Toxicologic Assessment of Jet-Propulsion Fuel 8 (2003) / Chapter Skim
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3 Toxicokinetics and Toxicodynamics of Jet-Propulsion Fuel 8
3 Toxicokinetics and Toxicodynamics of Jet-Propulsion Fuel 8
Pages 29-40
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From page 29... ...
The major determinants of hydrocarbon toxicokinetics following systemic uptake are disposition-related physiologic measures, such as alveolar ventilation, cardiac output and blood flow to organs, partition coefficients, and organ volume. Hydrocarbons with high blood:air partition coefficients will be absorbed to a greater extent than chemicals with poor blood solubility.
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From page 30... ...
enzymes metabolize most hydrocarbons by such reactions as aliphatic hydroxylation, aromatic hydroxylation, and epoxidation. For many hydrocarbons, alcohol and aldehyde dehydrogenases play an important role in metabolizing alcohols to their corresponding keto acids.
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From page 31... ...
Toluene is metabolized principally by series of oxidation reactions that lead to benzoic acid, which is conjugated with glycine to form hippuric acid. Unchanged toluene is readily removed in exhaled air.
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From page 32... ...
(1990) reported decreased motor and sensory conduction velocities and decreased amplitude of the sensory action potential of the tail nerve in rats exposed repeatedly to a mixture of diethylbenzene and its major metabolite, 1,2diacetylbenzene (DAB)
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From page 33... ...
In the model, all compounds in venous blood are available for gas exchange in Me lungs; this leads to simple relationships in which concentration in exhaled air is a straightforward function of concentration in blood, blood:air partition coefficient, total cardiac output, and alveolar ventilation. The models have proved successful for low-molecular-weight hydrocarbons; their application has not been established for the longer-chain n-alkanes.
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From page 34... ...
Interactions can also occur between inhaled compounds and metabolites formed in the body that require similar enzymes for biotransformation. Detailed kinetic studies with both benzene and n-hexane show inhibition of later metabolic steps, phenol to hydroquinone or methyl n-butyl ketone to 2,5-hexane dione, by high concentrations of inhaled benzene or hexane, respectively (Medinsky et al.
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From page 35... ...
Similar CYP450 enzymes and phase II conjugative metabolic pathways metabolize many alkane hydrocarbons (NRC 1996~. Depending on the Km and Vmax for the metabolism of individual chemicals, competitive metabolic interactions can result in lower or higher concentrations of chemicals and their metabolites.
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From page 36... ...
Ethanol ingestion might lead to increased metabolic activation of benzene, which might lead to bone marrow toxicity, hematotoxicity, and possibly leukemia (ACGIH 1996~. The metabolic and toxicologic interactions between ethanol consumption and the various hydrocarbon components inJP-8 have not been carefully studied.
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From page 37... ...
That suggests that environmental and lifestyle factors contributed to an increase in GST M1 null genotype independently of JP-8 exposure. The presence of GST M1 null genotype after low or moderate exposure may predispose people to adverse health effects compared to people with normal GST M1 activities.
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From page 38... ...
1981. Behavioral changes in mice following benzene inhalation.
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From page 39... ...
1996. Permissible Exposure Levels for Selected Military Fuel Vapors.
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From page 40... ...
1996. Glutathione S-transferase M1 null genotype as a risk modifier for solvent-induced chronic toxic encephalopathy.
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