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ENV 107 Env Hlth & Toxicology Final

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    Environmental Health

    &Toxicology

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    Environmental Health

    Environmental health addresses all the physical,

    chemical, and biological factors external to a

    person, and all the related factors impacting

    behaviours.

    It encompassesthe assessment and control of

    those environmental factors that can potentially

    affect health. It is targetedtowards preventing

    disease and creating health-supportive

    environments.

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    What is Environmental Hazards & Risks?

    Environmental hazardsare incidents we face from the

    environment that harm our physical, mental, moral, ethicaland spiritual wellbeing;

    Hazard is explained by the level of risks;

    Riskis the possibility of suffering harm from an event(Hazard) that can cause injury, disease, economic loss orenvironmental damage.

    E.g.; if we say the life time cancer risk from exposure of achemical is 0.001; this means 1 in 1000 people could have

    Cancer from the exposure of that chemical in a life span time(60-70 years);

    Risk assessment is the procedure through which probability ofharm to human health, to society or to environment are

    determined that may result from exposure to specific hazard.

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    A hazard is anything in the environment that can hurt you or makeyou sick;

    Things in the environment that are harmful are called hazards

    and include things like chemicals, disease-causing bacteria, loud

    noises and even stress. Hazards can be natural or anthropogenic.

    HazardsBacteria

    & virusesHarmful

    chemicals

    Loud noises

    Tobacco

    smoke

    Stress

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    What are the major types of Hazards?

    The categorization of hazards are mainly depends onhow it herms the Human being. The categorizationare:

    Cultural hazards: exampledrug addiction, unsafe

    working, smoking, poor diet, drinking driving, poverty; Chemical Hazards: Air pollution, Water Pollution, food

    poisoning, soil pollution;

    Physical Hazards: Noise, Fire, storms, earthquakes,volcanic eruption, floods;

    Biologicalhazards: Pathogen, pollen, Bird flue;

    Nuclear Hazards: Radiation leakage, excessiveexposure, UV radiation.

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    The 7 Core Concepts

    To understand the field of environmental health,

    you need to understand seven core concepts

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    Toxicmeans poisonous or dangerous;

    Toxicologyis the study of poisons;

    Toxicity is a measure of how dangerous a

    chemical is.

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    The 3 parts of exposure

    The

    Source

    of the hazard

    (bus exhaust)

    The

    Environmental

    Pathway

    (air)

    The

    Contact

    (inhaled fumes)

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    Route #1: Inhalation

    Inhalation:

    Breathing. When

    chemicals enter thebody through this

    route of exposure,

    they can get stuck in

    the lungs and/or be

    taken up into the

    bloodstream.

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    Route #2: Ingestion

    Ingestion:

    Swallowing(usually

    by eating or drinking).When chemicals enter

    the body through this

    route of exposure,

    they can easily be

    taken up into the

    bloodstream.

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    Route #3: Dermal Absorption

    Dermal Absorption:

    Absorbing a chemical through any part of the skin,including the eyes. When chemicals come in

    contact with the skin, they can sometimes enter

    the bloodstream through this route of exposure.

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    ExposureX

    X

    X X

    X

    X X

    X = hazard

    Dose

    Dose is the amount of a hazard that

    actually entersyour body.

    X

    XX

    XX

    XExposure

    XX

    X X

    X

    X X

    X = hazard

    Dose

    Dose is the amount of a hazard that

    actually entersyour body.

    X

    XX

    XX

    XExposure

    XX

    X X

    X

    X X

    X = hazard

    Dose

    Dose is the amount of a hazard that

    actually entersyour body.

    X

    XX

    XX

    XExposure

    XX

    What is dose?

    X X

    X

    X X

    X = hazard

    Dose

    Dose is the amount of a hazard that

    actually entersyour body.

    X

    XX

    XX

    X

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    Dose can depend on

    Duration of

    Exposure:How long?

    Frequency of

    Exposure:How often?

    Body Size:

    How big orsmall are you?

    S S

    Dose can depend on

    Duration of

    Exposure:How long?

    Frequency of

    Exposure:How often?

    Body Size:

    How big orsmall are you?

    S S

    The larger the dose, the more extreme

    the responsewill be.

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    Dose-Response Relationship:

    As the dose of a toxicant increases,

    so does the response.

    2

    3

    4

    0 1 DOSE

    RESPONSE

    0-1 NOAEL

    2-3 Linear Range

    4 Maximum Response

    DOSE DETERMINES THE BIOLOGICAL RESPONSE

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    Some people are more likely thanothers to get sick when they are

    exposed to environmental hazards.

    This might be because of their

    genetics, body size, age, gender orgeneral health. This is called their

    individual susceptibility.

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    Risks & Benefits

    What are the risks and benefitswhen grape growers use pesticides

    on their crops?

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    Risks & BenefitsRISKSBENEFITS

    No bugs!

    Better looking

    fruit that is morevisually appealing

    Bigger crops so

    farmers can makemore profit

    People ingestpesticides with the

    fruit and get sick

    Pesticides get into

    dirt and water

    Animals ingestpesticides and get

    sickBy understanding the risks and benefits that we face

    each day, we can make decisions that reduce our risk

    and keep us as safe and healthy as possible.

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    What is environmentaljustice?

    Environmental Justice(EJ) means that

    everyone has a right to live in an

    environment that doesnt make them sick,regardless of their race, culture, or income.

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    Well informed and well

    communicated communities can take

    necessary action to minimizeenvironmental hazards in a

    sustainable way,

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    The EJ Process

    Who is

    producing

    the hazard?

    Who is being

    exposed?

    Who are thedecision

    makers?

    Establish a dialog

    between the

    decision makers,

    scientists, and the

    affected

    community.

    Empower

    community

    members to bring

    about change.

    Share information

    and decisions with

    community

    members.

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    What is a Poison?

    All substances are poisons;

    There is none that is not a poison.

    The right dose differentiates a poison and a

    remedy.

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    Morbidity & Quality of Life

    Not everyone dies from disease, but still can causesevere suffering;

    Poorest people are most affected because they livein unhealthiest environments & dont have moneyfor health care;

    Lack of adequate housing, sanitation, safe drinkingwater causes most cases of diarrhea which is madeworse by malnutrition.

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    Pathogenic vs. Non-pathogenic

    43% of all disease-related

    deaths are from pathogens;

    57% from cardiovascular

    disease, cancer, lung

    disease, injuries, etc.

    Pathogenic

    Non-Pathogenic

    Environmental Health

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    Pathogenic: Infectious Diseases

    Onchocerciasis (river

    blindness)

    Vector: Black fly

    Many roundworms get intoeyes & die causing

    blindness

    Control with insecticide

    sprays Merck & Co. are providing

    free ivermectinto help

    eradicate.

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    Infectious Diseases.

    Elephantiasis

    Vector: Mosquitoes

    Roundworm gets into lymph

    system and blocks lymphvessels causing fluid build

    up in the extremities.

    SmithKline Beecham is

    supplying free albendazole

    to eradicate.

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    Infectious Diseases

    Dengue Fever

    Vector: Mosquitoes

    20 million new cases;

    2.5 billion currentcases

    What causes disease to spread so

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    What causes disease to spread so

    rapidly?

    Population density , so contact Moving into remote areas for agriculture exposure.

    Deforestation, pollution causing local & global climatechange (in temp = in mosquito pop.)

    Eliminating predators so in rodent, roach, mosquitopop.

    in speed & frequency of travel (airplanes, ships) toother countries

    in resistance (Malaria) = Superbugs

    Taking medication improperly leads to superbugs

    Antibiotics given to farm animals increases their

    resistance.

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    What determines how

    dangerous a chemical is?

    Persistence in

    environment

    Route/method ofexposure

    Characteristics of

    target organism

    FACTORS RELATED TO TOXIC AGENT

    1. Chemical composition & reactivity

    2. Physical traits- solubility, state of matter

    3. Presence of impurities

    4. Stability and storage traits

    5. Availability of vehicle to carry agent

    6. Movement of agent thru environment & into cellsFACTORS RELATED TO EXPOSURE

    1. Dose- concentration & volume of exposure

    2. Route, Rate, and site of exposure

    3. Duration and frequency of exposure

    4. Time of exposure (time of day, season, year)

    FACTORS RELATED TO ORGANISM

    1. Resistance to uptake, storage, or cell permeability

    2. Ability to metabolize or inactivate agent

    3. Tendency to change non-toxic to toxic in body

    4. Concurrent infections or physical stress

    5. Species and genes of organism

    6. Nutritional status of subject

    7. Age, sex, body weight, immunological status & maturity

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    Mechanisms for minimizing toxic effects

    Every material can be poisonous/toxic at somelevel.

    Most chemicals have safe levels or thresholds

    below which their affects are undetectable.

    EX: 100 cups of coffee have enough caffeine to killif consumed all at once- but most people dontconsume that much.

    Taken in small doses, chemicals can be broken

    down by the body and released.

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    Measuring Toxicity

    How a material is delivered plays a vital role in

    determining toxicity.

    1. At what rate? (a little over time or all at once)

    2. Through which route of entry? (skin, mouth,nose)

    3. In what medium?(solid, liquid, gas)

    Different species respond differently and different

    individuals in a species can react differently.

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    Axenobioticis a chemical which is found in anorganism but which is not normally produced or

    expected to present in it;

    It can also cover substances which are present inmuch higher concentrations than are usual;

    Specifically, drugs such as antibiotics arexenobiotics in humans because the human body

    does not produce them itself, nor are they part of a

    normal diet.

    Xenobiotic

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    Physiochemical properties of toxicants;

    Dose or concentration;

    Mode and duration of exposure; Environmental factors;

    Interaction, and

    Biological and nutritional factors.

    Factors affecting Xenobiotic

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    Conclusion

    Public health problems caused by environmental

    contamination and emerging infectious diseasesare a growing concern worldwide.

    Population growth and the associated pressures

    of development are increasing the difficultiesassociated with sustaining effective public health

    practices and policies.

    Well-targeted interventions can prevent much of theenvironmental risk;

    Worldwide, as many as 13 million deaths could bepreventedevery year by making our environmentshealthier;

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    Conclusion..

    Understanding environmental and ecological healthis a prerequisite to protecting public health;

    Advanced scientific knowledge and information

    will improve our understanding about theenvironmental co ntributions to disease and humanhealth in a sustainable way.


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