Copyright © 2010 John Wiley & Sons, Inc. Figure 4.1.1.1 Dose-Response Curve. This is a generic dose-response curve for a toxic substance. The threshold is the dose below which no effect is detected. The x-axis can range from micrograms (for very toxic substances) to grams (for less toxic substances). The y-axis is the percentage of a population that exhibits some illness or death. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.1.1.2 Dose-response Curve to Estimate an LD50. This graph indicates the methodology for the determination of an LD50. Several data points are measured above and below the LD50 value, which is then determined graphically. The data are not always linear, and the slopes of the plots can be steep or shallow. What are the safety implications of a steep, or shallow, curve? Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.1.1.3 Factors Affecting Toxicity. Many factors determine the toxic effect of a substance for a particular individual. It is not surprising that not all people exhibit the same effect from a particular exposure. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.1.2.1 Structure of vinyl chloride. The EPA has classified vinyl chloride as a Group A, human carcinogen. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.2.1.1 Dose-response Curve for Chronic Toxicity. This is a generic dose-response curve for chronic toxicity. The x-axis can refer to amounts of a substance inhaled or ingested. In this example, the threshold is about 3, below which no effects are detected. The y-axis is the incidence of some disease or death. The smooth line may imply many data points, but often sometimes only a relatively small data set is available to estimate the curve. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.2.1.2 Pathways for Xenobiotic Substances. The arrows represent pathways of the movement of a substance in an organism. A complete understanding of this involves both a detailed analysis of multiple, connected equilibria and various rate constants. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.3.1.1 Structure of Bis(chloromethyl) ether. This compound is a regulated carcinogen. The EPA recommends < 0.0000038 parts per billion (!) in lakes and streams. OSHA set a limit of 1 ppb as the highest acceptable level in workplace air. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure 4.3.2.1 DDT and Its Metabolites. DDT was a widely used and effective pesticide used to treat body lice infestations and to prevent the spread of malaria. However its persistence in the environment and its damage to the ecosystem led to its ban in many places, including the United States. Copyright © 2010 John Wiley & Sons, Inc.

Copyright © 2010 John Wiley & Sons, Inc. Figure Copyright © 2010 John Wiley & Sons, Inc.