G. Tyler Miller’sLiving in the Environment14th EditionChapter 19

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

Shohail Motahir ChoudhuryShohail Motahir Choudhury

Key ConceptsKey Concepts

Types of hazards people face Methods of toxicology Types and measurement of chemical

hazards Types and effects of biological hazards Risk estimation, management, and

reduction

Types of hazards people face Methods of toxicology Types and measurement of chemical

hazards Types and effects of biological hazards Risk estimation, management, and

reduction

Hazard and RiskHazard and Risk

AA riskrisk is a measure of your likelihood of suffering harm from a hazard.

Risks and hazards—some avoidable, some not—compromise everyday life.

Hazard Hazard may cause injury, disease, economic loss, or may cause injury, disease, economic loss, or environmental damage.environmental damage.

Risk assessmentRisk assessment is projected as a probability: It gives is projected as a probability: It gives the estimate of an event’s actually happening.the estimate of an event’s actually happening.

Risk managementRisk management involves deciding whether or how involves deciding whether or how to reduce a particular risk to a certain level and at to reduce a particular risk to a certain level and at what cost.what cost.

Hazard identificationWhat is the hazard?

Probability of riskHow likely is the event?

Consequences of riskWhat is the likelydamage?

Risk AssessmentRisk Assessment Risk ManagementRisk Management

Comparative risk analysisHow does it comparewith other risks?

Risk reductionHow much shouldit be reduced?

Risk reduction strategyHow will the riskbe reduced?

Financial commitmentHow much moneyshould be spent?

4 major types of hazards.4 major types of hazards.1.1. Cultural hazard:Cultural hazard: unsafe working unsafe working

conditions, smoking, poor diet, drugs, conditions, smoking, poor diet, drugs, unsafe sex, poverty, criminal assault, etc.unsafe sex, poverty, criminal assault, etc.

2. 2. Chemical hazardsChemical hazards are harmful chemicals are harmful chemicals in the air, water, soil, and food.in the air, water, soil, and food.

3. 3. Physical hazardsPhysical hazards : radioactivity, fire, : radioactivity, fire, earthquake, floods, etc.earthquake, floods, etc.

4. 4. Biological hazards:Biological hazards: pathogens, pollen, pathogens, pollen, other allergens, and animals such as bees other allergens, and animals such as bees and poisonous snakes.and poisonous snakes.

Toxicology: Assessing Chemical Toxicology: Assessing Chemical HazardsHazards

Toxicity measures how harmful a substance Toxicity measures how harmful a substance is in causing injury, illness, or death to a is in causing injury, illness, or death to a living organism. living organism.

Harm depends on factors:Harm depends on factors:

Dose:Dose: amount of a substance. amount of a substance. Frequency of exposureFrequency of exposureAge and sizeAge and size of the individual exposed, of the individual exposed,Body’s Body’s detoxification systemdetoxification system, and, andGenetic makeupGenetic makeup of the individual, of the individual,

Five major factorsFive major factors can affect the harm caused by a substance. can affect the harm caused by a substance.

Solubility:Solubility: Water-soluble toxins can move throughout the Water-soluble toxins can move throughout the environment. Oil- or fat-soluble toxins can in the body.environment. Oil- or fat-soluble toxins can in the body.

Persistence:Persistence: resist breakdown and have long-lasting harmful effects. resist breakdown and have long-lasting harmful effects.

Bioaccumulation:Bioaccumulation: absorbed and stored in the body at higher than absorbed and stored in the body at higher than normal levels.normal levels.

Biomagnification:Biomagnification: moved up from one trophic level to the next higher moved up from one trophic level to the next higher one.one.

Chemical interactions:Chemical interactions: can decrease or multiply the harmful effects. can decrease or multiply the harmful effects. Antagonistic interaction reduces. Synergistic interaction Antagonistic interaction reduces. Synergistic interaction multiplies the harmful effects.multiplies the harmful effects.

DDT in fish-eatingbirds (ospreys)

25 ppm

DDT in largeDDT in largefish (needle fish)fish (needle fish)2 ppm2 ppm

DDT in smallDDT in smallfish (minnows)fish (minnows)0.5 ppm0.5 ppm

DDT inDDT inzooplanktonzooplankton0.04 ppm0.04 ppm

DDT in waterDDT in water0.000003 ppm,0.000003 ppm,Or 3 ppmOr 3 ppm

VerySensitive

Majorityof population

VerySensitive

00 2020 4040 6060 8080

Dose (hypothetical units)Dose (hypothetical units)

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Effects can be chronic or acute.

PoisonsPoisons

25

100100

7575

5050

00 22 44 66 88 1010 1212 1414 1616

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Dose (hypothetical units)Dose (hypothetical units)

LD50

Fig. 16.5, p. 400See Table 16-1 p. 400

Five top toxic named by the EPA:Five top toxic named by the EPA: arsenic, lead, mercury, vinyl arsenic, lead, mercury, vinyl chloride, and polychlorinated chloride, and polychlorinated biphenyls.biphenyls.

A poison or toxin is a chemical that adversely affects A poison or toxin is a chemical that adversely affects the health of a living human or animal by causing the health of a living human or animal by causing injury, illness, or death.injury, illness, or death.

Lethal Dose:Lethal Dose: estimating toxicity

A median lethal dose (LD50)A median lethal dose (LD50) for a for a chemical is the amount in one dose chemical is the amount in one dose that kills 50% of the test animals that kills 50% of the test animals within a 14-day period.within a 14-day period.

Chemical HazardsChemical Hazards

Toxic chemicals can kill, and hazardous chemicals Toxic chemicals can kill, and hazardous chemicals can cause various types of harm.can cause various types of harm.

3 major types of toxic agents: 3 major types of toxic agents: MutagensMutagens are chemicals or ionizing radiation that are chemicals or ionizing radiation that cause or increase random mutations in the DNA cause or increase random mutations in the DNA molecules. No safe threshold for exposure. molecules. No safe threshold for exposure.

Teratogens Teratogens are chemicals that cause harm or are chemicals that cause harm or birth defects to a fetus or embryo. Ex: Alcoholbirth defects to a fetus or embryo. Ex: Alcohol

CarcinogensCarcinogens are chemicals or ionizing radiation are chemicals or ionizing radiation that cause or promote cancer.that cause or promote cancer.

Biological Hazards: DiseasesBiological Hazards: Diseases

Non-transmissible disease:Non-transmissible disease: Caused by living organisms, and do Caused by living organisms, and do not spread from one person to another. Examples: cancer, not spread from one person to another. Examples: cancer, diabetes, asthma, malnutrition, and blood vessel disorders. diabetes, asthma, malnutrition, and blood vessel disorders.

Transmissible disease: Transmissible disease: Caused by living organism and spread. Caused by living organism and spread. Infectious agents/pathogens are spread in air, water, food, and Infectious agents/pathogens are spread in air, water, food, and body fluids and by some insects and vectors.body fluids and by some insects and vectors.

Deaths/year : WHO Deaths/year : WHO 30% by non-transmissible cardiovascular disease, 30% by non-transmissible cardiovascular disease,

26% by transmissible infectious disease, 26% by transmissible infectious disease, and 12% by non-transmissible cancers.and 12% by non-transmissible cancers.

As a country industrializesAs a country industrializes infectious disease-caused deaths infectious disease-caused deaths decreases and chronic diseases of adulthood increase.decreases and chronic diseases of adulthood increase.

NEWS:NEWS: Death from infectious diseases has decreased, but many Death from infectious diseases has decreased, but many bacteria have developed immunity to widely used antibiotics.bacteria have developed immunity to widely used antibiotics.

3. Mosquito injects Plasmodium sporozoites into human host

2. Plasmodium develops in mosquito

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

Anopheles mosquito (vector)in aquatic breeding area

eggs

larva pupaadult

Solutions

Infectious Diseases

Increase research on tropicaldiseases and vaccines

Reduce poverty

Decrease malnutrition

Improve drinking water quality

Reduce unnecessary use of antibiotics

Educate people to take all of anantibiotic prescription

Reduce antibiotic use to promotelivestock growth

Careful hand washing by allmedical personnel

Immunize children against major viral diseases

Oral rehydration for diarrhea victims

Global campain to reduce HIV/AIDS

Risk AnalysisRisk Analysis There are scientific ways to evaluate and compare There are scientific ways to evaluate and compare

risk, to decide how much risk is acceptable, and risk, to decide how much risk is acceptable, and find affordable ways to reduce risk.find affordable ways to reduce risk.

Risk assessmentRisk assessment involves identifying hazards and involves identifying hazards and evaluating their associated risks.evaluating their associated risks.

Poverty:Poverty: the greatest risk. Premature deaths per year the greatest risk. Premature deaths per year and reduced life span.and reduced life span.

Reducing povertyReducing poverty would improve human rights, would improve human rights, provide more people with income to stimulate provide more people with income to stimulate economic development, and reduce environmental economic development, and reduce environmental degradation and the threat of terrorism.degradation and the threat of terrorism.

Avoidance of cultural hazardsAvoidance of cultural hazards also improves longevity also improves longevity of life.of life.

Cause of DeathCause of DeathAnnual DeathsAnnual Deaths

11 million (75)Poverty/malnutrition/disease cycle

Tobacco

Pneumonia and flu

Air pollution

HIV/AIDS

Diarrhea

TB

Auto accidents

Work-related injuryand disease

Malaria

Hepatitis B

Measles

5 million (34)

3.2 million (22)

3 million (21)

3 million (21)

1.9 million (13)

1.7 million (12)

1.2 million (8)

1.1 million (8)

1 million (7)

1 million (7)

800,000 (75)

7-10 yearsPoverty

Born male

Smoking

Overweight (35%)

Unmarried

Overweight (15%)

Spouse smoking

Driving

Air pollution

Alcohol

Drug abuse

AIDS

Drowning

Pesticides

Fire

Natural radiation

Medical X rays

Oral contraceptives

Toxic waste

Flying

Hurricanes, tornadoes

Living lifetime near nuclear plant

6-10 years

5 years

2 years

1 year

7 months

5 months

4 months

4 months

3 months

2 months

1 month

1 month

8 days

5 days

5 days

4 days

1 day

1 day

10 hours

Flu

Air Pollution

6 years

5 months

1 month

7.5 years

Hazard Shortens average life span in the United States by

Risk ManagementRisk Management

Risk management means answering the following Risk management means answering the following questions.questions.

How reliable is the risk analysis for each risk?How reliable is the risk analysis for each risk?Which risks have the highest priority?Which risks have the highest priority?How much risk is acceptable?How much risk is acceptable?How much is a life worth?How much is a life worth?How much will it cost to reduce each risk to an acceptable How much will it cost to reduce each risk to an acceptable

level?level?How should funds be spent to provide the greatest How should funds be spent to provide the greatest

benefit?benefit?How will the risk management plan be monitored, How will the risk management plan be monitored,

enforced, and communicated to the public?enforced, and communicated to the public?

Risk AnalysisRisk Analysis

Risk analysis Risk analysis

Comparative riskanalysis

Comparative riskanalysis

Cost-benefitanalysis

Cost-benefitanalysis

Risk management Risk management

Risk perception Risk perception

Riskprobability

Riskassessment

Riskseverity

Is the riskacceptable?

Acceptable ifbenefitsoutweigh costs

Cost–benefit ExpressedpreferencesAcceptable ifpeople agree toaccept the risks

Naturalstandards

Acceptable ifrisk is notgreater thanthose created bynatural hazard

RevealedpreferencesAcceptable ifrisk is notgreater thanthose currentlytolerated

Fig. 16.14, p. 412

Exam and QuizExam and Quiz

Structure of Review ClassStructure of Review Class