Showing papers on "Aquatic toxicology published in 1998"

Fish cell lines as a tool in aquatic toxicology

Abstract: In aquatic toxicology, cytotoxicity tests using continuous fish cell lines have been suggested as a tool for (1) screening or toxicity ranking of anthropogenic chemicals, compound mixtures and environmental samples, (2) establishment of structure-activity relationships, and (3) replacement or supplementation of in vivo animal tests. Due to the small sample volumes necessary for cytotoxicity tests, they appear to be particularly suited for use in chemical fractionation studies. The present contribution reviews the existing literature on cytotoxicity studies with fish cells and considers the influence of cell line and cytotoxicity endpoint selection on the test results. Furthermore, in vitro/in vivo correlations between fish cell lines and intact fish are discussed.

Evaluation of aquatic toxicity and bioaccumulation of C8- and C9-alkylphenol ethoxylates

Abstract: The extensive database of acute and chronic aquatic toxicity data for alkylphenol ethoxylates (APEs) and selected biodegradation intermediates was reviewed and summarized for freshwater and saltwater aquatic microorganisms, algae, invertebrates, and fish inhabiting cold and warm water bodies. Most acute toxicity studies that tested APE-9 and APE-10, the most common commercially relevant APEs, reported results that ranged from about 1,000 to 10,000 μg/L. Results from studies testing alkylphenols, intermediate by-products of APE biodegradation, ranged from about 20 to 3,000 μg/L. Chronic values are a factor of about 2 to 10 lower. Although most studies used one of several common species and standard protocols to assay conventional endpoints, many nontraditional species and toxicological endpoints were also used. This toxicological database encompasses virtually all important types of aquatic habitats and classes of aquatic species. Bioaccumulation data from both laboratory and field studies indicate that alkylphenols have a low to moderate bioaccumulation potential. Fresh weight, nonlipid-based bioconcentration factors (BCFs) measured in the laboratory ranged from < 1 to 1,250 for fish and 1 to 3,400 for invertebrates, whereas field bioaccumulation factors (BAFs) ranged from 6 to 487, with most values < 100. Overall, these data provide an extensive and useful database to support environmental risk assessment activities.

Immunochemical approaches to studies of CYP1A localization and induction by xenobiotics in fish

Abstract: There is an increasing understanding that polynuclear aromatic hydrocarbons (PAHs) and organochlorine compounds (like polychlorinated biphenyls (PCBs), certain pesticides and dioxins) in the aquatic environment may lead to physiological and pathological effects such as immunological disturbances, effects on reproduction and development, and even neoplasms. Exposure to pollutants may have consequences at all levels in the biological organization, from the cellular level over effects on the individual organism, population, to the entire ecosystem. The cytochrome P450 system (CYP or P450) has an essential function in the biotransformation of endogenous and exogenous compounds. The fact that many different environmental pollutants induce de novo synthesis of cytochrome P450 lA (CYP1A) proteins in fish, gives these enzymes an interesting position in aquatic toxicology. Many investigations concerning the CYP1A system in fish have been performed over the last two decades, demonstrating its usefulness as a biomarker for aquatic pollution. A general overview of the biochemical and toxicological aspects concerning the cytochrome P450 system will be given here, followed by a more detailed description of CYP1A induction responses in fish. Ecotoxicological consequences of CYP1A induction and the use of immunochemical techniques for CYP1A detection as a biomarker in environmental monitoring will be discussed.

Report of the OECD Workshop on Statistical Analysis of Aquatic Toxicity Data

Abstract: There are three required components of dynamic models for toxic effects: toxico kinetics, effects on a target parameter coupled to the internal concentration and the physiological component. The Dynamic Energy Budget (DEB) model, which is used to model the latter component, relates a change in a target parameter of a particular physiological process, such as the specific costs for growth, to an output variable, such as the cumulative number of offspring. We compare the logit/probit and the DEB-based models conceptually and numerically and conclude that the DEB-based model is more effective as an effect model. The DEB-based model solves the problem of estimating the No-Effect Concentration and provides the required information to evaluate the consequences of effects on individuals for population dynamics.

Establishment of quality assurance procedures for aquatic toxicity testing with the nematode Caenorhabditis elegans

Abstract: In this study initial data were generated to develop laboratory control charts for aquatic toxicity testing using the nematode Caenorhabditis elegans. Tests were performed using two reference toxicants: CdCl{sub 2} and CuCl{sub 2}. All tests were performed for 24 h without a food source and of 48 h with a food source in a commonly used nematode aquatic medium. Each test was replicated 6 times with each replicate having 6 wells per concentration with 10 {+-} 1 worms per well. Probit analysis was used to estimate LC{sub 50} values for each test. The data were used to construct a mean ({bar x}) laboratory control chart for each reference toxicant. The coefficient of variation (CV) for three of the four reference toxicant tests was less than 20%, which demonstrates an excellent degree of reproducibility. These CV values are well within suggested standards for determination of organism sensitivity and overall test system credibility. A standardized procedure for performing 24 h and 48 h aquatic toxicity studies with C. elegans is proposed.

Lewisʾ dictionary of toxicology

Abstract: Agricultural Toxicology * . Aquatic Toxicology * Biochemical Toxicology * Clinical Toxicology * Comparative Toxicology * Ecotoxicology * Embryotoxicology * En vironmental Toxicology * Forensic Toxicology * Genotoxicology * Immunotoxicology * Neurotoxicology * Nutritional Toxicology * Pharmacologic Toxicology * Regulatory Toxicology * Industrial Toxicology * Veterinary Toxicology * Zootoxicology * Wildlife Toxicology.

Incorporating hormesis in the routine testing of hazards

Abstract: The phenomenon of subtoxic stimulation of organism response is not uncommon in aquatic toxicology experiments. We describe the presence of hormesis in both growth and reproduction experiments in aquatic toxicology where these responses are observed in both animals and plants and at different trophic levels of an ecosystem. The implications of ignoring hormetic responses in the analysis of toxicity data are discussed. In particular, we note that specification of models that explicitly cannot accommodate or remove potential effects of hormesis may lead to biased potency estimates. Further, the presence of hormesis has implications for the design of toxicology experiments, with the spacing of concentration test conditions being critical.

Arsenic metabolism in aquatic ecosystems

Abstract: The concentration of arsenic is higher in marine organisms (Tables 6.1 and 6.2) than in freshwater organisms (Cullen and Reimer, 1989) and therefore arsenic in the sea and in marine organisms has received much greater attention than arsenic in freshwater environments; higher concentrations generally mean greater ease of study and greater fears of toxicity to be stilled. The contents of this chapter dealing with marine and freshwater environments will reflect this disproportionate attention.

Added risk and inverse estimation for count responses in reproductive aquatic toxicology studies.

Abstract: One of the experimental designs used to evaluate the toxicity of certain chemicals in aquatic organisms focuses on reproductive output. Toxic effects are manifested through a reduced level of reproduction in exposed organisms. Historically, evaluating risks in this context has focused on changes in the mean reproduction in a population of organisms. In this paper, we focus on the toxic effects at the level of the individual organism. This new method for count responses involves added risk, the probability of the production of young being suppressed below certain specified levels in individuals exposed to a particular concentration level relative to the probability of that level of suppression in control organisms. This probability serves as the basis of the individual-based risk estimation procedures. In particular, inverse estimation of the concentration associated with a specified added risk and estimates of the added risk associated with a particular concentration are discussed in the context of a negative binomial regression model. Confidence intervals are constructed for both of these quantities using the delta method. These methods are illustrated with a study of an aquatic organism, Ceriodaphnia dubia, exposed to the herbicide nitrofen.