Respiratory Disorders Secondary to Work in Hog Confinement Barns

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Respiratory Disorders Secondary to Work in Hog
Confinement Barns

• Susanna Von Essen M.D., M.P.H.
• University of Nebraska Medical Center

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Hog Confinement Facilities
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Worker Health

• There is a lot of evidence that workers have a
  variety of health risks
• Main problems identified include respiratory
  disorders, musculoskeletal problems, hearing loss
• Work-related infectious disease less common

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Why Does Worker Health Matter?

• Impact on peoples lives
• Impact on productivity of a farming operation
• Workers compensation claims costs
• Health insurance costs

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Features of the Environment that Affect Worker
Health

• Hog dust
• Feed particles
• Fecal matter
• Bacteria, fungi
• Endotoxin, peptidoglycan (?), mycotoxins (?)
• Hair, skin particles
• Insect parts

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Features of the Environment that Affect Worker
Health

• Gases
• 138 have been identified, only a few linked to
  worker health problems
• Ammonia
• Hydrogen sulfide
• Carbon monoxide
• Methane
• Carbon dioxide

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Features of the Environment that Affect the Human
Airways

• What correlates with a cross-shift drop in lung
  function (FEV1)
• Total dust gt 2.5 mg/m3
• Ammonia gt 7.0 ppm
• Endotoxin gt 0.1 mcg/m3 or 100 EU/m3
• Reynolds et al, Am J Ind Med 2933, 1996

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Kelleys first paper summarized

• Get slide

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Holness paper summarized
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Pulmonary Function in Workers with Airway Disease
Symptoms

• Spirometry often normal despite cough, chest
  tightness, shortness of breath on exertion
• Some workers will have mild airway obstruction
• See a cross-shift decline in FEV1
• Is associated with elevated dust, ammonia levels
• This predicts accelerated loss of lung function
• It is unclear if this can result in severe airway
  obstruction

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Case history Doug J.

• 40 yo swine confinement facility manager with 15
  years of work experience who complains of cough,
  chest tightness and shortness of breath with
  exertion when he is working.
• Life-long nonsmoker, no history of asthma

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Doug J. Summary

• This picture is most consistent with the
  asthma-like syndrome
• Management of this problem
• Wear a respirator
• Improve air quality in the barns
• Inhalers
• Consider changing professions (this man is now a
  teacher and his symptoms have persisted to some
  degree)

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Asthma-like Syndrome

• Cough, chest tightness, shortness of breath on
  exertion, work-related wheezing
• Symptoms more common if exposed least 2 hours per
  day for at least 6 years but can be seen within
  weeks or months of starting work
• May also have symptoms at night, daytime symptoms
  when away from work
• Better after days or weeks away from work

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Asthma-like Syndrome

• Chest X-ray normal
• Spirometry may show mild (5-18 below normal)
  airway obstruction but is often within normal
  limits
• Will see a gt10 cross- shift drop in FEV1
• This predicts accelerated lung function loss
• Normal lung diffusion capacity

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Asthma-like Syndrome

• Bronchoalveolar lavage shows an increase in
  neutrophils, macrophages, lymphocytes but not
  eosinophils,
• Therefore, this is not occupational asthma

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Unanswered Questions about the Asthma-like
Syndrome

• Does it lead to moderate or severe airway
  obstruction?
• Only anecdotal information available
• Prospective, population-based studies needed
• In my experience, this outcome is uncommon unless
  the worker also smokes cigarettes
• Hog barn, tobacco effects are additive
• Little is known about the worker exposed 40
  hours per week

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Hog Farmer with Asthma

• Symptoms of asthma present before work in hog
  confinement
• Moderate, reversible airway obstruction on
  spirometry

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Asthma in Swine Confinement Workers

• Asthma is an inflammatory disorder with
  reversible airway obstruction, often with allergy
  to specific antigens
• 5-10 of the population is asthmatic
• Asthma is not more common in farmers
• Serologic evidence of sensitization to pig
  proteins is common but does not correlate with
  respiratory complaints

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Asthma in Swine Confinement Workers

• Persons with pre-existing asthma are likely to
  have more difficulty with their disease as a
  result of the exposure to dust and ammonia
• Work in this environment contributes to
  exacerbations of asthma
• Compliance with medication, respiratory
  protection important

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The Venn diagram
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Mucous Membrane Irritation Syndrome

• Complaints of nasal, eye and throat irritation in
  hog confinement workers are very common

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Bronchitis

• Acute bronchitis most clinicians describe it as
  being an acute illness associated with cough
  productive of sputum.
• Appears to be work-associated in some swine
  confinement workers.
• Unanswered question do repeated episodes of
  acute bronchitis cause chronic bronchitis?

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Bronchitis

• WHO definition for chronic bronchitis daily
  sputum production for at least 3 months of the
  year for at least 2 years
• May or may not be associated with airway
  obstruction measured by spirometry
• There is no evidence that this progresses to
  severe disease unless the worker also smokes

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Evaluation of a Worker with Respiratory Complaints

• A detailed work history should be taken
• Other jobs/exposures including hobbies
• Factors that exacerbate or improve symptoms
• Use of respirators
• Lung disease history
• Must ask about smoking, pre-existing asthma,
  COPD, other lung disease

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Evaluation of a Worker with Respiratory Complaints

• Physical examination
• Usually normal rarely hear wheezing
• Spirometry
• Easily performed using a portable spirometer
• Also useful as part of pre-placement exam
• Chest x-ray
• Should be done if history suggests other
  diagnoses, such as lung cancer, heart failure

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Management of the Asthma-like Syndrome and Other
Airway Disorders

• Improve indoor air quality
• Choosing a waste management system that minimizes
  ammonia, dust from manure
• Frequent pressure washing, flushing or pumping of
  manure pit contents
• Adding fat to feed, choosing a feed and delivery
  system that minimizes dust
• Monitoring ammonia levels, air flow
• Consider using an oil mist to control dust
• Medications

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Assessment of Indoor Air Quality
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Assessment of Indoor Air Quality

• Ammonia is simple to measure
• Measuring total dust and endotoxin requires
  industrial hygiene expertise
• CO2 gt1500 ppm is a surrogate measure of poor air
  quality
• CO2 is easier to quantify
• It may be difficult to bring CO2 lower than 3000
  in cold weather

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Respirators

• 2-strap disposable respirator
• Considered most comfortable by workers
• Removes about 75 of dust
• Costs about 2
• Half-face mask respirator with disposable filters
  for dust, ammonia
• Costs about 20

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Respirators

• Rated by worker protection factor (WPF)
• Many are difficult to wear for persons with
  severe lung disease because they must breathe
  against resistance
• Difficult to wear if worker suffers from
  claustrophobia
• 1/3 of workers wear them in the hog barn

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Respirators

• WPF 16

• WPF 19

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Powered-air Purifying Helmet

• WPF 30
• No resistance
• Cost 500

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Other Respiratory/Systemic Disorders Associated
with Hog Confinement

• Poisoning by pit gases
• Influenza
• Organic dust toxic syndrome
• Carbon monoxide poisoning
• Latex Allergy (?)

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Death After Poisoning by Pit Gases

• Often involves multiple fatalities because rescue
  is attempted without proper procedures or use of
  appropriate safety equipment
• The safety program for the farm should include a
  plan for rescue should a worker be overcome by
  pit gases

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Causes of Death After Poisoning by
Pit Gases

• Toxicity from exposure to hydrogen sulfide
• Asphyxiation secondary to displacement of oxygen
  by gases
• The air normally has 21 oxygen, 19.5 is the
  minimum level for safe entry
• Disabling of worker, ? drowning or aspiration of
  manure ? pneumonia, acute lung injury

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Hydrogen Sulfide Poisoning

• Hydrogen sulfide is heavier than air
• Levels highest just above the floor, in gutters,
  in the air space above the pit contents and in
  holding tanks
• High levels most common in hot weather and after
  pit is agitated
• OSHA standard for confined space entry should be
  followed if pit or tank is entered

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Hydrogen Sulfide Poisoning

• Levels greater than 700 ppm are likely to be
  fatal to humans
• Binds to cytochrome oxidase system, blocking cell
  metabolism
• The human olfactory system is overwhelmed at 50
  ppm
• rotten egg smell of hydrogen sulfide will not
  be detected when levels are high

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NIOSH Recommendations for Manure Pit Entry

• All manure pits should be ventilated with
  explosion-proof equipment
• Methane and hydrogen sulfide can be explosive
• The atmosphere within the pit should be tested
  before entry
• A positive-pressure, self-contained breathing
  apparatus (SCBA) should be used if oxygen levels
  low or hydrogen sulfide levels high

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Influenza

• Swine influenza can infect humans
• It is a variant of Influenza A
• It is not known how often this occurs

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Organic Dust Toxic Syndrome

• ODTS is a systemic illness experienced after
  exposure to large quantities of organic dust by
  inhalation
• Seen after work in swine confinement barns, after
  cleaning grain bins, unloading silos
• Exposure to endotoxin is the cause

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Organic Dust Toxic Syndrome

• Symptoms begin 4-12 hours after heavy organic
  dust exposure
• Consist of headache, myalgias, fatigue, fever,
  occasionally also cough
• Often confused with influenza
• Treatment is aspirin or acetaminophen for fever,
  rest
• May predispose to cough, bronchitis

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Carbon Monoxide Poisoning

• Released by power washing equipment or heaters
  that are improperly vented

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Worker Health Program to Prevent Occupational
Respiratory Illness

• Pre-placement assessment
• Pulmonary disease history and spirometry
• Monitoring of respiratory symptoms on a yearly
  basis by questionnaire
• Spirometry, medical assessment if symptoms
  develop
• Monitoring of air quality in the hog barns
• Ammonia, carbon dioxide
• Routine use of respirators