Risk, Toxicology & Human Health Chapter 10

I. Risk A.The probability of hazard (injury, disease, economic or environmental damage B. Risk Assessment 1. What is the hazard? 2. How likely is the event? 3. How much damage is it likely to cause? C. Risk Management 1. How does it compare to other risks? 2. How much should it be reduced? 3. How will it be reduced? 3. How much will reduction cost? * Economic, health, and political implications

Smoking Accidental Alcohol Pneumonia & Influenza Suicide AIDS Hard Drugs Homicide 443,000 75, ,000 55,000 35,000 14,000 15,000 16,000 Auto Annual Deaths in the United States

D. Types of Hazards 1. Chemical Hazards 2. Physical Hazards 3. Biological Hazards 4. Cultural Hazards Tox21

II. Toxicology A.Toxicity 1. The measure of how harmful a substance is 2. Depends on: - Size of dose ***Threshold Level*** - Frequency of dose - Size/age of organism exposed - Body’s detox abilities (liver, lungs, kidneys) - Genetics amount of toxin ingested, inhaled, absorbed, injected, etc. - Toxin’s persistence in environment - Toxin’s solubility (in water, oil, fat) * Dose =

Number of Individuals Responding Dose (hypothetical units)

3. Important Bio/Chemical Interactions a) Bioaccumulation b) Biomagnification

c) Antagonistic Interactions: Interaction with a certain chemical will reduce the harmful effects of a toxin d) Synergistic Interactions: Interaction with a certain chemical will multiply the harmful effects of a toxin Exposure to Asbestos Lung CancerChance of Non-Smoker Smoker 20X 400X

4. Toxic Response a) Acute b) Chronic Effect *Epidemiology: study of illness in human populations

5. Dose-Response Curves Show effects of various dosages of toxin on a test group Dose Effect Dose Effect No ThresholdThreshold

a) LD 50 (Median Lethal Dose) The amount of a toxin that will kill 50% of a test population *Usually within 2 weeks Dose (hypothetical units) Percent Population Killed

b) LC 50 (Median Lethal Concentration) The concentration of a toxin in water or air that will kill 50% of a test population *Usually within 2 weeks - You don’t know how much an individual takes in (dose), just the concentration in the environment Why are animal tests controversial?

B. Chemical Hazards 1. Acute a) Flammable/explosive b) Caustic/Corrosive c) Asphyxiants d) Allergens

2. Chronic a) Mutagens

2. Chronic a) Mutagens b) Teratogens Thalidomide Mercury Minamata Disease

c) Carcinogens 1) Promote about 80% of all cancers * The other 20% caused by genetic factors & viruses 30-40% 20-30% 5-15% 1-10% cigarette smoke diet occupational exposure environmental pollutants

d) Neurotoxins 1) Hormone Disrupters e) Hormonally Active Agents (HAAs) Hormone Mimics Hormone Blockers

3. Scary Synthetic Chemical Facts a) Approximately 1,000 new chemicals are introduced to consumers each year b) 99.5% of these chemicals are not government regulated c) Only 10% of the near 100,000 commercial chemicals in use have been screened for toxicity But…. now we have Tox21!!! Scheduled to screen 10,000 chemicals over the next 2 years

C. Biological Hazards 1. Non-transmissible Diseases (Non-communicable) cardiovascular diseases cancers diabetes asthma etc. Not caused by living organisms and not spread from person to person

2. Transmissible Diseases (Communicable) Caused by pathogens - bacteria, protozoa, fungi, viruses, parasites Bacteria and viruses can be highly contagious and reproduce rapidly and in large numbers *Leads to fast microevolution

a. Bacterial Infections & Resistance The overuse/misuse of antibiotics has increased the number of genetically resistant bacteria Examples: *Very difficult to treat & kill MRSA (Methicillin-Resistant Staphylococcus aureus) Tuberculosis (TB)

TUBERCULOSIS: “The Silent Global Epidemic”

Approximately 14 million cases Bacteria has become drug resistant

b. Viral Infections Viruses are non-cellular pathogens Examples: Antibiotics have no effect on them!!! Influenza Ebola Need a host cell to replicate. How? Rabies HIV (Human Immunodeficiency Virus)

HIV & AIDS (Acquired Immunodeficiency Syndrome) It kills white cells, weakening the immune system *HIV is not deadly *Transmitted via: Leads to AIDS Sex, intravenous needles, exposure to blood, mother  child *Worldwide Spread: 7-10 years for symptoms to show About 5.5 million newly infected each year ~ 15,000/day

c. Malaria: A protozoal disease million new cases each year

c. Malaria: A protozoal disease million new cases each year Kills over 1 million people per year Vector: Anopheles mosquito Pathogen: Plasmodium sporozoites (4 types) Control Problems: Mosquitoes become resistant to insecticides Plasmodium become resistant to medications Locals develop natural immunity Ex. Sickle Cell Anemia

Vector Anopheles mosquitoes

D. Risk Analysis 1. Cost-Benefit Analysis Do the risks/costs outweigh the benefits? When using a new chemical, technology, etc… …Is it worth it? 2. Comparative Risk Analysis Compares (sometimes ranks) the relative risk of major environmental & health hazards

3. Perceived Risk The majority of people are pretty bad at assessing the relative risks of hazards around us… *Better education and communication needed