NCSU TOX 201 - _Risk_Assessment slides (12 pages)

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_Risk_Assessment slides



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_Risk_Assessment slides

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Pages:
12
School:
North Carolina State University at Raleigh
Course:
Tox 201 - Poisons, People and the Environment
Poisons, People and the Environment Documents
Unformatted text preview:

Poisons People and the Environment Lecture 14 Risk Assessment What is risk Risk the possibility of loss or injury Risk in Environmental Toxicology the possibility of an undesirable biological response toxicity that results from exposure to a toxicant Three Kinds of Risk observed directly through scientific observation e g cancer cholera reproductive decreases Perceived directly differing opinions of cause effect e g global warming HRT cell phones Perceived through science Virtual risk personal choice driving flying climbing a ladder Taken from Three Framing Devices for Managing Risk by John Adams UCL ac uk Risk can be expressed as a probability e g P 0 00001 or incidence e g 1 in 100 000 of a particular response occurring for a given exposure based on statistical estimates or other observations Differences in risk perception Activity Experts Ranking Lay people Ranking Motor vehicles 1 2 Smoking 2 4 Alcoholic beverages 3 Handguns 4 3 Surgery 5 10 Motorcycles 6 5 X rays 7 22 Pesticides 8 9 Electric power nonnuclear 9 Swimming 10 6 18 19 Risk assessment is the process of examining toxicological and epidemiological data for a suspected toxicant and if needed estimating the allowable exposure Steps for characterization toxicant identification Toxicant identification Toxicant evaluation Risk estimation Exposure evaluation toxicant evaluation exposure evaluation risk estimation Exposure evaluation Exposure for noncarcinogenic toxicants is expressed as maximum daily dose MDD mg kg day Exposure to carcinogens is stated as lifetime average daily dose LADD mg kg day lifetime Risk is approximated by the equation R TxE R risk T toxicity E exposure or as a function of the equation R T x f E Risk Management Examine risk assessment data Develop regulatory options addressing public health social concerns economic concerns Safety The possibility that an undesirable biological response toxicity will not result from exposure to a toxicant Estimated as 1 P If risk is P 0 00001 safety equals 1 divided by 0 00001 or 1 0 00001 Thus for every 100 000 exposures only 1 will result in an adverse response Safe Human Dose formula SHD mg day ED0 0 x At h x T1 2t h x Wt x Dt h SF ED0 0 threshold dose of toxicant NOEL At h ratio of absorption of toxicant in test organism and human T1 2t h ratio of half life of toxicant in test organism and human Wt weight of exposed individual Dt h ration of toxicant test dosages in animals to exposure dosages in humans SF safety factor Yeo h the J ob s got great benefits but mainly I like the safe work environment AtJD IT LGA X I WIT APP1I1VE 5 e wt c TKE f D A


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