Chapter 7Chapter 7Human Health and Environmental Human Health and Environmental Toxicology Toxicology

ActivityActivityo In small groups, examine the chart. In small groups, examine the chart.

Determine as a group the number of Determine as a group the number of individuals you know or have heard of individuals you know or have heard of getting the various diseases.getting the various diseases.

o Would this be different if we were in Would this be different if we were in another country? Why?another country? Why?

o What groups are more effected by health What groups are more effected by health problems around the world and why?problems around the world and why?

Overview of Chapter 7Overview of Chapter 7

o Human HealthHuman Health• Health issues in developed countriesHealth issues in developed countries• Health issues in developing countriesHealth issues in developing countries

o Environmental Pollution and DiseaseEnvironmental Pollution and Disease• Environmental ContaminantsEnvironmental Contaminants• Endocrine DisruptersEndocrine Disrupters

o Determining Health Effects of PollutantsDetermining Health Effects of Pollutantso EcotoxicologyEcotoxicologyo Risk AssessmentRisk Assessment

Human HealthHuman Health

o Two indicators of human healthTwo indicators of human health• Life expectancy- how long people are Life expectancy- how long people are

expected to liveexpected to live• Infant mortality- how many children die Infant mortality- how many children die

before age of 1 yearbefore age of 1 yearo Vary greatly Vary greatly

between countriesbetween countries• Developed Developed

countriescountries• Developing Developing

countriescountries

Health Issues in Health Issues in Highly Developed CountriesHighly Developed Countries

o By many measures- health is good in these By many measures- health is good in these countriescountries• Great sanitationGreat sanitation• Few childhood diseasesFew childhood diseases

o Average life expectancyAverage life expectancy• Men = 75 yearsMen = 75 years• Women = 80 yearsWomen = 80 years

o Leading causes of death in USLeading causes of death in US• Cardiovascular diseaseCardiovascular disease• CancerCancer• Chronic Obstructive Pulmonary Disease (of the Chronic Obstructive Pulmonary Disease (of the

lungs)lungs)

Health Issue inHealth Issue inHighly Developed CountriesHighly Developed Countries

o Premature deaths caused by lifestylePremature deaths caused by lifestyle• Poor dietPoor diet• Lack of exerciseLack of exercise• SmokingSmoking

o Obesity is big problemObesity is big problem• Body Mass Index (BMI)Body Mass Index (BMI)

• (Weight X 740)/ (height (in))(Weight X 740)/ (height (in))22

• < 18.5 is underweight< 18.5 is underweight• 18.5-24.9 is healthy weight18.5-24.9 is healthy weight• 25-29 is overweight25-29 is overweight• > 30 is obese> 30 is obese

Health Issues in Developing Health Issues in Developing CountriesCountries

o Biggest problemsBiggest problems• Malnutrition, unsafe water, poor sanitationMalnutrition, unsafe water, poor sanitation

o Life ExpectancyLife Expectancy• Overall is 65 yearsOverall is 65 years• Very poorest developing countries = 45 yearsVery poorest developing countries = 45 years

• Most of these countries have high AIDS epidemicsMost of these countries have high AIDS epidemics

o Childhood mortality is high (18% of Childhood mortality is high (18% of deaths)deaths)• Diarrheal diseasesDiarrheal diseases• MalnutritionMalnutrition• MalariaMalaria• AIDS/HIVAIDS/HIV

Emerging and Reemerging Emerging and Reemerging DiseasesDiseases

o Emerging Disease - Emerging Disease - not previously not previously observed in humansobserved in humans• Usually jumps from Usually jumps from

animal hostanimal host• Ex: AIDS, lyme Ex: AIDS, lyme

disease, West Nile disease, West Nile VirusVirus

o Reemerging Disease- existed in the Reemerging Disease- existed in the past and are recently increasing in past and are recently increasing in incidenceincidence• Ex: tuberculosis, yellow fever, malariaEx: tuberculosis, yellow fever, malaria

Reasons for Reasons for Emergence/ReemergenceEmergence/Reemergence

o Evolution of disease so it can move to Evolution of disease so it can move to human hosthuman host

o Evolution of antibiotic resistance in diseaseEvolution of antibiotic resistance in diseaseo Urbanization and overcrowdingUrbanization and overcrowdingo Increased pop. of elderly- susceptible to Increased pop. of elderly- susceptible to

diseasediseaseo Pollution and environmental degradationPollution and environmental degradationo Growth in international travel and Growth in international travel and

commercecommerceo Poverty and social inequalityPoverty and social inequality

Environmental Pollution and Environmental Pollution and DiseaseDisease

o Often difficult Often difficult to link to link pollutants to pollutants to their effects on their effects on peoplepeople• PersistencePersistence• BioaccumulatioBioaccumulatio

nn• BiomagnificatioBiomagnificatio

nn

PersistencePersistence

o A characteristic of certain chemicals A characteristic of certain chemicals that are extremely stable and may take that are extremely stable and may take many years to be broken down into many years to be broken down into simpler forms by natural processes simpler forms by natural processes • Synthetic chemicals (those not found in Synthetic chemicals (those not found in

nature)nature)• Ex: DDTEx: DDT

o Natural decomposers (bacteria) have Natural decomposers (bacteria) have not evolved a way to break it downnot evolved a way to break it down

DDT trucksDDT trucks

BioaccumulationBioaccumulation

o The buildup of a persistent toxic The buildup of a persistent toxic substance in an organism’s body, often substance in an organism’s body, often in fatty tissues in fatty tissues • Synthetic chemical do not metabolize wellSynthetic chemical do not metabolize well• They remain in the body for extended They remain in the body for extended

periods of timeperiods of time

BiomagnificatioBiomagnificationn

o The increased The increased concentration of concentration of toxic chemicals toxic chemicals in the tissues of in the tissues of organisms that organisms that are at higher are at higher levels in food levels in food webs webs

o Diagram is Diagram is example of example of biomagnification biomagnification of DDTof DDT

Endocrine DisruptersEndocrine Disrupters

o A chemical that mimics or interferes with the A chemical that mimics or interferes with the actions of the endocrine system in humans actions of the endocrine system in humans and wildlife and wildlife • i.e. It effects the ability of the hormones in the i.e. It effects the ability of the hormones in the

organisms to function properlyorganisms to function properly

o Examples include:Examples include:• PCBs, DioxinsPCBs, Dioxins• Heavy metals – lead and mercuryHeavy metals – lead and mercury• DDTDDT

o Animals exposed to these chemicals have Animals exposed to these chemicals have altered reproductive development and are altered reproductive development and are often sterileoften sterile

Endocrine DisruptersEndocrine Disrupters

o Case Study: 1980 chemical spill into Case Study: 1980 chemical spill into Lake Apopka, FLLake Apopka, FL• Male alligators began to exhibit low Male alligators began to exhibit low

testosterone levels and high estrogen testosterone levels and high estrogen levelslevels

Endocrine Disrupters and Endocrine Disrupters and HumansHumans

o Infertility and hormonally related Infertility and hormonally related cancers are increasingcancers are increasing• Breast cancer and testicular cancerBreast cancer and testicular cancer

o Phthalates have been implicated as Phthalates have been implicated as potential endocrine disrupterspotential endocrine disrupters• Common ingredient in: cosmetics, Common ingredient in: cosmetics,

fragrances, nail polish, medication, toys, fragrances, nail polish, medication, toys, food packagingfood packaging

o Cannot make a link between endocrine Cannot make a link between endocrine disrupters and human illnessdisrupters and human illness• Too few studies have been performedToo few studies have been performed

Determining Health Effects of Determining Health Effects of PollutantsPollutants

o Toxicology is the study of the effect of Toxicology is the study of the effect of toxicants on the human bodytoxicants on the human body• Toxicant- chemical with adverse human Toxicant- chemical with adverse human

health effectshealth effectso Acute toxicityAcute toxicity

• Adverse effects occur within a short period Adverse effects occur within a short period after exposure to toxinafter exposure to toxin

o Chronic toxicityChronic toxicity• Adverse effects occur some time after Adverse effects occur some time after

exposure, or after prolonged exposure to exposure, or after prolonged exposure to toxintoxin

• Symptoms often mimic other diseases- hard Symptoms often mimic other diseases- hard to assess sourceto assess source

StudiesStudies

o http://www.cdc.gov/ExposureReport/

o http://toxics.usgs.gov/pubs/FS-027-02/

o http://www.scientificamerican.com/article.cfm?id=bpa-study-plastic-chemica

o http://www.scientificamerican.com/article.cfm?id=plastic-not-so-fantastic

ToxicityToxicity

o Toxicity measured by dose and responseToxicity measured by dose and response• Dose: amount that enters that body of an Dose: amount that enters that body of an

exposed organismexposed organism• Response: the amount of damage caused by Response: the amount of damage caused by

a specific dosea specific dose

o LDLD5050

• Lethal dose to 50% of the test organismsLethal dose to 50% of the test organisms• Smaller the LDSmaller the LD5050, the more lethal the , the more lethal the

chemicalchemical• Determined for all new synthetic chemicalsDetermined for all new synthetic chemicals

ToxicityToxicity

o EDED5050

• Effective dose to 50% of the test organismsEffective dose to 50% of the test organisms• EDED5050 causes 50% of the population to causes 50% of the population to

exhibit whatever effect is under studyexhibit whatever effect is under study

o Dose-Response CurveDose-Response Curve• Illustrates the effect of different doses on a Illustrates the effect of different doses on a

populationpopulation• Threshold LevelThreshold Level

• Maximum dose with no measurable effectsMaximum dose with no measurable effects

EDED5050

Children and Chemical ExposureChildren and Chemical Exposureo Children more Children more

susceptible to chemicalssusceptible to chemicals• Weigh less than adultsWeigh less than adults• Bodies are still developingBodies are still developing• Play on floors and lawnsPlay on floors and lawns

• Exposed to cleaning Exposed to cleaning products and pesticidesproducts and pesticides

• Put things into their Put things into their mouthsmouths

o DiagramDiagram• Children in foothills not Children in foothills not

exposed to pesticidesexposed to pesticides• Children in valley were Children in valley were

exposedexposed

Identifying Cancer Causing Identifying Cancer Causing SubstancesSubstances

o ToxicologistToxicologist• Dose rats with varying levels of chemicals Dose rats with varying levels of chemicals

to see if they develop cancerto see if they develop cancer• Difficult to extrapolate results to humansDifficult to extrapolate results to humans

o EpidemiologistsEpidemiologists• Look at historical exposure of groups of Look at historical exposure of groups of

humanshumans• See if exposed group have increased See if exposed group have increased

cancer ratecancer rate

Chemical MixturesChemical Mixtures

o Most studies look at one chemical, but Most studies look at one chemical, but humans tend to be exposed to chemical humans tend to be exposed to chemical mixturesmixtures• Ex: automobile exhaustEx: automobile exhaust

o Chemical Mixtures interact byChemical Mixtures interact by• AdditivityAdditivity• SynergySynergy• AntagonismAntagonism

o These studies are expensive and take a These studies are expensive and take a while to completewhile to complete

Chemical TestingChemical Testing

EcotoxicologyEcotoxicology

o Dilution Paradigm is not validDilution Paradigm is not valid• ““Dilution is the solution to pollution”Dilution is the solution to pollution”

o Boomerang Paradigm is acceptedBoomerang Paradigm is accepted• ““What you throw away can come back and What you throw away can come back and

hurt you”hurt you”o EcotoxicologyEcotoxicology

• The study of contaminants in the biosphere The study of contaminants in the biosphere and their harmful effects on ecosystemsand their harmful effects on ecosystems

• Helps policy makers determine costs and Helps policy makers determine costs and benefits of industrial and technological benefits of industrial and technological “advances”“advances”

• And how they often adversely effect ecosystemsAnd how they often adversely effect ecosystems

Case Study: The OceanCase Study: The Ocean

o Land based nutrient Land based nutrient and pollution runoff and pollution runoff into ocean is affecting into ocean is affecting microorganismsmicroorganisms

o Ex: Red TideEx: Red Tide• Red pigmented Red pigmented

poisonous algal poisonous algal bloomsblooms

• Toxins kill off fish and Toxins kill off fish and make humans sickmake humans sick

Risk AssessmentRisk Assessment

o Risk- probability that a particular Risk- probability that a particular adverse effect will result from some adverse effect will result from some exposure or conditionexposure or condition

o We assess risk daily with four stepsWe assess risk daily with four steps1.1. Hazard identificationHazard identification

2.2. Dose response assessmentDose response assessment

3.3. Exposure assessmentExposure assessment

4.4. Risk characterizationRisk characterization

Risk AssessmentRisk Assessment

Risk AssessmentRisk Assessment

Ecological Risk AssessmentEcological Risk Assessment

o Difficult to assess because effect occur Difficult to assess because effect occur at wide range of scalesat wide range of scales• Individual plants and animalsIndividual plants and animals• Ecological communities over wide regionsEcological communities over wide regions

o Human-induced environmental Human-induced environmental stressors also range greatlystressors also range greatly• Good to badGood to bad• Acceptable to unacceptableAcceptable to unacceptable

o There is a need to quantify risks to the There is a need to quantify risks to the environmentenvironment