Health Effects

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Chapter 5

• Health Effects

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Air Pollution Disasters

• Meuse Valley, Belgium, 1930
• Donora, Pennsylvania, 1948
• Poza Rica, Mexico, 1950
• Cincinnati, Ohio. 1968
• London, England, 1952
• New York, 1962

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Meuse Valley, Belgium, 1930

• This is one of the first documented episodes in
  modern times
• Trapped by an inversion, pollutants accumulated
  in this steep-sided valley of 15 miles length.
• Coke ovens, steel mills, blast furnaces, zinc
  smelters, glass factories and sulfuric acid
  plants produced an estimated SO2 concentration of
  8 ppm.

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Meuse Valley

• Within a few days more than 600 people fell ill,
  and 63 people died from the polluted air.
• The major culprit was sulfur dioxide which, with
  the help of fog droplets oxidized to sulfuric
  acid mist with a particle size small enough to
  penetrate deeply into the lungs.
• Some recent studies have suggested that fluorine
  gas was also a major factor in these deaths

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Meuse Valley
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Donora, Pennsylvania, 1948

• In October 1948 the United States experienced its
  first pollution tragedy in the small town of
  Donora in the Manongahela River Valley, 20 miles
  southeast of Pittsburgh.
• Effluents from a number of industries such as a
  sulfuric acid plant, a steel mill, and a zinc
  production plant became trapped in a shallow
  valley inversion to produce an unbreathable
  mixture of fog and pollution.

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Donora, PA

• About 6,000 people or 43 percent of the
  population suffered various degrees of illnesses,
  such as sore throats, irritation of the eyes,
  nose, and respiratory tract, headaches,
  breathlessness, vomiting, and nausea.
• There were 20 deaths in three days. No ambient
  measurements were made during the disaster.
• It was suggested that sulfur dioxide reached peak
  values of about 5,500 ug/m

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Poza Rica, Mexico, 1950

• The disaster which struck Poza Rica, a town of
  15,000 people on the Gulf of Mexico, originated
  from an accident at one of the local factories
  which recovers sulfur from natural gas.
• The release of hydrogen sulfide into the ambient
  air lasted for only 25 minutes.
• The spread of the gas under a shallow inversion
  with foggy and calm conditions killed 22 people
  and hospitalized 320

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Poza Rica, Mexico
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Cincinnati, Ohio, 1968

• About 2,500 pounds of SO2 escaped into the air
  from a burst pipe at a chemical plant located in
  the northern industrial part of Cincinnati.
• The release of SO2 started at midnight and lasted
  for about 8 hours.
• People who were located within 200 meters to the
  east of the plant were affected. They were
  awakened by a rotten-egg smell and difficulty in
  breathing.
• No Fatalities

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Cincinnati, Ohio
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London, England, 1952

• From December 5 to 8, 1952, London experienced
  the worst air pollution disaster ever reported.
• The meteorological conditions were ideal for air
  pollution. Anti-cyclonic or high pressure weather
  with stagnating continental polar air masses
  trapped under inversions produced a shallow
  mixing layer with an almost complete absence of
  vertical and horizontal air motion.

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London, 1952

• The daily temperatures were below the average.
  Individuals stoked their fireplaces for warmth.
  With conditions perfect for air pollution, the
  concentrations of pollutants reached their
  highest levels.
• Elderly people were particularly affected.
• Deaths from bronchitis increased by a factor of
  10, influenza by 7, pneumonia by 5, tuberculosis
  by 4.5, other respiratory diseases by 6, heart
  diseases by 3 and lung cancer by 2.
• When a change in weather finally cleared the fog,
  4,000 Londoners had perished in their "pea soup".

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London, England
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New York, 1962

• New York, often with the nation's highest SO2
  concentrations normally avoids air pollution
  disasters because of its excellent ventilation.
• In December 1962, adverse weather conditions -
  low wind speeds and occurrence of shallow
  inversions combined with excessive SO2.
• Total deaths of 269, exceeded 3 standard
  deviations above the expected mortality for that
  week.

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New York
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Health Concerns Associated With Normal
Exposures to Air Pollutants

• The types and severity of air pollution disasters
  just discussed are rare.
• More typical symptoms from air pollutants
• Eye, nose, throat irritation
• Asthmatic attacks (sensitive individuals)
• Respiratory disease (chronic exposure)
• Cardiovascular disease (chronic exposure)
• Neurotoxic effects
• Cancer (chronic exposure)

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Cause-Effect Relationships

• What is a C-E relationship?
• Are C-E relationships easy or difficult to
  determine?
• How does a C-E relationship that is known and
  accepted for an indoor pollutant differ when we
  examine that relationship for the same pollutant
  outdoors?

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Epidemiology

• Using statistical methods, the epidemiologist
  attempts to establish statistical inference which
  suggests the strength or weakness of a connection
  between an agent and a disease or effect.
• This is one way (and one of the best ways) to
  establish the cause and effect relationship

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Epidemiology

• Cross-Sectional Studies
• Longitudinal Studies
• Case-Control Studies
• Prospective Studies
• Retrospective Studies

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Confounding Factors

• If one conducts an epidemiological study, what
  might be confounding factors for various air
  pollutants?
• Existing disease
• Age, sex, individual sensitivity
• SES, tobacco smoking, lifestyle, occupation
• Meteorological conditions temperature/RH
• Multiple pollutants pollutant interaction
• Pollutants and Infectious Diseases

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Interaction Effects

• Example SO2
• By itself, SO2 will typically react in the upper
  respiratory tract and mucous membranes Why is
  that?
• If adsorbed or absorbed onto PM, SO2 may enter
  the deepest part of the lungs (alveolar region)
  where it may enter the bloodstream and cause SO2
  toxicity effects

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Interaction Effects

• Interaction Effects may be categorized as
  follows
• Additive effect equal to sum ( 1 1 2)
• Synergistic effect greater than sum (1 1
  more than 2)
• Antagonistic effect is less than sum (1 1
  less than 2)
• To date, regulations are meant to account for
  individual effects.
• Which of the above interactions is disturbing
  based upon this information?

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Interaction Between Pollutants and Meteorological
Factors

• Most disasters in A.P. are due to the release of
  large amounts of toxics during near perfect
  meteorological conditions.
• What do you think these conditions are?
• Cold, Damp with thermal inversions
• Exceptions?
• LA Smog hot, sunny photochemical (O3, PAN)

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Interaction Ambient Pollutants and Other
Pollutant Exposures

• Cigarette Smoking (Number 1) this group is at
  special risk - several factors
• Some level of respiratory and cardiovascular
  disease and are therefore more sensitive to A.P.
• Impairment of respiratory clearance mechanisms
• Dust clearance in lungs is 5X slower in smokers
• Occupational Exposures greater than ambient
• Fireman, industrial worker, others?
• Americans spend 2 hours/day outside

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Interaction Between Pollutants and Infectious
Diseases

• What types of I.D. might cause interaction?
• Influenza, TB, Pneumonia (airborne diseases)
• In the 1952 London Fog incidence, many of the
  reported fatalities were excess pneumonia deaths.
• Lab studies have shown that O3 increases flu
  deaths and that NO2 increases pneumonia
  infections
• Silica and TB

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Problems With Exposure Assessment

• Most epidemiological studies (inherently) fail to
  gather information on
• Quantity of pollutant (exposure data)
• Characterization of mixtures
• Duration of exposure
• Most Epi studies utilize place of residence to
  determine duration of exposure what is the
  problem with this?
• cultural/ethical traits, living standards,
  occupations, existence of infectious agents, how
  long has the individual actually lived there?

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Population Susceptibility

• Populations at Risk?
• Aged or Very Young
• Cigarette Smokers
• Respiratory/Cardiovascular diseased
• Unlike our occupational exposure reference
  standards (ACGIH, NIOSH, OSHA), our air pollution
  standards are (supposedly) designed to protect
  the populations at risk

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When Epi Is Strong

• 1) There are a number of different populations in
  which a similar association is observed,
  including different kinds of people, locations,
  climate, and times of year
• 2) The incidence and/or severity of the health
  effect increases with increasing exposure and,
  conversely, decreases with decreasing exposure
  and
• 3) A plausible biological mechanism can be
  hypothesized for the observed association.

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When Epi Is Strong

• Epidemiological studies are strengthened when
  they are used in conjunction with controlled
  biological (toxicological) studies on humans or
  animals.
• Can you think of an example of such a study?
• Hiker-Health Study looking at ozone levels and
  increase/decrease in pulmonary function

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Toxicological Studies

• Typically Dose-Response Studies
• Acute Exposures high dose, short period
• Chronic Exposures low dose, long period
• Responses
• Death (LD50, LC50)
• Outward, physiological or pathological change
• Teratogenic, carcinogenic, gametotoxic or
  mutagenic effect
• Specific diseases

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Chronic versus Acute

• Why must acute and chronic studies be
  distinguished from one another?
• Because the symptoms produced by these 2 extremes
  of exposure usually bear no relationship to each
  other.
• Knowing the chronic effects of a chemical will
  not predict the effects of that same chemical on
  an acute exposure basis.

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Human Studies

• Strongest evidence of C-E/D-R relationships
• Most are limited to short term, acute exposures
• Long term exposures are expensive, may be
  irreversible, and carry huge ethical issues.
• Because of the severe limitations for carrying
  out human studies, we tend to rely on the less
  precise animal studies

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Animal Studies

• Animal studies present numerous limitations
• Sensitivity
• Longevity
• Ethical Considerations
• Extrapolation
• We can sacrifice animals for pathological
  analyses.
• We can look at both chronic and acute exposures

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Limitations of Animal Models

• Examples
• Methanol highly toxic to humans and other
  primates, but only causes ocular damage to
  humans.
• TOCP demyelenates nerve fibers in humans and
  chickens, but no other species
• Nitrobenzene converts hemoglobin to
  methemoglobin in humans, cats and dogs, but not
  monkeys, rats, and rabbits.

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Animal Studies

• Virtually all species absorb, metabolize, and
  excrete toxins in different ways.
• Finding the closes human to animal model is a
  significant challenge.
• Fortunately, the similarities of humans to other
  mammals are far more numerous than are the
  differences.
• Tox studies at the cellular level may be the most
  promising for the future.

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Occupational Exposures

• What do we know about the relative magnitude of
  toxics in the ambient air versus those found in
  the industrial environment?
• Since we rarely can study human exposures, it is
  nevertheless useful to look at retrospective
  studies of industrial exposures when trying to
  better understand air pollutants.

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Occupational Exposures

• In the absence of actual human exposure data,
  occupational exposures provide the best data we
  have on human dose-response
• Problems with using Occ Exp. Data
• Dont usually have same mix of chemicals
• Occupational exposures typically 40 hr work week
• Pop. of workers doesnt compare well to overall
  pop. in industry, what is the typical
  demographic of the worker?
• Age 18-65, male, healthy

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Impact of Pollutants on the Human

• Target Organs
• Direct respiratory tract
• Indirect pollutant enters blood systemic
  injury
• The principal target organs
• Respiratory tract
• Cardiovascular system
• Eyes and mucous membranes
• Skin

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Target Organ The Eyes

• Most prevalent reaction to air contaminants
• Typical irritation comes from
• Aldehydes (formaldehyde, glutaraldehyde)
• Photochemical oxidants (PAN)
• Eye irritation threshold by oxidants 0.1 to 0.15
  ppm
• Do you think that eye irritation should be
  categorized as an adverse health effect?

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Cardiovascular Effects

• The 2 common air pollutants that directly attach
  the cardiovascular system are lead and carbon
  monoxide
• Many other air pollutants indirectly attack the
  cardiovascular system. For example air
  pollutants that lead to respiratory disease (such
  as SO2, NOx, O3 etc) may cause cor pulmonale or
  right heart (ventricular) failure.

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Victim of Cor Pulmonale
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Respiratory System Effects

• Respiratory system is the principle organ for gas
  exchange in the body and therefore, receives the
  most direct exposure to air pollutants.
• The primary function of the respiratory system
  is?
• Supply O2, remove CO2
• Major units nasopharyngeal, tracheobronchial,
  and pulmonary systems

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Nasopharyngeal (upper airway)

• Aspects
• Nasal passages 2 cavities and septum lined
  with coarse hairs, winds and curves, large
  surface area, warm and moist
• Nasopharynx soft palate
• Oropharynx junction of trachea and esophagus
• Glottis vocal cords/larynx

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Nasopharyngeal System
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Tracheobronchial System

• Series of tubes and ducts which transport
  inspired air to lung tissue
• Aspects
• Trachea (largest tube)
• Bronchi Bronchial tubes (subdivides of trachea)
• Bronchioles
• 23 to 32 branches each generation is smaller in
  diameter
• Lining is ciliated cells interspersed with
  mucous-secreting cells

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Bronchi versus Bronchioles

• Bronchi larger airways, cartilage plates
  surrounded by muscles
• Bronchioles much smaller (less than 1 mm), no
  cartilage

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Tracheobronchial System
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The Pulmonary System

• Aspects
• Respiratory (terminal) bronchioles
• Alveolar ducts
• Alveoli
• A fully developed lung contains approximately 300
  million alveoli
• Inspiration and Expiration is accomplished by
  muscles of the chest and diaphragm

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Respiration

• During inspiration, air pressure in the alveoli
  decreases (what will this do?)
• During expiration, air pressure in the alveoli
  increases (what will this do?)

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Respiratory Defense Mechanisms

• Upper Respiratory Defense Mechanisms
• Large particles removed by the stiff, coarse
  hairs or impingement on the mucus layers of the
  winding air passages. Cilia sweep the mucus layer
  and entrapped particles toward the back of the
  mouth where they are swallowed or expectorated.
• Sneezing, coughing

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Defense Mechanisms

• Bronchi muscles constrict when irritant particle
  pollutants enter the airway. This reduces the
  amount of pollutant that can enter the airway.
  With the addition of the cough reflex, particles
  are removed.
• Mucociliary Escalator
• Branching of airways leading to impingement
• Phagocytes

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Mucociliary Escalator
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Phagocytes

• Phagocytes are large white cells that can engulf
  and digest foreign invaders.

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Air Pollution and Respiratory Disease

• Chronic Bronchitis
• Pulmonary Emphysema
• Lung Cancer
• Bronchial Asthma

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Chronic Bronchitis

• Inflammation of the membrane lining the bronchial
  airways
• May be caused by pathogenic infections or by
  respiratory irritants such as from cigarette
  smoke, industrial exposures, and ambient and
  indoor air pollution
• If bronchial inflammation occurs for more than 3
  months, we refer to it as Chronic Bronchitis

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Chronic Bronchitis

• Characteristics of the disease
• Persistent cough
• Excessive mucus or sputum production
• Destruction of cilia
• Thickening of bronchial epithelia
• DIFFICULTY BREATHING

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Obstructed Bronchi
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Implicated Air Pollutants

• Through epidemiological and toxicological
  studies, we believe that SO2 and Particulate
  Matter (PM) are the 2 pollutants most responsible
  for Chronic Bronchitis

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Pulmonary Emphysema

• Whereas C.B. is a disease of the upper
  respiratory system, P.E. is a disease of the deep
  lung, that is, the lung tissue where gas exchange
  occurs.

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Emphysema

• Disease of old age
• Characteristics
• Degeneration of the alveolar walls diminishing
  the available surface area for gas exchange
• Development of Pulmonary Hypertension
• Destruction of blood vessels
• Shortness of breath and difficulty in breathing
• Difficulty exhaling over-inflation of lungs,
  BARREL CHEST
• Animal tests implicate NO2

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Emphysema
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Finger Clubbing From Hypoxia
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Final 2000 data    Ten Leading Causes of Death
in the U.S.        Heart Disease 710,760
      Cancer 553,091       Stroke 167661
      Chronic Lower Respiratory Disease 122,009
      Accidents 97,900       Diabetes
69,301       Pneumonia/Influenza 65,313
      Alzheimer's Disease 49,558       Kidney
Diseases 37,251       Septicemia 31,224
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Lung Cancer

• Unrestrained cell growth which produces malignant
  tumors, destroying normal tissue
• Most metastasize and spread to various organs
  more so with lung cancer than others why is
  this?
• Approximately 92 mortality
• More typical with older individuals because it is
  a Latent Disease up to 30 years or more

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Lung Cancer

• Most common Bronchiogenic Lung Cancer
• Originates in the bronchial membrane and invades
  tissues of the bronchial tree
• Largest Cause of Lung Cancer?
• Cigarette Smoking - gt 130,000/yr
• Air Pollutants implicated in lung cancer
• PAHs such as benzo(a)pyrene
• Other pollutants might be Co-Carcinogens or
  Promoters

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Lung Cancer
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Bronchial Asthma

• Acute Respiratory Reaction - Characteristics
• Constriction of muscles (spasmodic) and swelling
  of the lining of the respiratory airways
• Excessive mucus production
• Increased resistance to air flow
• Shortness of breath and Chest tightness
• Cough
• B.A. is episodic
• SO2 and other A.P. gases or particulates
  implicated

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Bronchial Asthma