Toxicology

TOXICOLOGY definition toxicology: a qualitative and quantitative study of the adverse effects of toxicants on biological organism. definition toxicant : chemical/biological/physical agent that has a negative effect on the health of a person or an animal. toxicity : - property of the agent describing its effect on biological organisms. - the level of toxicity depends on quantity or dose - the toxicity of a chemical depends on the degree of exposure and absorption. toxic hazard : - likelihood of damage to biological organisms based on exposure resulting from transport and other physical factors of usage. source of toxicants : ~toxic release : vapour/gas/liquid release from source ~fire and explosion : fire and radiation. toxic release following explosion route of entry : = when toxicant enters the organism, it moves into the blood stream and its eventually eliminated or it is transpoted to the target organ. = damage is exerted at target organ. entry routes of toxic substance : 1) inhalation : - airborne toxic substances such as gases, vapor, dust, smoke, fumes, aerosols and mist can be inhaled and passed through the nose, brochiol tubes and lung to enter blood streams. - this is probably the easiest way for chemical to enter body respiratory system : = plays a significant role in toxicants entering the body through inhalation - nose, sinuses, mouth, pharynx, larynx and trachea - filtering, heating and humidifying the air - affected by toxicants that are soluble in water - these toxicants will react or dissolved in the mucus to form acids or bases - e.g : hydrogen halides and oxides - lungs, (bronchial tubes and alveoli for gases exchange with blood) - toxicants affect the function of alveoli by blocking the transfer of gases or by reaction with alveoli wall to produce corrosive or toxic substances - e.g : hydrogen sulfide and methyl cyanide 2) adsorption = a passage through the skin and into the blood stream. certain toxic agents can penetrate the barrier (skin) through adsorption = skin contact is the most common cause of widespread occupational disease dermatitis. the eyes are very porous and can easily absorb toxic vapors that cause permanent eye damage. 3) ingestion - an entry through the mouth (swallow). toxic agent sometimes contaminated the foods/hands, eventually be ingested during meal. 4)injection ~ introduction of a substance into the body by way of a needle and syringe. gastrointestinal (GI) tract : = GI tract plays the most significant role in toxicants entering the body