Class 3 o Substances of a chemical structure that permit no strong initial

Class 3 o substances of a chemical structure that

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Class 3 o Substances of a chemical structure that permit no strong initial presumption of safety, or may even suggest significant toxicity Table 5-2
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NOEL (mg/kg/day) 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 Cramer class 2 1 3 0 10 20 30 40 50 60 70 80 90 100 Percent of data 10 -2 Fig. 5-7 Class No 5th Centile TTC III 137 0.15 90 II 28 0.91 540 I 447 3.0 1800 Toxicological Threshold Concentration (μg/kg) From Munro et al 1996 Food Chem Tox 34: 829 Cramer Classes Criterion (5th Centile)
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The Probabilistic Approach
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Applying Probability is an Old Science…. The probability of occurrence is widely used in the characterization of risk from events in human society Ø Size of clothing Ø Insurance industry Ø Protection against failure in mechanical and civil engineering projects Probabilistic approaches are used for establishing thresholds of concern for ecological and human health risk assessment
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Toxicity to Aquatic Organisms 48 to 96-h LC50 (ng/L) 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 10 9 10 10 10 11 0 20 40 60 80 100 120 140 Frequency
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Probabilistic Characterization of Risk Exposure Toxicity Risk Concentration Frequency
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Using Cumulative Distributions Concentration, log scale Undetectable residues Limit of detection Detectable residues Exposure Cumulative frequency distribution of environmental concentrations Fig. 5-8 Probability that concentration will take on a value of X LC50 conc log scale Toxicity Cumulative frequency distribution of toxicity values Probability that concentration will take on a value of X
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Linearizing the Distributions Detectable residues Exposure Toxicity Cumulative frequency distribution plotted on a probability scale Fig. 5-8 LC50 Conc log scale Concentration, log scale Probability that concentration will take on a value of X Probability that concentration will take on a value of X Cumulative frequency distribution plotted on a probability scale
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Combining Distributions 50 99 90 70 30 10 1 Concentration 100 1000 10 1 50 99 90 70 30 10 1 Cumulative frequency distribution of environmental concentrations Cumulative frequency distribution of toxicity values Fig. 5-8 100-93 = 7% 10th Centile
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Combining Distributions 50 99 90 70 30 10 1 Concentration 100 1000 10 1 Cumulative frequency distribution of environmental concentrations Cumulative frequency distribution of toxicity values Fig. 5-8 100-93 = 7% 50 1 10 30 70 90 99 10th Centile
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