What is the Study of Harmful Effects of Chemicals on Humans and Other Organisms?

Do you know that there are so many branches of chemistry? Do you know that there is a study in chemistry which focused on chemicals effects toward living thing? What is the study of harmful effects of chemicals on humans and other organisms called? yep, it is called Toxicology.

What is Toxicology?

Toxicology is a study of chemistry, which is a sub-branch of pharmacology. It is the study of the harmful effects of chemicals on humans and other organisms. The chemicals that are studied in the field of Toxicology may occur naturally or made artificially in the factory or lab.

The organisms that are observed in this study are humans, pets, livestock, or microbes living in the pond. People who study the field of Toxicology are called Toxicologists. They study the relationship between the dose of a chemical and its effects on the exposed organisms (e.g. Humans). The effects of the chemicals are influenced by several factors, including the dosage, species, age, sex, environment, etc.

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Factors influencing toxicity

In the study of harmful effects of chemicals on humans and other organisms, there are many factors that affect the toxicity level of a chemical. Some of the factors may be related to the chemicals, some others may be related to the organisms. Some toxicity factors can be seen as listed below.

1. Form and innate chemical activity

Form of a chemical may have some impact on determining its toxicity level, especially when it comes to metallic elements. Let’s take chromium as an example. A CR3+ is relatively nontoxic to humans, but a CR6+ may cause you nasal corrosion or even worst, lung cancer.

2. Dosage

Dosage is on one important factors influencing toxicity that is related to the chemicals. It determines whether a chemical will be an acute or a chronic toxicant. We can say that all chemicals can be potentially acute if we use it in sufficiently large doses.

Often, that a toxic target a different organ depending whether it is an acute or a chronic toxicity. We can use Arsenic in dosage example. Arsenic, in an acute toxicity, may cause you gastrointestinal damage whereas when it is in a chronic toxicity, Arsenic may cause you skin or liver cancer.

3. Exposure route

Exposure route corresponds on how an organism comes in contact with the chemicals. One route of a chemical may be toxic to an organism, but it may not be toxic when exposed with a different route. The key of this factor is the absorption and distribution of the chemicals within an organism’s body.

Some chemicals may not be toxic to an organism when it is ingested, because it may be detoxified immediately, but the chemicals may be toxic when it is inhaled. 

4. Ability to be absorbed

An ability to be absorbed of a chemical corresponds on how a chemical is ready or how poor it is to be absorbed. It is essential to systemic toxicity. E.g. almost alcohol is ready to be absorbed when it is ingested to human body, but most polymers have virtually no absorption when ingested.

5. Species

Responses on toxic differ greatly between species. Those responses may be caused by the metabolism, anatomical, or even physiological difference that different species of organisms have. There is also the term “selective toxicity”, which explains that certain chemicals have certain degree of toxicity across species.

For example, a pesticide (specifically insecticides) may be lethal for insects, but non toxic for larger animals. Antibiotics are also selectively toxic to microorganisms while it shows no toxicity to humans.

6. Life stage

This factor corresponds on how effective that a chemical toxic works according to the life stage of an organism, whether they are infant, young adult, or elderly adult. For example, in certain species, Nitrosamines are more carcinogenic to their infant or youngster than their adult.

7. Gender

Gender plays an important role in the effectiveness of chemicals in organism’s body. This may be due to the pharmacokinetics and pharmacodynamics difference between the males and females that can affect the chemicals activity within the organisms.  Studied have also identified the gender-related difference that may affect the chemicals within an organism body. For example, female rats are twice more sensitive to parathion that male rats do. In other hand, male rats are 10 times more sensitive than their females to liver damage from DDT.

8. Metabolism

Metabolism is the factor that explains on how chemicals transform from one form to another form in an organism. It is a major factor in determining toxic influence of a chemical. There are two known metabolism types, detoxification and bioactivation. Detoxification is a natural defense mechanism of an organism. It converts chemicals to a less toxic form. In other hand, bioactivation converts chemicals to its more reactive or more toxic form.

9. Distribution within the body

Distribution within the body determines where the sites that the chemical’s toxic will occur are. It is highly determined by the lipid solubility of a chemical for it to work. 

10. Excretion

11. Health of the individual

Health status of an organism may also affect the influence of chemical’s toxic. It is related to the organism’s organ function, which involves physiological changes that could influence toxicity level of a chemical. Certain condition of an organism may affect those physiological changes. For example, pregnancy is related to the physiological changes in the kidney which can also affect the toxic potential of a chemical.

12. Nutritional status

Nutritional status, or diet, also determines whether a toxic may or may not develop inside an organism’s body. For example, consumption of fish that has absorbed mercury from contaminated water can result in mercury toxicity. Food additives can also be taken as an example in this factor of toxicity.

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13. Circadian rhythms

Although it is not major, circadian rhythms can play role in the toxic influence of a chemical. Circadian rhythms correspond to the time of day that a chemical (or other substances) is administered.

14. Presence of other chemicals

Presence of other chemicals at the same time, sooner or later, may also affects the toxicity of one chemical. The presence of other chemicals may decrease, enhance, or increase the toxicity of a chemical. For example, alcohol may enhance the effect of antihistamines and sedatives.

So, that’s the complete explanation about what is the study of harmful effects of chemicals on humans and other organisms!