Skin sensitisation is not the biggest danger

Having just read the otherwise excellent article ‘Under Surveillance’ (Occupational Health September, page 26), I feel that I should comment on some aspects of what has been written regarding skin and the working environment.

The impression from reading this article might be that the only risk of damage to health from skin exposure is due to sensitisation. In fact, while sensitisers causing allergic contact dermatitis are a problem, the most common cause of occupational skin disease is irritant contact dermatitis. It has been estimated that around 70-80% of all occupational skin disease is either this, or includes significant irritant damage as a causative factor. In the words of an internationally renowned dermatologist, Professor H I Maibach: “There is probably no such thing as a non-irritant substance. Given sufficient exposure, any substance will have an irritant effect on the skin.” Perhaps this explains why statistics show that exposure of the skin to water (wet work) is one of the most common causes of occupational skin disease.

One of the problems with workplace exposure to irritant chemicals is that irritant contact dermatitis is almost always chronic and multi-factorial – ie, it is caused by repeated exposures to many different irritants, both at work and at home. This creates a problem when attempting to conduct a risk assessment.

A worker may complete a number of tasks, each involving exposure to a different chemical (possibly including water). No single task, taken in isolation, would give cause for concern. However, in total, the cumulative effect of these exposures, together with any exposures away from the workplace, could cause sub-clinical damage that, over time, possibly years, results in irritant contact dermatitis.

The cumulative effect remains asymptomatic – ie, undetectable by normal visual inspection of the skin, until the point is reached, called the ‘threshold’ according to research by K E Malten, whereupon the dermatitis will quickly develop. Techniques do now exist that allow detection of this accumulation of damage while it is still invisible.

Given the problem with risk assessment for skin exposure to irritants, skin health surveillance can be one very effective way of limiting such damage, and thus avoiding outbreaks of occupational skin disease.

Incidentally, many chemicals that are skin irritants will not have been allocated a risk phrase, and will therefore not appear on most safety data sheets. Furthermore, there are several common sensitisers that have not been accorded a risk phrase, and will also probably not appear on the safety data sheet.

However, a supplier of a product has a duty under section 6-1 of the Health and Safety at Work etc. Act 1974 to provide: “… adequate information about the use for which it is designed and has been tested, about any conditions necessary to ensure that, when put to that use, it will be safe and without risks to health.” The information on the safety data sheet, which is provided to comply with Chemicals (Hazardous Information and Packaging for Supply) regulations (CHIP) rather than the Control of Substances Hazardous to Health regulations (COSHH), may well not meet this legal duty.

Any health surveillance system that includes skin health surveillance needs to take account of the many different factors that can affect the skin – eg, ambient conditions, weather, and physical as well as chemical exposures.

Chris Packham is managing director of EnviroDerm Services.

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