BASIC ENVIRONMENTAL TOXICOLOGY “What is there that is not poison? All things are poison and nothing without poison. Solely the dose determines a thing is not a poison.” Paracelsus 1500 AD (from: Philosophia Magna Brickmann, Cologne, 1567)

DOSE - RESPONSE RELATIONSHIP What is DOSE? - The total amount of the hazard that actually enters the body relative to the individual’s body weight The right dose differentiates a poison and a remedy The body’s response to chemicals depends on the dose received

Terminologies in Toxicology Hazard Risk Exposure Toxicity Toxin Toxicant A. Something that can harm the health of humans or the environment B. Toxic substances produced naturally C. Measure of how dangerous a chemical is D. The likelihood that a harmful consequence may occur E. The total amount of a chemical that comes into direct contact with the body F. The study of harmful effects of chemicals on living things G. Toxic substances produced or by-product of human activities F A D E C B G

ENVIRONMENTAL CONCENTRATION OF TOXICANTS Is the concentration of an agent in an environmental medium Refers to the agent’s presence in that particular medium expressed quantitatively 2 Major Concepts: Bioaccumulation Biomagnification

The green fill represents contaminants BIOACCUMULATION YOUNGER OLDER  The green fill represents contaminants The cellular mechanism which involves absorption and storage of molecules within an organism

BIOMAGNIFICATION Ex. DDT (dichloro-diphenyl-trichloroethane) It occurs when the toxic burden of a large number of organisms at a lower trophic level is accumulated and concentrated by a predator in a higher trophic level

CLASSIFICATION OF TOXIC CHEMICALS 1. IRRITANTS - Corrosives; damages tissues or materials 2. ASPHYXIANTS - Interferes with Oxygen uptake & distribution 3. NARCOTICS or ANESTHETICS - Depresses the CNS 4. NEUROTOXINS - specifically attacks the nerve cells; extremely toxic & fast acting 5. MUTAGENS - Alters genetic material in cells 6. TERATOGENS - Specifically causes abnormalities during embryonic growth & development 7. CARCINOGENS - Induces cancer & malignant tumors 8. SYSTEMIC POISONS - Produces internal damages to organs

IRRITANTS DERMATITIS Primary Irritants Example Exposure Duration Effect of Exposure Strong Acids Hydrochloric Acids Sulfuric Acids Nitric Acids Brief Severe Burns Strong Caustics Sodium Hydroxide Potassium Hydroxide Strong Solvents Paint Remover Alcohol Prolonged Inflammation Acne

Examples of asphyxiating gases are nitrogen (N2), helium (He), neon (Ne), argon (Ar), methane (CH4), propane (CH3CH2CH3), and carbon dioxide.

NARCOTICS OR ANESTHETICS Lidocaine Lidocaine is a common anesthetic used for local and regional anesthesia. Sevoflurane Sevoflurane is a rapid-acting, inhaled general anesthetic, which is used to put people to sleep and keep them asleep during a surgical procedure. Propofol Propofol is an intravenous general anesthetic, which is commonly used to put people to sleep and maintain anesthesia.

NEUROTOXINS Arsenic, Ammonia, , Lead, Ethanol, n-Hexane, Nitric oxide MUTAGENS X-rays, uv rays