Sept 20 - Environmental Determinants Handout

8/3/2019 Sept 20 - Environmental Determinants Handout

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Pleasereadpriortoclass!HandoutforEnvironmentasaDeterminantofHealthsession

Dr.LauraMcLeod

September20,2010

Whatisenvironmentalhealth?1. effectsofenvironmentonhumanhealth,nothealthofecosystem,thoughtheseare

interrelated.

2. apublichealthdiscipline,carriedoutbypublichealthinspectorsalsocalledenvironmentalhealthofficers

3. amedicalfieldofpractice notaRoyalCollegeSpecialtyyet,butengagedinbyOccupationalMedicineandCommunityMedicinespecialistsandfamilyphysicians.

Whatistheimpactoftheenvironmentonhealth?TheCanadianInstituteforAdvancedResearchin2001estimatedthatthephysicalenvironmentwas

responsibleforabout10%ofhealthstatusinCanada.Incountrieswithpoorsanitationandhygiene,

thispercentageismuchhigher.(Sewagesystemsreducediarrheaincidenceby3060%.)

Itsimportanttorecognizethatthedeterminantsofhealthseldomactinisolation,butareinterrelated

socioeconomicstatusaffectsyourphysicalenvironment.e.g.wealthyneighbourhoodsarentbuiltnexttoindustrialareas.

educationaffectsyourknowledgeofhazardsintheenvironmentandhowtoavoidthem. personalhealthpracticesareinfluencedbytheenvironmentyoulivein:

healthyeatingisstronglyinfluenced bythesupplyofsafe,nutritiousfoodsvs.unsafefoodsorjunkfoods.Somestudieshaveshownincreasedobesityinneighbourhoods

withmoreaccesstofastfoodrestaurantsthantosupermarkets.Exposuretofoodborne

infectiousdiseaseswillbemuchhigherwhentherearefewsafefoodstochoosefrom.

Activelivingishighlyinfluencedbyurbanplanning,availabilityofparks,bikepaths,andsafestreets.Atrendinurbanplanning,NewUrbanism(AndresDuanyandcolleagues)

looksatneighbourhooddesignandhowitaffectsactivityaswellassocialinteraction.

Squareblockneighbourhoods(likethosebuiltbeforethe1960s)areeasierfor

pedestrianstonavigatethanneighbourhoodsbuiltwiththecurvingstreetsofmost


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modernsuburbs.Peoplelivinginmodernsuburbsaremorelikelytodriveevenshort

distancesthanpeopleingridneighbourhoods.

Smokingpatternsarestronglyinfluencedbypublicpoliciesbanningsmokinginpublicplaces.Smokefreebuildingshavedramaticallybetterairqualitythanthoseinwhich

smokingispermitted.

Healthychilddevelopmentisstronglyinfluencedbyexposuretoeitherinfectionsorchemicalpollutants,especiallythosethathaveneurotoxiceffects.Childrenaremorevulnerableto

pollutantsthanadults,foravarietyofreasons.Theyexploretheworldwiththeirmouthsas

infants,soingestmore;theyplayinthesoilsoingestmoresoilcontaminants;theyhavemore

rapidrespiratoryratessoinhalemoreairpollutantsfortheirmass;theyaresmall,sothesame

doseisagreaterdose/kg;andtheirorgansarestilldeveloping,somorevulnerabletodamage,

particularlytheirbrains.

biologyandgenetics:Certaindiseasessuchasasthmamakesomepeoplemorevulnerabletopollutantsthanothers.Aswell,biologicalprocessesofagingmaketheelderlymorevulnerable

tosomeenvironmentalthreats,particularlyheat.Thereisdevelopinginterestinthegene

environmentinteraction.Thenewscienceofepigenomicswhichlooksathowspecific

chemicalsmodifyDNAtoturnspecificgenesonoroff,ishelpingustoseeexactlyhow

environmentalexposures

can

affect

health,

but

also

why

people

can

react

differently

to

acommonexposure.Ithinkthatthegeneenvironmentinteractionwillbeagrowingfieldof

medicineinthefuture.


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Theabovecombustionbyproductsarecommoninwoodburning,cigarettesmokeandautomobile

emissions.Whenlookingatindustrialemissions,alloftheaboveareproduced,butalsoSulphur

Dioxide.Sulphuriscommonincoal,socountrieswherecoalisusedforindustryorheating(Chinaisa

biguserofcoal,aswasBritainuntilrecenttimes)havemuchhigherSO2levels. SO2isanacidaerosol,

andatriggerofbronchoconstrictionandcomponentofacidrain.

Photochemicalsmog.

InLondonin1952therewasanairinversionthatelevatedlevelsofSO2andparticulatesby310times,

hospitalbedswereovercapacity,andmanypeoplediedfromrespiratoryandcardiaccauses.This

episode,knownastheLondonFog,wasatriggerforrecognitionofthehealtheffectsofairpollution.

InAlberta,SO2isprimarilyproducedbyflaringofsourgas,butthisflaringhasdecreasedby70%since

the1970s.SourgasdrillingisabigindustryinAlberta.Thegasiscalledsourbecauseitcontains

HydrogenSulphide,H2S,whichcanbeinstantlyfatalinlargeamountsandcausesirritanteffectsand

nauseainsmallerdoses. Excessgasoranemergencyreleaseofgasisburned,whichproducesSO2,

whichisarespiratoryirritant,butnotfataltomostpeople.

Sourgasflare

GroundlevelOzone,alsocalledtroposphericozone(differentfromstratosphericozonediscussedlater)

isanothersecondarypollutant,becauseitisntproducedimmediatelybycombustionbutfromthe

reactionreferred

to

above,

of

NO2

and

UV

light

and

Hydrocarbons.

Ground

level

Ozone

is

arespiratory

irritant,andhastheinterestingeffectoftriggeringareflexinthelungsofasthmaticsthatblocksdeep

inhalation.Nonasthmaticsexercisingwhileexposedtoozonewillhaverespiratorysymptomsranging

fromnoseandthroatirritation,tocough,wheezeandchestpain,andothernonrespiratory

symptomslikeheadacheandfatigue.InAlberta,themajorcitieshaveregularexceedancesofthe

thresholdforozonesoarerequiredbyAlbertaEnvironmenttodevelopozonemanagementplans.


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Otherhazardsinair:Asbestoswasusedininsulationuntilthemid20thcentury,soolderbuildingscancontainasbestos,

usuallyasinsulationofpipes.Manyhavebeenremediated,soyoucantjudgeitspresencesimplyby

theageofthebuilding.Asbestosisntairborneunlessitisdisturbed,somainlybecomesaproblem

whenolderbuildingsarebeingrenovated. Ifasbestosfibresareinhaled,theyareahighriskfactorfor

asbestosis(whitelung)andthedevelopmentofmesothelioma,ahighlymalignantcancerofthepleura,

andlungcancer.(Smokingmagnifiesthisriskoflungcancerfromasbestos,soisnotjustanadditive

risk.)

Lead:leadusedtobeacommonadditiveingasoline,sowasanairpollutantanddepositedonsoils

nearmajorroadways.Childrenlivingnearmajorroadsoftenhadelevatedleadlevels.Sinceleadhas

beenbannedingasolineinCanada,leadlevelsinthepopulationhavefallensignificantly.Itwas

commoninpaintsuntilthemid20thcentury.Itisreleasedfromthepaintwhenthepaintisdisturbed,

suchaswhensandingthepaintedsurface.(Infantsandyoungchildrencouldalsoingestleadfrom

gnawingonpaintedsurfacessuchascribrailings.)Inthe1980sleaddustwasidentifiedonwindow

miniblinds.Elevatedleadlevelscauseneuropsychologicaleffects,includinglearningdifficulties.

Volatileorganiccompounds(VOCs): thisgroupofchemicalsincludebenzene,chloroform,methanol,

formaldehydeand

hundreds

of

others.

Indoors,

they

emanate

from

paints,

dry

cleaning

residues

on

clothing,upholsteredfurnitureandcarpetglues.

Theycancauserespiratoryirritation,headachesandathighlevelsneurologicaleffects.(Theseare

usuallyseeninoccupationalexposures.)

Newbuildingshavethehighestlevelsandovertime(about6months)theydiminish;tospeedtheoff

gassingoftheVOCs,buildingsaresometimesbakedoff,whereinthetemperatureisraisedandthe

ventilationmaximizedtocleartheVOCsmorerapidly.

Allergens:pollen,animaldander,mouldsporesandinsectfeces(primarilydustmiteandcockroach)

willtriggerallergicreactionsinsensitivepeople. Humidityincreasesbothdustmitesandmould.

Mould

is

often

found

in

buildings

with

water

damage,

from

floods

or

leaking

pipes

or

roofs.

Its

health

effectsarecontroversial,withclearevidenceofallergyinsusceptibleindividuals,andriskofinfection

inimmunecompromisedpeopleandsomeothers.Thecontroversialeffectsaretheneurotoxicones

frommycotoxinsfromcertainblackmoulds.TheCollegeofEnvironmentalandOccupationalMedicine

saysthesemycotoxinsareheavypeptidesandnoteasilyairborne,soareonlyarisktopersons

disturbingthemduringmouldremediation.Howevertherearemanypeoplewhobelievetheycan

becomeillfromthepresenceofthesemouldsinabuilding,andmanybuildingshavebeendestroyed

becauseofmould.


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Physicalhazardsthattravelthroughtheairincludeheatandcold,airpressure,soundandradiation.

Thesehavetheobviouseffectsassociatedwiththosehazards,butIwontdiscussthemindetail.

Radiationcanbenonionizing(visiblelight,UVlight,lasers,andelectromagneticfields)orionizing(the

kindthatisusedinXrays,radiationtherapyandnuclearweapons.)Ionizingradiationathighlevels

causesskinburns,bonemarrowsuppression,radiationsicknessanddeath.UVeffectsarediscussed

belowintheozoneholesection.Healtheffectsofelectromagneticfieldsareanongoingcontroversy,

firstwithpublicconcernsthatchildrenlivingnearhighvoltagepowerlineshadanincreasedriskof

leukemiaandlymphoma,forwhichnoclearevidencehasshownarelationship.Morerecentlycell

phonesandbraintumourshasbeenapublicconcern,andmostrecentlywirelessnetworks,withsome

schoolsineasternCanadabanningwirelessintheschools.Forbothofthesetherehasbeennostrong

evidenceeither.

HealtheffectsofAirPollution:

Irritanteffects:conjunctivitis,rhinitis,asthma.

Cancer:nasopharyngeal,lung,mesothelioma.

Infections:theinflammatorychangestriggeredbyairpollutionhavebeenshowntodecreasethe

immuneresponseandphysicaldefenses(ciliaryclearance)toinfections,soincreasetheincidenceof

otitismedia,bronchitisandpneumonia.SomenewepidemiologicalresearchattheUofC(Dr.Gil

Kaplaan)hasshownarelationshipbetweenairpollutionandappendicitis,andheisnowlookingat

inflammatorybowel

disease

and

air

pollution.

It

appears

that

the

immune

changes

induced

by

air

pollutantsarenotrestrictedtotherespiratorytract.

Neurotoxicity:fromCO,heavymetalsandVOCs. Headache,learningdifficulties,andmoresevere

neurotoxicityifhigherlevelsthaninnormalairconcentrations.ThereisanincreasedrateofSudden

InfantDeathSyndromeininfantsexposedtoindoortobaccosmoke.

Reproductivetoxicity:increasedriskoflowbirthweightinfantsinmotherswhosmoke.Thereis

controversyaboutwhetherairpollutioncontributestomiscarriageinhumansandanimals.(Thisis


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particularlyanissuewithsourgasemissions,wherestudieshavebeenconflictingastowhetherthere

isanincreaseinlossofcalvespriortobirthorinthefirstyearoflife.)

Cardiotoxicity:someairpollutants(CO,Particulates,Sulphuroxides)havebeenshowntoexacerbate

symptomsinthosewithunderlyingheartdisease,socancauseincreasedangina.

Death:fromcancer,cardiopulmonarycauses,orneurotoxicity.

TheBurdenofAirPollution:Alberta2008 Canada2008 Canada2031

Deaths 173 21,000 39,000ERvisits 8638 30,000 (N/A)Cost $600million $8billion $18billionCMAJSept23,2008/www.cma.ca

Clearlyareduction

in

air

pollution

could

lead

to

significant

health

system

savings,

as

well

as

loss

of

life.

Globally,theburdenofairpollutionismuchgreater.Industryislessregulatedindevelopingcountries,

whatregulationsexistareoftennotenforced,andthecountrieseconomiesoftencantaffordtolimit

industrialactivity.TheBrownAsianSmogcloudisapermanentsmogcloud3kmthickoverlyingparts

ofChinaandSEAsia,andkillingthousandsandadverselyaffectingthehealthofmillionsofpeople.

(RememberwhentheOlympicstookplaceinBeijingandthegovernmentshutdowntheindustriesfor

thedurationofthegames?)Similarsmallercloudsexistelsewhereintheworld.

Indoorairpollutionismuchhigherinplaceswherepeoplecookinsidewithoutchimneys. Smoky

indooraircontributestorespiratoryinfectionsthatkill4millionayear

(WorldBankfigure),mostlychildrenunder5yrs.

Particulatelevelsabove50100micrograms/m3cancauseseriouslungdiseaseandriskofcancer;

insidehomesinNepalandPapuaNewGuinealevelsof10,000havebeenrecorded.


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WATERWaterisusuallycategorizedasdrinkingwaterorrecreationalwater.Hazardsinwaterareusually

ingested,butcanalsohavedermaleffects,likecontactdermatitisfromirritantchemicalsinwater.

Schistosomiasisisaparasiticinfectionthatentersthebodythroughskinexposuretofreshwater

infestedwiththemicroscopiclarvae.Thediscussionbelowwillfocusoningestedhazards.

Drinkingwater:Waterforconsumptioncanbefromasurfacesourceoragroundwatersource.Belowisaschematicof

asurfacewatersystem.

Surfacewatersarealwayscontaminated,tovaryingdegrees,fromrainwaterrunofffromtheland

surface,ordirectlyfromanimalsorbirdsdefecatinginthewater,orfromhumansewagepipedinto

thewaterbody.Groundwaterisusuallypurer,butitcanbecontaminatedfromleakywells,or

excessivesepticfieldpercolation,orchemicalcontamination.

Walkerton,Ontario

had

an

infamous

crisis

of

E.coli

O157:H7

contamination

of

well

water

with

surface

manure,causingmanypeopletobecomeilland7todiefromhemolyticuremicsyndrome(kidney

damagefromtheinfection).ThetownofBraggCreekwestofCalgaryisonapermanentboilwater

advisoryduetobacterialcontaminationofgroundwaterfromsepticfields. LargeareasofAlberta

havegroundwaternexttocoalseams,andmethanefromcoalcontaminatesthewater.Peopleliving

intheseareascanlighttheirwateronfire!Currentindustrialactivitydrillingforcoalbedmethaneisa

potentialrisktoincreasesuchcontamination.(Therearenohealtheffectsfromthemethaneasitoff

gasesatroomairpressure,butitisanexplosiverisk.Aswell,othertracehydrocarbonsfromthecoal

poseapotentialriskfromingestion.)


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surfacewater.Itisalsocommoninreturningtravelers,whooftenpresentwithchronicdiarrheaand

gas.

(Mostwaterborneinfectionscanalsobetransmittedpersontoperson,orviafood.)

Giardia Cryptosporidium

Chemicalhazardsinwater:Naturallyoccurring:arsenic,fluoride(inexcessiveamounts,wellabovewhatisusedinfluoridation.)

ArsenichasbeenabigprobleminBangaldeshafterwellswereprovided.EveninAlbertawehavesome

communitieswitharsenicinthewater.

Agriculturalrunoff:nitratesinwellwaterfromfertilizercancausemethemoglobinemiaininfants.

Pesticidescanbeanothercontaminant(seeFoods).

Industrialwastewater:

heavy

metals

(more

afood

chain

issue

than

water

ingestion),

and

persistant

organiccompoundssuchasdioxins(commonfrompulpmills)andfurans.

Leachatesfromlandfills:heavymetalsandhydrocarbons.

Pharmaceuticals,especiallyfemalehormones,fromcontraceptivesandmenopausalreplacement

therapy.Effectsonfish,andpossiblyhumans.?decreasingspermcounts,possiblecarcinogens.

Distributionsystem:oldwaterpipesweremadeoflead,andmorerecentonesmayhavehadlead

solder.(newerpipesareplasticorcopper).


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PhotosofresidentsofavillageinMexicowithhighleadandarsenicinthewater.Notetheleadlines

inthe

gums.

(Photos

courtesy

of

Dr.

David

Bethune,

hydrogeologist,

who

worked

in

the

community.)

HAZARDSINSOIL

Soilpollutants

usually

affect

human

health

through

contamination

of

foods.

However,

there

are

some

soilpollutantsthataffecthealthdirectly.

Biologicalhazards:Parasiticdiseasessuchashookworm,orcutaneouslarvamigransarepickedupfromeggsorlarvaein

thesoil.Inthecaseofhookwormtheeggsareingestedoffhandsthatcontactedsoilwhereeggswere

depositedinhumanfeces;withlarvamigransthelarvacontacttheskindirectlyfrombarefeetwalking

onsandcontaminatedwithanimalfeces.


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Hookworm(scanningEM) Cutaneouslarvamigrans

Thehookwormlatchesontotheintestinalwallandcausesanemia.Larvamigransisjustanirritating

selflimitingdisease,butoneyouarelikelytoseeinreturningtravellersfrombeachholidays.

Bacterialinfectionsfromsoil:Clostridialinfectionsfromthesoilcancausebothgasgangrene(Clostridiumperfringens)andtetanus

(Clostridiumtetanii). Botharecausedbybacteriainfectingasoilcontaminatedwound. Ingas

gangrene,theoutcomeisoftenamputationoftheinfectedbodypart,ordeath,andintetanus,itis

usuallydeath,ifnotpreventedbyimmunizationortetanustoxoid.Tetanuscausesspasmodic

contractionofmuscles,dominatedbythestrongermusclegroup,soarmflexionandbackandneck

extension.Deathoccursfromrespiratoryfailure. Itiscommonininfantsincountriesofpoorsanitation

andlowimmunizationrates,wheretheportalofentryistheumbilicalcordstump.

GasGangrene

Tetanus


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Radiationhazardsinsoil:Radonisacommonhazardinmanypartsoftheworld.InAlbertathereisnotmuchradon,butthereis

inSaskatchewan.Itisradiationfromthebedrockthroughsoils,anditcanriskpenetratebasementsof

housesthroughvariousentrypoints(seediagram).Radoniscarcinogenic,particularlyforlungcancer.

NaturalResourcesCanada

Chemicalsinsoil:Industrialcontaminants:Aspreviouslymentioned,leadcancontaminatesoils,bothbyroadwayswhere

leadedgasolineisstillused,andfromindustrialcontamination.Otherheavymetalslikecadmium and

mercurycanbefoundinindustrialsites.

Pesticides:Manydifferentpesticidesarespreadonsoiltokillweeds,fungiorinsects.Theyaremost

commoninagriculturalareas,butthecosmeticuseofpesticidesforweedcontrolinlawnsandpublic

parksisgettingincreasingattention.Pesticidescanhavemanydifferenthealtheffects,dependingon

thetypeofchemicalandhowitisabsorbed,whetherinhalationofvapours,ingestiononfoods,or

throughskin

contact.

Someinsecticidesarecholinesteraseinhibitors,andcauseneurologicalsymptomsrangingfromblurred

visionandheadachetoneuropathy.Otherpesticidescancausefetaltoxicity,teratogenicity,irritantor

photodermatitis,cataractsandimmunesystemdamage.Somesourcessaypesticidescantrigger

asthmaandlymphomasmaybelinkedtopesticides.Moreresearchislikelyneeded.Thosemostatrisk

frompesticidesarethosewithoccupationalexposures,particularlyinpoorercountrieswherethe

storageandadministrationofpesticidesispoorlyregulated.Ihavemetoccupationalmedicine

specialistsandintegratedpestmanagementspecialistswhohaverepeatedlyfoundopenbarrelsof

pesticidesstoredunderbedsinhomes.


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HAZARDSINFOODS:

Microbial:Themostcommonfoodbornhazardismicrobialcontamination.

Thesemicrobescancontaminatefoodanywhereonthefarm to forkpath,fromirrigation(Iwaspart

ofaninvestigativeteamthatlinkedaCalgaryrestaurantoutbreakofShigellatoparsleyfarmedinBaja

Californiawheretheirrigationwaterwascontaminated),fecalcontaminationoffields(animalor

human)ormeat,harvesting,transporting,storage,displayingforsale,transporthome,storage,

preparationandcooking.Inrichercountries,refrigerationoffoodisstandard,butnotinpoorer

countries.

Bacteriagrowwellinthetemperaturerangeof4o60

oC.Buffetfoodsareoftenleftforlongperiods

atroomtemperature,iftherestaurantdoesntprovidegoodhotandcoldtables.Crosscontamination

offoodswithrawmeatjuicesisacommonsourceoffoodinfectioninthehome.

Anicemodelofhowfecaloralcontaminationcanoccur.ThanksagaintoDr.DavidBethune.


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Consequenceofmanyfoodborneillnesses!

Commonfoodborneinfectionsare:E.coliO157:H7(socalledhamburgerdisease,butcommononmanymeats.Grindingdistributesthe

bacteriathroughoutthemeat,whereasasteakwilljusthavebacteriaonthesurfacesoitseasiertokill

theorganismswithcooking)

SalmonellaandCampylobacter(bothcommononpoultry,aswellasothermeats)

Listeria(delimeats,softcheeses)whichisahigherriskinfectiontopregnantwomen,andpersonsover

60

Staphylococci:thebacteriaproduceatoxinwhichcausesnauseaandvomitingandabdominalpain,but

notusuallydiarrhea.Becauseitisatoxin,symptomoccurrenceisrapidafteringestion,withinafew

hours,comparedtodaysneededforsufficientnumbersofbacteriatoreproduceandcauseillnessin

otherinfections.

HepatitisA,theviraloneofthegroup(ofteninshellfishthatgrewinsewagecontaminatedseawater).

Priondiseasesareaspecialcaseoffoodborneillnesses.BovineSpongiformEncephalopathy(BSE)is

thebest

known.

In

the

1980s

and

90s,

prions

in

the

brain

and

spinal

cord

of

cattle

were

transmitted

whenanimalfeedcontainedanimalparts.Meatfrominfectedcattletheningestedbyhumansledto

humandisease,whichpresentsasarapiddementiaandlossofcoordination.Cattlearenolongerfed

animalprotein,andtheslaughteringprocessnowminimizesanycontaminationofmeatwithspinal

cordorbrain,sohumancasesarenolongeroccuringindevelopedcountries.


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Chemicalhazardsinfood:Manychemicalsarefoundinfood,frompesticides,toantibioticsandhormonesgiventoanimals,to

foodadditives.Somefoodsrequiremorepesticidestogetthemtomarketlookingappealingto

consumers,andothersless.(Youcancheckoutlistsoftheseonthewebifyouareconcerned.mostof

thetimewashingyourfruitsandvegetables,especiallywithsoap,willremovemostoftheresidue).

Thehealtheffectsofmostofthesearepoorlyunderstood.Antibioticsinanimalscontributeto

antibioticresistantorganismsinhumans.HealthCanadahassaidthatthefoodinCanadianstores

containssuchsmallamountsofthesechemicalsthatthereisnocauseforconcern.

Naturallyoccurringtoxins:manyfoodscontainnaturallycarcinogenicchemicals.Thisisarealsurprise.

Broccoliisone.Butthegoodnutrientsinthefoodsoutweighanypotentialharmfromthem,sothereis

noreasontogiveupeatingvegetables.

Onetypeofnaturaltoxinhowevershouldbeavoided:aflatoxinsaremycotoxinsproducedby

Aspergillisspeciesonfoodssuchaspeanuts,grains,andoils,inwarmhumidconditions.These

aflatoxinsarelinkedtoprimarylivercancers,especiallyincombinationwithHepatitisB.

Bioaccumulatedcontaminants:theseareheavymetalsorpersistantorganiccompoundslikePCBs,that

persistin

fat,

and

are

accumulated

up

the

food

chain.

Many

persistent

organic

compounds

are

present

inbreastmilk.Largecarnivorousfishareamajorsourceofbioaccumulatedchemicals,sincewedont

eatmanycarnivorousmammals.Mercuryisaneurotoxin,particularlytodevelopingnervoussystems.

OneofmanychildrenexposedtomercuryinuteroinMinamataJapan,inthe1950swhenindustrial

effluentcontaminatedthefisheatenbypregnantwomen.Thereweremanychildrenwithmental

handicapsand

neurological

damage.

WASTESWastesarejustgroupingsoforganismsandchemicalsthathavebeendiscussedaboveinwaterand

soil,butitisimportanttoconsiderthembecauseaddressingtheminvolvesknowinghowtheyare

disposedof.


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Biomasswastes:sewage,decayinganimalsandplants

SewageenteringthemediterraneanoffMalta.

Solidwastes: plastic,metal,glassetc.

dumpingofhouseholdwastes

Hazardouswastes:radioactive,chemical,biomedical

Chemicalwastesareoftenstoredinbarrelsthaterodeovertime,releasingtheircontents.Radioactive

wastehas

to

be

stored

safely

almost

forever.

Biomedical

waste

is

usually

incinerated

to

kill

any

pathogens.Therehavebeencommunitiesadverselyaffectedbychemicalwastes,suchastheLove

Canal,theSydneyTarPonds,andmanyRioGrandecommunities.


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Hazardsfromanimals:

Physical Trauma(bites)Chemical Venoms(wasps,bees,jellyfish)

BiologicalInsectvectorbornediseases:malaria,Japaneseencephalitis,dengue,WestNilefever,yellowfeverare

allmosquitoborne;Lymedisease,tickborneencephalitis,andRockyMountainspottedfeveraretick

borne;plagueandtyphusareflea borne.LymediseasehasnotbeenaprobleminAlberta,althoughit

hasbeenpresentinsoutheasternB.C.foranumberofyears. However,inthelastfewyears,several

ticksofoneofthespecies(Ixodes)whichcancarrytheLymediseaseorganismhavebeenfoundtobe

infectedinAlberta,sowewilllikelystartseeingcases.

Zoonoticdiseases:

Rabies

is

a

virus

that

attacks

the

central

nervous

system,

and

is

almost

universally

fatal

by

the

time

it

is

diagnosed.Itistransmittedinsalivaofamammalatthetimeofabiteorscratch.Itisverycommonin

developingcountries,mostlycarriedbydogsandmonkeys,butfewcasesoccurinCanada,dueto

variouspreventiveprograms.InAlberta,themostcommonlyidentifiedrabidanimalsarebats,and

occasionallycatsanddogs.Verysmallmammalssuchasrodentsandsquirrelsarerarelytransmitters

ofrabies.


20/24

Hantavirusisavirusdiseaseofrodents,particularlydeermice,whichisexcretedintheurineandfeces

ofthemice,theninhaledwhenaerosolizedduringcleaningofdroppings.Itcausesasevereacute

respiratorydistresssyndromewhichcanbefatal.InAlbertaweusuallyhaveacoupleofcasesayear,

usuallyinspringwhenpeoplecleanupoutdoorsorinsheds.Duetoaclusterofcasesonareservein

CentralAltaafewyearsago,HealthCanadadidanepidemiologicstudyofmiceincentralAlta,and

foundmanymicewereinfected,especiallyinoldbarnsandotherabandonedbuildings,wherethey

cameincontactwithothermice,onandoffreserve.

EntericinfectionssuchasSalmonellacanbetransmittedfromhouseholdpetstotheirowners.Turtles

andreptilesarecommoncarriersofSalmonella,anddogsandcatsfedrawmeatsareofteninfected.

Fungalinfectionslikeringwormcanbespreadfrompetstoowners.BirdscancarryPsittacosis,alung

infection.

Plagueisaveryrarediseasenow,afterallthecarnageitcausedinthemiddleages,butstilloccurs

occasionallyinthesouthwesternUS,VietnamandIndia.itisarodentinfection,transmittedtohumans

byfleas.

EmergingZoonoses:

Ashumanspushdevelopmentfartherintoforestedareas,theycomeintocontactinlargernumbers

withanimaldiseases. SARS,Ebola,SimianBvirus,andLymediseaseareallattributedtothisincreased

contactwithanimaldiseases.EvenHIV,althoughnolongeremerging,isthoughttohaveoriginated

withcontactwithprimateblood.


21/24

THEBUILTENVIRONMENT:

Asmentionedabove,thebuiltenvironmentincludeseverythingbuiltbyhumans,sobuildings,roads,

phones,computers,toys,clothing,furniture,etc.

Mostofthehazardsinthebuiltenvironmenthavebeendiscussedabove,exceptphysicalhazards

causingtrauma.

Idlike

to

pay

particular

attention

to

acommon

issue

referred

to

as

sick

building

syndrome.

This

is

a

misnomer,sincethebuildingisntsick;itsthepeopleinitwhofeelill.Modernbuildingsarebuiltvery

tightlytomeettheneedforenergyefficiency,butasaresultareoftennotventilatedwell.Aswe

discussedinthechemicalairpollutants,manybuildingmaterialsgiveoffVOCs.Aswell,peoples

personalbehavioursindoorscontributetopoorairquality;smokingindoorswascommonuntilrecent

years,andstilloccursinmanyprivatebuildings.Perfumesandotherscentedbodyproductsrelease

VOCs.EvenbreathingindoorsreleasesCO2,whichifitreacheshigherconcentrationscancause

headachesandirritability.

HVAC(Heating,ventilationandairconditioning)systemsinbuildingsneedtobedesignedand

operatedproperly,

to

take

in

air

from

arelatively

clean

source,

appropriately

humidify

it,

and

exchange

itfrequentlyenoughtomeettheneedsforfreshairforthenumberofpeopleinside.Somebuildings

havetheirairintakesnexttothetruckloadingdocks,oronabusystreet,ornexttotheairexhaust!

Peoplecomplainingofheadaches,eye,noseandthroatirritationandcoughsinofficebuildingsthat

improvedwhentheywenthomeusedtobedismissedasmasspsychologicalphenomena,orpeople

whohatedtheirjobs,butinmorerecentyearsithasbeenrealizedthatbuildingaircanbecausing

theirsymptoms.Indoorairqualitycanbemeasuredandifinadequatecanbeimprovedinmostcases.

AsomewhatrelatedissueisthatofMultipleChemicalSensitivity,iepeoplewhoreportbeingmadeill

byamuchlargerrangeofsubstancesthanareknowntoirritateallergicpeople.Again,thishasbeen

attributedtopsychologicalproblemsbymostphysiciansandscientists,butothersfeelthatitisatrue

hypersensitivity.


22/24

GLOBALENVIRONMENTALISSUES:Ozonedepletion:

NASAGFSC2006.

Thissectionisreferringtostratosphericozone(good),notgroundlevelozone(bad).

ThelayerofozoneinthestratosphereprotectstheearthfromtheUVradiationofthesun.Chemical

catalystssuchasChlorofluorocarbons(fromindustry,refrigerationandairconditioning,andaerosol

cans)combine

with

ozone

in

the

presence

of

cold

temperatures,

and

create

oxygen

and

ahole

in

the

ozonelayer,mostpronouncedoverthepoles.EventhoughtheCFCsarentbeingproducedanymore,

theyhaveahalflifeof75yearsormore,sotheireffectsareexpectedtocontinue.HealtheffectsofUV

radiationincludesunburn,skincancer,retinaldamageandcataracts.Thereissomeevidenceof

decreasedimmuneresponseaswell.ThesearegoingtobemostpronouncedinsouthernChileand

Argentina,AustraliaandNewZealand.EffectsinCanadasnortharentlikelytobeasgreat,sincethe

northernpoleozoneholeissmallerthanthatofthesouthernpole.

GlobalWarmingandClimateChange:Althoughthereisstillsomedebate,particularlyintheenergysector,abouttheexistanceofglobal

warming,theglobalmeantemperatureisatitshighestsincetemperatureswererecorded.Regardless

ofthecause,thiswillhaveincreasingimpactsonhealthifitcontinuestorise.

GreerAetal.ClimatechangeandinfectiousdiseasesinNorthAmerica:theroadahead.CMAJMar11,2008


23/24

Youareundoubtedlyaware(ifnotfromAlGoresfilmAnInconvenientTruth,fromnumerousbooks

andmediaarticles)oftheenvironmentaleffectsofglobalwarmingandclimatechange.Risingsea

levelswouldfloodlowlyingfoodproducingareasliketheNiledeltaandBangladesh,displacing

millionsofpeopleandlimitingfoodsupplies.(Thiskindofimpactissimilartowhatweareseeingnow

inPakistanfromsevereinlandflooding.)Heatcouldcausedroughts,desertificationofnowarable

land,cropfailures(likeweareseeingnowinCanada,RussiaandtheUkraine),andlossofforeststo

firesandinsects(likeweareseeinginBCwiththeforestfiresandpinebeetledevastation).Airquality

candecreaseduetoincreaseddust,photochemicalsmog,andfiresmoke.Insectvectorswillmove

fromcurrenttropicalareasintonewareasasthoseheatup.Climatechangecanbringstorms,flash

floods,soilerosionandlandslides. Massmigrationsofpeoplewouldbelikelyduetofamineorlossof

homes,climaterefugees.

Thehealtheffectsofglobalwarminginclude: increasedrespiratoryandcardiovasculardiseasefrompoorerairquality malnutritionandfaminefromdecreasedfoodproduction increasedvectorborneandwaterborneinfections(floodscontaminatewatersupplies) increasedinjuriesinfloodsandstorms increaseddeathsfromheatstress(butlessfromcold!onegoodthingaboutglobalwarming.) mentalhealthstressors

EGProjectedmovementofLymediseasevector:

GreerAetal.ClimatechangeandinfectiousdiseasesinNorthAmerica:theroadahead.CMAJMar11,2008.


24/24

Muchofwhatwewillbeabletodoaboutglobalwarmingisalreadyintherangeofaccommodation

tochangesratherthanbeingabletoreverseorslowthewarming.Emergencypreparednessand

disasterplanninginAlbertaincludessuchnaturaldisastersasfloodsandtornados.Asfuture

physicians,youneedtobeawareoftheseglobaltrendstobeabletoshapehealthpolicy,service

deliveryetctomeettheneeds.Canadamaybeinafortunateposition(otherthanthedroughtprone

areasoftheprairiesandthefires)withincreasedfoodproductioncapacityinthenorth,andgreater

waterresourcesthanmostoftherestoftheworld,sowilllikelybeatargetofincreasingmigration

morethanoffamine.Migrationmovesmicroorganismsintonewgeographies.Beingculturally

competentandbeingawareofthepsychologicaltraumaofdisplacedpersonswillbeincreasingly

importantskills.

Backtotheenvironment!

Finalglobalissue: warWarcreatesspecificenvironmentalhealthhazardsfromtrauma,andthepotentialforchemical,

biologicalandnuclearwarfare.Inwar,thenaturalenvironmentisusuallydestroyed,sofood

production,waterandfuelsuppliesaredisrupted.Massmigrationsofpeopleoccur,fleeingtosafety.

Refugeecampsrequirespecifichealthplanningandservicedelivery.

InCanada

we

are

not

immune

to

conflicts

in

other

parts

of

the

world,

and

particularly

terrorist

acts,

so

wehaveplanstodealwithchemical,biologicalandnuclearexposures.In2001thereweresome

isolatedusesofanthraxasaweapon,butwidespreadpanicandimitatorsmailingbenignwhite

powdersrequiredemergencyresponses.Thethreatofsmallpoxishighonthelistofbiologicalweapon

concerns,sincetherearefewpeoplewithnaturalorvaccineimmunityanymore,sinceitwas

eradicatedinthe1970s(exceptforafewlaboratories).

SUMMARY:Theenvironmentismadeupofthenatural(air,water,soil)andbuiltenvironments.Hazardsexist

whichmaybebiological,chemical,orphysical.Healtheffectsofexposurestothesehazardsaremany,

ranging

from

developmental

and

reproductive

toxicity,

organ

toxicity

such

as

lung,

brain,

liver

or

kidney,toinfectionsandcancers.

Childrenaremorevulnerabletoenvironmentalexposuresthanadults.

Environmentalissuesarenotonlylocalexposurestohazards,butalsoglobaltrendsthatimpactthe

environmentandtherebyhumanhealth.

Sept 20 - Environmental Determinants Handout

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