What do you think is the single biggest threat to your life? What do you think is the single biggest threat to a teenager in a developing country? What do you think is the single biggest threat to someone of my generation?

Ordering of Perceived Risk ActivityLeague of Women Voters College Students Experts Nuclear Power1120 Motor Vehicles251 Handguns324 Smoking432 Motorcycles566 Alcoholic Bev.673 General Aviation71512 Police Work8817 Pesticides948 Surgery10115 Firefighting X-rays22177

Risk, Toxicology, and Human Health G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11 G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11

Key Concepts Types of hazards people face Types of hazards people face Methods of toxicology Methods of toxicology Types and measurement of chemical hazards Types and measurement of chemical hazards Types and effects of biological hazards Types and effects of biological hazards Risk estimation, management, and reduction Risk estimation, management, and reduction

Risk and Probability  Risk  possibility of suffering harm from a hazard that can cause injury, disease, economic loss, or environmental damage.  Risk  possibility of suffering harm from a hazard that can cause injury, disease, economic loss, or environmental damage.  Probability  mathematical statement about how likely it is that some event or effect will occur. Risk = pExposure x pHarm  Probability  mathematical statement about how likely it is that some event or effect will occur. Risk = pExposure x pHarm

Risk Assessment and Management

Risk Analysis 1)Identifying hazards Risk assessmentRisk assessment 2)Ranking risks Comparative risk analysisComparative risk analysis 3)Determining options Risk managementRisk management 4)Informing decision makers Risk communicaitonRisk communicaiton

How well do we perceive risks? Most of us do poorly at assessing the relative risks from the hazards that surround us.

Major Types of Hazards  Cultural hazards  Chemical hazards  Physical hazards  Biological hazards Fig p. 228

ToxicologyToxicology Toxicity measures how harmful a substance is. Toxicity depends on.. Dose Dose – the amount of a potentially harmful substance a person has ingested, inhaled, or absorbed. ResponseResponse – the type or amount of damage

ToxicityToxicity Dose - the amount of a potentially harmful substance a person has ingested, inhaled, or absorbed. SolubilitySolubility PersistencePersistence BioaccumulationBioaccumulation BiomagnificationBiomagnification Chemical interactionsChemical interactions –Antagonistic: reduces –Synergistic: multiplies

Bioaccumulation and Biomagnification Fig p. 231

ToxicityToxicity Response - the type or amount of damage Acute effect: immediate or rapidAcute effect: immediate or rapid Chronic effect: permanent or long lastingChronic effect: permanent or long lasting

Genetic Variation in Individual Responses to Toxins Fig p. 230

“The dose makes the poison.” Paracelsus, 1540 Anything can be harmful if ingested in a large enough quantity.

Poisons a chemical that has an LD 50 of 50 mg or less per kg of body weighta chemical that has an LD 50 of 50 mg or less per kg of body weight LD 50 –The median lethal dose The amount that kills exactly 50% of the animals in a test population, within a 14 day periodThe amount that kills exactly 50% of the animals in a test population, within a 14 day period Determined by controlled experimentsDetermined by controlled experiments

Dose-Response Curves  Nonthreshold  Threshold Fig p. 233

Chemical Hazards Toxic chemicalsToxic chemicals – substances that are fatal Hazardous chemicalsHazardous chemicals – cause harm Flammable or explosiveFlammable or explosive Irritating or damaging to skin or lungsIrritating or damaging to skin or lungs Interfering or preventing oxygen uptakeInterfering or preventing oxygen uptake Inducing allergic reactionsInducing allergic reactions

Chemical Hazards MutagensMutagens –Cause random changes in DNA –Passed on to future generations TeratogensTeratogens – cause birth defects – alcohol, PCBs, thalidomide, steroid hormones, heavy metals

Chemical Hazards CarcinogensCarcinogens – promote uncontrollable cell growth (malignant or cancerous tumors) – metastasis cells break off from tumors and travel in body fluids cells break off from tumors and travel in body fluids Immune, Nervous, and Endocrine System disruptorsImmune, Nervous, and Endocrine System disruptors –Viruses (HIV), Ionizing radiation, Diet, Neurotoxins, Hormonally Active Agents

Biological Hazards: Diseases Non-transmissible diseaseNon-transmissible disease – not caused by a living organism – is not spread from one person to another Transmissible diseaseTransmissible disease – caused by living organisms Bacteria, virus, protozoaBacteria, virus, protozoa – is spread from one person to another

Biological Hazards: Diseases Pathogens – infectious agentsPathogens – infectious agents Vectors – organisms that spread pathogensVectors – organisms that spread pathogens –Insects World’s Seven Deadliest Diseases – acute respiratory infection – acquired immune deficiency syndrome (AIDS) – diarrheal diseases – tuberculosis – malaria – hepatitis B –measles

Biological Hazards: Diseases Common Viral DiseasesCommon Viral Diseases 1) influenza or flu 2)Ebola 3)West Nile Virus 4) rabies 5) AIDS TreatmentTreatment –Immunization with vaccines

Anopheles mosquito (vector) in aquatic breeding area 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 3. Mosquito injects Plasmodium sporozoites into human host 2. Plasmodium develops in mosquito eggs larva pupa adult Malaria - A Protozoal Disease