Occupational Asthma Seminar Summary
February 2, 2001
Portland Conference Center
Portland, Oregon
Occupational asthma is a serious problem that affects
many Oregonians. Experts were assembled on this problem and this symposium provided
useful information for employees and employers on its detection, impacts and prevention.
Background
Occupational asthma is the leading work-related lung disease in
the United States. It causes significant morbidity among the working population.
It has a huge socioeconomic impact on both workers and their families, and the
organizations that employ them. It is also preventable. For these reasons, occupational
asthma is an issue that deserves increased attention.
Between 5 and 10% of adults in the United States have asthma. Of these, it
is estimated that at least 15% are either caused by or aggravated by the workplace.
In the United States, the systems for recognizing and counting cases of occupational
asthma are extremely poor. The cases that are identified are considered the ïtip
of the icebergÍ, with many, many more cases going unrecognized.
In Oregon, data indicates that 7.7% of adults have active asthma. A study is
currently underway to identify more precisely the amount of adult-onset asthma
that is associated with exposures in the workplace. Preliminary data indicates
that the number of cases related to work is actually closer to 30% of adult-onset
asthma cases.
There are three factors needed for occupational asthma to occur. First is an
agent capable of causing asthma. Over 250 agents have been identified as causing
asthma. These are a broad spectrum of natural and synthetic compounds. With the
constant introduction of new products and materials, this number can be expected
to rise. Second, there must be sufficient exposure to the agent to actually cause
the disease. Finally, a person must be susceptible to developing asthma from the
exposure to the agent.
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Occupational asthma in the Pacific Northwest
Occupational asthma is not limited to a few occupations or industries. For
example, bakers have developed asthma from flour dust, painters from isocyanate
paints, health care workers from powdered latex gloves, and lab technicians from
handling animals. Here in the Pacific Northwest, some of the common industries
with potential for exposure to asthma causing agents are aluminum refining, hard
metals processing (tungsten carbide, cobalt, and nickel), wood products (particularly
western red cedar), automotive spray finishing, grain processing, and shell fish
processing.
Diagnosis
Diagnosing occupational asthma can be a challenge. The health care provider
must associate the disease with the workplace. A detailed occupational history
must be taken. The pattern of symptoms must be evaluated. It is very common for
symptoms to occur only in the evenings of workdays, indicating a delayed response.
Other pulmonary illnesses must be ruled out. An exposure assessment is needed
to determine what the person is exposed to at work. A case was described in which
the Material Safety Data Sheet for the product the patient handled stated it contained
no hazardous components. A phone call by the physician to the manufacturer revealed
this was not the case - it contained a material well known to cause asthma. If
it is available, exposure data for the patient or people doing similar tasks with
the same product can be extremely useful. However, good exposure measurements
can be difficult to obtain. Identifying the specific causative agent may not be
possible, particularly if it is a by-product of a process. If it is identified,
accurately measuring the agent may be difficult and costly.
Once an exposure measurement is obtained, there may not be an exposure limit
to compare it to. Or the exposure limits published by various organizations may
vary widely. The Occupational Safety and Health Administration has permissible
exposure limits for many chemicals, but they may not be protective enough for
someone who already has asthma. Finally, a chemical may have no recommended exposure
limits. In that case, having an accurate measurement may not be particularly useful,
except for comparison to other jobs or tasks.
Objective medical tests are available to diagnose asthma, but these are often
not used. In the state of Washington, only 57% of workerÍs compensation claims
for new onset asthma had objective testing to diagnose asthma, and only 14% of
cases had objective testing to attribute the asthma to the workplace. To add to
the challenge, there is no clear, universally accepted definition of occupational
asthma.
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Workers compensation claims
An additional aspect of this disease is that Workers Compensation claims are
rarely made. Of those claims that are made, the denial rate is high. There are
many reasons for this, including a failure to recognize that the disease is associated
with work, inadequate objective medical tests to prove the disease is caused by
work, or simply a fear on the part of the worker that filing a claim will jeopardize
his or her employment. There is work aggravated asthma and there is new onset
asthma. It is believed that the majority of people with occupational asthma have
pre-existing asthma that is aggravated by work. These cases often go unrecognized
as occupational asthma for a variety of reasons - objective tests to identify
the cause are not done, it is not recognized by either the provider or the patient
as related to work, and workers compensation claims are not made. New onset asthma
can be of two types. There can be a latency period between the time of initial
exposure and the development of asthma. Occupational asthma can also occur without
latency - typically after a significant, one-time exposure.
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Managing the disease in the workplace
For those people with asthma, efforts must be made to manage the disease. This
typically includes medication, patient education, and control of non-occupational
triggers. For those with occupational asthma, the workplace exposure needs to
be addressed. If the asthma is induced by a sensitizer, it is prudent to avoid
any further exposure to the agent. In the past, this has meant that a worker would
be automatically told to leave the job, often with devastating consequences. This
does not have to be the only option. One case was presented in which the employer
made changes so that the causative agent was used only one day a week, rather
than every day. On the day it was used, the patient wore a powered air purifying
respirator to prevent exposure. It was a successful solution - the employer retained
a trained employee, and the patient kept a job she did was desperate to keep.
If the asthma is due to irritant exposure, it is key to reduce exposure to as
low as possible. Workers with this type of asthma can tolerate low level exposure
to the causative agent. As with sensitzer-induced asthma, an employee may be told
to leave a job. However, there are usually relatively simple changes that can
be made to reduce exposures to a level that will not put the worker at risk for
further breathing problems.
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Workplace modification and prevention
Cases of occupational asthma should be viewed as sentinel events that automatically
trigger further action in the workplace. Assume that other people with similar
exposures are at similar risk. To prevent further cases, modifications in the
workplace can control exposures. Despite an initial investment by the employer,
this is actually the most cost-effective way to deal with this issue. Depending
on the situation, the change can be quick and inexpensive. For example, purchase
a product in a ready-to-use form so the worker does not have to pour a concentrate
that results in exposures to the chemical vapor.
Primary prevention is the best way to control occupational asthma. This focuses
on preventing cases from ever developing. It is done by performing a risk assessment
of the task to anticipate exposure to asthma causing agents. Reviewing the contents
of the products, how the products are used, the potential by-products, and actually
observing the task are the next steps. A written or verbal description of how
something is done may leave out some very important details, so observation is
essential. Air samples may be collected to determine actual exposures, if, given
their limitations, they are appropriate. Once the risk has been assessed, it can
be managed.
Some workplace interventions are extremely simple provided the right questions
are asked: Is the task really necessary? Can the product be substituted with a
less hazardous product? If the task is done earlier or later in the process, can
the exposure be reduced? Can the process be enclosed or isolated from the worker,
or can ventilation be used? If nothing else controls it, can respirators be used
effectively? Experience has shown that it is crucial to involve both management
and workers in the risk assessment and management process. The workers know the
task the best and will often have insights for changes that are very effective.
They are also much more likely to accept changes if they have been involved in
the decision making process.
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Worker education
Perhaps the most effective way to reduce and control occupational asthma is
through education. We tend to focus education on the patient. It is important
to go beyond this and include all workers potentially exposed to asthma causing
agents, their supervisors, and others who can have an impact, such as planners
and purchasing agents. The Hazard Communication standard requires that workers
be informed of the hazards associated with the products they use and ways to protect
themselves from exposure. This is required when an employee is initially assigned
to a task and whenever new products are introduced. It has been shown that education
programs can actually result in an increase in reported cases of occupational
illness. This is not a bad thing. It is an opportunity to use these sentinel cases
to focus intervention efforts to prevent new cases from occurring. It may also
result in earlier detection of cases so that they can be managed quickly and have
the least effect on the worker and the employer.
Occupational asthma is a serious health problem affecting many workers, their
families, and their employers. This is a disease that is preventable through control
of workplace exposures. Recognizing that until controls are in place, more cases
will occur, the medical community, employers, and employees need to work together
to reduce the impact of this disease.
