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Environmental Health, Pollution, and Toxicology


Why Are Even Tiny Amounts of Pollutants a Major Concern? ... Can the environment make you sick? ... Synergism is an important concept ... – PowerPoint PPT presentation

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Title: Environmental Health, Pollution, and Toxicology

Chapter 8
  • Environmental Health, Pollution, and Toxicology

Big Question Why Are Even Tiny Amounts of
Pollutants a Major Concern?
Case Study Demasculinization and Feminization of
Frogs in the Environment
Some Basics
  • Can the environment make you sick?
  • Disease depends on several factors, including
    physical environment, biological environment, and
  • Are we the only problem?
  • Many natural events are hazardous

  • Pollution refers to an unwanted change in the
    environment caused by introducing harmful
    materials or by producing harmful conditions
  • Contamination implies making something unfit for
    a particular use through the introduction of
    undesirable material

  • A toxin is a substance that is poisonous (toxic)
    to people and other living things
  • Toxicology is the science that studies chemicals
    that are or could be toxic
  • A carcinogen is a toxin that increases the risk
    of cancer

  • Synergism is an important concept
  • It is the interaction of different substances,
    resulting in a combined effect that is greater
    than the effects of the separate substances
  • Antagonism is when to substances work to
    counteract each other or cancel each other out

  • How do pollutants get into the environment?
  • Point sources
  • Area sources (also called non-point sources)

  • Mobile sources

Categories of Pollutants
  • Infectious Agents
  • Toxic Heavy Metals
  • Organic Compounds
  • Thermal pollution
  • Particulates
  • Electromagnetic Fields
  • Noise

Heavy Metals
  • These are all around us
  • Heavy metals tend to accumulate over time in
    fatty body tissue. As a result, a little arsenic
    each day may eventually result in a fatal dose
  • Mercury, thallium, and lead are very toxic to

Toxic Pathways
  • One pathway is biomagnification
  • accumulation or increase in the concentration of
    a substance in living tissue as it moves through
    a food web
  • Also known as bioaccumulation

Four Lessons about Heavy Metals
  • Individuals vary in their response to the same
    dose, or amount, of a pollutant
  • Pollutants may have a threshold for observation
  • Some effects are reversible
  • The chemical form of a pollutant, its activity,
    and its potential to cause health problems may be
    changed markedly by ecological and biological

Lead and the Urban Environment
  • Lead is one of the most common toxic metals in
    our inner-city environments

  • Lead affects nearly every system of the body
  • Even small amounts may affect children
  • may increase risk of attention-deficit disorder,
    aggressive behavior, and delinquency

Organic Compounds
  • Organic compounds are carbon compounds produced
    naturally by living organisms or synthetically by
    industrial processes
  • Synthetic organic compounds are used in
    industrial processes, pest control,
    pharmaceuticals, and food additives
  • Over 20 million chemicals!

  • Persistent organic pollutants were produced
    decades ago, when their harm to the environment
    was not known, and are now banned or restricted
  • Properties
  • They have a carbon-based molecular structure,
    often containing highly reactive chlorine.
  • They are persistent in the environment
  • They are polluting and toxic
  • They are soluble in fat and therefore likely to
    accumulate in living tissue
  • They can be transported by wind, water, and
    sediments for long distances

  • One example is polychlorinated biphenyls (PCBs)
  • Originally used to insulate electric transformers
  • The transformers deteriorated over time and
    leaked PCBs into soil and waterways
  • PCBs entered the food chain and bioaccumulated in
  • Fish were caught by fishermen and eaten
  • PCBs may be concentrated in human fatty tissue
    and mothers milk

  • Another example is dioxin
  • Dioxin is a by-product, typically of combustion
    of chemicals and waste
  • Times Beach, Missouri became a dioxin ghost town
    in 1983

  • We know that dioxin is harmful to many living
  • How dioxin affects people is less certain
  • The good news is that dioxin emissions have
    decreased significantly

Thermal Pollution
  • Thermal pollution occurs when heat released into
    water or air produces undesirable effects
  • May be a sudden, one-time event
  • Volcanic eruption
  • Or a long-term, chronic problem
  • Electric power plants
  • Cooling Towers
  • Storage Lagoons

  • Particulates are small particles of dust
    (including soot and asbestos fibers) released
    into the atmosphere

  • Asbestoshow dangerous is it really?
  • Asbestos is used as insulation and protection
    from overheating
  • Excessive contact has led to asbestosis and
    cancer in some industrial workers

  • Removal of chrysolite asbestos in homes and
    public buildings is extremely expensive, and
    there is little evidence that it actually poses a

Noise Pollution
  • Noise pollution is unwanted sound energy waves
  • Loudness depends on the intensity of the energy
    carried by the sound waves
  • Measured in units of decibels (dB) a
    logarithmic scale

  • Rock concerts can reach 110 dB
  • Noises greater than 140 dB cause pain, and high
    levels can cause permanent hearing loss
  • Loudness isnt the only problem

General Effects of Pollutants
  • Almost every part of the human body is affected

Dose and Response
  • Large amounts of any substance can be dangerous,
    while an extremely small amount can be relatively
  • Even true for water!
  • Copper, chromium, and manganese are some chemical
    elements required by animals in small amounts but
    toxic in higher amounts

Dose and Response
  • Not everyone responds the same way to the same
  • Who is more vulnerable? Why?
  • Regulators face many challenges in trying to
    establish levels that are safe to be emitted into
    the environment
  • What is being done?

Agricultural Pesticides
  • Children may suffer neurologically from
    pesticides and show increased levels of anger,
    aggression, autism, and attention deficit

What about combinations of toxins?
  • Two or more chemicals in the same medium (air,
    water, soil)
  • Most studies only look at single chemical impacts

Variation in Response to Pollutants
  • Tolerance may vary among populations
  • Pollutants can have immediate (acute) and/or
    long-term (chronic) effects.

Risk Assessment and RiskManagement
  • Risk assessment is the process of determining
    potential health effects of pollutants. It
  • Identification of the hazard
  • Dose-response assessment
  • Exposure assessment
  • Risk characterization

  • Risk management requires us to make scientific
    judgments in conjunction with technical, legal,
    political, social, and economic considerations
  • Risk assessment and risk management can lead to
    arguments since the scientific opinions may be
    open to debate
  • The appropriate action may be to apply the
    Precautionary Principle
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