Toxicology: Study of Poisons and Insecticides

Toxicology and Insecticides

• Toxicology is the study of the adverse effects that chemicals or physical agents may produce in living organisms under specific conditions of exposure.

Basic Definitions

• Toxic: having the characteristic of producing an adverse health effect.
• Toxicity: any toxic (adverse) effect that a chemical or physical agent might produce within a living organism.
• Toxicant: any substance that causes a harmful (or adverse) effect when in contact with a living organism at a sufficiently high concentration.
• Dose: the total amount of a toxicant administered to an organism at specific time intervals.
• Target organ dose: the amount of toxicant reaching the organ (known as the target organ) that is adversely affected by the toxicant.
• Exposure: to cause an adverse effect, a toxicant must first come in contact with an organism.

Types of Toxicity

• Acute toxicity: an adverse or undesirable effect that is manifested within a relatively short time interval ranging from almost immediately to within several days following exposure (or dosing).
• Chronic toxicity: a permanent or lasting adverse effect that is manifested after exposure to a toxicant.
• Local toxicity: an adverse or undesirable effect that is manifested at the toxicant’s site of contact with the organism.

The Basic Components of Toxicity Test

• The selection of a test organism
• The selection of a response to measure
• An exposure period
• The test duration (observation period)
• A sequence of doses to test

Factors Affecting Toxicity

• Form and innate chemical activity
• Dosage
• Exposure route
• Age
• Sex
• Presence of other chemicals

Metal Toxicity

• Metals are extensively used in commercial and industrial applications and, as a result, exposure can occur from direct and indirect pathways.
• Classification of metals: essential and nonessential metals.

Essential Metals

• Have important biological roles and are essential for good health.
• Examples: cobalt, copper, iron, magnesium, manganese, and molybdenum.

Nonessential Metals

• Have no known beneficial role to play in biological function.
• Examples: beryllium, cadmium, lead, mercury, thallium, titanium, and uranium.

Toxicology of Selected Metals

Arsenic

• A gray-colored metal found in the environment in both organic and inorganic compounds.
• Human exposure may involve inhalation of arsenic dusts; ingestion of arsenic in water, food, or soil; or dermal contact with dust, soil or water.
• Symptoms of toxicity: nausea or vomiting, abdominal pain, diarrhea, garlic odor on breath, headache, vertigo, fatigue, paresthesia, paralysis, kidney failure.

Mercury

• Found in the environment in a metallic or elemental form, as an inorganic compound, or as organic mercury compounds.
• Symptoms of toxicity: metallic taste in the mouth, excess salivation, gingivitis, tremors, stomach and kidney troubles, shyness, irritability, apathy and depression, psychosis, mental deterioration, and anorexia.

Toxicology and Insecticides

• Toxicology is the study of the adverse effects of chemicals or physical agents on living organisms under specific conditions of exposure.

Basic Definitions

• Toxic: having the characteristic of producing an adverse health effect.
• Toxicity: any toxic (adverse) effect that a chemical or physical agent might produce within a living organism.
• Toxicant: any substance that causes a harmful (or adverse) effect when in contact with a living organism at a sufficiently high concentration.
• Dose: the total amount of a toxicant administered to an organism at specific time intervals.
• Target organ dose: the amount of toxicant reaching the organ (known as the target organ) that is adversely affected by the toxicant.
• Exposure: the means by which an organism comes in contact with the substance.

Acute and Chronic Exposure

• Acute exposure: exposure over a brief period of time (generally less than 24 hours).
• Chronic exposure: exposures over a long period of time (greater than 3 months).

Toxicity Types

• Acute toxicity: an adverse or undesirable effect that is manifested within a relatively short time interval following exposure.
• Chronic toxicity: a permanent or lasting adverse effect that is manifested after exposure to a toxicant.
• Local toxicity: an adverse or undesirable effect that is manifested at the toxicant's site of contact with the organism.

Hazard and Safety

• Hazard: the qualitative nature of the adverse or undesirable effect resulting from exposure to a particular toxicant or physical agent.
• Safety: dose will not produce a toxic effect.

Types of Toxicants

• Chemical toxicants: include inorganic substances and organic compounds.
• Biological toxicants: include bacteria and viruses that can induce disease in living organisms.

The Basic Components of Toxicity Test

• The selection of a test organism
• The selection of a response to measure
• An exposure period
• The test duration (observation period)
• A sequence of doses to test

Lethal and Sub-Lethal Toxicity

• Lethal toxicity: the median lethal concentration or time at which 50% of the test population die (LC50 or LT50).
• Sub-lethal toxicity: the median effective concentration or time at which 50% of the test populations show a defined response (EC50 or ET50).

Factors Affecting Toxicity

• Form and innate chemical activity
• Exposure route
• Dosage
• Age
• Sex
• Presence of other chemicals
• Selective toxicity

Insecticides and Resistance

• Not mentioned in the provided text.

This quiz covers the basics of toxicology, including the definition of toxicity, factors affecting it, and metal toxicity, as well as pollution.