A toxicant is a chemical compound that has an effect on organisms. Toxicants are typically introduced into the environment by human activity.The effects depend on the concentration of the compound. Generally three concentration ranges can be delineated of all chemical compounds
too little: the metabolic behaviour deviates more from the natural behaviour for decreasing concentrations
enough: the metabolic behaviour is rather insensitive to changes in the concentration
too much: the metabolic behaviour deviates more from the natural behaviour for increasing concentrations
The effect of toxicants can be quantified on the basis of the concentration inside the organism. The Dynamic Energy Budget theory can be used to specify the mode of action of the compound for the individual organism under study: one or more parameters of the DEB model change as function of the internal concentration. Dynamic Energy Budget (DEB) theory aims to identify simple quantitative rules for metabolic organisation of individual organisms that can be understood from basic physical chemical principles, such as conservation of mass, energy and time, relationships between surface area and volume, and stoichiometric constraints on production. ...
Some toxicants are specifically developed to fight pests,the so-called pesticides such as A cropduster spreading pesticide. ...
insecticides to kill insects (or protect plants as some would prefer to stress)
herbicides to kill "unwanted" weeds,
food conservation products to kill micro-organisms that feast on our food
Many other toxicants are unwanted by-products of some production process, or accidental spoils. A insecticide is a pesticide used against insects in all development forms. ... A herbicide is a pesticide used to kill unwanted plants. ...
Toxicity is usually divided into two types, acute or chronic, based on the number of exposures to a poison and the time it takes for toxic symptoms to develop.
Acute toxicity is due to short-term exposure and happens within a relatively short period of time, whereas chronic exposure is due to repeated or long-term exposure and happens over a longer period.
The commonly used term to describe acute toxicity is LD LD means lethal dose (deadly amount) and the subscript 50 means that the dose was acutely lethal to 50% of the animals to whom the chemical was administered under controlled laboratory conditions.
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