What is toxicology?

toxic compounds

physical agents

toxicology … ……… Is the study of the harmful effects of chemicals and physical agents on living organisms Examines adverse effects ranging from acute to long-term Is used to assess the probability of hazards caused by adverse effects Is used to predict effects on individuals, populations and ecosystems `

These adverse effects may occur in many forms, ranging from immediate death to subtle changes not realized until months or years later. They may occur at various levels within the body, such as an organ, a type of cell, or a specific biochemical.

Sources of toxic compounds Synthetic organic compound 1. Air, water, and food pollutants Air-CO, oxides of nitrogen, oxides of sulfur, hydrocarbons and particulates Water-agricultural chemicals including pesticides, herbicides, fugicides, nematocides, rodenticides, fertilizer Halogenated hydrocarbons- chloroform, dichloroethane, tetrachloride Clorinated aromatics-PCB, TCDD Detergents-alkyl benzene sulfonates

2. Chemical additives in food As preservatives-antibacterial, antifungal, or antioxidant To change physical characteristics, taste, color, odor

. 3.Chemicals in work place Inorganics-metals and flurides, CO, etc. Organic compounds-aliphatic hydrocarbons (hexene) aromatic hydrocarbons (eg. benzene, toluene) halogenated hydrocarbons alcohols esters organometallics amino compounds 4. Drugs of abuse CNS depressants-ethanol,secobarbital CNS stimulants-cocaine, methamphatamine, nicotine, caffeine Opioids-heroin, morphine Hallucinogens-PCP, LSD,THC

5.Therapeutic drugs The danger to the individual depends on : the nature of the toxic response the dose necessary to produce the toxic response the relationship between the therapeutic dose and the toxic dose eg, anticancer drugs are carcinogens Diethylstilbestrol (DES) Thalidomide Chloroquinol-SMON-subacute myelo-optic neuropathy Methyldopa, chloropromazine, methotrexate In general, toxic side effects are not common and may occur only in susceptible individuals or populations.

6. Pesticides 7. Solvents 8. Polycyclic aromatic hydrocarbons (PAH) 多環芳香 Incomplete combustion of organic materials, in smoke from wood, coal, oil, tobacco, in tar and broiled foods Carcinogens 9. Cosmetics Allergic reactions and contact dermatitis Bromate, cold-wave neutralizer Thioglycolates and tioglycerol-cold-wave lotion and depilatories Sodium hydroxide-hair straighteners

Naturally occurring toxins 1. Mycotoxins 2. Microbial toxins 3. Plant toxins 4. Animal toxins  "Toxin"=refers to toxic substances that are produced naturally  "Toxicant"=substance that is produced by anthropogenic origin

An interdisciplinary field… ……… Descriptive Toxicology: The science of toxicity testing to provide information for safety evaluation and regulatory requirements. Mechanistic Toxicology: Identification and understanding cellular, biochemical and molecular basis by which chemicals exert toxic effects. Regulatory Toxicology: Determination of risk based on descriptive and mechanistic studies, and developing safety regulations.

Clinical Toxicology: Diagnosis and treatment of poisoning; evaluation of methods of detection and intoxication, mechanism of action in humans (human tox, pharmaceutical tox) and animals (veterinary tox). Integrates toxicology, clinical medicine, clinical biochemistry/pharmacology. 毒藥物防治諮詢 Occupational Toxicology: Combines occupational medicine and occupational hygeine. Environmental Toxicology: Integrates toxicology with sub-disciplines such as ecology, wildlife and aquatic biology, environmental chemistry.

The scope of toxicity A.Mechanisms of Toxic Action 1. Biochemical toxicology 2. Behavioral toxicology-behavior is the final integrated expression of nervous function 3. Nutritional toxicology-the effects of diet 4. Carcinogenesis-cell growth 5. Teratogenesis-developmental process 6. Mutagenesis-genetic material 7. Organ toxicity-organ function

B. Measurement of toxicants and toxicity 1. Analytic toxicology 2. Toxicity testing 3. Toxicologic pathology 4. Structure-activity study 5. Biomathematics and statistics 6. Epidemiology C. Applied Toxicology 1. Clinical toxicology 2. Veterinary toxicology 3. Forensic toxicology 4. Environmental toxicology 5. Industrial toxicology

B. Measurement of toxicants and toxicity 1. Analytic toxicology 2. Toxicity testing 3. Toxicologic pathology 4. Structure-activity study 5. Biomathematics and statistics 6. Epidemiology C. Applied Toxicology 1. Clinical toxicology 2. Veterinary toxicology 3. Forensic toxicology 4. Environmental toxicology 5. Industrial toxicology

D. Chemical use classes 1. Agricuture chemicals 2. Clinical drugs 3. Drugs of abuse 4. Food additives 5. Industrial chemicals 6. Naturally occurring substances- phytotoxin, mycotoxin, inorganic minerals 7. Combustion products

E. Regulatory Toxicology 1. Legal aspects-formulation of laws and regulations and their enforcement 2. Risk assessment- the definition of risks, potential risks and risk-benefit equations F. Development of antidotes

Toxic Effects 1.Immediate effect and delayed effect CO, cyanide 2. Local effect and systemic effect target organ 3. Reversible and irreversible effect 4. Anaphylactic reaction (allergic reaction) 5. Idiosyncratic reaction 特異體質反應

Dose Dose by definition is the amount of a substance administered at one time. However, other parameters are needed to characterize the exposure to xenobiotics. The most important are the number of doses, frequency, and total time period of the treatment. For example: 650 mg Tylenol as a single dose 500 mg Penicillin every 8 hours for 10 days 10 mg DDT per day for 90 days