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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. Hog Confinement Facilities. Worker Health. There is a lot of evidence that workers have a variety of health risks

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respiratory disorders secondary to work in hog confinement barns

Respiratory Disorders Secondary to Work in Hog Confinement Barns

Susanna Von Essen M.D., M.P.H.

University of Nebraska Medical Center

worker health
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
why does worker health matter
Why Does Worker Health Matter?
  • Impact on people’s lives
  • Impact on productivity of a farming operation
  • Worker’s compensation claims costs
  • Health insurance costs
features of the environment that affect worker health
Features of the Environment that Affect Worker Health
  • Hog dust
    • Feed particles
    • Fecal matter
    • Bacteria, fungi
      • Endotoxin, peptidoglycan (?), mycotoxins (?)
    • Hair, skin particles
    • Insect parts
features of the environment that affect worker health1
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
features of the environment that affect the human airways
Features of the Environment that Affect the Human Airways
  • What correlates with a cross-shift drop in lung function (FEV1):
    • Total dust > 2.5 mg/m3
    • Ammonia > 7.0 ppm
    • Endotoxin > 0.1 mcg/m3 or 100 EU/m3
        • Reynolds et al, Am J Ind Med 29:33, 1996
pulmonary function in workers with airway disease symptoms
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
case history doug j
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
doug j summary
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)
asthma like syndrome
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
asthma like syndrome1
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 >10% cross- shift drop in FEV1
    • This predicts accelerated lung function loss
    • Normal lung diffusion capacity
asthma like syndrome2
Asthma-like Syndrome
  • Bronchoalveolar lavage shows an increase in neutrophils, macrophages, lymphocytes but not eosinophils,
  • Therefore, this is not occupational asthma
unanswered questions about the asthma like syndrome
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
hog farmer with asthma
Symptoms of asthma present before work in hog confinement

Moderate, reversible airway obstruction on spirometry

Hog Farmer with Asthma
asthma in swine confinement workers
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
asthma in swine confinement workers1
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
  • 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?
  • 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
evaluation of a worker with respiratory complaints
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
evaluation of a worker with respiratory complaints1
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
management of the asthma like syndrome and other airway disorders
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
assessment of indoor air quality1
Assessment of Indoor Air Quality
  • Ammonia is simple to measure
  • Measuring total dust and endotoxin requires industrial hygiene expertise
  • CO2 >1500 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
  • 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
  • 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
powered air purifying helmet
Powered-air Purifying Helmet
  • WPF = 30
  • No resistance
  • Cost ~$500
other respiratory systemic disorders associated with hog confinement
Other Respiratory/Systemic Disorders Associated with Hog Confinement
  • Poisoning by pit gases
  • Influenza
  • Organic dust toxic syndrome
  • Carbon monoxide poisoning
  • Latex Allergy (?)
death after poisoning by pit gases
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
causes of death after poisoning by pit gases
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
hydrogen sulfide poisoning
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
hydrogen sulfide poisoning1
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
niosh recommendations for manure pit entry
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
Swine influenza can infect humans

It is a variant of Influenza A

It is not known how often this occurs

organic dust toxic syndrome
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
organic dust toxic syndrome1
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
worker health program to prevent occupational respiratory illness
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