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Introduction to Environmental HealthJonathan M. Links, PhDJohns Hopkins University

Section AObjectives and Definitions

Course Learning Objectives Define the major types, sources, and environmentaldistribution of environmental agentsDescribe how these agents interact with biological systems,and describe the mechanisms by which they exert adverseeffectsPredict the nature of the agent’s adverse effects from itsphysical, chemical, or infectious properties, and how that mayinfluence environmental or public health4

Course Learning Objectives Describe and use models for prediction of the magnitude ofadverse effects in biological systemsIdentify significant gaps in the current knowledge baseconcerning health effects of environmental agents, and areasof uncertainty in the risk-assessment processDescribe current legislation and regulation regardingenvironmental issues5

Definitions: Environment The circumstances, objects, or conditions by which one issurroundedorThe complex of climatic, edaphic (soil-based), and bioticfactors that act upon an organism or an ecologic community6

Public Health Definition of “The Environment” All that which is external to the individual host. [It] can bedivided into physical, biological, social, and cultural factors,any or all of which can influence health status in populations. Last, J. M. (Ed.). (1995). A Dictionary of Epidemiology (3rded.). New York: Oxford University Press.7

Definitions: Health The condition of being sound in body, mind, or spiritA flourishing condition or well-being—not just the absence ofdiseaseor8

Definitions: Health A state of complete physical, mental, and social well-beingand not merely the absence of disease or infirmity WHO. (1948).9

Definitions: Disease Trouble or a condition of the living animal or plant body orone of its parts that impairs the performance of a vitalfunction10

Definitions: Safe Free from harm or riskSecure from threat of danger, harm, or lossZero risk11

Definitions: Risk Possibility of loss or injury, perilThe chance of loss; the degree of probability of such loss12

What Is Environmental Health Sciences? NIEHS charter: “The study of those factors in the environmentthat affect human health” Factors (“pollutants” or “toxicants”) in air, water, soil, orfood Transferred to humans by inhalation, ingestion, orabsorption Production of adverse health effects13

Contributors to the “Environment” Chemical Air pollutants, toxic wastes, pesticides, VOCsBiologic Disease organisms present in food and water Insect and animal allergensPhysical Noise, ionizing and non-ionizing radiationSocioeconomic Access to safe and sufficient health care14

WHO Definition of Environmental Health Environmental health comprises those aspects of humanhealth, including quality of life, that are determined byphysical, biological, social, and psychosocial factors in theenvironment. It also refers to the theory and practice ofassessing, correcting, controlling, and preventing thosefactors in the environment that can potentially affectadversely the health of present and future generations.15

Facets of Environmental Health Environmental epidemiology Associations between exposure to environmental agentsand subsequent development of diseaseEnvironmental toxicology Causal mechanisms between exposure and subsequentdevelopment of diseaseEnvironmental engineering Factors that govern and reduce exposurePreventive medicine Factors that govern and reduce disease developmentLaw Development of appropriate legislation to protect publichealth16

Section BEnvironmental Health Issues

Question Do you think that environmental issues are among the topthree public health issues in this country?18

The “Right” First Question What criteria do you use to identify an important publichealth issue?19

Traditional Public Health Approach1.2.3.4.Define the problemIdentify and characterize the parameters governing theproblemDesign appropriate PH interventionsImplement and evaluate the interventions20

Another Possible Approach1.2.3.4.5.Define the health parameters of importanceIdentify the problems most impacting the health parametersIdentify and characterize the parameters governing theproblemDesign appropriate PH interventionsImplement and evaluate the interventions21

Measure of Disease Burden and NIH Funding Source: (1999). NEJM, 340, 1181.Measure(Year Assessed)UnitsCorrelationCoefficient ( r )P ValueIncidence(1990)No. of new casesper year-0.050.82Prevalence(1990)No. of existingcases0.250.23Hospital days(1994)Days in acute carehospitals0.240.21Mortality(1994)Deaths per year0.400.03Years of life lost(1994)Years0.420.02Disabilityadjusted lifeyears (1990)*Years0.62 0.001Source: Adapted from (1999). NEJM, 340, 1181*Loss of one year of healthy life to disease22

Disability-Adjusted Life-Years and NIH Funding Relationship between NIH disease-specific research fundingand disability-adjusted life-yearsSource: Adapted from (1999). NEJM, 340, 1181.23

Should You Care about EHS? Acute environmental catastrophes (high-level exposures)Chronic (low-level) exposuresIndirect effects of global environmental changes24

The Wake-up Calls: Environmental Catastrophes Minamata disease (1953–1961) Methyl mercury poisoningSeveso, Italy (1976) Leak of toxic gas (TCDD)Bhopal (1984) 16.5 tons of toxic pesticide released25

The Wake-up Calls: Environmental Catastrophes Chernobyl (1986) Nuclear reactor accidentMilwaukee incident (1993) Cryptosporidium in drinking water26

Major Air Pollution EpisodesDatePlaceXs DeathsDec. 1882London, England1,000Dec. 1930Meuse Valley,Belgium63Oct. 1948Donora, Penn.20Dec. 1952London, EnglandDec. 1962Osaka, Japan60Jan. 1963New York City200–405Nov. 1983New York City2504,000Excess deaths refers to the additional number of fatalities countedabove the number expected under otherwise normal conditions.27

The London “Killer” Smog of 1952Source: Adapted from Turco, R. P.28

Chemicals in the Environment Roughly 70,000 different synthetic chemicals are on theglobal market; many others are emitted as by-products oftheir production, use, or disposalProduction of synthetic organic chemicals (e.g., dyes, plastics,solvents) has increased from less than 0.15 billion kilograms(1935) to more than 150 billion kilograms (1995)29

World Production of Synthetic Organic ChemicalsMillions of Kilograms10000001000001000010001001915Data from Mitchell, J.D.193519551975199530

Substance-Specific Toxicity and Health Information Substance-specific toxicity and health information (NRC/NAS,1984)100%80%compl HHE60%partial mHHE health hazard evaluation; meds medications; pests pesticides;food food additives; cosm cosmetics; chem commercial chemicals31

Why Don’t We Know More about These Chemicals? Number of chemicals (1984—NRC/NAS) Pesticides3,350 Drugs1,815 Cosmetics3,410 Food additives8,62732

Why Don’t We Know More about These Chemicals? Chemicals in commerce (1984) 1 million lbs/yr 1 million lbs/yr Production unknown12,86013,91121,75233

Why Don’t We Know More about These Chemicals? Each year 1,000 new chemicals come on lineIt costs 2 million to do a cancer toxicology screen on eachchemical (NTP guidelines)The cancer toxicology screen takes 2 years34

Routes of Exposure Routes of exposure through gaseous, liquid, and solid nSoilAdapted from Moeller, D.W.35

Pollutant Source PathwaysPollutant SourceRoot UptakeSoil rationPlantConsumptionPlantConsumptionCattleCattle && tMilkMilkDermalExposureHuman ReceptorAdapted from Derelanko, M. J.Egg and PoultryConsumptionDairy and BeefConsumption36

Environmental Pathways for Selected Toxic naire’sdiseaseSoil, coolingtowersAir, uman oranimal fecesWater, meat,eggsDioxinChloracne,soft tissuetumorsHerbicides,paper mills,incineratorsAir, water,foodPesticidesNervoussystem tox.AgricultureFood, waterAsbestosAsbestosis,lung cancerInsulation,auto brakesAir, water37

Agents and Vectors Agents Chemical, biological, and physicalVectors Water, air, soil, and foodRoutes of entry Inhalation, ingestion, absorption38

The Toxicological ParadigmExposureInternal doseSusceptibilityGenetic factorsBiologically effective doseEarly biologic effectsEffect red structure and functionClinical disease39

The Toxicological ParadigmExposureInternal doseSusceptibilityGenetic factorsBiologically effective doseEarly biologic effectsEffect red structure and functionClinical disease40

The Toxicological ParadigmExposureInternal doseSusceptibilityGenetic factorsBiologically effective doseEarly biologic effectsEffect red structure and functionClinical disease41

Severity of Adverse Health EffectsDeathSignificant diseaseManifest dysfunctionClinical nuisance effectsSub-clinical chronic alterationsAcute reversible (functional) effectsPopulation exposed42

Health Effects Adverse vs. beneficialAcute vs. delayed onsetClinical vs. subclinical manifestationsTransient (reversible) vs. chronic (irreversible)43

Examples of Manifestations Lung diseaseReproductive effectsTeratogenic effectsNeurologic effectsImmunosuppression and hypersensitivityCancer44

Environment Pulls the ealth/DiseaseAge/Time“Genetics loads the gun,but environment pullsthe trigger.”— Judith SternUC Davis45

Vulnerable Groups Low socioeconomic statusWomenChildrenElderlyEthnic minoritiesDisabledIndigenous peoplesAll of whom are often more vulnerable because of— Genetics They are not empowered to change their environment46

Section CProblem Solving

Problem-Solving Paradigm: Six Steps1.2.3.4.5.6.Define the problemMeasure its magnitudeUnderstand key determinantsDevelop intervention/prevention strategiesSet policy/prioritiesImplement and evaluateRisk assessmentRisk management48

Selecting Priorities Risk assessment The determination of the probability that an adverseeffect will result from a defined exposure1. Hazard identification2. Exposure assessment3. Dose-response assessment4. Risk characterization Pure “science” activities49

Selecting Interventions Risk management The process of weighing policy alternatives and selectingthe most appropriate regulatory actions based on theresults of risk assessment and social, economic, andpolitical concerns50

Commonplace Risks Calculated Commonplace risks calculated as number of deaths per100,000 per yearActivity or ExposureRisk/YearMotorcycling2,000Smoking (all causes)1,000Hand gliding80Driving24Fires2.84 TBS peanut butter per day(aflatoxin)0.8Being struck by lightning0.05Being hit by a meteor0.00000651

Major Environmental Legislation70Number of Laws6050403020100193519451955196519751985199552

The Cost of Cleanup The closer we get to the goal of zero emissions of a pollutant,the more costly it becomes to eliminate each unit of pollution53

The Cost of Cleanup Reason First control method is usually the most effective andeasiest to implement, and produces the largest benefit atthe lowest cost Continued progress requires using more and moreexpensive methods that remove smaller amounts ofpollutant At some point, costs outweigh benefits54

The Law of Diminishing ReturnsHighPollutionPollutant Emissions1086420LowPollution13579111315171921Cost of Emission Controls ( Million)55

Societal Determinants Human needs and wants drive choices that produceenvironmental impacts which, in turn, may result in adversehealth consequences56

Societal Determinants Flowchart57