CHAPTER 8: Toxicology

WHAT IS TOXICOLOGY?

     Toxicology is the scientific study of adverse effects that occur in living organisms due to chemicals. It involves observing and reporting symptoms, mechanisms, detection and treatments of toxic substances, in particular relation to the poisoning of humans.

     It includes environmental agents and chemical compounds found in nature, as well as pharmaceutical compounds that are synthesized for medical use by humans. These substances may produce toxic effects in living organisms including disturbance in growth patterns, discomfort, disease and death.

     It also studies the harmful effects of chemical, biological and physical agents in biological systems that establishes the extent of damage in living organisms. The relationship between dose and its effects on the exposed organism is of high significance in toxicology. Factors that influence chemical toxicity include the dosage (and whether it is acute or chronic); the route of exposure, the species, age, sex and environment.

(http://www.toxicologyguide.com/886-environmental/)

Environmental health toxicology is the study of the adverse effects of environmental chemicals on human health.

TYPES OF TOXICANTS:

ALLERGENS

    Any substance, often a protein, that induces an allergy : common allergens include pollen, grasses, dust, and some medications

MUTAGENS

      Biological, chemical, or physical agent, process, or substance that causes permanent genetic change (mutation) in a cell (other than which occurs during normal cell growth) due to genetic alterations or loss of genes or chromosomes. Such mutations may be the early steps in a sequence of events that ultimately lead to development of cancer.

TERATOGEN

     A teratogen is anything that can disrupt the development of an embryo or fetus in a pregnant mother's womb. A teratogen may cause a birth defect, malformation, or terminate the pregnancy altogether.

NEUROTOXIN 

    Any substance that is capable of causing damage to nerves or nerve tissue. For example, arsenic and lead are neurotoxins.

ENDOCRINE DISRUPTORS 

     The endocrine system is a complex system consisting of glands in the body that produce hormones. Examples are the thyroid gland in the throat, the pituitary gland in the brain, the adrenals, pancreas and ovaries in the abdomen, and the testicles, which lie outside the abdomen.

(http://pesbritneyf.blogspot.my/2012/09/smoking.html)

It can divided into 2 broad categories:

Toxic- Poisonous

It can be general or very specific and it often harmful even in dilute concentrations.

Hazardous -Dangerous

It can be flammable, explosive, irritant, acid and very corrosive substance.

EXPOSURE AND SUSCEPTIBILITY 

• Condition of organism and timing of exposure also have strong influences on toxicity

• Airborne toxins generally cause more ill health than any other exposure (lining of lungs easily absorbs toxins)

• Largest toxin exposure reported in industrial settings.

(https://www.researchgate.net/figure/6423230_fig3_Fig-3-Traditional-epidemiology-evaluates-possible-associations-between-either-risk)

HOW TO DETERMINE THE DANGEROUS OF CHEMICAL?

Most of the chemicals you might use at work are not dangerous if you use them properly and know what to do if something goes wrong (such as spillage). But some chemicals need more careful handling than others. Labels can help you identify the more hazardous chemicals, tell you what the dangers are, and how to avoid them

HAZARD SYMBOL These are always black on orange . They alert you to the main dangers posed by the chemical. Other symbols you might expect to see are illustrated overleaf. Not all labels will have symbols, but all will contain the brief list of warnings and safety advice.

INDICATION OF DANGER This gives the meaning of the symbol.

WARNINGS AND SAFETY ADVICE The label also contains a brief list of warnings and safety advice. The law requires suppliers of chemicals to tell you what hazards a chemical might pose and how to use it safely. The information is brief but important. If it advises you to avoid contact with skin then you should do just that. The advice is on the label for your safety.

(http://www.planetdeadly.com/nature/10-dangerous-chemical-elements)

TYPES OF EFFECTS:

• Local effects – damage at the site where a chemical first comes into contact with the body; examples are redness, burning and irritation of the skins.

• Systemic effects – adverse effects associated with generalized distribution of the chemical throughout the body by bloodstream to internal organ.

• Target organ effects – some chemical may confine their effects to specific organ; the most common organs affected by such chemicals are liver, lungs, heart, kidneys, brain and nervous system, and the reproductive system.

REFERENCES

• ://www.planetdeadly.com/nature/10-dangerous-chemical-elements
• https://www.ucu.org.uk/media/2774/Read-the-label-how-to-find-out-if-chemicals-are-dangerous---HSE-factsheet/pdf/hse_chemicals.pdf
• https://www.researchgate.net/figure/6423230_fig3_Fig-3-Traditional-epidemiology-evaluates-possible-associations-between-either-risk
• http://pesbritneyf.blogspot.my/2012/09/smoking.html
• http://www.greenfacts.org/en/endocrine-disruptors/l-2/endocrine-disruptors-1.htm
• http://www.medicinenet.com/script/main/art.asp?articlekey=11751
• http://www.alleydog.com/glossary/definition.php?term=Teratogen
• http://www.businessdictionary.com/definition/mutagen.html
• http://www.dictionary.com/browse/allergen
• http://www.toxicologyguide.com/886-environmental/
• http://www.news-medical.net/health/What-is-Toxicology.aspx