Reviewed by: BD Editors

Toxicology Definition

Toxicology is the study of how an organism reacts to various concentrations of chemicals. Toxicologist use model organisms to test various chemicals and estimate the concentration of chemical which can cause effects. Chemicals which will be used to produce goods used by people will undergo rigorous testing to ensure their safety. Toxicology also focuses on the structure of poisons, toxins, and venoms. Advanced methods, such as Nuclear Magnetic Resonance Spectroscopy, are used in toxicology to classify new toxins and understand their chemical structure. As we understand more about the world around us and seek to use new chemicals to our advantage, toxicologists are continually presented with a broader field of study.

History of Toxicology

Toxicology is an ancient science. Since the dawn of man, humans have sought to understand and manipulate the substances found in their environment. Ancient Roman and Middle-Eastern and Asian texts have descriptions of toxins along with their treatments. While ancient forms of the field relied on various belief in magic, the influence of stars, and other fantastical origins to explain and cure the effects of toxins, modern toxicology is a much more scientific pursuit.

Many fields have influenced and informed toxicology, and our understanding of chemicals and their interactions in general. A general understanding of chemistry and biology allowed the father of toxicology, Mathieu Orfila, to publish the first work on toxicology in 1813. Orfila went on to establish forensic toxicology by using his techniques to find evidence of arsenic in the body of a murder victim. Since the 1800’s toxicology has greatly expanded and advanced. Today, toxicology contains many branches of study and specialization.

Careers in Toxicology

While some schools have Bachelor’s and Master’s level toxicology programs, the majority of toxicologist go on to receive a PhD and specialize in a certain area of toxicology. Many area of toxicology exist, but in general toxicologists focus on a few themes and specialize from there. Medicinal toxicology is the branch most concerned with humans and what we are exposed to. Many toxicologists in this field work for government organizations or testing labs, and approve the products released to consumers. Others in this field understand toxins and poisoning and assist criminal investigators as forensic toxicologists. Everyone with a human focus on toxicology must understand human biology, and most are medical doctors that specialize in toxins.

Another area of toxicology focuses on the toxins themselves, and the species that produce the toxins. Because the chemicals in venom and animal toxins are so biologically active, they are extremely interesting for academics and pharmacists alike. For instance, a mycotoxicologist studies the toxins produced by fungi and their relatives. Many professionals studying toxicology study how the toxins form, act on their target, and eventually break down. This information is crucial to those on the defending edge of toxicology, like the doctors treating deadly snake-bites or accidental poisonings. Others search for ways to use the effects of the toxin in therapeutic ways. Venom, toxins in plants, and other biologically active substances could possibly be used to target specific unwanted cells or simply shut down nerves temporarily. A key convention in toxicology is that the dose makes the poison. In other words, the way we use chemicals determines their effect on us. Pharmaceutical companies are very interested in using toxins in beneficial ways, and hire toxicologist to research and analyze new chemicals.

The final focus in toxicology is of a broader scope. Ecotoxicologist, a combination of ecology and toxicology, study toxins in a larger context, and how they affect ecosystems and populations. Organizations like the Environmental Protection Agency employ toxicologists to study and monitor the health of the environment and discover potential disruptive toxins. It is this branch of toxicology that is responsible for the discovery of PCBs affecting the ozone and of the pesticide DDT reducing populations of eagles. Using the same tools as their peers, these scientists try to isolate and detect large-scale sources of potentially environmentally hazardous materials. Since the chemical revolution of the 1960’s, this branch of toxicology has expanded rapidly. Books like Silent Spring, by Rachel Carson, helped shed light on environmental destruction being caused by unregulated chemical usage. Since then, many organizations have been created to monitor and try to control the spread of dangerous substances.

Ethics and Technology in Toxicology

Toxicology has always required the use of model organisms in testing. To understand the effects of a new chemical, toxicologists first introduce the chemical to these model organisms. The effects of the chemical in different concentrations and doses are observed. This helps inform scientists of how the chemical reacts with living cells in general, and how it can specifically irritate or mutate cells. The most common of these tests involves exposing a test population to varied concentrations until half of the organisms are dead. Throughout history, different organism have been used as models, with different ethical implications.

Traditionally, some reprehensible methods have been employed in testing toxicology. From experiments on human prisoners to forced toxin inhalation tests in primates, toxicology is one of many branches of science with a dark history of morally questionable experiments. While these more questionable practices have been phased out and abolished, the need for experimentation still exists. The chemical revolution of the 1960’s created millions of new commercial and agricultural chemicals. Poor practices in toxicology led to epidemics like the use of the insecticide DDT, which ended up affecting the thickness of bird eggs and greatly reduced populations of birds of prey. Modern organizations, like the FDA, test chemicals and products for various industries before they are allowed to be sold or used commercially.

While there is still a need for experimentation, the methods of experimenting have changed drastically. New methods include testing chemicals on non-sentient organisms such as bacteria, yeast, and other single-celled organisms. The effects found in observing these smaller organisms can be extrapolated to other organisms. For products that must be tested on higher organisms, limits have been set on the number of subjects needed and animals are not allowed to suffer. These methods have created a more ethics-friendly toxicology. However, even more advanced methods of computational toxicology are emerging and will soon replace animal models completely. Computer simulations and understanding of chemistry and biology has advanced to a point that toxicology simulations can now be carried out by the computer. Advances in this field may lead to the elimination of model organisms all together, and the ethics of testing would be much more agreeable for scientists.


  • American Chemical Society. (2018, February 5). Toxicology. Retrieved from
  • Nelson, D. L., & Cox, M. M. (2008). Principles of Biochemistry. New York: W.H. Freeman and Company.
  • Rollin, B. E. (2006). Animal Rights and Human Morality (3rd ed.). New York: Prometheus Books.
  • Sarkar, S. (2005). Biodiversity and Environmental Philosophy: an introduction. New York: Cambridge University Press.

Cite This Article

MLAAPAChicago Editors. "Toxicology." Biology Dictionary,, 12 Feb. 2018, Editors. (2018, February 12). Toxicology. Retrieved from Editors. "Toxicology." Biology Dictionary., February 12, 2018.

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