Download or read book Method for Assessing Additive Toxicity of Chemical Mixtures written by LL. Marking and published by . This book was released on 1977 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixtures of chemicals or pesticides may produce unexpected effects; some are hazardous and some are beneficial. A method was divised in which individual toxic contributions of chemicals are summed, and the additive toxicity is defined by an index for two or more chemicals in combination. This linear index expresses the toxicity quantitatively: zero indicates simple additive toxicity, negative values indicate less than additive toxicity, and positive values indicate greater than additive toxicity. The significance of index values near zero is assessed by substituting values from the 95 percent confidence intervals into the formula to determine whether the range for the additive indices overlaps zero (simple additive toxicity). The range is derived by selecting values of the 95 percent confidence interval yielding the greatest deviation from the additive index.
Download or read book Aquatic Toxicology and Hazard Evaluation written by F. L. Mayer and published by ASTM International. This book was released on 1977 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mixture Toxicity written by Cornelis A. M. van Gestel and published by CRC Press. This book was released on 2016-04-19 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade and a half, great progress has been made in the development of concepts and models for mixture toxicity, both in human and environmental toxicology. However, due to their different protection goals, developments have often progressed in parallel but with little integration. Arguably the first book to clearly link ecotoxicology an
Download or read book Investigations in Fish Control 67 Method for Assessment of Toxicity Or Efficacy of Mixtures of Chemicals written by Leif L. Marking and published by . This book was released on 1975 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The individual toxic contributions of poisons were summed, and the additive toxicity was defined by a linear index for two chemicals in combination. This index expresses the toxicity quantitatively: zero indicates additive toxicity, negative values indicate less than additive toxicity, and positive values indicate greater than additive toxicity. We selected examples from the literature and conducted tests in the laboratory to assess the additive toxicity of selected chemical mixtures to fish.
Download or read book EPA 630 R written by and published by . This book was released on 1998 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Complex Mixtures written by National Research Council and published by National Academies Press. This book was released on 1988-02-01 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the laboratory, testing the toxic effects for a single compound is a straightforward process. However, many common harmful substances occur naturally as mixtures and can interact to exhibit greater toxic effects as a mixture than the individual components exhibit separately. Complex Mixtures addresses the problem of identifying and classifying complex mixtures, investigating the effect of exposure, and the research problems inherent in testing their toxicity to human beings. A complete series of case studies is presented, including one that examines the cofactors of alcohol consumption and cigarette smoke.
Download or read book Guidance Manual for the Assessment of Joint Toxic Action of Chemical Mixtures written by and published by . This book was released on 2001 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Toxicity of Complex Chemical Mixtures written by Annika Margaret Gillespie and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex chemical mixtures may be released into the environment from a variety of sources including hazardous waste sites. Components of chemical mixtures and their metabolites may be genotoxic leading to cancer and heritable gene mutations. Chemical analysis alone does not always provide the most accurate information from which to estimate the risk of adverse effects associated with exposure to mixtures. Current methods to estimate the human health risk for complex mixtures assume additive effects of the components. Although it is assumed that this approach is protective of human and ecological health, it is also recognized that chemical mixtures may induce a variety of interactions including potentiation, synergism, and antagonism. A combined testing protocol, using chemical analysis coupled with a battery of in vitro, in vivo, and in situ bioassays, provides the most accurate information from which to estimate risk. Such a combined testing protocol provides information to describe the major organic and inorganic constituents, as well as the pharmacokinetics and potential interactions of chemical mixtures. This research was conducted to investigate the potential genotoxic effects of complex chemical mixtures of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated aromatics (PCA) using microbial bioassays (Salmonella/microsome assay and the E. coli prophage induction assay), the 32P-postlabeling assay in mice, and in situ measurements of genotoxicity using flow cytometry. Samples of environmental media and wildlife tissues were collected from four National Priority List Superfund sites within the United States. In general, chemical analysis was not always predictive of mixture toxicity. Although biodegradation reduced the concentration of total and carcinogenic PAHs in soils and groundwater, the genotoxicity of extracts from environmental media did not display a corresponding reduction. Mixtures of polychlorinated biphenyls (PCBs) extracted from sediments were found to inhibit the genotoxicity of PAH mixtures when administered dermally to rodents. This inhibition exhibited a dose-response relationship, with the adduct frequency reduced at increasing doses of sediment extract. Finally, PAH concentrations in environmental media and tissues were found to correlate with DNA damage in wildlife receptors. An integrated approach, combining in vitro and in vivo methods to characterize genotoxicity provides more accurate information from which to estimate uptake and risk associated with exposure to complex mixtures and should be considered in both the human and ecological risk assessment process.
Download or read book Technical Support Document on Risk Assessment of Chemical Mixtures written by United States. Environmental Protection Agency. Environmental Criteria and Assessment Office (Cincinnati, Ohio) and published by . This book was released on 1990 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supplementary guidance for conducting health risk assessment of chemical mixtures written by and published by DIANE Publishing. This book was released on with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Phthalates and Cumulative Risk Assessment written by National Research Council and published by National Academies Press. This book was released on 2009-01-19 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: People are exposed to a variety of chemicals throughout their daily lives. To protect public health, regulators use risk assessments to examine the effects of chemical exposures. This book provides guidance for assessing the risk of phthalates, chemicals found in many consumer products that have been shown to affect the development of the male reproductive system of laboratory animals. Because people are exposed to multiple phthalates and other chemicals that affect male reproductive development, a cumulative risk assessment should be conducted that evaluates the combined effects of exposure to all these chemicals. The book suggests an approach for cumulative risk assessment that can serve as a model for evaluating the health risks of other types of chemicals.
Download or read book Science and Decisions written by National Research Council and published by National Academies Press. This book was released on 2009-03-24 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: Risk assessment has become a dominant public policy tool for making choices, based on limited resources, to protect public health and the environment. It has been instrumental to the mission of the U.S. Environmental Protection Agency (EPA) as well as other federal agencies in evaluating public health concerns, informing regulatory and technological decisions, prioritizing research needs and funding, and in developing approaches for cost-benefit analysis. However, risk assessment is at a crossroads. Despite advances in the field, risk assessment faces a number of significant challenges including lengthy delays in making complex decisions; lack of data leading to significant uncertainty in risk assessments; and many chemicals in the marketplace that have not been evaluated and emerging agents requiring assessment. Science and Decisions makes practical scientific and technical recommendations to address these challenges. This book is a complement to the widely used 1983 National Academies book, Risk Assessment in the Federal Government (also known as the Red Book). The earlier book established a framework for the concepts and conduct of risk assessment that has been adopted by numerous expert committees, regulatory agencies, and public health institutions. The new book embeds these concepts within a broader framework for risk-based decision-making. Together, these are essential references for those working in the regulatory and public health fields.
Download or read book Chemical Mixtures and Combined Chemical and Nonchemical Stressors written by Cynthia V. Rider and published by Springer. This book was released on 2018-02-16 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, both basic and advanced concepts are discussed for considering mixtures from initial exposure characterization through evaluation of risk associated with combined exposures. This book will provide an introduction to key issues and multiple options for evaluating both the toxicity of mixtures as well as the risk associated with exposure to mixtures. Additionally, promising tools adapted from other disciplines will be discussed in the context of mixtures toxicology and risk assessment. Finally, the discussion will move beyond chemical mixtures to address incorporating non-chemical stressors into toxicity studies and cumulative risk assessments. Although exposure to multiple chemical and non-chemical stressors is the rule, not the exception, consideration of mixtures in toxicology and risk assessment continues to be a significant challenge. This book will be an essential resource for researchers and professionals in the fields of toxicology, epidemiology, exposure science, risk assessment, and statistics.
Download or read book Tis a Gift to be Simple written by Alan J. Bergmann and published by . This book was released on 2017 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Assessing the risk from exposure to a chemical mixture in the environment can seem prohibitively challenging. Most components of the mixture are not readily identifiable, chemicals may interact to cause other-than-additive toxicity, and the number of potential combinations of environmental contaminants is enormous. These challenges can make it seem impossible to accuractely assess risks associated with chemical mixtures. In reality, not all chemicals in the environment are accessible for organismal uptake, there are a limited number of predictable combinations of chemicals in the environment, and a minority of chemicals are likely responsible for the majority of toxicity in any given sample. This dissertation addresses the seemingly daunting challenge of assessing mixture toxicity by strategically adapting and implementing a collection of sampling and analytical methods to reduce complex environmental mixtures into manageable components. In the first study, personal exposure to chemical mixtures in rural Peru was assessed with silicone wristbands. The samples naturally clustered into groups that were defined by distinct classes of chemicals and were associated with broad demographics of the study participants. The results revealed chemical patterns in wristbands that are possibly indicative of common mixtures in the personal environment and suggest regional sources and routes of chemical exposure. The second study simplified environmental mixtures from a contaminated urban waterway into the most hazardous components. Effect-directed analysis of passive sampling device extracts using a zebrafish bioassay, chromatographic fractionation, and various chemical analyses, eliminated priority pollutants as suspect toxicants and identified responsible toxicants. Specifically, fatty acids and possibly dithiocarbamates were previously unrecorded components of LDPE extracts that likely drive the toxicity of the whole mixtures. Indeed, a minority of chemicals in the whole mixture was responsible for the majority of effects. In total, this dissertation demonstrates that complex mixtures are not unsolvable by applying passive sampling and compatible techniques for simplifying exposure to, and effects of, environmental mixtures.
Download or read book The Toxicology of Chemical Mixtures Risk Assessment for Human and Ecological Receptors written by and published by . This book was released on 2005 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixtures of chemicals represent a concern in all areas of toxicology and a challenge to risk assessors as most sites with environmental contamination, including Department of Defense sites, involve simultaneous or sequential exposures of multiple chemicals to human or ecological receptors. A major concern with mixtures is that they may lead to outcomes (health effects) or increased toxicity (synergism) not expected from the risk characterization of individual chemicals at the site. The focus of this literature review is 0 examine the principles used to determine toxicity in chemical mixtures risk assessment for human and ecological receptors at hazardous waste sites. This review provides an overview of current practices useful to a remedial project manager or risk assessor prior to their first chemical mixtures risk assessment.
Download or read book Method for Assessment of Toxicity Or Efficacy of Mixtures of Chemicals written by Leif L. Marking and published by . This book was released on 1975 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pesticides in the Diets of Infants and Children written by National Research Council and published by National Academies Press. This book was released on 1993-02-01 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many of the pesticides applied to food crops in this country are present in foods and may pose risks to human health. Current regulations are intended to protect the health of the general population by controlling pesticide use. This book explores whether the present regulatory approaches adequately protect infants and children, who may differ from adults in susceptibility and in dietary exposures to pesticide residues. The committee focuses on four major areas: Susceptibility: Are children more susceptible or less susceptible than adults to the effects of dietary exposure to pesticides? Exposure: What foods do infants and children eat, and which pesticides and how much of them are present in those foods? Is the current information on consumption and residues adequate to estimate exposure? Toxicity: Are toxicity tests in laboratory animals adequate to predict toxicity in human infants and children? Do the extent and type of toxicity of some chemicals vary by species and by age? Assessing risk: How is dietary exposure to pesticide residues associated with response? How can laboratory data on lifetime exposures of animals be used to derive meaningful estimates of risk to children? Does risk accumulate more rapidly during the early years of life? This book will be of interest to policymakers, administrators of research in the public and private sectors, toxicologists, pediatricians and other health professionals, and the pesticide industry.
