tailieunhanh - Dose - Response Relationships

Understand the quantitative relationship between toxicant exposure and induced effects. • Describe frequently encountered toxic effects. • Interpret frequency (normal distribution) and dose response curves. • Understand threshold effects with dosage increase. | Dose - Response Relationships Principles of Environmental Toxicology Instructor Gregory Möller . University of Idaho Principles of Environmental Toxicology Learning Objectives Understand the quantitative relationship between toxicant exposure and induced effects. Describe frequently encountered toxic effects. Interpret frequency normal distribution and dose -response curves. Understand threshold effects with dosage increase. 2 Principles of Environmental Toxicology Learning Objectives 2 Understand effective dose margin-of-safety and the relationship of effective vs. toxic dose. Examine the use of actual data for no observed effect and lowest observed effect in risk assessments. Summarize effective lethal and toxic doses. Understand a linearized multi-stage model for non-threshold responses. 3 Principles of Environmental Toxicology What is a Dose The amount of a substance administered at one time. Dosage is the amount per unit weight of the exposed individual. Exposure is characterized by - Number of doses - Frequency of dosing - The total period of time for the exposure. 4 Principles of Environmental Toxicology Quantifying the Dose Gram g is the standard unit but mg is typical of most exposures in toxicology. Dosage mg dose I kg bw I day duration - mglkgld Exposures are quantified in relation to the media. - mgIL in water. - mglkg in food. - mglm3 in air. Variation in units common ppm ppb . 5 Principles of Environmental Toxicology Key Concepts Dosage - response mathematical relationship positive slope . Causal relationship. Observable responses. Statistical management of variability of individual responses. - Species genetics age sex. 6 1 Principles of Environmental Toxicology Responses Toxic Effects Inflammation. - Local or systemic response. Necrosis. - Cell or tissue death. Enzyme inhibition. - Biochemical pathway interruption. - Competitive non-competitive. Biochemical uncoupling. - Interference with phosphate molecule synthesis ATP 7 Principles of .