What is Toxicology?


Toxicology Subject

Toxicology is an applied discipline that studies the harmful effects of exogenous factors (chemical, physical, and biological factors) on biological systems. It is a science that studies the toxicity, severity, frequency, and mechanism of toxic effects of chemical substances on organisms, as well as qualitative and quantitative evaluation of toxic effects. It is a discipline that predicts its harm to the human body and the ecological environment, and provides a scientific basis for determining the safety limit and taking preventive measures.​​


Diagram showing purpose of toxic tests

What is theoretical basis of toxicology?

Mainly apply the theory and technology of basic disciplines such as physiology, pharmacology, biology, biochemistry and pathology; study the absorption, distribution, metabolism and excretion, and toxic effects of foreign substances through animal experiments, clinical observations and epidemiological investigation methods. 

Its mechanism and poisoning treatment are not only to protect human beings and other organisms from the harmful effects of chemical substances and protect people's health, but also to directly develop poisons with good selective effects. 

More selective drugs and pesticides, etc., and conduct safety evaluation or risk evaluation of chemical substances, formulate health standards, and provide scientific basis. 

Toxicology is closely related to pharmacology, and has now developed into an independent discipline with certain basic theories and experimental methods, and has gradually formed some new branches of toxicology.​​


What is the effect of toxicology?

The currently accepted definition of toxicology is the science that studies the harm of exogenous chemicals to living organisms. 

Since the purpose of toxicology research is to provide a scientific basis for the protection of the health or safety of organisms, toxicology belongs to preventive medicine in terms of the nature of the discipline, and runs through the idea of ​​prevention first. 

Since the research objects of toxicology are wide, including chemical factors, physical factors, and biological factors, and organisms include humans, animals, and plants, toxicology is related to pharmacology, physiology, pathology, chemistry, biochemistry, and biology.

It is connected to industry, agriculture, the economy.

It is connected to forensic science, clinical medicine, ecology and environmental protection.

It is connected, so to speak, to the entire future of life on earth. Therefore, toxicology is widely used in clinical medicine, pharmacy, environmental protection, zoology, prenatal and postnatal care, occupational labor protection and food hygiene. Therefore, the classification of toxicology is very complicated, and it can be classified from different angles, and it is not completely consistent.​​


Tests on toxicology

Toxicological Classification

From the research content, it can be divided into three parts: descriptive toxicology, mechanism toxicology and management toxicology (also known as regulatory toxicology). It can be divided into: forensic toxicology, clinical toxicology, management toxicology or regulatory toxicology, research toxicology, etc. 

From applied toxicology viewpoint, it can be divided into: food toxicology, industrial toxicology, pesticide toxicology, military toxicology, radiotoxicology, environmental toxicology, ecotoxicology and other branches. 

The research objects can be divided into: insect toxicology, veterinary toxicology, human toxicology and plant toxicology. 

From the research fields, it can be divided into: drug toxicology, environmental toxicology, food toxicology, industrial toxicology, clinical toxicology, forensic toxicology, analytical toxicology, military toxicology, management toxicology, etc. 

From the target organs or systems studied, it can be divided into: organ toxicology, liver toxicology, renal toxicology, ocular toxicology, ear toxicology, neurotoxicology, reproductive toxicology, immune toxicology.


Toxicology Overview on Toxicology and Us

Toxicology sounds like a very deep and emerging discipline, far from us. In fact, it has a profound history and is closely related to our lives. Toxicology is the study of the adverse effects (side effects or harmful effects) of chemical substances and physical factors on an organism. 

The adverse effects can be very obvious, such as death, cancer, pain, dermatitis, etc., or they can be subtle effects, such as the developing children's brains are extremely sensitive to trace lead exposure, which will lead to the decline of learning and memory, and harm life. Realizing this is far more important than knowing what doses of lead can kill children.


Chemical substances in the definition of toxicology can be naturally occurring products or artificially synthesized substances. These things may be necessary, or they may be deadly poisons. And different dosages will make these chemicals have different effects on humans. For example, botulinum toxin is the most deadly poison, and at the same time it is used reasonably in a very small amount, and it is also a powerful tool for medical beauty to remove wrinkles. 

Physical factors are often associated with occupational health problems. temperature and noise. Lack of sleep, the adverse effects of jet lag, etc., can all cause irritating inefficiencies. These factors also have a huge impact on the environment, including changes in temperature that can affect the survival and reproduction of fish.

Toxicology and Environmental Health

Toxicology can also be considered in the context of environmental health. The environments we generally consider are the home, school, workplace, outdoors, indoors, ocean, air, etc. And we define environmental health as "ensure that all organisms have the best chance of maintaining or exploiting the full range of genetics". The value of this definition is best seen in children. This is also why ethical assessments of efficacy tests for relevant children and pregnant women are difficult to pass. For example, the lead exposure mentioned earlier, even in very low doses, can lead to learning disabilities in children. These harmful environmental changes can affect children throughout their lives, affecting their best chances of maintaining and realizing their full genetic potential. In other words, the life and death of an adult who has given birth to a baby is relatively less important.


What is the History of Toxicology?

The history of toxicology can be traced back to 2696 BC, the father of Chinese herbal medicine, Shennong, famous for tasting 365 kinds of Chinese herbal medicines, is said to have died of poisoning caused by excessive drug doses. The Black Death (1347-1351) bubonic and pneumonic plague swept across Europe during the Middle Ages, causing one of the worst plagues in human history. 

Bioaccumulation of experimental poisons in animals by Leonardo da Vinci (1452-1519) during the Renaissance. Paracelsus (1493-1541) physician, alchemist, father of toxicology. Attempts have been made to combine medicine and alchemy to form a new medical chemistry. 

Who is known as the Father of Modern Toxicology?

Matthew Swiss scientist Paul Offila (1787-1853), known as the "father of modern toxicology", published "Toxicology" in 1813, in which the symptoms of poisoning were described in detail. 

Who discovered DDT?

Hermann Muller discovered the insecticidal properties of DDT in 1939 and won the Nobel Prize in Physiology and Medicine in 1948, while DDT was banned in 1972. 

Until recently, Fukushima, Japan, in 2011, the nuclear power plant accident caused massive human and property damage. 

Visible toxicology related events throughout almost the entire history of our human development. 


Public safety incident pertaining to toxicology

Understanding the toxicological properties of some legal or illegal drugs is important for developing sound public policy. The Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) were established in the United States to protect the health and welfare of people and the environment. 

In 1962, a new anti-pregnancy drug called thalidomide (thalidomide) was found to have the side effect of causing birth defects in babies, now known as dolphin babies. This new drug has been widely promoted in Europe before, leading to the tragedy of tens of thousands of families in Europe, but it failed to enter the US market under the strong blocking of US FDA experts, so that Americans escaped this nightmare. 

Later legislation mandated that all new drugs must be fully tested in animals and humans before they can be approved for use by the FDA.


Rachel Carson published her landmark book Silent Spring in 1962, which focused on the environmental impact of chemicals and expressed concerns about the adverse effects of pesticides on human health. Among them, DDT, as an efficient insecticide, does not directly cause animal death, but it will thin the eggshells of birds, resulting in the reduction of especially carnivorous birds. Moreover, such pesticides accumulate in the fat of animals and eventually enter the human body through the food chain. 

DDT also passes into the baby's body with breast milk during breastfeeding. Eventually DDT was banned in 1972.


There are many other similar public safety incidents. For example, we are familiar with the poisoned milk powder incident, the poisoned rice incident, the aggravation of environmental pollution in recent years, and the public's attention to the risky ingredients in daily cosmetics.


What is the Role of Toxicology?

Toxicology cannot solve all environmental health problems, but it can help us better critically analyze the surrounding environment and events that affect local and even global, better judge the impact of chemical substances and physical factors on our lives and work. This leads to forward-looking questions that in turn lead to reducing the risk of exposure to hazards, both across industries and within, and promoting humans to “maintain or realize their full genetic potential.”


Knowing more about toxicology can help us make some day-to-day decisions. When promoting human health and improving environmental quality, it can also act according to the basic principles of toxicology (dose-response relationship, individual susceptibility). 

Actions were taken to reduce the exposure of infants and young children, for example, once it was realized that infants and children were underweight, have particularly sensitive developing nervous systems, and were more susceptible to chemicals than adults. 

Knowledge of toxicology will help us better judge the impact of chemical substances and physical factors on our lives, provide forward-looking insights, and ultimately influence decision-making.

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