Disciplines of Toxicology

Toxicology addresses a variety of questions. For example, in agriculture, toxicology determines the possible health effects from exposure to pesticides or herbicides, or the effect of animal feed additives, such as growth factors, on people. Toxicology is used in laboratory experiments on animals to establish dose-response relationships, agriculture, forensic, environmental etc. Toxicology also deals with the way chemicals and waste products affect the health of an individual

The field of toxicology can be further divided in to following sub-discipline on various basis
  • Mode of Toxic Action: This includes the consideration, at the fundamental level of organ, cell and molecular function, of all events leading to toxicity in vivo: uptake, distribution, metabolism, mode of action, and excretion.

Biochemical and molecular toxicology consider events at the biochemical and molecular levels, including enzymes that metabolize Toxins, generation of reactive intermediates, interaction of Toxins or their metabolites with macromolecules, gene expression in metabolism and modes of action.

Behavioral toxicology deals with the effects of toxicants on animal and human behavior. This involves both the peripheral and central nervous systems.

Nutritional toxicology deals with the effects of diet on the expression of toxicity and with the mechanisms of these effects.

Carcinogenesis includes the chemical, biochemical, and molecular events that lead to the large number of effects on cell growth collectively known as cancer.

Mutagenesis is concerned with toxic effects on the genetic material and the inheritance of these effects.

Organ toxicity considers effects at the level of organ function (neurotoxicity, hepatotoxicity, nephrotoxicity, etc.).

  • Measurement of Toxicants and Toxicity. These important aspects deal primarily with analytical chemistry, bioassay, and applied mathematic

Analytical toxicology is a branch of analytical chemistry concerned with the identification and assay of toxic chemicals and their metabolites in biological and environmental materials.

Toxicity testing involves the use of living systems to estimate toxic effects.

Toxicologic pathology is the branch of pathology that deals with the effects of toxic agents manifested as changes in sub cellular, cellular, tissue, or organ morphology.

Epidemiology as it applies to toxicology is of great importance as it deals with the relationship between chemical exposure and human disease in actual populations rather than in experimental settings.


  • Applied Toxicology. This includes the various aspects of toxicology as they apply in the field or the development of new methodology or new selective toxicants for early application in the field setting.

Clinical Toxicology is concerned with diseases and illnesses associated with short term or long term exposure to toxic chemicals. Clinical toxicologists include emergency room physicians who must be familiar with the symptoms associated with exposure to a wide variety of toxic substances in order to administer the appropriate treatment.

Forensic Toxicology is used to help establish cause and effect relationships between exposure to a drug or chemical and the toxic or lethal effects that result from that exposure.

Occupational (Industrial) Toxicology is concerned with health effects from exposure to chemicals in the workplace. This field grew out of a need to protect workers from toxic substances and to make their work environment safe.

Environmental Toxicology is concerned with the study of chemicals that contaminate food, water, soil, or the atmosphere. It also deals with toxic substances that enter bodies of waters such as lakes, streams, rivers, and oceans.

Veterinary toxicology is the diagnosis and treatment of poisoning in animals other than humans, particularly livestock and companion animals, but not excluding feral species.


  • Chemical Use Classes. This includes the toxicology aspects of the development of new chemicals for commercial use. In some of these use classes, toxicity, at least to some organisms, is a desirable trait; in others, it is an undesirable side effect. Use classes are not composed entirely of synthetic chemicals; many natural products are isolated and used for commercial and other purposes and must be subjected to

the same toxicity testing as that required for synthetic chemicals.

Agricultural chemicals include many compounds, such as insecticides, herbicides, fungicides, and rodenticides, in which toxicity to the target organism is a desired quality whereas toxicity to ‘nontarget species’ is to be avoided.

Clinical drugs are properly the province of pharmaceutical chemistry and pharmacology.

Drugs of abuse are chemicals taken for psychological or other effects and may cause dependence and toxicity.

  • Regulatory Toxicology concerned with the formulation of laws, and regulations authorized by laws, are intended to minimize the effect of toxic chemicals on human health and the environment.

Legal aspects are the formulation of laws and regulations and their enforcement.

Risk assessment is the definition of risks, potential risks, and the risk-benefit equations necessary for the regulation of toxic substances.