What Is Environmental Toxicology? Core Principles and Real-Life Examples
Toxicology is the branch of science that deals with the study of toxicants or toxic substances, their mechanism of action, chemical structure, potency, and effects on animal or human bodies.
As we all know, environmental pollution has become a cause of concern all over the world. Pollution is a result of certain environmental pollutants that exert a toxic effect on the normal functioning of our surroundings that leads to pollution in the environment.
Thus, the pollutants that are damaging the environment can be regarded as toxicants causing degradation in environmental quality. It becomes essential for us to study such toxicants to reduce the incidence of pollution. This comes in the form of environmental toxicology that forms a connecting link between toxicology and environmental health sciences.
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Environmental Toxicology and Chemistry
Environmental toxicology or Entox or Environ Toxicol is the study of the toxic effects of pollutants on environmental health. It also gives a detailed account of environmental toxicity caused due to the different sources of pollution and pollutants. As the nature of environmental pollutants can be both natural as well as synthetic, environmental toxicology deals with the effect of both types of pollutants.
There have been several developments in environmental toxicology ever since the study of environmental pollution began. This led the research about environmental health and toxicology giving rise to a separate branch in science.
Environmental Toxicology and Pharmacology
As toxicology and pharmacology are two interrelated branches in chemistry, environmental toxicology is also associated with pharmacology. Under the pharmacological counterpart of environmental toxicology, people study the toxic effects of harmful chemicals or drugs on the environment.
It provides information regarding the effect of environmental toxicity on human as well as animal health. The effects of environmental pollution are not limited to just our surroundings as they penetrate deep into the body-systems of living organisms and exert a negative effect. Environmental toxicology and pharmacology deal with publishing reports and analysis about such effects and their trends over a designated period. This study is also given the term environ Toxicol Pharmacol for short.
Environmental Toxicology and its Branches
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Due to the differentiation of environmental pollutants and their side-effects, environmental toxicology is divided into different branches.
For the scope of this discussion, we shall consider two branches of environmental toxicology that are:
Environmental health toxicology, and
Ecotoxicology
Let's discuss these branches in detail:
Environmental Health Toxicology:
As the name suggests, environmental health toxicology deals with the study of the effects of harmful environmental pollutants on the human body and animal body. This branch deals with the mechanism of action, toxicokinetic, toxicodynamic, and treatment that is associated with the pollutant when it comes in contact with a living system.
The phenomenon associated with environmental health and toxicology are:
Bioaccumulation: One of the biggest problems of environmental pollution is that of bioaccumulation. It is the process by which the toxic chemicals or pollutants present in the environment enter the body of living organisms particularly human beings, and create a reserve in the body. These chemicals are accumulated from abiotic sources and are ingested through passive diffusion. The visceral organs of the body namely GIT, liver, kidney, lungs, and gills will accumulate the toxicants that put the normal physiology in danger.
Ecotoxicology:
The other component of environmental toxicology is ecotoxicology that relates to the harmful effect that the environmental pollutants impose on the ecosystems of the living communities that form the part of the biosphere.
An ecosystem has several mechanisms of interactions occurring within the living and the non-living components. Under ecotoxicology, there are two factors considered as causes for environmental degradation, and these include:
Abiotic Factors: The abiotic factors refer to the non-living components of the environment or an ecosystem that behave as toxicants. These factors cause environmental degradation through hydrolysis and photolysis.
Biotic Factors: The living organisms present in an ecosystem are known as the biotic components. Some of these biotic components may cause environmental degradation. It can be useful at the same time harmful. The fungi and other microorganisms that help in degradation through scavenging and decomposition are vital servers of the ecosystem. The activities of mankind on the other hand can cause the liberation of toxicants in the environment.
Did You Know?
An estimated 25% of India’s coral reefs have been destroyed as a result of environmental degradation.
Society of Environmental Toxicology and Chemistry
SETAC (Society of Environmental Toxicology and Chemistry) is dedicated to environmental sciences. The main objectives of the organization are to develop strategies regarding the improvement of the environment and prevention of pollution in the environment. The organization does by organizing meetings, workshops, rallies as well as symposia to discuss the developments in environmental toxicology. They also promote education in the field of environmental toxicology with the help of online courses and organizing various public awareness campaigns. The society also publishes an Environmental toxicology and Chemistry journal that accounts for the details of the position of environmental pollution.
FAQs on Environmental Toxicology: Essential Guide for Chemistry Students
1. What is Environmental Toxicology from a chemistry perspective?
Environmental Toxicology is a specialised branch of chemistry that studies the adverse effects of chemical substances, or toxicants, on living organisms and ecosystems. It investigates the sources, fate, transport, and chemical transformation of these pollutants in the environment, as well as the biochemical mechanisms through which they cause harm at a molecular level.
2. What are the main categories of environmental toxicants relevant to the CBSE syllabus?
For chemistry students, environmental toxicants are typically categorised based on their chemical nature and source. Key categories include:
- Heavy Metals: Elements like lead (Pb), mercury (Hg), and cadmium (Cd) that are persistent and can bioaccumulate.
- Pesticides: Synthetic organic compounds such as insecticides (e.g., DDT) and herbicides designed to be toxic.
- Gaseous Pollutants: Compounds like sulphur dioxide (SO₂), nitrogen oxides (NOx), and carbon monoxide (CO) that contribute to acid rain and smog.
- Persistent Organic Pollutants (POPs): Highly stable chemical compounds that resist degradation, such as dioxins and PCBs.
- Hydrocarbons: Often released from petroleum spills or incomplete combustion, impacting soil and water quality.
3. How do toxic chemicals move through and impact an ecosystem?
Toxicants move through an ecosystem via environmental media—air, water, and soil. A chemical released into the air can travel long distances before settling in water or on land (deposition). In water, it can be absorbed by aquatic life. In soil, it can be taken up by plants. The ability of a chemical to persist without breaking down and its potential to move between these media determine its overall environmental impact and how widespread its toxic effects become.
4. What is the fundamental difference between bioaccumulation and biomagnification?
While both describe the concentration of toxicants in organisms, they operate at different levels. Bioaccumulation refers to the gradual build-up of a chemical in a single organism over its lifetime, as it absorbs the substance faster than it can metabolise or excrete it. In contrast, biomagnification (or bioamplification) is the process where the concentration of a toxicant increases at successively higher levels in a food chain. For example, small fish bioaccumulate mercury, and a larger fish that eats many small fish will end up with a much higher, magnified concentration.
5. Why are heavy metals like lead and mercury considered particularly dangerous environmental toxicants?
Heavy metals are exceptionally dangerous for two main chemical reasons. First, they are non-biodegradable, meaning they cannot be broken down by environmental processes and thus persist for very long periods. Second, they have a high affinity for sulphur atoms found in the amino acids of enzymes. By binding to these enzymes, they disrupt or inhibit crucial biochemical pathways, leading to severe neurological damage and other systemic health problems in humans and animals.
6. How does photochemistry lead to the formation of environmental toxicants like smog?
Photochemistry plays a critical role in creating secondary pollutants. Photochemical smog, for example, is not emitted directly. It forms when primary pollutants like nitrogen oxides (NOx) and volatile organic compounds (VOCs) from vehicle exhaust react in the presence of sunlight (photo-). These photochemical reactions produce a toxic mixture of ozone (O₃), peroxyacetyl nitrate (PAN), and other oxidants, which are highly harmful to respiratory systems and plant life.
7. What is the role of green chemistry in mitigating environmental toxicity?
Green chemistry provides proactive solutions to prevent pollution by designing chemical products and processes that are inherently safer. Its role in mitigating environmental toxicity is to minimise or eliminate the use and generation of hazardous substances from the start. This includes creating biodegradable pesticides, using less toxic solvents in industrial processes, and developing catalysts that enable more efficient reactions, thereby reducing harmful byproducts and waste.
