Investigating a suspected occupational skin problem

Figure 1. Contributary causes of skin disorders.

No matter how carefully we assess and control risks of exposure, we will never be able to completely eliminate the possibility of an adverse skin reaction owing to exposure of the skin to the working environment. There are many reasons for this, some of which are shown in Box 1.

It is important, should a skin condition be identified where an occupational cause is suspected, that it is properly investigated and the appropriate action taken, both to treat the condition and eliminate the suspected cause.

Most occupational skin disease will take the form of contact dermatitis. From this, it follows that for there to be an occupational problem there must be contact with some workplace condition that can cause the condition. However, the position is not as simple as many assume. We need to always keep in mind that while we may spend up to 48 h each week at work and possibly, around the same in bed, this leaves a minimum of 70 h each week unaccounted for. Thus, when investigating a skin problem we must always include potential nonoccupational circumstances that might either be the true cause or a contributory factor.

It is estimated that 70–80% of all occupational contact dermatitis will be either irritant contact dermatitis or will include, as a causative factor, damage to the skin due to exposure to irritants. Irritant damage to the skin, which may be subclinical and, therefore, difficult to detect without the appropriate skin condition measurement equipment, will enhance the potential for allergic skin reactions. Since irritant contact dermatitis is almost always the result of contact with the skin by many different chemicals, repeatedly, and over a considerable period of time [1], it may require considerable investigative effort to establish the true cause. In fact, as will be shown, there is frequently no single cause, but a combination of effects.

Assuming a skin condition has been reported and that it is suspected this may be due to conditions within the workplace, what action should be taken?

In the first place, the earlier such a problem is detected, the easier it will be to either prevent a serious skin condition from arising or to take the necessary action to prevent further exposure and thus to allow the skin to recover. An effective skin health surveillance program should therefore be part of any effective skin management system. How such a program can be operated is beyond the scope of this article.

However, the first step would be to interview the person reporting the skin problem. A full history is essential and must include nonoccupational factors that could be significant. Some of the information required should already be available from the regular health surveillance program or pre-employment questionnaire, for example. However, it is important that this is updated to ensure that any changes are identified and recorded.

The next step is a workplace visit. This is essential in order to establish just what the person affected actually does while at work and which chemicals he is, or may be, exposed to. Relying on the job title, job description or on the person’s description of what he or she does can easily lead to an incorrect assessment of the cause and to inappropriate treatment. This could conceivably exacerbate the problem.

While at the workplace, checks should be made to see if other workers are showing a similar skin condition. It can occur where one person reports a problem that others are also experiencing but are accepting ‘as part of the job’. Of course, should a significant number of workers in one environment evince similar skin problems, this will tend to suggest an occupational cause, although, this will not always be the case.

Unless the cause of the skin problem is clear, a medical consultation will almost certainly be needed in order to obtain an accurate diagnosis. This will mean referral to either an occupational health physician or a dermatologist. Whoever is selected will need to be experienced in the techniques of prick and patch testing. These are used to determine whether an allergy is present, and if so, to what. It is important that the medical practitioner conducting the test is briefed fully, so that they can test for all relevant substances. This is not always as simple as it may at first appear.

The following example should serve to illustrate how easy it is to fail to identify a causative substance. In a large metalworking facility, two workers had been diagnosed with irritant contact dermatitis. They both worked on a special machine tool that used neat oil as a cutting fluid; that is, oil that was not diluted first with water. When new, the oil was a clear honey color, but after a period of use in the machine had turned black. Patch testing had been conducted with both the new and used oil, with negative results. Hence, the diagnosis of irritant contact dermatitis. However, when patch testing this is always done with the chemical diluted to what is sometimes referred to as the ‘highest nonirritant concentration’, since under the occlusion of the patch test otherwise an irritant reaction would occur which would mask any allergic response. In this case, the dermatologist had diluted the complete oil to 1%.

We hypothesized that the used oil might contain a contaminant that was a sensitizer at a level sufficient to elicit an allergic reaction but, in the diluted form used for the patch test, was in such minimal concentration that no response would occur. The oil was analyzed and shown to contain a significant level of chromate from the machining process. Since both workers had been shown to be sensitized to chrome the diagnosis was changed to one of allergic contact dermatitis.

Once the diagnosis has been received, it is important to identify its relevance. In other words, does the diagnosis relate to what is really happening in the workplace? Again a case study should serve to illustrate this point.

In a factory assembling very small and complex components, some of the parts were nickel plated. Nickel is a very common sensitizer. Owing to the dexterity required, the assembly was done with bare hands, particularly since no chemicals were involved. One lady who had been doing this work for around 2 years developed dermatitis of the hand. This cleared when she went on holiday but returned after a few days back at work. She had been patch tested and found to be allergic to nickel. The assumption was therefore made of an occupational allergic contact dermatitis. The company had accepted this diagnosis and was concerned that action was taken to prevent others from developing the same problem. However, by carrying out a test we were able to show that none of the components this lady would have handled in her work released nickel. Thus, the nickel involved in her work could not be the cause of her dermatitis. Further investigation revealed that in her spare time she worked as a hair stylist. What she was suffering from was an irritant contact dermatitis from the shampoos and other chemicals used in her hair-styling work.

Since the company was about to put all workers into single-use, occlusive gloves, not only did this result save the company considerable expense, but it also avoided the problems that can arise from the long term use of occlusive gloves.

Once a diagnosis has been obtained and its relevance tested, then action can be taken to attempt to keep the worker gainfully employed without further skin problems. The action should also consider the potential for others to be affected. However, once again, the answers may not be as simple as they might at first appear. A skin problem may have a number of contributory causes, as shown in Figure 1.

The diagram illustrates some of the factors that can interact in the development of a skin problem. Take the theoretical case of a construction site worker who develops dermatitis of the hand. Patch testing reveals that he is allergic to chromates, which are found in the cement he has been handling. However, cement is also an extreme irritant. The extent to which his dermatitis is due to the irritant damage or to a truly allergic reaction is not easy to determine. In addition, his skin may have suffered some physical damage from the handling of rough bricks or concrete blocks and possibly, from exposure to winter weather [2,3]. He may also have some form of endogenous – or constitutional – problem that may be so mild as not to have been identified. However, this could be predisposing him to a skin problem. Now, add in the effects of psychosomatic conditions, as described by Harth and Gieler [4], and consider that there will be both occupational and nonoccupational factors to consider and it should be evident that identifying the real cause of a skin problem may sometimes be almost impossible. Of course, not all of these factors will apply in every case, but if we fail to take them all into consideration, then there is a possibility that we may fail to identify a significant causative element, arrive at an incorrect conclusion and take remedial action that at best will not have the desired result and, at worst, may actually exacerbate the condition.

Conclusion

Identifying the true cause of a suspected case of occupational skin disease is not as simple as many assume. Almost certainly it will require the involvement of more than just the occupational health practitioner. Those responsible for the processes will need to identify what chemicals are present, whether these are in a form where they can cause a problem in contact with the skin and whether significant skin exposure is occurring. The occupational health practitioner will need to ensure that all relevant information, both occupational and nonoccupational has been obtained and brief the dermatologist so that the patch test is conducted in such a way to be relevant. Interpretation of the diagnosis may need collaboration between dermatologists, occupational health practitioners and process engineers for example, to ensure both a relevant diagnosis and adequate corrective action.

Box 1. Factors influencing the occurrence of a skin problem.

•	Individual

- Genetic variability

- Endogenous skin conditions

- Nonoccupational exposure

- Past exposure and acquired sensitivity or resistance

- Working habits

- Personal hygiene standards (at work and home)

•

Workplace

- Substances to which exposed

- Substance control standards

- Duration and frequency of exposure

- Location of contact on body

- Ambient conditions

- General workplace hygiene

- Personal protective equipment

- Knowledge and training

- Skin surveillance systems

- Hygiene facilities

Financial & competing interests disclosure

The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.