Scope and importance of toxicology

Toxicology is the scientific study of adverse effects that occur in living organisms due to chemicals. It involves observing and reporting symptoms that arise following exposure to toxic substances.

1. SCOPE AND IMPORTANCE OF TOXICOLOGY

2. CONTENTS Toxicity Categories of toxicology Principles aspects of Toxicology Scope and Importance of Toxicology

3. TOXICITY Actually toxicity is a relative term generally applied in comparing one chemical with another. Toxicity of a chemical may be defined as the capability to cause injury in a living organism. A highly toxic substance is that which causes damage to an organism if administered in a very small amount. But a substance of low toxicity will not produce an effect unless the amount is very large. In fact, toxicity may not be defined without reference to the quality of a substance administered or absorbed (Dose), The way in which this quantity is administered (e.g., inhalation, ingestion, injection), And distributed in time (e.g., single dose, repeated dose), The type and severity of injury and the time required to produced that injury.

4. Thus, toxicity is a relative property of a chemical which refers to its potential to have a deleterious effect on a living organism. Also, toxicity is a function of the concentration of the chemical and the duration of exposure. Toxicity data are generally used in comparing toxic potentialities of chemicals. The nature and extent of toxicity varies depending upon the origin of toxicants. They may be natural or synthetic in origin. Naturally occurring toxicants may originate from animal, plant or mineral sources. Animal toxins as venom belong to this category. Many plants contain toxic agents and many of these are developed for pharmacological applications. Some among these are atropine, opium, reserpine, quinine, picrotoxin etc.

5. A number of antibiotics come from microbes, including mycotoxins. The majority of toxicants stem from industrial or commercial pool of synthetic chemicals. The toxic effects of the chemical may be physiological, biochemical, and pathological in nature. The changes produced by the toxicants may be complex, damaging one or different organs/ tissues/ cells. These, in action, may be corrosives, irritants, narcotics etc.

6. Categories of Toxic effects Toxic effects may be grouped into: Local and systemic effect Reversible and irreversible effect Immediate and delayed effect Morhological effect Functional effect Biochemical effect

7. Principal aspect of Toxicology The following are the principal aspects of Toxicology: Toxicometrics : It is the study of measurement of poisons. Toxicodynamics : It deals with the biochemical and physiological effects of xenobiotics and mechanisms of their action Toxicokinetics : It deals with the absorption, distribution, biotransformation and excretion of xenobiotics.

8. SCOPE AND IMPORTANCE OF TOXICOLOGY Toxicology incorporates a very broad scope. It is primarily concerned with the identification of deleterious agents and, secondly, with the treatment of these agents for detoxication, i.e., removal of the toxin. Apart from this a toxicologist is also concerned with the character, properties, signs and symptoms and the chemical detection of the toxin, where offensive intent is suspected. Actually, toxicology has its impact on human life from the day of conception in the womb till the last moments of life. Nevertheless, certain toxicants are even deleterious for the spems and the ova.

9. Toxicology deals with the toxicity studies of chemicals used: In medicine for diagnostic, preventive and therapeutic purposes. In food industry as direct and indirect additives. In agriculture as pesticides, growth regulators, artificial pollinators, and animal food additives. In chemical industry as solvent, components, and intermediates of plastics and many other types of chemicals. Toxicology is also concerned with the health, effects of metals (as in mines and smelters), petroleum products, paper and pulp, toxic plants and animal toxins.

10. The study of toxicology may be system-wise and also agent-wise. In this way, we may have systemic toxicology involving toxicology of central nervous system, hepatic system, respiratory system, ophthalmic system, etc. The study would include defences of each of these systems against assault from foreign chemicals, responses and reactions as also injuries caused through excesses. An agent-wise study would take up drugs, pesticides, food additives, chemicals, heavy metals, trace elements, polymers, radiation, chemical carcinogens, teratogens. There is hardly much of generalization which can be made and many of the agents have to be studied individually in different species before being precisely conclusive.

11. Application of toxicology for practical purposes can be broadly divided into three areas which are, however, flexible and overlapping: Forensic toxicology where medical science has a role. Economic or industrial toxicology which includes drugs, pesticides, food additives, containers (like cans and packing materials) etc. Environmental toxicology which includes pollutional studies, residue analysis, industrial hegiene and occupational health. Besides, many other divisions and names are also given by different scientists.

12. When standard procedures may not be able to predict the toxicity in human, then the predictions have to be based on chemical and physical properties, molecular structure, biological activity relations, pharmacokinetics etc. This is termed as Speculative Toxicology and is based upon certain speculative studies. Usefulness of the study of toxicology to human beings be described in the following points:

13. Toxicology may be helpfu in the development of: Suitable and safer food additives, Suitable and safer pesticides, Suitable drugs against any specific disease.

14. 2. The data on acute toxicity tests for various xenobiotics against different fauna may be valuable in following ways: Provides an idea of toxic dose of a specific toxicant for specific animal. Makes certainty of sublethal doses of the toxicants for specific animal. Provides precise idea about maximum ermissible limits for the pollutants in the ambient air or the drinking water. Assists in evaluation of maximum acceptable daily intake of specific chemical. Aids in determination of sensitive species. Aids in ascertaining sublethal dose of any chemical for long-term toxicity tests.

15. 3. The data on long-term toxicity tests provides reliability for: In evaluation of after levels of xenobiotics. In determining the most sensitive stage of a particular target animal against any toxicant. In elucidation of mode of toxicity of chemicals. In rational therapy of intoxification . In establishment of sensitive predictive tests useful in achieving information for risk assessment.

16. 4. Toxicology may be helpful in the antidotal therapy. 5. It may be helpful in the monitoring of environmental pollution. 6. Toxicology may be helpful in monitoring of risk assessment. 7. An understanding of the mechanism of toxic action also contributes to the basic knowledge of pharmacology, physiology, biochemistry and cytology. 8. Analytical toxicology provides suitable procedures to evaluate the presence or absence of different types of substances and their levels in the environment. 9. It aso contributes an idea about the permissible limit of any toxicant in any segment of the environment. 10.Comparative toxicology is concerned with the study of different species of animals exposed to chemical stresses to evaluate how clos these are to human systems. 11. It gives an idea about the factors affecting the toxicity of any toxicant.

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