Glossary of terms and concepts

Fertilization, also known as insemination, fecundation and impregnation, is the fusion of two gametes – male and female – to initiate the development of a new organism of the same species. This cycle of fertilisation and development of new individuals is called sexual reproduction. The single cell resulting from the fusion of gametes (a female egg with a male sperm) is called zygote.

Embryo, is an early stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development refers to the portion of the life cycle that begins after fertilization and continues through the formation of tissues and organs. In the first stages a single cell called zygote undergoes rapid cell divisions to form a ball of cells named blastula. Next, the cells in the blastula-stage embryo start rearranging into layers in a process called gastrulation. For humans we use the term embryo until the ninth week, after which we use the term fetus.

Larvae, is a distinct juvenile form before metamorphosis of some animals into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The larvae generally look very different from the adults – e.g. caterpillars and butterflies – including unique structures and organs that do not persist in adulthood.

Ecotoxicology, is a discipline aimed to study the man-to-biosphere relations for the sustainability of life existence on earth. The basis of ecotoxicology is classical toxicology – the research of drugs and chemical compounds effects on human. The modern concept of ecotoxicology studies migration, transformation, degradation and utilization of toxic ingredients (with organic, inorganic or organic-mineral chemical nature; with natural biotic or abiotic origin and artificial, mainly anthropogenic origin) in the environment and their impact on macrobiological systems.

Ecotoxicological studies can be conducted in two ways:

• Epidemiological studies consisting of the observations of a given human population being exposed to the particular substance, that allows for an estimation of the exposure risk.

• Application of laboratory methods with the use of different experimental models, and further on, an attempt to apply the obtained results to evaluate the risk of exposure.

Exposure Assessment, a branch of environmental science that focuses on the processes that occur at the interface between a contaminated environment and organisms. It measures how much of a contaminant can be absorbed by an organism, in what form, at what rate and how much of the absorbed amount is able to produce a biological effect. The majority of applications of exposure assessment are concerned with human wellbeing, making it an important tool in public health.

Sampling, the selection of a subset of representative individuals from within a population, or an area within a territory, in order to estimate characteristics of the whole population or the territory. It is used extensively in statistics, quality assurance and monitoring schemes.

Biomonitoring, the measurement of the response of organisms, called bioindicators, to changes in the environment. Biomonitoring aims to collect information on the concentration of the chemicals and to predict its effects. Bioindicators can be divided into two types: 1) organisms that appear in a habitat contaminated with a given substance and are characteristic of this contamination; 2) species sensitive to a specific factor that disappear from a given habitat in the presence of a toxic substance.

Monitoring in Medicine, the observation of a disease or medical parameters over time. It can be performed by continuously measuring certain parameters – for example, vital signs by a bedside monitor – and/or by repeatedly performing medical test such as blood glucose level for several times.

Biotests, an experimental biological sample used to to determine the potency or concentration of a compound by its effect on live organism – animals, isolated tissues, or microorganisms – based on a comparison with the control sample. There are two main methods of conducting research with the use of a biotest:

• Tests performed in the laboratory in which the chemical is artificially introduced into the environment. These tests provide information on toxicity under controlled conditions.

• Tests to monitor a natural envirorment, using a population of organisms living in that environment as biotests.

The organism classified as a biotest must meet a number of conditions:

• Relatively easy maintenance in laboratory conditions, allowing to obtain a large number of individuals,
• Easy isolation of organisms from the environment,
• Knowledge of the genetic structure of the organism and its sensitivity to toxic substances,
• The selected organism with high sensitivity should represent a given species or group to which it belongs, and moreover it must be a native species, characteristic for the studied ecosystem,
• The test organisms should respond similarly to the dose or concentration of the toxin at different sites and with a defined degree of exposure to contaminants.