What Is Environmental Toxicology Definition Types Sources and Adverse Effects
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 and Its Impact on Ecosystems and Human Health
1. What is environmental toxicology in chemistry?
Environmental toxicology is the study of how chemical pollutants affect living organisms and ecosystems in air, water, and soil. It combines principles of chemistry and toxicology to understand:
- The chemical nature and structure of pollutants (e.g., heavy metals, pesticides, hydrocarbons)
- Their transformation reactions such as oxidation, hydrolysis, and photolysis
- Their movement through environmental compartments (air–water–soil)
- Their toxic effects at molecular, cellular, and ecosystem levels
2. What are the main types of environmental pollutants?
The main types of environmental pollutants are chemical, physical, and biological pollutants, with chemical pollutants being most important in environmental toxicology. Key chemical categories include:
- Heavy metals: Pb, Hg, Cd, As
- Organic pollutants: pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs)
- Air pollutants: SO2, NO2, CO, O3
- Nutrients: NO3-, PO43- (cause eutrophication)
- Emerging contaminants: pharmaceuticals and microplastics
3. What is bioaccumulation and how does it occur?
Bioaccumulation is the process by which a chemical substance builds up in an organism faster than it is eliminated. It occurs when:
- The substance is lipophilic (fat-soluble), such as DDT or PCBs
- It is resistant to metabolic breakdown
- Exposure is continuous through water, food, or air
4. What is biomagnification in environmental toxicology?
Biomagnification is the increase in concentration of a toxic chemical at higher levels of a food chain. It occurs because:
- Lower trophic organisms accumulate pollutants
- Predators consume many contaminated prey
- The chemical is not easily metabolized or excreted
5. How do heavy metals cause toxicity in the environment?
Heavy metals cause toxicity by binding to proteins and enzymes, disrupting essential biochemical reactions. Chemically, metal ions such as Hg2+, Pb2+, and Cd2+ can:
- Bind to sulfhydryl (–SH) groups in enzymes
- Displace essential metal ions like Zn2+ or Ca2+
- Generate reactive oxygen species (ROS)
6. What is the difference between acute and chronic toxicity?
Acute toxicity refers to harmful effects occurring shortly after a single or short-term exposure, while chronic toxicity results from long-term, repeated exposure to lower doses. In environmental toxicology:
- Acute toxicity is often measured by LD50 (lethal dose for 50% of test organisms)
- Chronic toxicity includes cancer, reproductive harm, or organ damage over months or years
7. What is LD50 in toxicology?
LD50 (lethal dose 50%) is the amount of a substance required to kill 50% of a test population under controlled conditions. It is usually expressed in mg/kg of body weight and indicates relative toxicity:
- Lower LD50 value → higher toxicity
- Higher LD50 value → lower toxicity
8. How do persistent organic pollutants (POPs) affect ecosystems?
Persistent organic pollutants (POPs) are toxic organic compounds that resist degradation and accumulate in ecosystems. They are characterized by:
- Chemical stability against photolysis and biodegradation
- High lipid solubility, leading to bioaccumulation
- Long-range atmospheric transport
9. What is eutrophication and how is it related to environmental chemistry?
Eutrophication is the excessive enrichment of water bodies with nutrients, mainly NO3- and PO43-, leading to algal blooms and oxygen depletion. Chemically, it involves:
- Runoff containing fertilizers or sewage
- Rapid algal growth
- Decomposition that consumes dissolved O2
10. How are toxic chemicals degraded in the environment?
Toxic chemicals are degraded in the environment through chemical, photochemical, and biological processes. The main degradation pathways include:
- Photolysis: breakdown by sunlight (UV radiation)
- Hydrolysis: reaction with water
- Oxidation–reduction reactions in air or soil
- Biodegradation by microorganisms
