Occupational Asthma And Bronchitis

WHAT ARE OCCUPATIONAL ASTHMA AND BRONCHITIS?

If you get asthma or bronchitis from your workplace it is called "occupational asthma" or "occupational bronchitis". This definition sounds simple and straightforward but in reality the diagnosis of either condition is often very difficult. Generally, the following criteria must be met to diagnose occupational asthma or occupational bronchitis:

1) No pre-existing asthma or bronchitis before exposure at the workplace;

2) Some substance in the workplace environment (a chemical compound, or some type of dust or fume), usually inhaled, can be identified. The worker may not be able to name the actual substance, but he or she can usually identify a process or work activity that identify cough or shortness of breath;

3) The worker suffers cough and/or shortness of breath, and often has wheezing;

4) If the diagnosis is asthma, the worker will have hyper-reactive airways when tested in the pulmonary laboratory.

WHY IS IT DIFFICULT TO DIAGNOSE THESE CONDITIONS?

Despite the straightforward definitions, and the specific criteria listed above, the diagnosis of occupational asthma or bronchitis is often very difficult. First, there may be a several hour delay between inhaling the offending substance and onset of symptoms; delayed reactions are actually quite common. For example, the worker may be exposed to a substance while at work, but not start wheezing or feel breathless until later at home. As a result, connection between the workplace and symptoms may not be apparent, at least not right away.

Second, asthma is very common in the general population. A worker with pre-existing asthma may wheeze or have an asthma attack while at work, for a number of reasons: viral infection (including the common cold), heavy exertion, cold air or dust. An asthma attack, in a known asthmatic, from one of these stimuli would therefore not constitute occupational asthma. Instead, it would be non-occupational asthma that is made worse by something at work. Occupational asthma must be caused by the workplace. Often it is difficult to know if the worker has occupation-caused asthma, or non-occupation-related asthma that happens to flare up at the workplace.

Third, bronchitis is very common among cigarette smokers. Someone who smokes, and then later claims "bronchitis" from the workplace, will have a difficult time proving the cause is not from his own cigarettes.

Fourth, despite a physician's best efforts at making a correct diagnosis, the diagnosis of occupational lung disease will likely be questioned in some fashion: by the employer if deemed occupational, or by the patient if deemed non-occupational. In many cases the diagnosis will end up being argued by lawyers and doctors on both sides of the issue.

WHY IS THE DIAGNOSIS OF OCCUPATIONAL ASTHMA OR BRONCHITIS OFTEN CONTESTED?

The diagnosis is often contested because the employer, either directly or indirectly, will be asked to pay for it. In all cases a disease that is truly caused by the job is compensable. Even when payment comes from the state Bureau of Workers' Compensation (BWC) no-fault fund, the employer experiences an increase in premiums he must pay into the state fund. Compensation to the worker might be in the form of a percentage of wages if he can no longer work, or a salary while he retrains for another job, or just medical expenses associated with treating the asthma or bronchitis.

Medically, asthma and bronchitis are treated the same whether or not they are caused by the job. Since the same tests are done, and the same drugs are used, it doesn't matter medically what the cause is (except that the patient with occupational asthma must be removed from the offending environment). Legally, financially and emotionally, however, it matters a great deal. Typically, when occupational lung disease is diagnosed, the employer will disagree in some fashion. The employer may argue that the asthma preceded the job, or that it was not caused by the workplace, or that the cause is cigarette smoking. Argument, of course, means lawyers; the employee will hire lawyers and other experts, and a resolution will almost certainly be delayed.

For all these reasons a seemingly straightforward case of occupational asthma or bronchitis can become extraordinarily complex. Physicians can (and do) land on both sides of the issue: is the patient's problem compensable or not?

IS THERE A SPECIFIC DIFFERENCE BETWEEN OCCUPATIONAL ASTHMA AND OCCUPATIONAL BRONCHITIS?

Unfortunately, many physicians and non-physicians alike get "hung up" on terminology. A patient may go to several doctors for a breathing problem, and one doctor will call it "asthma," another "bronchitis," and a third "asthmatic bronchitis." Labels attached to the worker sometimes cloud the central issue in any claim: does the patient have airway disease caused by his occupation?

Viewed in this manner it is not so important what label is applied. However, for medical and scientific purposes there are differences between asthma and bronchitis, as discussed in the preceding two chapters. "Asthma" denotes a hyper-sensitive airway reaction to something inhaled, with periods of normal air flow in between. "Bronchitis" denotes a more or less daily coughing up of phlegm, without the hypersensitivity response. Both conditions may or may not arise from the workplace.

When patients have continuous coughing of phlegm and hyper-sensitive airway responses, I call that "asthmatic bronchitis." However, not all physicians use terms the same way; some physicians might call the same condition "asthma" and others just "bronchitis." Everyone reviewing an occupational claim should remember the central question: does the patient have airway disease due to workplace exposure? Or, asked another way: Would the patient not have the disease without the workplace exposure?

WHAT ARE THE TYPES OF OCCUPATIONAL ASTHMA?

There are several ways to classify occupational asthma, none of them wholly satisfactory. One classification in particular seems to be useful: allergic vs. non-allergic or irritant asthma.

So called allergic asthma is actually the classical definition of occupational asthma. In allergic asthma the inhaled material "sensitizes" the worker's airways so that later exposures to the same substance bring on cough and wheezing. Allergic asthma affects only some of the exposed people and not others.

Non-allergic asthma is also termed irritant asthma, and may actually be more common than the classical allergic asthma. Irritants such as volatile acids can cause wheezing and shortness of breath in anyone who inhales them. A severe form of irritant-induced asthma is called reactive airways disease syndrome, or RADS.

WHAT IS RADS?

RADS is reactive airways disease syndrome, a condition only characterized in the 1980's. In RADS the worker is exposed one time only to a high level of an airway irritant, such as hydrochloric acid, chlorine, acetic acid, ammonia fumes. The result is a very severe, acute respiratory illness, often leading to emergency care and/or hospitalization, and from which the patient eventually recovers. Initially the patient has shortness of breath, wheezing, cough and much respiratory distress. Gradually the symptoms improve, but the sequelae of that one time intense exposure is continued "reactive airways," i.e., asthma that flare-ups around dust and fumes of almost any type. Thus, an intense, one-time exposure to an airway irritant can lead to asthma. To make this diagnosis the patient cannot have had asthma previously. Specific criteria for RADS are listed below.

Criteria for the Diagnosis of Reactive Airways Dysfunction Syndrome

1. Absence of preceding respiratory complaints is documented.

2. The onset of symptoms occurred after a single specific exposure incident or accident.

3. The exposure was to a gas, smoke, fume, or vapor that was present in very high concentrations and had irritant qualities.

4. The onset of symptoms occurred within 24 h after the exposure and persisted for at least 3 months.

5. Symptoms simulated asthma, with cough, wheezing, and dyspnea predominating.

6. Pulmonary function tests may show airflow obstruction.

7. Methacholine challenge testing was positive.

8. Other types of pulmonary disease were ruled out.

ARE THERE ANY MEDICAL DIFFERENCES BETWEEN OCCUPATIONAL AND NON-OCCUPATIONAL ASTHMA AND BRONCHITIS?

No. Asthma is a condition of hypersensitive airways that can come about from a variety of causes. Most non-occupational asthma, in fact, is of unknown cause. When asthma occurs from the workplace the offending agent can often (but not always) be identified. However, apart from removing the worker from the environment, treatment does not differ from non-occupational asthma. The same is true for bronchitis: treatment is the same.

THEN WHAT ARE THE DIFFERENCES BETWEEN OCCUPATIONAL ASTHMA/BRONCHITIS AND NON-OCCUPATIONAL ASTHMA/ BRONCHITIS?

Perhaps the most important difference is how the occupational condition affects the worker's livelihood. A worker who contracts asthma or bronchitis on the job should no longer work at that job; he or she must avoid the offending agent or environment. While this sounds simple, in reality it almost never is. Most affected workers are unable to just pick up and find another job. Yet there may be no other area in the company or factory in which to work. The sad result is a "Hobson's choice": give up a good job and risk economic hardship in order to avoid continued lung damage, or continue working and risk further lung damage that, ultimately, may make it impossible to work anywhere.

Unfortunately, masks and ventilators are almost never effective in preventing inhalation of offending substances. In no case should masks or other "ventilator devices" be relied upon to protect the worker diagnosed with occupational asthma or bronchitis. The worker must be removed from the offending environment.

The second major difference between occupational and non-occupational airway disease is the potential argument over diagnosis. No one questions the physician who diagnoses "asthma" or "bronchitis" when it is unrelated to the job. Many people will question the diagnosis of occupational asthma or occupational bronchitis. At the least, the claim will come under intense scrutiny by administrators before the patient is compensated, a process that takes at best several months, and at worst several years.

A broken leg is easy to diagnose as job-related or not. A chronic condition like asthma, which affects so many people in a wide variety of circumstances, is much more difficult to diagnose as job-related. Major areas of disagreement involve the nature and dose of the inhaled material that caused the symptoms, the severity of the patient's condition, the importance of the worker's smoking history (if any) and, often, the question of pre-existing asthma. It is not unusual for these issues to be resolved only by a trial with jury.

HOW MANY DIFFERENT SUBSTANCES OR AGENTS CAN CAUSE OCCUPATIONAL ASTHMA?

The list grows all the time. Currently about 200 substances or agents are known to cause occupational asthma. However, not being exposed to one of the "known" agents does not rule out occupational asthma. Not identifying the specific culprit does not exclude the diagnosis of occupational asthma.

Below is a partial list of known causes of occupational asthma. They are divided into three groups of materials: animal, vegetable and chemical.