Lipid-rich tissues, accumulation

No mortality was found in any embryo exposed to the controls. On the contrary, all the embryos exposed to the non-diluted samples of penta-, octa-, and deca-BDE commercial mixtures were dead after 24 h (Fig. 10). When the untreated PBDEs samples were diluted at 50%, a gradient of toxicity was observed penta > octa > deca. After dilution at 5%, no embryos exposed to untreated samples were dead. In agreement with our results, it has been demonstrated that the toxicity of deca-BDE is commonly lower than for octa- and penta-BDE commercial products exposures with mammalian models [64]. The different toxicity found in mammalian models and also in zebrafish should be related to the higher accumulation of lower brominated congeners in the body, because of their greater partitioning and retention in lipid-rich tissues and lower rates of metabolism and elimination in relation to deca-BDE. 

Toxaphene accumulates in tissues of many aquatic species, especially in lipid-rich tissues of polar fish and marine mammals (Swackhamer and McConnell 1993). Toxaphene concentrations in livers of Arctic fishes of 2.9 mg/kg FW and in Canadian cod liver oil of 28 mg/kg FW are recorded... 

As with the structurally related PCBs (ATSDR 2000), PBBs are rapidly (minutes to hours) cleared from the blood and initially accumulate mainly in the liver, lungs, and muscle (Domino et al. 1982 Matthews et al. 1977). Due to their high affinity for lipid-rich tissues, PBBs are subsequently redistributed to adipose and skin for storage or metabolism in the liver, and a dynamic equilibrium of PBB concentrations is established among all tissues for each PBB homolog (Tuey and Matthews 1980). 

PBBs and PBDEs tend to accumulate in lipid-rich tissues and are slowly metabolized and eliminated from the body (see Section 3.4). Several methods to enhance the elimination of PBBs from the body have been examined in animals and are also relevant to PBDEs, including the restriction of caloric intake (to reduce total body fat), and the administration of various agents that interact with bile acids including activated charcoal, mineral oil and bile-binding resins such as cholestyramine (Kimbrough et al. 1980 McConnell et al. 1980 Polin and Leavitt 1984 Polin et al. 1985, 1991 Rozman et al. 1982). It should be mentioned, however, that based on the pharmacokinetic considerations discussed in Section 3.8.1, a rapid breakdown... 

For many organic compounds that accumulate in lipids, bio accumulation potential can be estimated from the Kow. Since perfluoroalkyl compounds are inherently oleophobic, and do not partition preferentially to lipid rich tissues [67], the K0w is not a useful predictor of bioaccumulation and direct evidence derived from the laboratory or field is required. Additionally, tissue concentrations of perfluoroalkyl substances should never be lipid normalized. The dietary accumulation, bioconcentration, and biomagnification potential of various perfluoroalkyl carboxylates and sulfonates have been assessed in the laboratory and in the Great Lakes food web (Table 4). 

Humans are exposed to pollutants via inhalation, dermal uptake and dietary and nondietary ingestion. In fact, human exposure begins from the womb and continues until death. Since POPs are lipophilic contaminants, they tend to accumulate in large quantities in lipid rich tissues. Their accumulation in human milk has received considerable attention because of... 

The presence of high levels of pentachlorophenol in mammalian blood is well-known. The fact that as many as 120 or more phenolic OHS are present in both human and fish (salmon) blood demonstrates, in addition to lipid rich tissues, the potential importance of blood for the accumulation of environmental contaminants or their metabolites. Phenolic OHS are not strongly accumulated... 

Loss of CFC-113 from tissues is rapid during the postexposure period with virtually 100% clearance within 24 h of exposure. Freons are eliminated entirely by the respiratory tract. Chlorofluorocarbon compounds partition preferentially into lipid-rich tissues and are poorly metabolized. Significant accumulation occurs in brain, liver, and lung tissues compared to blood levels. 

Finally, for biological samples the PCB concentration is generally expressed as g g of wet or dry weight of sample and as g g of extractable lipids since, as already stated, PCBs are lipophilic in nature and accumulate in lipid-rich tissues and organs. The latter approach allow for better data comparison. It is also worth mentioning that the determination of non-ortho and mono-ortho substituted PCBs is often performed in these samples, since they are the most toxic congeners (13, 55). 

Long-chain and branched hydrocarbons that are primary components of JP-8, include -nonanc, -dccanc, -dodccanc, -tridecane, isopropylbenzene, -propylbcnzcnc, trirnethylbenzene, -dimcthylbenzene, naphthalene, n-pentylbenzene, and -tricthylbcnzcnc. Inhaled long-chain aliphatic hydrocarbons generally show poor blood uptake because of lower blood solubility. They have relatively high lipid blood partition coefficients this can result in accumulation in lipid-rich tissues, such as brain and fat. In laboratory studies, brain concentrations of hydrocarbons and their metabolites greatly exceed their plasma concentrations. 

Overall, almost all recently developed PB-PK models of various JP-8 components based on nonane or naphthalene do not predict accurately the JP-8 or component concentrations in blood, breath, or tissue. Given that most JP-8 components have a propensity to accumulate in lipid-rich tissues, there is a need for more accurate PB-PK models that can predict tissue concentrations of important classes of JP-8 components. Such data are critical in assessing the long-term safety of JP-8 occupational exposure. 

PCBs are soluble in fatty and lipid-rich tissues and organs of biota where they have accumulated. They can act as cancer initiators and may cause reproductive failure in animals [30,55,57]. 

As do most organic contaminants, PAHs accumulate in certain tissues with the highest proportions found in the liver of vertebrates or the hepatopan-creas of invertebrates. In general, lipid-rich tissues preferentially accumulate parent PAHs because of their strongly hydrophobic nature. Metabolites of biotransformed PAHs tend to accumulate in certain vertebrate tissues, such as bile and liver. In invertebrates, metabolite concentrations are generally highest in the hepatopancreas. 

Accumulation of PAHs occurs in all marine organisms however, there is a wide range in tissue concentrations from variable environmental concentrations, level and time of exposure, and species ability to metabolize these compounds. PAHs generally partition into lipid-rich tissues, and their metabolites can be found in most tissues. In fish, liver and bile accumulate... 

Good skin absorbance accumulated in adipose tissues and in lipid-rich organs 0.008- 0.037 0.139 Insecticide... 

In contrast, other types of storage tissue—corns, tubers, bulbs—accumulate low amounts of fats. The major types of lipids in these tissues are phospholipids and glycolipids, and they contain the same major fatty acids. Although the actual distribution of fatty acids varies somewhat, palmitic, linoleic, and linolenic are the most abundant. A few examples of distributions are given in Table XI. The division between lipid-rich and other tissues is somewhat vague, but 10% dry weight and above is probably a reasonable... 

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