Lesson 8: Environmental Health, Pollution, and Toxicology

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Lesson 8 Environmental Health, Pollution, and
Toxicology

• Big Question
• Why Are Even Tiny Amounts of Pollutants a Major
  Concern?

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Some Basics

• Volcanic gases spewing from Mt. St Helens
  adversely affected air quality.

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Terminology

• 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.

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Synergism

• 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

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How Do Pollutants Get into the Environment?

• Point sources
• Area sources (also called non-point sources)

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Mobile Sources
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Categories of Pollutants

• Infectious agents
• Toxic heavy metals
• Organic compounds
• Thermal pollution
• Particulates
• Electromagnetic fields
• Noise

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Heavy Metals
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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.

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Pathways for Mercury
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Mercury and Minamata, Japan

• A strange illness began to affect animals and
  people in the middle of the 20th century.
• It was first recognized in birds, cats, and then
  families of fishermen. A vinyl chloride factory
  on the bay used mercury in an inorganic form.
  Methylation increased absorption into fish tissue
  from the water by a factor of 100.
• See the Wikipedia article on Minamata Disease.

The crippled hand of a Minamata disease
victim. (Photo Wikipedia)

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Organic Compounds
DHMO home page http//www.dhmo.org/
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Selected Common Persistent Organic Pollutants
(POPs)
Chemical Example of Use
Aldrin Insecticide
Atrazine Herbicide
DDT Insecticide
Dieldrin Insecticide
Endrin Insecticide
PCBs Liquid insulators in electric transformers
Dioxins By-product of herbicide production

• Banned in the U.S. and many other countries
• Restricted or banned in many countries
• Source Data in part from Ann Platt McGinn,
  "Phasing out Persistent Organic Pollutants," in
  Lester R. Brown et al., State of the World 2000
  (New York Norton 2000).

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Dioxin

• Dioxin-contaminated site in South Park area of
  Seattle, WA

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Hormonally Active Agents (HAAs)

• HAAs are also persistent organic pollutants. HAAs
  include a wide variety of chemicals, such as some
  herbicides, pesticides, and phthalates. Studies
  link HAAs to reproductive abnormalities among
  wildlife, including Florida alligators
• Do HAAs play a role in human diseases? Is there a
  link with breast cancer?

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Thermal Pollution
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Wet and Dry Cooling Towers
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Particulates
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Chrysolite Asbestos

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

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Electromagnetic Fields

• If you think that cell phones don't generate much
  power, see the information from the University of
  Pittsburgh Cancer Institute.

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Noise Pollution
Sound Source Intensity of Sound (dB) Human Perception
Threshold of hearing 0 Threshold of human hearing
Rustling of leaf 10 Very quite
Faint whisper 20 Quiet
Average home 45 Quiet
Light traffic (30 m away) 55 Quiet
Normal conversation 65 Quiet
Chain saw (15 m away) 80 Moderately loud
Walkman at maximum volume 100 Very loud
Rock music concert (close) 110 Very loud
Thunderclap (close) 120 Uncomfortably loud
Jet aircraft takeoff at 100 m 125 Uncomfortably loud
Takeoff of fighter jet (close) 140 Threshold of pain
Rocket engine (close) 180 Traumatic injury
Note chronic exposure to very loud sound levels can cause hearing problems such as "ringing" in the ears. Note chronic exposure to very loud sound levels can cause hearing problems such as "ringing" in the ears. Note chronic exposure to very loud sound levels can cause hearing problems such as "ringing" in the ears.
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Voluntary Exposure to Toxins
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General Effects of Pollutants
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Dose and Response

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

DHMO web site http//dhmo.org
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Dose-Response
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Risk Assessment

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

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Risk Management

• 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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Lesson 8 Environmental Health, Pollution, and
Toxicology

• Questions? E-mail your TA. eschelp_at_u.washington.ed
  u