Baussant, T. Sanni, S. Jonsson, G. Skadsheim, A. Bprseth, J.F. 2001, Bioaccumulation of polycyclic aromatic compounds 1. Bioconcentration in two marine species and in semipermeable membrane devices during chronic exposure to dispersed crude oH.Erwiron. Toxicol. Chem. 20 1175—1184. 

Examination of the data on occurrence of chlorinated aromatic compounds in the environment, summarised in Tables 8 and 9, makes it clear that PCB, PCT, PCN, and HCB show a marked tendency to accumulate in biological tissues, particularly the fatty tissues of higher animals, both aquatic and terrestrial. Bioconcentration factors of 3 orders of magnitude between water and fish may be deduced, with a further 1-2 orders of magnitude between whole fish, and the fat storage tissues of predators on them such as cormorant, heron and seal. Some bioconcentration is also indicated in the case of dichloro- and trichlorobenzenes, but data are not adequate for any quantitative assessment. 

Benzofuran is a colorless organic liquid with an aromatic odor. It is produced by the destructive distillation of coal, and may also be formed during processing of fossil fuels, such as coke production and coal gasification. Limited data indicate that 2,3-benzofuran may partition to soils and sediments from water, but the information available is insufficient to predict the environmental fate of this compound. Substantial bioconcentration in aquatic organisms is not expected based on the physical/chemical properties of 2,3-benzofuran. 

PCBs are industrial compounds which were widely used as organic diluents, plasticizers, pesticide extenders, adhesives, dust-reducing agents, cutting oils, flame retardants, heat transfer fluids, dielectric fluids for transformers and capacitors, hydraulic lubricants, sealants and in carbonless copy paper. PCBs have entered the environment via multiple pathways and residues of these compounds have been identified in air, water, wildlife and human adipose tissue, serum and milk.89-91 Like many other aromatic hydrocarbons, PCBs are highly lipophilic and chemically stable and this has contributed to their environmental persistence and bioconcentration in the food chain. PCBs were originally... 

Degradation and metabolic transformation often result in reduced apparent bioconcentration (Spacie, Landrum and Leversee, 1983 Gobas and Schrap, 1990), due not only to the reduction in the concentration of the parent compound but also to the increased polarity of the metabolites formed. The bioconcentration of surfactants as well as, for example, organophosphates (Bruijn and Hermens, 1991a,b) and aromatic amines (Wolf et ai, 1992a) is significantly influenced by the (bio)transformation of the parent compounds. 

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. ... 

The predictive power of this nonempirical model Will now be tested on two groups of chlorinated hydrocarbons, alkyl and alkenyl benzenes, polycyclic aromatic hydrocarbons, and other structurally similar compounds. Altogether our test set consists of 44 new compounds (see TABLE 5). The second-order valence molecular connectivity indices of these test compounds were calculated and their bioconcentration factors were predicted from the molecular connectivity model, equation 7. These results are shown in TABLE 5 with the corresponding experimental bioconcentration factors in fish. 

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