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.
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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.
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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.
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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
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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.
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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.
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