T. Stobbe, R. Westra
the coating job well. The recommended approach (from a health and safety perspective) is to use either a wire
brush or a grinder to remove the coating in the area to be welded. On some occasions, removal is attempted with
some form of paint stripper, but the stripping materials are generally quite toxic and require special handling and
work conditions. A third, and commonly used way of removing the coating is to use a welding torch to burn the
paint off the area to be welded.
From a “production” standpoint, this is the most efficient way to remove the coating. It is quick. Compared to
wire brushing or grinding, it typically less than 10% of the work time. It is effective, since it removes all of the
coating which, if left on the metal, would impair the integrity of the weld. It is easy—you just start the torch,
apply the flame, and watch the coating literally “go up in smoke”. It requires no special training or chemical
handling skills (anyone who can do production or maintenance welding can do it). It is particularly useful in
maintenance work because that is often done in field (away from the production line) situations where chemicals
and grinders are not readily available, and where a lot of worker time would be used going to and from the shop
to get tools, chemicals etc. In some cases, it is also done to remove paint which was applied to a surface incor-
rectly, and there is a large area that needs to have the paint removed quickly. In this situation, wire brushing,
grinding, and/or chemicals would work, but the same time constraints would apply.
So, here we have the classic workplace “occupational health & safety” problem: what is more important, to do
it quickly and efficiently or to do it the safe but slow way. In considering this question please remember that in
most cases doing the unsafe way will not result in an injury or immediately observable health effect. This fact,
combined with the fact that the company having the work done is in business to make money and not to provide
the safest of workplaces, means that usually the quick cheap way is chosen. Similarly, for the worker, in most
cases the choice will be to use the “quick and easy” way rather than the correct way because the correct way
means more work for the worker with the added risk of being reprimanded for working too slowly.
Part of the reason the workers choose the “quick and easy way” is that when it comes to health hazards, they
are not aware of the hazard, they have not been educated about it, typically they cannot see the effect imme-
diately (much like cigarette smoking), and they do not think about how difficult life will be later in time when
have developed lung disease or some form of cancer from their work exposures. In some case management is
also unaware of a specific health hazard associated with a work activity (like burning a protective coating off a
piece of metal). This is where the occupational health and environmental health professionals come into the pic-
ture. Their job is to “anticipate, recognize, evaluate, and control” workplace and environmental health hazards
that may affect the workers or the general population. In this case we are talking primarily about workers, so it is
the occupational health professionals (typically referred to professionally as either Occupational Hygienists or
Industrial Hygienists depending on what country you are located in) that need to act to protect the workers. They
can only do this to the extent that they are aware of the potential health hazards. This paper discusses some as-
pects of a poorly understood worker health problem that may result from the burning of coatings prior to, or
during welding.
2. Situation
This health hazard initially came to our attention when the supervisor of a painting line in a railroad car manu-
facturing facility presented at an occupational health clinic complaining of severe respiratory distress. His
symptoms were initially diagnosed as asthma, later to occupational asthma, and then to isocyanate exposure re-
lated occupational asthma. The third diagnosis was assumed because during further medical evaluation and in-
dustrial hygiene investigation, it was determined that some of the paints he was exposed to on the paint line
were isocyanate based. At this point he was sent to a pulmonary medicine specialist who tested him for an aller-
gic reaction to isocyanates, and it was found that he was NOT allergic to isocyanates. This led to further testing,
which eventually determined that he was allergic to phthalic anhydride. Phthalic anhydride (sometimes referred
to as phthalic acid anhydride) is known to be a pulmonary irritant and is capable of causing hypersensitivity
pneumonitis (which has many symptoms in common with isocyanate related occupational asthma). This then led
to a final diagnosis of hypersensitivity pneumonitis secondary to pthtallic anhydride exposure. The only problem
with the diagnosis was the source of exposure. There was no phthalic anhydride in the paint being used in the
paint shop. Here again is where the industrial hygienist enters the picture. When a worker is diagnosed with a
disease thought to be work related, it is their job to determine the source of exposure and to implement control
measures that will eliminate or at least significantly reduce exposures.
