Dioxins and pcbs
Dioxins and PCBs
Acute(急性) and chronic(慢性) toxicity Acute toxicity refers to a rapid and serious response to a high but short-lived dose Acute poisons interfere with essential physiological processes, leading to a variety symptoms of distress, even death Chronic toxicity refers to a time-lagged response to a relatively low but prolonged exposure Effects are more subtle Set in motion a chain of biochemical events that lead to disease states, including cancer
Acute (急性) and chronic (慢性) toxicity • Acute toxicity refers to a rapid and serious response to a high but short-lived dose. – Acute poisons interfere with essential physiological processes, leading to a variety symptoms of distress, even death. • Chronic toxicity refers to a time-lagged response to a relatively low but prolonged exposure. – Effects are more subtle. – Set in motion a chain of biochemical events that lead to disease states, including cancer
Index of acute toxicity: LD50 LDso is the lethal dose for 50% of a population Toxicant A Toxicant B 0 Log Dose Illustration of a dose-response curve in which the response is the death of the organism; the cumulative percentage of deaths of organisms is plotted on the y-axis Dose is expressed as the weight of a chemical consumed by an experimental animal per kg of body weight of the animal
Index of acute toxicity:LD50 LD50 is the lethal dose for 50% of a population. Dose is expressed as the weight of a chemical consumed by an experimental animal per kg of body weight of the animal
LD50 of selected chemicals for rats or mice Chemical LD50(mg/kg) Chemical LD50(mg/kg) Sugar 29,700 Caffeine 130 ethanol 14,000 DDT 100 Vinegar 3,310 Arsenic 48 Table salt 3,000 Parathion 3.6 Atrazine 1,870 Nicotine Malathion 1,200 Dioxin(TCDD) 0.001 Aspirin 1,000 Botulin toxin 0.00001 Almost every chemical is toxic at some level, and the difference between toxic and nontoxic chemicals is a matter of degree
LD50 of selected chemicals for rats or mice Chemical LD50 (mg/kg) Chemical LD50 (mg/kg) Sugar 29,700 Caffeine 130 ethanol 14,000 DDT 100 Vinegar 3,310 Arsenic 48 Table salt 3,000 Parathion 3.6 Atrazine 1,870 Nicotine 1 Malathion 1,200 Dioxin (TCDD) 0.001 Aspirin 1,000 Botulin toxin 0.00001 Almost every chemical is toxic at some level, and the difference between toxic and nontoxic chemicals is a matter of degree
Dioxins(二嗯英): General structures The term dioxins denotes a family of chemical compounds known as polycholorinated dibenzo para-dioxins(Pcdds) and polycholrinated dibenzofurans(PCDFs) General structure Dibenzodioxin Dibenzofuran PCDD PCDF
Dioxins (二噁英): General structures • The term dioxins denotes a family of chemical compounds, known as polycholorinated dibenzopara-dioxins (PCDDs) and polycholrinated dibenzofurans (PCDFs) O O Dibenzodioxin PCDD O Dibenzofuran PCDF Clx Cly Clx Cly General structure