The Environmental Exposure History

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The Environmental Exposure History
George L. Delclos, M.D., M.P.H.Associate
Professor of Occupational Medicine
University of Texas School of Public Health
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Case Study
In 1974, a plant doctor in Louisville diagnosed 3
cases of a very rare form of liver cancer
(hemangiosarcoma). All 3 persons with this tumor
worked in the same factory, where vinyl chloride
monomer was used to make PVC. Nationwide there
were only a total of 25 cases. The doctor
suspected there could be a relationship between
the work environment and the cancer. This astute
observation was later confirmed by more detailed
studies.
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JUST THE FACTS!

• Historically, clusters of possible new
  environmental disease are identified more from
  citizen reports than from surveillance systems
• There are notable examples of new environmental
  disease being first identified from a cluster
• Public health agencies have the obligation to
  promptly respond to community health concerns
• BUT.
• Public health agency investigations of clusters
  most often do not lead to meaningful outcomes

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CDC Guidelines for Investigation of Clusters
(MMWR, 1990)

• STAGE 1 Initial contact and response
• STAGE 2 Assessment
• Preliminary evaluation
• Case evaluation
• Occurrence evaluation
• STAGE 3 Major feasibility study
• STAGE 4 Etiologic (causal) epidemiological
  investigation

Balancing the science with the social dimensions
of the problem
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Epidemiology Basic Concepts
1. Human disease doesnt just happen. 2. There
are causal and protective/preventive factors
identifiable through systematic investigation of
different populations, and subgroups within
a population, in different places and/or
at different times.
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What is epidemiology?
The study of the distribution and determinants of
disease frequency in human populations. or the
relationship between exposure and disease
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Case Study
A 10 year old previously healthy boy comes to you
with a 3 week history of headaches, mild nausea
and no vomiting. The headache is dull, and not
relieved by acetaminophen, lasting anywhere from
30 minutes to all day. Last Sunday, shortly
after awakening, he woke up with the headache.
His physical examination and routine blood tests
are normal.
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JUST THE FACTS!

• Most environmental diseases present either as
  common medical problems or have nonspecific
  symptoms.
• It is the ETIOLOGY (cause) that distinguishes a
  disorder as an occupational/environmental
  illness.
• Most persons with environmental disease present
  initially to non-specialists.
• If an exposure history is not taken, the cause
  may be missed, the exposure can continue, and
  treatment may be inappropriate.

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When should you suspect an environmental disease?
In academic primary care practices

• 76 of charts fail to mention patient
  occupation
• Only 2 of charts have information on
  exposures, duration of present employment,
  hobbies and past jobs.
  
• Adolescents are rarely questioned about work
  exposures

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When should you suspect an environmental disease?
You dont have to be a toxicologist or
epidemiologist to diagnose an occupational or
environmental disease!

• JUST
• Ask the right questions
• Know where to find information
• Form a referral network

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When should you suspect an environmental disease?
Information sources

• Material safety data sheets (MSDS)
• Consultants in same or other disciplines
• NIOSH Education and Research Centers (ERCs)
• Association of Occupational and Environmental
  Clinics (AOEC)
• Certified Poison Centers
• Online and other computerized data sources
• Government resources and state/local health
  departments

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When should you suspect an environmental disease?
Use the same criteria you use when diagnosing
other medical problems

• History (onset and temporal patterns of
  symptoms, precipitating and relieving
  factors, etc.)
• Physical examination
• Laboratory results
• Sound clinical judgment
• Appropriate referrals

Remember Common things are common.
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What suggests an environmental or occupational
cause?

• Is the condition biologically plausible (does
  it make sense)?
• Are the symptoms consistent with the diagnosis?
• Are the signs consistent with the diagnosis?
• Is the temporal relationship of exposure and
  disease clear?
• Do fellow workers or neighbors with similar
  exposure have similar problems?
• Was (is) there a confirmed exposure?
• Is epidemiologic evidence available to support
  a cause and effect relationship?

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• Which organ systems are likely to be affected?
• What kind of exposures should you look for?
• What are the main components of an exposure
  history?
• Examples of specific exposures

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Which organ systems are likely to be affected?
The respiratory system

• A high visibility target organ
• Both a target and portal of entry
• Morbidity is high
• gt 100 toxicants known to cause asthma
  many more unknown

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Which organ systems are likely to be affected?
The skin

• Contact dermatitis (irritant and allergic)
  account for gt90 of occupational skin
  disease
• Pigment disorders, acne/folliculitis,
  infections and skin tumors make up the rest

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Which organ systems are likely to be affected?
The liver

• Over 100 chemicals are known to be liver toxins
• The main routes of exposure are inhalation and
  ingestion. Rarely, skin absorption (e.g.,
  TNT).
• Acute liver disease (toxic hepatitis) is more
  common and easier to detect than chronic
  disease.
• Alcohol and viral illness are major confounders.

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Which organ systems are likely to be affected?
The kidneys

• Over 4000 new cases of renal disease of
  unknown cause are diagnosed every year
• Organic solvents and heavy metals are just 2
  types of toxicants that can affect renal
  function

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Which organ systems are likely to be affected?
The nervous system

• Neurotoxins can cause peripheral neuropathy,
  parkinsonism,
• balance problems, seizures or even death
• Central neurotoxic effects may be misdiagnosed
  as personality disorders or depression

The reproductive system

• 200,000 infants are born every year with some
  type of birth defect. In most cases, the
  cause is unknown

The cardiovascular and hemotologic systems

• New cardiovascular disease, as well as
  worsening of prior cardiovascular disease,
  can occur as a result of exposure to noise,
  carbon monoxide, tobacco smoke, etc.
• Bone marrow changes, including leukemia, have
  been associated with certain environmental
  exposures

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• Which organ systems are likely to be affected?
• What kind of exposures should you look for?
• What are the main components of an exposure
  history?
• Examples of specific exposures

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What kind of exposures should I look for?
Indoor Air Pollutants

• Tobacco smoke
• Wood stoves/gas ranges (gases, CO, NOx,
  particulates, hydrocarbons)
• Building materials
• Asbestos
• Radon

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What kind of exposures should I look for?
Common Household Products

• In 1987, EPA found 12 common organic
  pollutants at levels 12-15 times higher in indoor
  air than in outdoor air from use of
  household products
• Chlorinated hydrocarbons, solvents and various
  respiratory irritants are commonly found in
  most homes

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What kind of exposures should I look for?
Pesticides and Lawn Products

• 2.6 billion pounds of these products are used
  each year
• There are over 34,000 available preparations of
  insecticides, herbicides and fungicides with
  over 1400 active ingredients
• Main routes of exposure are through skin,
  inhalation or ingestion
• Children are especially prone to hazardous
  exposures
• Do your patients know what to do in case of
  accidental poisoning?

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What kind of exposures should I look for?
Lead Products and Waste

• Although currently banned, millions of homes
  still contain significant amounts of lead paint
  (57,000,000 housing units)
• Other sources drinking water, poorly fired
  pottery,home remedies, soil, workclothes, leaded
  gas
• Main routes of exposure inhalation, ingestion
• Children are especially susceptible (10,000,000
  children, including 400,000 fetuses)
• Over 3,000,000 U.S. workers potentially exposed,
  100 different occupations

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What kind of exposures should I look for?
Recreational Hazards

• Fishing and swimming (contaminated
  waters?)
• Wooden playground structures (non-sealed
  wood preservatives?)
• Play sands and clays (asbestos-like
  fibers?)
• Arts and crafts materials (silica,
  solvents, lead, cadmium?)

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What kind of exposures should I look for?
Water Supply

• Both public water supplies and private wells
  can be a source of toxic exposures
• Can be contaminated with industrial solvents,
  heavy metals, pesticides, fertilizers, or
  infectious organisms

Soil Contamination

• Can be contaminated with lead, dioxin, or
  pesticides
• Some toxins may last for years in soil
• Children lt6 yrs. of age are especially prone

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• Which organ systems are likely to be affected?
• What kind of exposures should you look for?
• What are the main components of an exposure
  history?
• Examples of specific exposures

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The Exposure History
Think I PREPARE
I - Investigate potential exposures P
- Present Work R - Residence E -
Environmental Concerns P - Past Work A -
Activities R - Referrals and Resources E -
Educate
Source ATSDR, 2001
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Case Study
A 10 year old previously healthy boy comes to you
with a 3 week history of headaches, mild nausea
and no vomiting. The headache is dull, and not
relieved by acetaminophen, lasting anywhere from
30 minutes to all day. Last Sunday, shortly
after awakening, he woke up with the headache.
His physical examination and routine blood tests
are normal.
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The Exposure History
Scenario 1 Your patient has always attended the
same elementary school and has lived in the same
house since birth.
Exposure Survey reveals

• My mommy is also having a lot of headaches
• My headaches seem to get better at school or
  when Im playing outdoors. Weekends are the
  worst, especially when I have a lot of homework
  to do. Ive been sick every weekend for the past
  month.

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The Exposure History
Scenario 2
Environmental History reveals

• We live a couple of miles from an abandoned
  dump. My headaches are worse when I ride
  my bicycle near the dump.

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The Bottom Line

• An exposure history should be taken on EVERY
  patient
• in order to
• Identify current or past exposures
• Reduce or eliminate current exposures
• Reduce adverse health effects

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• Which organ systems are likely to be affected?
• What kind of exposures should you look for?
• What are the main components of an exposure
  history?
• Examples of specific exposures

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Classification of Asbestos-related Diseases

• NON MALIGNANT
• Pleural
• Parenchymal
• MALIGNANT
• Pleural
• Parenchymal

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Asbestos-Associated Diseases
Pleural plaques
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Asbestos-Associated Diseases
DIFFUSE PLEURAL THICKENING
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Asbestos-Associated Diseases
ASBESTOSIS
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Asbestos-Associated Diseases
LUNG CANCER
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Asbestos-Associated Diseases
MESOTHELIOMA
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Asbestos-Associated Diseases
Latency periods(Years since 1st exposure)
Pleural thickening 15 yrs. Pleural effusion
lt 10 yrs. Asbestosis 15-20
yrs. Lung cancer 20-30
yrs. Mesothelioma 35-40 yrs.
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Solvent Exposures

• Solvent a substance (usually a liquid) that
  dissolves another substance
• Over 30,000 different solvents.
• Important classification characteristics
• Solubility (lipid versus water, or both)
• Flammability and explosiveness
• Volatility
• Chemical structure
• Basic aliphatic, alicyclic and aromatic
• Functional groups halogens, alcohols, ketones,
  glycols, esters, ethers, carboxylic acids,
  amines, amides

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Solvent Exposures

• Main routes of exposure inhalation, dermal
  (varying degree)
• Distribution preferentially to lipid-rich
  tissues (nervous system, adipose tissue, liver)
  and organs with large blood flows (cardiac and
  skeletal muscle)
• Metabolism varies tremendously from solvent to
  solvent.
• Excretion urine (unchanged or metabolites),
  exhalation
• Health Effects Distinguish acute versus
  chronic exposures. Focus on target organs.
• Use your MSDSs and general toxicology texts a
  lot is known about solvents!

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Vinyl Chloride (Chloroethene)

• Distinguish monomer (vinyl chloride) from
  polymer (PVC)
• Risk
• Occupational gt Environmental
• PVC polymerization gt PVC fabrication
• Inhalation is the main route of exposure
• Metabolizes to chloroethylene oxide, which can
  bind to RNA and DNA (? responsible for
  carcinogenicity)
• Target organs CNS, respiratory, liver,
  circulatory, ?reproductive

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Vinyl Chloride (Chloroethene)

• Acute effects
• Respiratory tract irritation
• CNS depression
• Chronic effects
• Acro-osteolysis (terminal phalanges of the
  fingers)
• Raynauds phenomenon
• Skin nodules and thickening
• Hepatosplenomegaly, hepatic fibrosis, liver
  dysfunction
• Hepatic angiosarcoma
• ? reproductive effects (male workers)

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Ethylene Dibromide (1,2-Dibromoethane)

• A manufactured chemical (pesticide, gasoline
  additive, wood preservative)
• Environmental exposures may be important. Main
  sources are contaminated water, contaminated
  workplace air, playing in contaminated soil.
• Routes of exposure inhalation, ingestion,
  dermal
• Health effects
• Oral and GI inflammation, blistering and gastric
  ulcers if large amounts are swallowed
• CNS depression and collapse (high-level
  exposures)
• ? reproductive effects in men (damaged sperm)
• Uncertain cancer potential

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Thank you!