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Objectives
Differentiate hazards and risk Give examples of Environmental Hazards Give examples of Environmental Hazards
according to area Explain several pathway of environmental
hazards Explain several routes of exposure of
environmental hazards
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Hazard vs Risk
A hazardis defined as 'a factor or exposure thatmay adversely affect health" (Last,1995);
it is basically a source of danger .Hazard is a qualitative term expressingthe potential of an environmental agent toharm the health of certain individuals ifthe exposure level is high enough and/ orif other conditions apply.
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A risk is defined as "the probability that an event will
occur, e.g., that an individual will become ill or die within a stated period of time or beforea given age;
the probability of a (generally) unfavorableoutcome " (Last, 1995).
It is the quantitative probability that a healtheffect will occur after an individual has beenexposed to a specified amount of a hazard.
Hazard vs Risk
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Types of Environmental HealthHazards
Sources of Environmental health hazards :natural and anthropogenic (human caused).Biological hazards : bacteria, viruses, parasites,
and other pathogenic organismsChemical hazards : toxic metals, air pollutants,solvents, and pesticidesPhysical hazards : radiation, temperature, andnoiseMechanical hazards : motor vehicle, sports,home, agriculture, and workplace injury hazardsPsychosocial hazards : stress, lifestyledisruption, workplace discrimination, effects of
social change, marginalization, andunemployment
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Traditional Versus ModernHealth Hazards
Traditional Hazards Modern Hazards
Disease VectorInfectious agentsInadequate housing & shelterPoor quality drinking water &sanitationIndoor air pollution fromcookingDietary deficienciesHazards of Child BirthWildlife & domestic animals
Injury hazards in agriculture
Tobacco smokingTransport hazardsPollution from sewage &industryOutdoors air pollution fromindustries & motorcars
Overuse or misuse ofchemicalsIndustrial machineryUnbalanced diet
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Common Classes of EnvironmentalHealth Hazards
Chemical Physical Biological Mechanical PsychosocialLead Noise Bacteria Vibration Violence
CarbonMonoxide
IonizingRadiation
Parasites RepetitiveMotion
Stress
Benzene Electromagneticfields
Viruses Lifting High demand/Low controloccupation
VinylChloride
Temperaturesextremes
Vectors
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Route of Exposure
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Biological Hazards
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Types of Biological Hazards
all of the forms of life (as well as the nonlivingproducts they produce) that can cause adversehealth effects.
These hazards are plants, insects, rodents, andother animals, fungi, bacterial, viruses, and awide variety of toxins and allergens.
A disease that can spread from one person toanother it is called an infectious orcommunicable disease
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Spread of Biological Hazards
Water polluted by human excreta : cholera, typhoidfever, dysentery, other diarrheal diseases, hepatitis,and schistosomiasis.Inadequate sanitation, the dumping of untreated
sewage into surface water, and poor hygienicpracticesOvercrowding and poorly ventilated housingcontribute to the airborne transmission oftuberculosis, measles, influenza, pneumonia,pertussis, and cerebrospinal meningitis.Unhygienic animal husbandry helps to transmitzoonoses (animal diseases that can also afflicthumans)
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Spread of Biological Hazards
Many parasites cause tropical diseases, which occuralmost exclusively in tropical areas. It is dependent onan insect vector, which can only survive in certainclimates. Examples : malaria, schistosomiasis, filariasis,and dracunculiasis (Guinea worm disease).Environmental changes and disturbances to the balanceof natural habitats may have profound effects on thespread of infectious diseases. New outbreaks such asthe one reported in Congo in 1995 caused by the Ebolavirus, have emerged lately when people encounteredthem by entering an unfamiliar or remote habitat.
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Routes of Exposure
The main environmental exposure routes forbiological hazards are air, water, and food.Some parasites enter the body by penetrating
the skin (e.g., hookworm, schistosomiasis) andothers enter a human body by insect bites (e.g.,malaria).Bacteria and parasites may also spread fromcontaminated soil to the skin or via dust to theair, and eventually infect a person.
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Routes of ExposureVia air : respiratory diseases, due to small droplets created while coughing or
sneezing. Example : common cold, tuberculosis bacteria, and
the Legionnaire's disease bacterium.Via water: When the drinking water supply for a community is
contaminated with feces from one sick person, a largenumber of people drinking the water can fall ill and inturn spread the disease via their feces.
Example : Cholera
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Routes of Exposure
ingestion of foodthe problem of helminths (worms) from aninfected person that defecates on soil.
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Health Effects
Infections : Diarrhea, cholera, typhoid, paratyphoid,
salmonella, and shigella. Respiratory infections HIV/ AIDS tuberculosis
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Spread of Chemical Hazardsnatural geological processesmining and dredging,as wastes from many industrial, agricultural,commercial, domestic, and manufacturingsourcesproduction, storage, and transportation ofproducts such as household products.
Air, soil, fresh waters, and oceansContamination of foodNatural toxins (aflatoxins, ochratoxins,pyrrolizidne alkaloids)
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Route of Exposure
Inhalation (mostly occupational)Oral ingestion (mostly non occupational)
Absorption through the skin (mostly
occupational) Absorption through the eyesPlacental transfer from a pregnant womanto the fetusInoculation and direct penetration to targetorgansfrom mother to child through breastfeeding
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Distribution, Metabolism, andElimination
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Toxicity Testing in ExperimentalAnimals
Tests to determine the toxicological profileof a chemical assess acute, sub chronic,
and long term toxicity or focus on specificareas of toxicityThe toxicological profile and the doseresponse relationship first stages in riskassessment.
Acute Toxicity Studies Acute animal studies to predict human effects of short term,
high level exposures
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Physical Hazards
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Types of Physical HazardsNoise and Vibration Risk of incurring hearing loss begins with
prolonged exposure to sound of approximately 7 5dB (A) (WHO). Many countries use 85 dB as thenoise safety limit in workplaces.
Vibration is transmitted by air to the ear, anddirectly to other parts of the human body.
The use of many tools or hand equipment canresult in adverse health effects as a result of armand hand vibration.
Vibrations can also be transmitted to the entirebody when driving vehicles like bulldozers,excavators, trucks, and cars on rough lands orbumpy roads. These vibrations may damage themusculoskeletal system.
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Types of Physical HazardsIonizing Radiation
Ionizing radiation emerges when an electron isremoved from a neutral atom and a pair of ions
are produced a negatively charged electron and apositively charged atom. It is the ionization of atoms in the human body that
causes harmful biological effect. The ions arehighly reactive and damage critical cell structures,including proteins and DNA.
Ionizing radiation is defined as electromagneticradiation with sufficient energy to displace anelectron from an atom.
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Environmental Hazards according to Area(Local to global area)
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Living Problems
Environmental tobacco smoke Noise exposure
Urban Crowding Residential lead-based paint
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Work Hazards
Toxic substances Machine-operating hazards
Repetitive motion injuries Carcinogenic work exposure
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Atmospheric Quality
Greenhouse gases and global warming Depletion of the ozone layer Aerial spraying of herbicides and pesticides Acid rain
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Water Quality
Contamination by human waste Oil and chemical spills in waterways Pesticide/ herbicide contamination of
groundwater and runoff to local waterways Aquifer contamination by industrial
pollutants Toxic contamination of fish and seafood
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Housing
Rodent and insect infestations Particulates from woodburning stoves
Houses and buildings with poor ventilationsystems sick building syndrome Off gases from carpets and plastics used
in home construction
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Radiation
Nuclear facility emissions Radioactive nuclear waste Radon gas Nuclear testing Excessive exposure to X rays Ultraviolet radiation (UVB) due to global
depletion of stratospheric ozone
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Violence
Proliferation of handguns Pervasive images of violence in the media Violent acts against women and children Excessive incidents of violence in
workplaces, schools, and communitysettings
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Effects of air pollution
Human health Ecosystems Property Aesthetics Economy Weather
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Vulnerable PopulationsIndividuals vary widely in their susceptibility to adversehealth effects following exposure to toxic substances.
Personal characteristics : Age Genetic
compositionNutritionalstatus
Sex Preexistingdiseases state
Physiologicstatus
Weight Behavior &lifestyle factors
Concomitant/last exposure
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Vulnerable PopulationsThe unique vulnerabilities of individuals at thetwo extremes of the life cycle, that is, youngchildren and the aged. Why ?
Young children have immaturity infunctioning of major physiologic processesThe aged have normal decline in that.
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Assignment
NOTICE THIS DATA !
Deaths in the Population Supplied by the Southwark &Vauxhall Water Company & the Lambeth Water Company,London 1853
Name of WaterCompany
No. of Homes Deaths fromCholera
Deaths in each10.000 Homes
Vauxhall &Southwark Co.
40.046 1263 315
Lambeth Co. 26.107 99 37
Rest of London 256.423 1422 59
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AssignmentSouthwark and Vauxhall Company took their water fromdownstream of Thames river, while Lambeth Company took itswater from upstream of Thames river.Questions :
1.Who have risk to get cholera ?2.What is the type of environmental hazard in this case ?3.What is the area level of environmental hazard this case ?4.How can this case probably happen ? What is the pathway ?
5.What is the route of exposure of this hazards ?6.Write one paragraph that addresses the events that impacthuman health !