Environmental Toxicology or Eco-toxicology
Ecotoxicology is defined as, “A multidisciplinary field of science concerned with the study of harmful effects of various chemical, biological and physical agents on living organism.”
Eco-toxicology is a discipline that studies the harmful effects of toxicants on the population and ecosystem levels. Rachel Carson is considered as the mother of Entox due to her book “Silent Spring” written in 1962 and it covered the effects of uncontrolled pesticide use.
Environmental toxicology deals with the effects of environmental toxicants on health and the environment. Environmental toxicants are agents released into the general environment that can cause adverse effects on health. The word “health” here refers to not only human health but also the health of animals and plants. The study of environmental toxicology stems from the recognition that:
Human survival depends upon the well-being of other species and upon the availability of clean air, water, and food.
Anthropogenic chemicals as well as naturally occurring chemicals can have detrimental effects on living organisms and ecological processes.
An Interdisciplinary Approach
Environmental toxicology is thus concerned with how environmental toxicants, through their interaction with humans, animals, and plants, influence the health and welfare of these organisms. It is an interdisciplinary field and encompasses multiple disciplines including ecology, chemistry, molecular biology, genecology, mathematics, statistics, and pharmacology. Environmental toxicology requires a multidisciplinary approach of a variety of specialists.
Components of environmental toxicology:
- Analytical chemistry
- Chemistry, chemical engineering
- Evolutionary Biology
- Marine Biology and Oceanography
- Mathematical and Computer Modelling
- Molecular genetics
- Population biology
- Risk Assessment
- Risk management
Organisms can be introduced to toxicants at various stages of the life cycle. The degree of toxicity can vary. Bioaccumulation occurs when molecular compounds are stored in an organism’s fatty tissue. It leads to the establishment of trophic cascade and bio-magnification of specific toxicants. Biodegradation releases CO2and water as by-products into the environment. This process is typically limited in areas affected by environmental toxicants. Environmental toxicology is the science and practice of the adverse effects – mainly of chemicals and other man-made agents – in the environment and through the environment. The targeted receptors of these adverse effects may be both the ecosystem and the human. Environmental toxicology attempts to anticipate where these substances go in the environment (their fate) and what ecological effects they have when they get there.
Environmental toxicology includes the study of chemical substances- potential and actual Contaminants- polluting air, water, soil, and food, their impacts upon the structure and function of ecological systems, including man as well as the use of these results for decision making and environmental management. As an overall assessment of the whole ecosystem is still impossible and also very expensive, environmental toxicology uses typical species selected from the ecosystem or laboratory test-organisms to examine their response to the chemicals. We may extrapolate from these data to the whole ecosystem.
Effects of Chemicals on The Environment
Chemical substances in the environment can be hazardous to the structure and function of the ecosystem and through that to humans. The aim of environmental toxicology is to characterize the adverse effects of chemical substances on the ecosystem and humans, though we cannot measure these effects directly. The two main reasons for measuring the ecological effects of chemicals are:
To assess what changes are taking place in ecological systems under the influence of released substances, so to assess the environmental risks of the chemicals.
Chemical substances in the environment cause global problems. Not only xenobiotics (men made artificial substances) but also natural substances can be harmful when unusually distributed in the environment or if extreme high values enter the element cycle of the ecosystem. The hazard of a chemical substance originates from its chemical structure. A chemical substance is hazardous either found on a laboratory shelf or referred to in the computer of the designer chemical engineer. However, the risk of a chemical substance is manifested once it gets into the environment. The risk, among others, depends on the properties of the organisms using the environment.
Significance of Eco-Toxicity Results
In the case of humans, we cannot measure the effect of chemical substances as we do with test organisms. lt is not possible to examine the effect of chemicals at various concentrations on a group of individuals and different populations to determine the no-effect concentration. In the case of ecosystems, we cannot test the same ecosystem either. We cannot include in the protocol the testing of all the constituents of the whole system and the interactions between them, as we are not perfectly familiar with the functioning and structure of a healthy and unharmed ecosystem.
Based on the results of eco-toxicity tests we can predict the effect of chemical substances on humans and on the ecosystem. We can extrapolate the effects on humans from the test results with test organisms, which have a similar metabolism to humans. The effects on the ecosystem can be predicted by eco-toxicity tests performed with test-organisms from different tropic levels and based on various principles. Eco-toxicity tests may aim at investigating any level of an ecological system: from the molecular level through communities to the whole ecosystem. Eco-toxicity aims at defining the no adverse effect concentration of a chemical substance in the environment. This can be determined from the concentration-response relationship. Environmental quality criteria should also be based on that. In human toxicology, the dose of the chemical substance added to the test animal or the contaminant concentration of the inhaled air is the basis of setting the no adverse effect concentration to humans.
Subject Nature of Environmental Toxicology
Environmental Toxicology is a young and interdisciplinary science that uses both basic and applied scientific knowledge to understand natural and anthropogenic pollutants’ life cycle and their impacts upon structure and functions of biological and ecological systems. Research in Environmental Toxicology includes both laboratory experiments and field Studies. Environmental Toxicology wants to answer these main questions.
How the release pollutant causes harmful effects?
What can we do to prevent or minimize risk to the biological and ecological system?
What Chemicals kill weeds?
Objective of Environmental Toxicology
The objective of Environmental Toxicology is broken down into a 5-steps understanding process useful for research/regulation:
- Release of pollutant into the environment
- Transport and fate into biota (with/out chemical transformation)
- Exposure to biological and ecological system
- Understanding responses and/or effects (molecular to ecological systems)
- Design remediation, minimization, conservation, and risk assessment plans to eliminate, prevent or predict environmental and human health pollution situations.
People misunderstand Environmental Toxicology is a scientific discipline that only focuses on chemicals in the environment. Not true. It represents environmental chemistry and chemo-dynamics. The rich fabric of ideas, core concepts, literature body, technology, and ideologies that merge together to develop Environmental Toxicology is rather a dissimilar process through most educational institutions. This may be the point in case that Environmental Toxicology is a young interdisciplinary science and controversy regarding what to include in a curriculum is an ongoing matter of discussion. Reading the objectives for each discipline that merge into Environmental Toxicology should decrease the confusion:
- Classical toxicology protects humans (sub-cellular to individual) from toxic substances at harmful concentrations.
- Eco-toxicology (ecology + toxicology) wants to protect many individuals, populations, communities, and ecosystems from exposure to toxic substances at harmful concentrations.
- Environmental science is an interdisciplinary science that studies the earth, air, water, living environments, and social components.
- Environmental chemistry and chemo-dynamics is the study of chemical sources, reactions, transports, effects, and fate in the environment.
Therefore, although these terms do not mean the same, they are related through a linear logical progression (Pollutant Release-Exposure-Dose-Response Paradigm). Environmental Toxicology embraces both disciplines: classical toxicology and eco-toxicology. Further, it includes other sciences to make a more logical approach to understanding and solving real and complex pollution problems that society faces today or will encounter in the future. The interdisciplinary core of Environmental Toxicology borrows heavily from a range of disciplines such as environmental science, environmental chemistry and chemo-dynamics, analytical chemistry, organic chemistry, biochemistry, molecular genetics, cell biology, genomics, pharmacology, pharmacy and toxico-kinetics, physiology, mathematics, and statistics, computer modelling, risk assessment, soil science, geology, ecology, meteorology, marine biology and oceanography, limnology, and wildlife biology.