1. 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)

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

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

10. 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.

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