Water: the hidden enemy of our skin in a working environment


Everyone’s skin will be exposed to chemicals in the course of their work, irrespective of the nature of their occupation. Chris Packham discusses some of the risks.

How many workers could claim that they are never exposed to dihydrogen monoxide (H2O, or water)? For many of us this exposure will present little or no hazard to our skin. However, in some occupations where the skin is in contact with water often enough, the damage can lead to occupational contact dermatitis. Virtually all chemicals can cause skin damage, even though they may not be officially classified as hazardous.

What is an irritant?

“An irritant is defined as any agent, physical or chemical, capable of producing cell damage. Everything can be an irritant if applied for sufficient time and in sufficient concentration. Water, being the most abundant element of the skin, is usually regarded as banal and gentle. However, the irritancy of water is beyond doubt” (Zhai and Maibach, 2008).

In fact, statistics show that “wet work”, ie skin’s exposure to water, is one of the most common causes of occupational skin disease and it is one of the most frequently and consistently reported causes of irritant occupational contact dermatitis. It is the term used to describe tasks involving prolonged or frequent contact with water, particularly in combination with soaps and detergents. It is interesting to note that the wearing of occlusive (waterproof) gloves is also equivalent to wet work, due to the excessive moisture that will accumulate inside the glove and the damage that this can cause to the skin.

How to conduct a chemical risk assessment

The issue, then, for the person responsible for a risk assessment for any task, is to determine whether or not there is any exposure to chemicals and, if so, to what extent this exposure can cause damage to health. We need to consider more than just damage to the skin as many chemicals can penetrate the skin and cause damage to internal organs and systems.

Herein lies a problem. How do we identify the hazard to which we are exposed? An employer’s safety data sheet will provide limited information, but in many cases this will be insufficient for us to identify the real
hazard that arises when the task under assessment is carried out. Indeed, the latest edition of the Approved Code of Practice (ACoP) for the Control of Substances Hazardous to Health Regulations 2002 (COSHH) recognises this.

Paragraph 57 states: “The risk assessment should consider the work activity, including: all the substances hazardous to health (including biological agents, and simple asphyxiants) arising from the work (used, produced, synthesised, created as waste or by-products, or released from processes or during accidents, incidents and emergencies).”

We generally purchase chemicals to use for a particular purpose or process. When using, it is highly probable that we will change their properties. We may mix two or more chemicals together, or chemically react them – as happens when we use twopack paint. We may contaminate a cleaning chemical with the soiling that it is removing, about which we may have little information. Some chemicals are also more hazardous to the skin when diluted with water. The hazard may change both during the actual task or where the same chemical is used repeatedly, perhaps for the same or similar tasks.

Frequently, when attempting to conduct a risk assessment for a particular task, the most fundamental part of this is the correct identification of the hazard. In many cases this may be fairly simple, but in others it can be difficult and require specialised knowledge of chemistry and skin toxicology. The same chemical used in the same workplace but for two different tasks may present completely different hazards.

The ACoP for COSHH recognises this. Paragraph 35 states:

“When deciding whether the substances used or produced in the workplace are covered by COSHH, employers should also consider the following:

  • Different forms of a substance may present different hazards, eg substances may not be hazardous in solid form but may be hazardous when ground into fine powder or dust that can be inhaled into the lungs.
  • Nanoparticles (ie particles less than 100 nanometers) may be more toxic than larger particles of the same chemical substance.
  • Impurities in a substance can make it more hazardous, eg crystalline silica is often present in minerals that would otherwise present little or no hazard.
  • Some substances have a fibrous form which may present a potentially serious risk to health if the fibres are of a certain size or shape.
  • Some substances have a known health effect but the mechanism causing it is unknown, eg certain dusts of textile raw materials cause byssinosis.
  • Exposure to two or more substances at the same time or one after the other may have an added or synergistic effect.
  • Epidemiological or other data, eg reports of illness due to new and emerging agents, indicate that a biological agent that does not already appear in “The approved list of biological agents” could nevertheless cause a hazard to health.
  • One-off emergency situations arising out of the work activity, such as a dangerous chemical reaction or fire, could foreseeably produce a substance hazardous to health.”

Of course, if we have not correctly identified the true hazard then there is a real probability that we will end up with an invalid risk assessment. As a result the employer may feel compelled to implement expensive exposure control measures that are not really needed or may continue to exposure his workers to a hazardous substance in the mistaken belief that there is no significant hazard and therefore no significant risk. One problem here is that the effect may well be chronic, ie does not appear at once, but only after a long period, possibly years. The results can then be serious, possibly even fatal.

So the concept that some companies promote that they can provide an employer with risk assessments based on the employer sending them the safety data sheets, and perhaps a brief description of the product’s use, could well result in risk assessments that bear little or no relationship to the true situation.

Those charged with the responsibility for safe use of chemicals should perhaps review whether their risk assessment strategies and procedures are really adequate for determination of the real hazard to which their workforce could be exposed.


Zhai H, Maibach HI (2008). Dermatotoxicology. Seventh edition, CRC Press.


About Chris Packham

Chris Packham FRSPH, FIIRSM, FInstSMM, MCMI, RSP, MBICSc is director at EnviroDerm Services
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