Annals of Occupational Hygiene Advance Access originally published online on May 20, 2004
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Ann. occup. Hyg., Vol. 48, No. 4, pp. 377-378, 2004
© 2004 British Occupational Hygiene Society
Published by Oxford University Press
Letters to the Editor |
Dermal Exposure Risk Assessment
Enviroderm Services 2 Amery Lodge Farm North Littleton Evesham WR11 8QTY UK
Received 28 October 2003; published online on 20 May 2004
Garrod and Rajan-Sithamparanadarajah (2003) describe the approach taken for dermal exposure assessment by COSHH Essentials.
While this a welcome first step, I suggest that the dermal exposure approach that is described needs to be regarded with some caution.
It appears that the dermal exposure approach relies to a large extent on the hazard data of substances in use on the R-phrases applied for skin exposure (see Table 6 in the paper). Unfortunately, there are many substances in general use in many workplaces that are capable of causing occupational skin disease that have not been allocated such an R-phrase. Presumably, if the approach described in the paper is adopted as a comprehensive approach, these would not be identified as hazardous, with the result that for the tasks in which these are being used no significant risk of damage to health from dermal exposure would be recorded.
To illustrate this point, earlier this year we were asked to investigate a problem in a factory employing around 200 workers. There had been an outbreak of contact dermatitis involving some 20 workers, some of whom had problems significant enough to require time off work. Our investigation revealed that the dermatitis was irritant in nature and that the major cause was excessive hand washing and contact with water. Of course, neither the hand cleanser nor the water carried R-phrases.
It is, perhaps, worth noting here that in Germany wet work is officially recognized as a hazard. Where the exposure to water, or wet working conditions, is for >25% of the working shift in total, a special regulation (Technische Regel für Gefahrstoffe, TRGS541) applies. In fact, with the food processing factory mentioned, changing some of the working procedures, in particular those pertaining to hand washing, resulted in the elimination of the skin problems. Using the approach described by Garrod and Rajan-Sithamparanadarajah, the health and safety team in this factory would not have identified a potential hazard to the skin.
What is needed is a much more comprehensive list of substances hazardous to the skin. With sensitizers, a start could be made simply by taking the list of sensitizers recognized as such by the European Contact Dermatitis Research Group.
With irritants the problem is more complex. Almost all chemicals have the potential to irritate the skin. Water, for example, is considered a skin irritant by most dermatologists involved in contact dermatitis. Furthermore, while with sensitizers it is normal for the dermatitis to be caused by one particular substance, this is not the case with irritants, particularly those that have a chronic effect. As described by Malten (1981), irritant contact dermatitis is generally the result of cumulative damage caused by repeated exposure to many different substances.
At present we have no validated method for categorizing chronic irritants. Thus creating a list, similar to that which we can generate for sensitisers, is currently simply not feasible. In the words of Professor Howard Maibach, a leading US dermatologist: ‘There is probably no such thing as a non-irritant substance. Given sufficient exposure almost any substance will probably have an irritant effect on the skin.’
The COSHH Essentials approach described will undoubtedly identify acute skin hazards. Unfortunately, experience suggests that most occupational irritant contact dermatitis is not acute, but chronic in nature. Thus there is a need to address the question of how we can generate data in an easily assimilated form on substances with chronic irritant effects on the skin. There are techniques that can help to achieve this. Measurement of trans-epidermal water loss indicates acute perturbation of the skin barrier function, such as would occur from skin contact with a mild irritant. Laser Doppler imaging allows us to gain data on the relative effect of such irritants by recording increases in blood flux within the dermis as a result of the skin contact. Since there is evidence that this may be relative to the irritancy potential of the substance, this may indicate a method for classification of chemicals as irritants. However, much development work remains to be done in this field before we can produce a system for the classification of irritancy potential.
In conclusion, while I welcome the advent of COSHH Essentials, it is essential also to stress that this does not provide a comprehensive method for assessing dermal exposure and its significance as a risk of damage to health. Much more work is needed before a system can be developed that will achieve this.
REFERENCES
Garrod ANI, Rajan-Sithamparanadarajah R. (2003) Developing COSHH Essentials: dermal exposure, personal protective equipment and first aid. Ann Occ Hyg; 47: 525–9.
Malten KE. (1981) Thoughts on contact dermatitis. Contact Dermatitis; 7: 238–47.[Medline]
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