摘要:

AbstractSoil ingestion was measured under farm conditions by use of the titanium content of feces and soil as an indicator. Ingestion of soil ranged from 1.2 to 5.7% of dry matter in the diet when swine were on lots with bare soil and from 3.3 to 8.0% when swine were on grass pasture. Background levels of soil ingestion ranged from 0.3 to 0.8% when swine were confined to concrete. Soil ingestion can be an important source of animal exposure when chemical contaminants occur in soil.

ISSN:0730-7268    

DOI:10.1002/etc.5620010302

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe toxicity of three samples of pentachlorophenol (PCP) containing various impurities was evaluated in 90‐d, partial life‐cycle toxicity studies with fathead minnows (Pimephales promelas Rafinesque). Samples of purified PCP, Dowicide EC‐7, and a composite of commercial PCP were used in the studies. The exposure concentrations were 10 to 142 μg/L of the purified PCP; 8 to 139 μg/L of the Dowicide EC‐7; and 6 to 121 μg/L of the commercial composite of PCP. The purified PCP contained relatively high amounts of chlorinated phenoxyphenols; Dowicide EC‐7 contained more types of impurities, but generally at lower concentrations than in either the purified PCP or the commercial composite; and the commercial composite contained relatively large quantities of hexachlorobenzene, chlorinated phenoxyphenols, chlorinated dibenzodioxins, and chlorinated dibenzofurans.Concentrations of the purified PCP equal to or greater than 85 μg/L reduced the growth of the fathead minnows but did not adversely affect survival. Dowicide EC‐7 concentrations as high as 139 μg/L did not adversely affect growth or survival of fathead minnows. The commercial composite of PCP reduced growth at concentrations of 13 μg/L or higher and reduced survival at concentrations of 27 μg/L or higher. Degeneration of the fins and opercles, and malformations of the anterior regions of the skull were also noted in fathead minnows exposed to the commercial composite of PCP. Impurities clearly increased the toxic effects of PCP

ISSN:0730-7268    

DOI:10.1002/etc.5620010303

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe theme of SETAC's Second Annual Meeting was Environmental Risk Assessment, with emphasis on the use of data in the risk assessment and overall decision making process for chemicals. Needs for specific types of data were emphasized by the theme of the meeting and in no area was the void more obvious than in inhalation toxicology. Sufficient information for decision making in this area simply is not available, and no better combination of expertise exists for making judgments of risk than that of the environmental and mammalian toxicologists. To foster further communication between the two, a symposium was held in which experienced mammalian‐oriented toxicologists were asked to address the state‐of‐the‐art of inhalation toxicology for the benefit of those more oriented toward the traditional environmental toxicology area. Papers for the symposium are published herein to encourage continued efforts by all toxicologists to share in the data development and decision making process essential for healthy humans to enjoy a quality environment. The present paper is introductory in nature but utilizes recent findings in the author's laboratory concerning inhalation exposure and retention of chemical vapors in rats to demonstrate the rationale for selecting other topics for prese

ISSN:0730-7268    

DOI:10.1002/etc.5620010304

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe respiratory system has an extremely large surface area covered with a thin aqueous film of either mucus or a lipoprotein surfactant‐containing fluid. The large total surface area and minute separation between the air space and the blood make the lung an efficient organ for the rapid, systemic absorption of xenobiotics with a variety of physicochemical characteristics.Gases are absorbed throughout the entire respiratory system, the dominant driving force being diffusion. Highly water soluble gases are rapidly absorbed and may be cleared significantly through the surfaces of the upper respiratory tract before penetrating the deeper recesses of the lung.Inhaled particles are deposited in the respiratory system according to their size. Particles with aerodynamic diameters of 5 to 30 μm are similarly trapped in the nasopharyngeal region; those from 1 to 5 μm are largely deposited in the tracheal and bronchiolar regions, the major portion of particles smaller than 1 μm penetrate to the alveoli.Solute absorption studies indicate that the respiratory epithelium behaves like a lipoid–pore type membrane. Lipid soluble compounds are most rapidly absorbed at rates roughly related to their lipid/water partition coefficient at pH 7.4. Lipid insoluble substances are absorbed by nonsaturable diffusion with absorption rates related to the size of the molecules, i.e., the higher the molecular weight, the slower is the absorption. Organic ions can be absorbed by diffusion and by saturable, carrier‐mediated processes. Pulmonary exposure to substances known to produce lung damage, i.e., ozone, silica, or acids, can alter carrier‐mediated absorption of solutes and increase the passive absorption of lipid insoluble compounds alone or of both lipid soluble and lipid insoluble compounds.Age appears to be an important factor in absorption rate of lipid insoluble compounds. The lungs of 3‐ to 12‐day‐old rats absorb lipid insoluble compounds twice as rapidly as those of 18‐ to 27‐day‐old or adult animals. Age is unimportant, however, in the absorption of lipid soluble compounds.Species differences also exist for the absorption rates of lipid insoluble compounds but not for those of lipid soluble compounds. Mice will absorb lipid insoluble compounds 2 to 3 times more rapidly than rats, while rats absorb 1.3 to 3 times more r

ISSN:0730-7268    

DOI:10.1002/etc.5620010305

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractRecent interest in the investigation of the effect of environmental pollutants on the nonrespiratory and respiratory functions of the lung has stimulated the refinement and application of the technique of perfusing isolated intact lung preparations from suitable experimental animals in toxicological and biochemical studies. Available techniques include perfusion with whole blood or constituted perfusion media via pulmonary artery while maintaining ventilation with alternating negative or positive pressure. Viable, ventilating lung preparations can be maintained for 3 h. Such preparations have been employed for studies of uptake, metabolism and disposition of intratracheally or vascularly administered endogenous or exogenous chemicals. Recent development in unilateral or split‐lung perfusion preparations will undoubtedly further enhance the application of these techniques in the study of the interactions of endogenous and exogenous substances in the lung tissue. Isolated, perfused split‐lung preparations are particularly suited to investigate early toxic effects of inhaled pollutants in an attempt to gain insight into underlying mechanisms that lead to lung injury. Areas in which intact perfused lungs have been employed extensively with notable success include uptake, metabolism and disposition of toxic chemicals. These preparations have been used to study the effects of gases such as SO2, NO2, O3and CO on lung metabolism. Perfused lung preparations have been particularly useful in demonstrating pulmonary activation of toxic chemicals and in the demonstration of specific effects on the lung after chronic administration of chemicals. Areas which have not been actively investigated include the uptake and disposition of gases or vapors, effects of toxic chemicals on respiratory and nonrespiratory functions of the lung and alteration in the hemodynamics of the pulmonary circulation in the presence of interacting chemical or physical agents. It should be technically feasible to adapt the perfused lung preparations for such investigations, and interest in this area will conti

ISSN:0730-7268    

DOI:10.1002/etc.5620010306

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

Abstract[14C‐]Carbonyl carbofuran toxicity, metabolism and pharmacokinetics in male Sprague‐Dawley rats were studied after 4.1 μm (50 min, 0.2 and 1.2 μg/L) and 1.5 μm (70 min, 0.2 μg/L) aerodynamic diameter monodisperse aerosol exposures. Regional carbofuran deposition for each particle size was similar to human and rodent models for insoluble aerosols. Total carbofuran deposition was greater than expected in the rodent model but similar to that in human models.3‐Hydroxycarbofuran/carbofuran ratios in gastrointestinal tract and liver (1.3, 3 × greater after 4.1 μm) provided additional deposition indices. Rapidin vitrosolubility t1/2(17 min) for 4.1 μm particles and minimal differences in plasma carbamate (% total14C/animal) after varied particle size exposure indicated primary clearance by dissolution, irrespective of deposition site. Carbofuran (1.2 μg/L, 4.1μm) inhibited red blood cell acetylcholinesterase (55% at 10 min postexposure with recovery by 2 h). Eight‐hour14C metabolic fate in14CO2(31–38%), urine (9–12%), feces (2–5.5%) and carcass (44–58%) were similar for each particle size. Carbamate pharmacokinetics measured for 2 h postexposure to 4.1 μm particles described monoexponential elimination. Plasma half‐lives for carbofuran (36 min) and 3‐hydroxycarbofuran (62 min) were similar to those previously determined

ISSN:0730-7268    

DOI:10.1002/etc.5620010307

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractUsing the vapor pressure, water solubility and molecular weight of a chemical, the partitioning of that chemical between the major environmental compartments can be quickly assessed. Thus it is possible to estimate what percentage of the chemical will be located in the ground, bottom sediments, water and air. Combining this information with a knowledge of the known degradation rates an estimation of the relative persistence of the chemical can be made. The technique is illustrated by ranking 84 of the 119 priority pollutants according to their potentials for contaminating water. A final example demonstrates how the model may be used to identify the potential environmental impact of a new chemical.

ISSN:0730-7268    

DOI:10.1002/etc.5620010308

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY

ISSN:0730-7268    

DOI:10.1002/etc.5620010301

出版商:Wiley Periodicals, Inc.    

年代:1982

数据来源: WILEY