Adverse effects of pure chemicals are usually characterized by the concentration- response or dose-response curve. The effective concentration or effective dose can be read from this curve, given that the concentration, mass or volume of the chemical substance used in the study is exactly known. The test results indicate the hazard posed by the chemical substance. When the environmental concentration is known, the risk can be calculated from the scale of the hazardous effect. The assessment of adverse effects of environmental samples is different because the concentration of the contaminants in water or soil samples is not known, and in most cases an unidentified mixture of contaminants is present. Studies, tests, bioassays or microcosms can measure the toxicity quantitatively based on the actual adverse effects of environmental samples. The actual adverse effect is in direct relation to risk. Direct toxicity assessment (DTA) ensures high environmental relevance representing all possible interactions between contaminants, ecosystem members and soil phases aggregating the effect of all contaminants present in the sample. In addition to this, DTA can simulate different water and soil uses and real, multiple exposures. On the other hand, directly measured toxicity of environmental samples cannot be expressed in concentration thus it does not fit the chemical risk assessment model and concentration-based screening values applied to pure chemicals. DTA provides the effective or non-effective soil doses or dilutions as test end point, read from the dose-response curve. This is a shortcoming not only from the regulatory point of view but also for most environmental professionals who think and act mechanically, according to the chemical model. The authors have introduced an option to bridge direct toxicity assessing methods with the chemical model of environmental risk assessment. The equivalency methodology applies the copper equivalency toxicity to waters and soils contaminated with inorganic and the 4-chlorophenol equivalent to organic chemicals. A separate section is devoted to statistics in toxicology. An overview of statistical methods, the most frequently applied methods and the relevant IT tools are discussed in detail. A short summary is given on the use of toxicity results in risk assessment.
|Title of host publication||Engineering Tools for Environmental Risk Management|
|Subtitle of host publication||2. Environmental Toxicology|
|Number of pages||100|
|Publication status||Published - Jan 1 2015|
ASJC Scopus subject areas
- Environmental Science(all)
- Chemical Engineering(all)