Presentation on theme: "Risk, Toxicology, and Human Health"— Presentation transcript:
1 Risk, Toxicology, and Human Health G. Tyler Miller’sLiving in the Environment14th EditionChapter 19
2 Key Concepts to Chapter 19 Types of hazards people faceDefining and measuring toxicologyTypes and measurement of chemical hazardsTypes and effects of biological hazardsRisk estimation, management, and reduction
4 Sections 1 and 2 Key Concepts What is risk? What are the major types of hazards?What determines if a chemical is hazardous?What are the basic principles of toxicology?Can a little bit of pollution actually be good for you?How good are estimates of toxicity?
5 Risk, Probability and Hazards Risk: is the possibility of suffering a harm from a hazard that can cause injury, disease, death, economic loss, or environmental damage.Risk Assessment: the scientific process of estimating harm a particular hazard may cause.Risk Management: deciding whether or not to reduce a risk and at what cost.
6 What is risk? Risk is expressed in probabilities. Example: “The lifetime risk of developing lung cancer is 1 in 250 from smoking a pack a day”Plane crash: 1 in 10 millionLightning: 1 in 1.4 millionHouse Fire: 1 in 200
7 Risk and Probability Risk Risk assessment Risk management Probability Fig p. 410
8 Hazards: Types of RiskCultural hazards: working conditions, diet, driving,unsafe sex, poverty, etc..Physical hazards: fire, tornado, volcanic eruption,earthquake, etc..Chemical hazards: harmful chemicals in the air,water, soil and food. Example: DDT or PCBsBiological hazards: pathogens (bacteria, virus,parasites), pollen, animals, plants.
10 Toxicology Toxicity Dosage Bioaccumulation Biomagnification Synergism Fig p. 411ToxicityDosageBioaccumulationBiomagnificationSynergismResponseAcute effectChronic effectFig p. 411
11 TOXICOLOGY: Assessing Chemical Hazards Toxicity: measure of how harmful a substance is in causing injury, illness, or death to living organisms.FACTORS AFFECTING TOXICITY:1) Dose: the amount of substance ingested, inhaled or absorbed.
12 Factors Affecting Toxicity 2) Age of individual3) Immune System (detoxification)4) Genetic Makeup5) Length and frequency of exposure
13 Factors Affecting Harm Caused By A Substance Solubility (water soluble move through environment easily)2) Fat Soluble (can accumulate in body tissue and cells)3) Persistence (how long before it breaks down)BioaccumulationBiomagnifications
14 Factors Affecting Harm Caused By A Substance 4) Chemical interactionsFor instance: workers exposed to asbestos increase risk of long cancer by 20 times, if they smoke also 400 times.Response: they type of damage (acute vs. chronic)
15 Principles of Toxicology Any synthetic or natural chemical can be harmful if ingested in large enough quantity.THE DOSE MAKES THE POISONCritical questions: what is the lowest level that will cause harm?
16 Principles of Toxicology Trace amounts of chemicals in the environment may or may not be harmful.Some say they are not, look at life expectancy over last several centuries.Some say they are, look at cancer rates and say it is hard to know long-term impacts.
17 PoisonsMedian lethal dose (LD50): at what dosage does the toxin kill 50% of animals (usually mice or rats)Fig p. 413
18 Principles of Toxicology How do scientists determine toxicity:Epidemiologic case studiesAnimal Testing (usually with control groups)Computer modeling
19 Dose-Response Curves Dose-response Nonthreshold Threshold Fig p. 414
20 Principles of Toxicology How good are the estimates of toxicology?There are serious limitations to all these types of studies.Therefore, most allowable limits are set well below estimated harmful levels.
21 Sections 1 and 2 ReviewWhat is risk? What are the major types of hazards?What determines if a chemical is hazardous?What are the basic principles of toxicology?Can a little bit of pollution actually be good for you?How good are estimates of toxicity?
22 Section 3: Chemical Hazards What are toxic and hazardous chemicals?What are some possible impacts from chemical hazards?Are hormonally active agents a human health threat?Why do scientists no so little about the impacts of chemicals on human health?Is pollution prevention the answer?
23 What are toxic and hazardous chemicals? Toxic Chemical: a chemical through that can cause temporary or permanent harm or death.Hazardous Chemical: can harm humans because it is flammable or explosive.
24 Types of Toxic Agents Mutagen: causes changes to ones DNA. Teratogens: chemicals that cause birth defects to fetus or embryo. (alcohol)Carcinogens: cause cancer (growth of cancerous tumors)
25 Impacts of Chemicals on Humans Chemicals may also impact:Immune system (arsenic, dioxin)Nervous System (neurotoxins, brain, spinal cord, etc.)Endocrine System (levels of hormones)
26 Hormonally Active Agents Exposure to low level certain synthetic chemicals may disrupt a bodies hormone levelsEndocrine disrupters or hormonally active agentsSo called, gender benders
27 Establishing Guilt Is Difficult Under current laws, most chemicals are considered innocent until proven guilty.“Toxicologist know a great deal about a few chemicals, a little about many, and nothing about most.”
28 Establishing Guilt Is Difficult U.S. National Academy of Sciences estimates that only 10% of the 80,000 chemicals in commercial use have been tested for toxicity.Why?Not required (considered innocent)Lack of funds, personnel, facilitiesExpensiveDifficult to test interactions
29 Pollution Prevention Model Where do we go from here?We do not know much about all of the chemicals inside us, around usEliminating them mean other problemsSome say Pollution Prevention,
30 Pollution Prevention Model Precautionary Principle: where there is plausible, but incomplete scientific evidence of significant harm we need to take action to reduce the risk.“Better Safe Than Sorry”
31 Pollution Prevention Model First: new chemical technologies would be considered harmful until studies say otherwise.Second: existing chemicals that appear to be harmful would be removed from use.EU close to adopting this type of approach.
32 Review Chapter 19 Section 3 What are toxic and hazardous chemicals?What are some possible impacts from chemical hazards?Are hormonally active agents a human health threat?Why do scientists no so little about the impacts of chemicals on human health?Is pollution prevention the answer?
33 Chemical Hazards Hazardous chemicals Mutagens Teratogens Carcinogens NeurotoxinsHormonally active agentsPrecautionary principle
34 Section 4: Biological Hazards What are nontransmissible and transmissible diseases?Case studies: 1) Germ resistance to antibiotics, 2) Global Tuberculosis Epidemic, 3) HIV and AIDS Threat, 4) Malaria Comeback, 5) Bioterrorism: A Growing Threat, 6) Solutions: How can we reduce the Incidence of Infectious Diseases?
35 Transmittable and Nontransmittable Diseases Nontransmissible: caused by something other than a living organism and does not spread from person to person. (cancer, diabetes, etc.)Transmissible: caused by living organisms and can spread from person to person. (bacteria, virus, parasite)
36 Transmittable and Nontransmittable Diseases According to WHO: 30% of deaths are nontransmissible and 26% transmissible IDs and 12% nontransmissibe cancers.
37 Transmittable and Nontransmittable Diseases Good News: Since 1950, ID death rates fallen dramatically.Bad News: Bacteria resistance growing and insects becoming immune to pesticides.
38 Biological Hazards: Diseases Nontransmissible diseaseFig p. 425Transmissible diseasePathogensVectorsTuberculosisHIV/AIDSMalaria
47 Bioterrorism Possible targets: air, water, and food Inexpensive Fairly easy to produce biological agentsRecombinant DNA techniquesRefer to Fig p. 427
48 Case Studies Jigsaw1) Germ resistance to antibiotics, 2) Global Tuberculosis Epidemic, 3) HIV and AIDS Threat, 4) Malaria Comeback, 5) Bioterrorism: A Growing Threat, 6) Solutions: How can we reduce the Incidence of Infectious Diseases?