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1.4.3 What is Occupational Asthma?


This article is from the Asthma FAQ, by Patricia Wrean and Marie Goldenberg mwg@radix.net with numerous contributions by others.

1.4.3 What is Occupational Asthma?

Occupational Asthma is asthma that is caused by sensitization from
exposures in the workplace. Asthmatics whose asthma is exacerbated by
exposures in the workplace would not be classified as having
occupational asthma.

There are over 200 substances that have been documented as causing
occupational asthma, but there are probably more that have not been
recognized. The substances that are known to cause occupational asthma
can be divided into two main categories.

High molecular weight proteins of animal or plant origins are common
causes. Things like animal dander, flour proteins, and animal scales
are frequently causes of occupational asthma. These same things are
also common causes of non-occupational asthma. These are usually
IgE-mediated responses.

Low molecular weight chemicals that have the ability to bind with
proteins or act as haptans are causes of occupational asthma. There
may be other mechanisms involved besides the classic IgE-mediated
responses as not all those that are sensitized have specific
antibody production. Reactions may have reflex, inflammatory,
pharmacological, or immunologic pathways or a combination of several.

Often occupational asthma is difficult to diagnosis. There are may be
immediate, late, or biphasic reactions. In late reactions the symptoms
may not occur until away from the work place. Frequently the asthma
worsens as the workweek progresses and improves over the weekend.

Treatment for occupational asthma is basically the same as any other
asthma with a few very important exceptions. For those that have
chemically induced asthma from sensitization to that chemical;
avoidance of the trigger is essential. While steroids and other
medications are helpful in treating the symptoms, they do not
prevent the underlying sensitivity from increasing.

Once sensitized to a substance, some react to minute amounts. Levels
below current TLV levels still trigger reactions. For a sensitized
individual any exposure can cause symptoms.

Continued exposure to the triggering chemical can cause permanent lung
damage, chronic asthmatic conditions, and even death. Medication
should never be used to allow the worker to continue to work in an
environment where there is exposure to the triggering substance. Early
recognition and removal from exposure is essential in preventing long
term disability from asthma.

Chemically induced asthma can occur both in the workplace and outside
of the workplace. There are many exposures outside of the workplace
that there are exposures to chemicals that can induce asthma. Most
physicians are not familiar with this type of asthma. For anyone that
has chemically induced asthma, avoidance of the trigger is essential.


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