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 Main problems identified include

respiratory disorders, musculoskeletal problems, hearing loss Work-related infectious disease less

common

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

Hog dust Feed particles Fecal matter Bacteria, fungi

Endotoxin, peptidoglycan (?), mycotoxins (?)

Hair, skin particles Insect parts

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

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

Kelleys first paper summarized Get slide

Holness paper summarized

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. 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 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 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 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 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

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

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 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

The Venn diagram

Mucous Membrane Irritation Syndrome

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

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?

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 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 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 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 Quality

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

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

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

Respirators WPF = 16 WPF = 19

Powered-air Purifying Helmet WPF = 30 No resistance Cost ~$500

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

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 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 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 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 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

Influenza Swine influenza

can infect humans It is a variant of

Influenza A It is not known

how often this occurs

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 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

Carbon Monoxide Poisoning Released by

power washing equipment or heaters that are improperly vented

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