Ecotoxicology
Ecotoxicology can be understood as a combination of ecology and toxicity . Ecology is the study of the interaction of living beings with each other and with the environment in which they live. Meanwhile, toxicology is a science that seeks to understand the types of reactions caused by chemical, biochemical substances and the biological processes responsible for such effects, taking into account the sensitivity of different types of organisms and the relative toxicities of different substances.
Thus, the objective of ecotoxicology is to understand and predict the effects of chemical substances on living beings and natural communities.
How did ecotoxicology come about?
The term ecotoxicology was coined by René Truhaut in 1969, who defined it as “the branch of toxicology concerned with the study of toxic effects caused by natural or synthetic pollutants, on any constituents of ecosystems: animals (including humans), plants or micro-organisms, in an integral context”.
The publication of the book “Silent Spring”, by Rachel Carson in 1962, marked the separation of ecotoxicology from classical toxicology. The revolutionary element introduced by the author was the extrapolation of the effects on a single organism to an entire ecosystem.
Other sciences involved in ecotoxicology
Ecotoxicology is a broad discipline, as it incorporates aspects of other sciences such as ecology, toxicology, physiology, molecular biology and analytical chemistry .
Importance of ecotoxicology
As highlighted earlier, this area of knowledge has the purpose of predicting the effects of pollutants. Thus, if an incident occurs, it is possible to define effective actions to remedy the consequences caused by these toxic substances. Eco toxicologists, for example, are responsible for protecting the environment and existing ecosystems, including the world’s fauna and flora.
In ecosystems that are already impacted by pollution , ecotoxicological studies can inform which is the best course of action for the ecosystem to be able to recover its services and functions.
What is an ecotoxicological test
The ecotoxicological test, also called bioassay, is used to measure the effects of different concentrations of a sample on individuals of a given species.
The effect concentration or the lethal concentration corresponds to the concentration of the sample responsible for the effect in 50% of the organisms tested, being represented by the abbreviations EC50 and LC50, respectively.
These tests can be acute or chronic, depending on their duration and the observed effect.
In the case of acute tests, the evaluated effect is related to mortality, immobilization or growth inhibition rates. The lower this value, the higher the toxicity of the sample. This often leads to erroneous interpretations of the results obtained.
Thus, the Toxicity Unit (TU) began to be used, which corresponds to (1/EC50*100) to express the results. Ecotoxicological tests can be performed using aquatic or terrestrial organisms and vary according to the type of study performed.
These studies can be carried out at the level of the individual, the population, the community and even the ecosystem, and can last for several years.
Examples of organisms used in ecotoxicological tests
Several organisms can be used in ecotoxicological tests, such as:
Vibrio fischeri
Vibrio fischeri is a non-pathogenic marine bacterium that naturally emits light. According to studies, the metabolism of this organism can be affected by low concentrations of toxic substances. This directly interferes with the intensity of the emitted radiation.
The higher the toxicity, the greater the degree of inhibition of light production.
daphnia magna
Daphnia magna is a freshwater microcrustacean, belonging to the Order Cladocera, commonly called “water flea” due to its swimming style that resembles small “jumps”.
Under favorable conditions, this organism reproduces asexually by parthenogenesis. However, in adverse environmental situations, it begins to reproduce sexually and gives rise to resistant eggs – Egyptian.
