Environmental Health: Risk, Toxicology, and Human Health

Environmental Health: Risk, Toxicology, and Human Health

Key ConceptsKey Concepts

Hazards people face Hazards people face

Defining and measuring toxicology Defining and measuring toxicology

Chemical hazards Chemical hazards

Biological hazards Biological hazards

Risk estimation, management, and reduction Risk estimation, management, and reduction

Risk and ProbabilityRisk and Probability

RiskRisk

ProbabilityProbability

Riskassessment

Riskassessment

Riskmanagement

Riskmanagement

HazardsHazards

Cultural hazardsCultural hazards

Physical hazardsPhysical hazards

Chemical hazardsChemical hazards

Biological hazardsBiological hazards

HazardsHazards

ToxicologyToxicology

ToxicityToxicityDosageDosageBioaccumulationBioaccumulationBiomagnificationBiomagnificationSynergismSynergismResponse Response Acute effectAcute effectChronic effectChronic effect

ToxicologyToxicology

ToxicologyToxicology

PoisonsPoisons

Poison Poison

Median lethal dose (LD50)

Median lethal dose (LD50)

Dose-Response CurvesDose-Response Curves

Dose-response Dose-response Nonthreshold Nonthreshold Threshold Threshold

Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans

Toxicity Rating

Supertoxic

Extremely toxic

Very toxic

Toxic

Moderately toxic

Slightly toxic

Essentially nontoxic

LD50 (milligrams perkg of body weight)*

Less than 0.01

Less than 5

5–50

50–500

500–5,000

5,000–15,000

15,000 or greater

Examples

Nerve gases, botulism toxin,

mushroom toxins, dioxin (TCDD)

Potassium cyanide, heroin, atropine,

parathion, nicotine

Mercury salts, morphine, codeine

Lead salts, DDT, sodium hydroxide,

sodium fluoride, sulfuric acid, caffeine,

carbon tetrachloride

Methyl (wood) alcohol, ether,

Phenobarbital, amphetamines (speed),

kerosene, aspirin

Ethyl alcohol, Lysol, soaps

Water, glycerin, table sugar

Average Lethal Dose†

Less than 1 drop

Less than 7 drops

7 drops to 1 teaspoon

1 teaspoon to 1 ounce

1 ounce to 1 pint

1 pint to 1 quart

More than 1 quart

*Dosage that kills 50% of individuals exposed†Amounts of substances in liquid form at room temperature that are lethal when given to a 70.4-kg (155-pound) human

Chemical HazardsChemical Hazards

Hazardous chemicalsHazardous chemicalsMutagensMutagensTeratogensTeratogensCarcinogensCarcinogensNeurotoxins Neurotoxins Hormonally active agentsHormonally active agentsPrecautionary principlePrecautionary principle

Hormone

Receptor

Cell

Normal Hormone Process Hormone Mimic Hormone Blocker

Estrogen-like chemical Anti-androgen chemical

Endocrine MimicsEndocrine Mimics

Biological Hazards: DiseasesBiological Hazards: Diseases

Nontransmissible diseaseNontransmissible diseaseTransmissible diseaseTransmissible diseasePathogensPathogensVectorsVectorsTuberculosisTuberculosisHIV/AIDSHIV/AIDSMalariaMalaria

MalariaMalaria

Viruses HIV(AIDS)

Hepatitis B

Smallpox

Ebola

On this scale, a human hair would be 6 meters (20 feet) wide

1 micrometer

Bacteria Vibrio cholerae(cholera)

Mycobacteriumtuberculosis

(tuberculosis)

Treponema pallidum (syphilis)

6 micrometers

Protozoa

Plasmodium(malaria)

10 micrometers

Painful and sometimes fatal.Carried by four related viruses and strikes during rainy season. 2.5 million people at risk;50 million new cases a year.Dengue Fever

Endemic in more than 100 countries.Caused by four protozoa species.270–500 million new cases and1 million deaths per year.Malaria

Dreaded far more than 400 years.Viral disease that causes symptoms frommild to severe illness and death. 200,000 new cases and 30,000 deaths a year.

Yellow Fever

Genetic material

Surface proteins

HIV VirusHIV Virus

The viral geneticmaterial uses thehost cell's DNA toreplicate againand again.

Each new copy ofthe virus directs thecell to make it aprotein shell.

The new viruses emerge fromthe host cell capable of infectingother cells. This process oftendestroys the first cell.

The virus attaches to thehost cell. The entire virusmay enter or it may injectits genetic material, or genome.

Virus

Cell membrane

Host cell

New viruses

Disease(type of agent)

3.2 millionPneumonia and flu

(bacteria and viruses)

HIV/AIDS(virus)

Diarrheal diseases(bacteria and viruses)

Tuberculosis(bacteria)

Malaria(protozoa)

Hepatitis B(virus)

Measles(virus)

Deaths per year

3.0 million

1.9 million

1.7 million

1 million

1 million

800,000

Deaths per100,000 people

<2.5

2.5-10

10-35

35-70

70-100

100+

120 40 20 0

100+

95-99

90-94

85-89

80-84

75-79

70-74

65-69

60-64

55-59

50-54

45-49

40-44

35-39

30-34

25-29

20-24

15-19

10-14

5-9

0-4

Male Female

Population (thousands)

Ag

eWith AIDS

608010 20 100 120806040

Without AIDS

7-10 yearsPoverty

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

Born male

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 campaign to reduce HIV/AIDS

BioterrorismBioterrorism

Possible targets: air, water, and food

Inexpensive

Fairly easy to produce biological agents

Recombinant DNA techniques

Agent

Smallpox(virus)

Hemorrhagicfever (viruses)

Inhalationanthrax(bacterium)

Botulism(bacterium)

Pneumonicplague(bacterium)

Tularemia(bacterium)

Contagious

Yes

Yes

No

No

Yes

No

Symptoms

Fever, aches, headache, red spots on face and torso

Vary but include fever,bleeding, shock, and coma

Fever, chest pain, difficultybreathing, respiratory failure

Blurred vision, progressiveparalysis, death within 24 hours if not treated

High fever, chills, headache,coughing blood, difficultybreathing, respiratory failure

Fever, sore throat, weakness,respiratory stress, pneumonia

Mortality(if untreated)

30%

Varies

90–100%

60–100%

90–100%

30–60%

Existenceof vaccine

Yes

No

Yes

Yes

No

Yes(in testing)

Treatment

Vaccination within 4 days afterexposure, IV hydration

Ebola has no cure, antiviralriboflavin and some antibioticsmay help

Early treatment with Cipro andother antibiotics

Equine antitoxin given early.Intensive care, respirator

Antibiotics

Antibiotics

Risk AnalysisRisk Analysis

Risk analysisRisk analysis

Comparative risk analysisComparative risk analysis

System reliabilitySystem reliability

Risk managementRisk management

Risk perceptionRisk perception

Risk AnalysisRisk AnalysisComparative Risk Analysis

Most Serious EcologicalAnd Health Problems

High-Risk Health Problems•Indoor air pollution•Outdoor air pollution•Worker exposure to industrialor farm chemicals•Pollutants in drinking water•Pesticide residues on food•Toxic chemicals in consumer products

High-Risk Ecological Problems•Global climate change•Stratospheric ozone depletion•Wildlife habitat alteration and destruction•Species extinction and loss of biodiversity

Medium-Risk Ecological Problems•Add deposition•Pesticides•Airborne toxic chemicals•Toxic chemicals, nutrients, and sediment in surface waters

Low-Risk Ecological Problems•Oil spills•Groundwater pollution•Radioactive isotopes•Acid runoff to surface waters•Thermal pollution