Aquatic Ecotoxicology: Fundamental Concepts and Methodologies

Edited By Alain Boudou, Francis Ribeyre

in Aquatic Ecotoxicology

Research into ecotoxicology can be classified into three fundamental concerns: abiotic factors, which characterize the physicochemistry of environments; biotic factors, relating to biological structures and functions; and contamination factors, which define the modes of pollution of ecosystems. The most significant research methodologies currently being developed in aquatic ecotoxicology are presented, specifically experimental approaches in the laboratory

Fundamentals of Aquatic Toxicology

Edited By Gary M. Rand

in Fundamentals Of Aquatic Toxicology

This text is divided into three parts. The first part describes basic toxicological concepts and methodologies used in aquatic toxicity testing, including the philosophies underlying testing strategies now required to meet and support regulatory standards. The second part of the book discusses various factors that affect transport, transformation, ultimate distribution, and accumulation of chemicals in the aquatic environment, along with the use of modelling to predict fate.; The final section of the book reviews types of effects or endpoints evaluated in field studies and the use of structure-activity relationships in aquatic toxicology to predict biological activity and physio-chemical properties of a chemical. This section also contains an extensive background of environmental legislation in the USA and within the European Community, and an introduction to hazard/risk assessment with case studies.

Environmental Epidemiology

Jerry D. Rench

in Basic Environmental Toxicology

This chapter provides an overview of the basic concepts and methods of study used in environmental epidemiology. One approach that epidemiologists take to identify factors that cause or influence disease occurrence is to evaluate time, person, and place characteristics. Diseases which result in mortality are of considerable interest for public health assessment because of the suffering and cost associated with death, particularly when it occurs at a young age. Measurement of exposure is a component of epidemiologic studies in which the objective is to assess a relationship between an environmental contaminant and a disease. The larger the value of relative risk, the more convincing the evidence that an etiological relationship exists between exposure and the disease. Another measure of disease occurrence is the standardized mortality ratio, a measure of risk relative to that of another population called the standard or reference population. The cross-sectional study evaluates the prevalence of a disease or illness in a population.

The Use of Epidemiology in Environmental Risk Assessment

Published in Human and Ecological Risk Assessment: An International Journal

By Joel Schwartz 

Epidemiology provides estimates of the concentration–response relation for environmental and occupational toxicants in the species of interest, in or close to the dose range of interest. As such, when available, they provide the primary source for risk assessments. Further information can be acquired by using modern biostatistical techniques to assess the shape of the dose response relation, examine effect modification, and assure control for confounding. These approaches are particularly effective if they are done in the context of a meta-analysis or hierarchical model. This is illustrated with examples from the air pollution literature.

Scientific Foundations of Hormesis. Part 2. Maturation, Strengths, Limitations, and Possible Applications in Toxicology, Pharmacology, and Epidemiology

Published in Critical Reviews in Toxicology

Karl K. RozmanJohn Doull 

The notion of hormesis has undergone numerous modifications in the course of the 20th century. Because of its unfortunate association with homeopathy, hormesis did not gain acceptance among biomedical professionals. The lack of a plausible mechanism for its occurrence may have contributed much to the rejection of this concept. This treatise outlines the conceptual struggle for an understanding of the widespread occurrence of low dose effects that appear to be opposite to those caused by high doses as also seen in hormesis. An incomplete conceptualization of time as a fundamental variable of effects (in addition to dose) is identified as one of the major reasons why hormetic responses were not observed more frequently than was reported by Calabrese and Baldwin.7 The definition of hormesis as an (over)compensation response to an inhibitory signal lacks a designation for (over)compensation responses to stimulatory signals in the other direction. Hormoligosis, which was coined by Luckey for all low-dose stimulatory responses of toxins, is suggested as a suitable term for generalizing the latter types of effects. Both types of effects are recognized as originating in a homeostatic overcompensation response that optimizes the ability of an organism to meet challenges beyond the limits of normal (unexercised) adaptation.

Pyrethroid epidemiology: a quality - based review

Published in Critical Reviews in Toxicology

Carol J. BurnsTimothy P. Pastoor

Numerous epidemiology studies have evaluated the association between health outcomes in humans and pyrethroid exposure. The purpose of this review was to identify and evaluate the quality of pyrethroid-related epidemiology studies that addressed chronic health effects, and compare findings with animal toxicology studies. We evaluated the quality of 61 studies published between 2000 and 2016 by using elements of outcome, exposure metric, exposure level, and study design. None of the 61 publications demonstrated strong quality for all elements. A few of the outcome measures were strong, particularly those relying upon medical diagnoses. Most of the pyrethroid epidemiology studies used a poor exposure metric, relying upon a single sample of pyrethroid urinary metabolites, which is subject to misclassification of past exposures. In addition, many studies were a cross-sectional design, preventing an evaluation of the temporality of the exposure-disease association.