What do you think is the single biggest What do you think is the single biggest threat to your life?threat to your life?

What do you think is the single biggest What do you think is the single biggest threat to a teenager in a developing threat to a teenager in a developing country?country?

What do you think is the single biggest What do you think is the single biggest threat to someone of my generation? threat to someone of my generation?

Ordering of Perceived RiskOrdering of Perceived RiskActivity League of

Women VotersCollege

StudentsExperts

Nuclear Power 1 1 20

Motor Vehicles 2 5 1

Handguns 3 2 4

Smoking 4 3 2

Motorcycles 5 6 6

Alcoholic Bev. 6 7 3

General Aviation 7 15 12

Police Work 8 8 17

Pesticides 9 4 8

Surgery 10 11 5

Firefighting 11 10 18

X-rays 22 17 7

Risk, Toxicology, and Human HealthRisk, Toxicology, and Human Health

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 11

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 11

Key ConceptsKey Concepts

Types of hazards people faceTypes of hazards people face

Methods of toxicologyMethods of toxicologyTypes and measurement of chemical Types and measurement of chemical

hazardshazards

Types and effects of biological hazardsTypes and effects of biological hazardsRisk estimation, management, and Risk estimation, management, and

reductionreduction

Risk and ProbabilityRisk 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 ManagementRisk Assessment and Management

Risk AnalysisRisk Analysis

1)1) Identifying hazardsIdentifying hazards• Risk assessmentRisk assessment

2)2) Ranking risksRanking risks• Comparative risk analysisComparative risk analysis

3)3) Determining optionsDetermining options• Risk managementRisk management

4)4) Informing decision makersInforming decision makers• Risk communicaitonRisk communicaiton

How well do we perceive risks?How well do we perceive risks?How well do we perceive risks?How well do we perceive risks?

Most of us do Most of us do poorlypoorly at assessing the at assessing the relative risks from the hazards that relative risks from the hazards that surround us.surround us.

Major Types of HazardsMajor Types of Hazards

Cultural hazardsCultural hazards

Chemical hazardsChemical hazards

Physical hazardsPhysical hazards

Biological hazardsBiological hazardsFig. 11-1 p. 228Fig. 11-1 p. 228

ToxicologyToxicologyToxicologyToxicology

Toxicity measures how harmful a Toxicity measures how harmful a substance issubstance is. Toxicity depends on . .. Toxicity depends on . .

• DoseDose

– the amountthe amount of a potentially of a potentially harmful harmful substancesubstance a person has ingested, inhaled, a person has ingested, inhaled, or absorbed.or absorbed.

• ResponseResponse

– the type or amount of the type or amount of damagedamage

ToxicityToxicityToxicityToxicity

DoseDose - - the amount of a potentially harmful the amount of a potentially harmful substance a person has ingested, inhaled, or substance a person has ingested, inhaled, or absorbed.absorbed.

• SolubilitySolubility• PersistencePersistence• BioaccumulationBioaccumulation• BiomagnificationBiomagnification• Chemical interactionsChemical interactions

– Antagonistic: reducesAntagonistic: reduces– Synergistic: multipliesSynergistic: multiplies

Bioaccumulation and BiomagnificationBioaccumulation and BiomagnificationBioaccumulation and BiomagnificationBioaccumulation and Biomagnification

Fig. 11-4p. 231

ToxicityToxicityToxicityToxicity

Response Response - - the type or amount of damagethe type or amount of damage

• Acute effect: immediate or rapidAcute effect: immediate or rapid

• Chronic effect: permanent or long Chronic effect: permanent or long lastinglasting

Genetic Variation in Individual Responses to Toxins

Genetic Variation in Individual Responses to Toxins

Fig. 11-3p. 230

““The dose makes the poison.”The dose makes the poison.”Paracelsus, 1540Paracelsus, 1540

““The dose makes the poison.”The dose makes the poison.”Paracelsus, 1540Paracelsus, 1540

Anything can be harmful if ingested in Anything can be harmful if ingested in a large enough quantity.a large enough quantity.

PoisonsPoisons

• a chemical that has an a chemical that has an LDLD5050 of 50 mg or less per of 50 mg or less per kg of body weightkg of body weight

• LDLD5050

– The The medianmedian lethal dose lethal dose• The amount that The amount that kills kills

exactly 50%exactly 50% of the of the animals in a test animals in a test population, within a 14 population, within a 14 day periodday period

• Determined by Determined by controlled experimentscontrolled experiments

Dose-Response CurvesDose-Response Curves

Nonthreshold Nonthreshold Threshold Threshold

Fig. 11-6 p. 233

Chemical HazardsChemical Hazards

• Toxic chemicalsToxic chemicals– substances that are fatalsubstances that are fatal

• Hazardous chemicalsHazardous chemicals– cause harmcause 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 HazardsChemical Hazards

• MutagensMutagens– Cause random changes in DNACause random changes in DNA

– Passed on to future generationsPassed on to future generations

• TeratogensTeratogens– cause birth defectscause birth defects

– alcohol, PCBs, thalidomide, steroid alcohol, PCBs, thalidomide, steroid hormones, heavy metalshormones, heavy metals

Chemical HazardsChemical Hazards

• CarcinogensCarcinogens– promote uncontrollable cell growth promote uncontrollable cell growth

(malignant or cancerous tumors)(malignant or cancerous tumors)– metastasismetastasis

• cells break off from tumors and travel in body cells break off from tumors and travel in body fluidsfluids

• Immune, Nervous, and Endocrine System Immune, Nervous, and Endocrine System disruptorsdisruptors– Viruses (HIV), Ionizing radiation, Diet, Viruses (HIV), Ionizing radiation, Diet,

Neurotoxins, Hormonally Active AgentsNeurotoxins, Hormonally Active Agents

Biological Hazards: DiseasesBiological Hazards: Diseases

• Non-transmissible diseaseNon-transmissible disease– not caused by a living organismnot caused by a living organism– is not spread from one person to is not spread from one person to

anotheranother

• Transmissible diseaseTransmissible disease– caused by living organismscaused by living organisms

• Bacteria, virus, protozoaBacteria, virus, protozoa

– is spread from one person to anotheris spread from one person to another

Biological Hazards: DiseasesBiological Hazards: Diseases

• PathogensPathogens – infectious agents – infectious agents• VectorsVectors – organisms that spread pathogens – organisms that spread pathogens

– InsectsInsects

World’s Seven Deadliest DiseasesWorld’s Seven Deadliest Diseases– acute respiratory infectionacute respiratory infection– acquired immune deficiency syndrome (AIDS)acquired immune deficiency syndrome (AIDS)– diarrheal diseasesdiarrheal diseases– tuberculosistuberculosis– malariamalaria– hepatitis Bhepatitis B– measlesmeasles

Biological Hazards: DiseasesBiological Hazards: Diseases

• Common Viral DiseasesCommon Viral Diseases1)1) influenza or fluinfluenza or flu

2)2) EbolaEbola

3)3) West Nile VirusWest Nile Virus

4)4) rabiesrabies

5)5) AIDSAIDS

• TreatmentTreatment– Immunization with vaccinesImmunization with vaccines

Anopheles mosquito (vector)

in aquatic breeding area

1. Femalemosquito bitesinfected human,ingesting bloodthat containsPlasmodiumgametocytes

4. Parasite invadesblood cells, causingmalaria and makinginfected persona new reservoir

3. Mosquito injects Plasmodiumsporozoites into human host

2. Plasmodiumdevelops inmosquito

eggs

larvapupa

adult

Malaria -

A Protozoal Disease