This is a brief introduction to the problem of ensuring that when gloves are selected and used for protection against chemical hazards they will provide the protection required. The selection and use of gloves to provide protection against chemical hazards is far more complex – and uncertain – than many realise. This short article attempts to outline some of the complexity and uncertainty.
It does not claim to be a comprehensive guide to the creation of an effective glove selection and use system; merely to explain why the selection and use of gloves for chemical protection is not as simple as many assume.
EnviroDerm Services has many years of experience on advising employers
on the selection and use of gloves and has developed a structured system for this, more information on which can be obtained by contacting us.
When should gloves be used for chemical protection?
In most developed countries the use of personal protective equipment such as gloves against chemical hazards is, with certain exceptions, considered to be a last resort, provided once all other practicable means of managing exposure have been implemented. There are good reasons for this approach. The result is that in most cases long term use of gloves should only be considered as protection against residual risk after all other measures have been implemented.
It should be noted that all occlusive gloves present a hazard to the skin. So we need to balance the damage that the chemical can do to unprotected skin against the damage to the skin that wearing occlusive gloves can do. Where the latter is greater than the former, then the use of gloves is not appropriate.
There is a large range of different glove materials. There is no material suitable for use in a glove that will provide universal protection. Furthermore, nominally identical gloves from different manufacturers may have very different performance characteristics. In order to be able to select the correct glove for a particular application it is necessary to have an understanding of how gloves work and how they fail.
Which gloves should we use?
Let’s look at ways in which gloves can fail to protect misuse.
Misuse of gloves includes: using the wrong glove for the particular type of chemical and exposure; using the glove beyond its performance limits; not donning or removing the glove correctly.
Using the glove in such a manner that it will become abraded, cut, split or punctured. Note that even the EN standard does not exclude the possibility that gloves may be supplied with holes and the test for holes is only conducted on a sample from each production batch.
Degradation is where the glove material is attacked by the chemical against which it is supposed to be protecting. There is no glove material that is immune to degradation across the range of chemicals that will be found in workplaces. Unfortunately, there is currently no mandatory method for testing for degradation. Each manufacturer is free to use their own degradation test protocol, so comparing degradation between different manufacturers is extremely uncertain.
Permeation is where a chemical in contact with the outside of the glove is absorbed into the glove material and migrates through at a molecular level, emerging on the inside of the glove as a vapour. Permeation does not result in any visible or tactile change in the glove and, as a vapour, is undetectable by the glove wearer until there is some visible sign or feeling of damage as a result of exposure to the chemical inside the glove. What is needed, therefore, is information about the time taken for the particular chemical to permeate through the glove being worn. EN374 is the current standard for chemical protective gloves and prescribes a specific test protocol for testing for permeation breakthrough time.
Testing for permeation breakthrough
Under the revised EN374 glove standard all gloves sold for protection against chemicals must be tested for permeation. The test exposes a sample of the actual glove type to the chemical in question and measures the time for it to permeate through the sample. Different test requirements exist depending upon the classification that the glove will receive. However, these are of little assistance in determining the actual performance that will be obtained when gloves are worn against one or more particular chemicals.
In the first place the test procedure is flawed in that it tests gloves at room temperature, defined as 23°C ±1°C. The reality is that when gloves are worn, they will tend to adopt skin temperature, which can range from 32 to 36°C. The table shows how the permeation breakthrough time at the elevated temperature can be very different to that shown in the manufacturer’s performance data. If we then add the effects of flexing and stretching in use the end effect can be key to deciding which glove to provide and how long it can protect for.
Permeation breakthrough in real life
In a study conducted by EnviroDerm Services in collaboration with Sunderland University, very little correlation between actual performance and manufacturers’ published data was found. In one workplace where a nitrile glove was being worn as protection against xylene, and where the manufacturer’s permeation breakthrough time was given as 36 minutes, in one task no permeation breakthrough was found after two hours, whereas in a different task permeation breakthrough occurred in just five minutes!
The factors that can affect how a glove will perform under actual working conditions are shown in the table. Unfortunately, there is no standard way in which these can be correlated to provide a meaningful performance time. So, deciding which glove to use and for how long it may be used is often not as simple as many believe.
The majority of performance data provided by manufacturers will relate to the performance against single chemicals. Unfortunately, in most working environments we will be dealing with mixtures. This adds a whole new level of uncertainty.
For example, consider a glove that, when tested with each of methyl ethyl ketone and toluene, demonstrated a permeation breakthrough time in excess of 240 minutes. When tested against a 1:1 mixture of these two chemicals the permeation breakthrough time dropped to just nine minutes!
Gloves as a hazard to skin
As mentioned earlier in this document, all occlusive gloves present a hazard to the skin. Wearing an occlusive (waterproof) glove will inevitably result in the skin becoming excessively moist, i.e. hyperhydrated. The common misconception is that this is due to sweat.
In reality, hyperhydration will occur even where there is no sweating. The skin loses moisture continuously. We call this trans-epidermal water loss (TEWL). This in undetectable by the person and normally evaporates from the skin. With skin in good condition this can reach around 700ml per day, but will be much higher if skin is damaged, even if the damage is still asymptomatic. Underneath an occlusive glove this moisture cannot evaporate and will be reabsorbed into the skin. Any sweating will, of course, increase the level of hyperhydration. The hyperhydration has adverse effects on certain cells in the skin and can contribute to what has been called hydration dermatitis by dermatologists.
Some manufacturers attempt to resolve this issue by producing a cream that it is claimed will block the pores so that sweat cannot be absorbed into the skin to cause the hyperhydration. EnviroDerm Services do not believe this is a realistic approach.
In the first place, this ignores that much of the moisture that causes skin hyperhydration underneath occlusive gloves is not sweat but TEWL. TEWL emerges from the skin itself, so blocking pores will have little or no effect. Secondly, blocking the pores does not inactivate the sweat gland. This will continue to produce sweat causing a rise in the pressure in the duct leading from the gland to the pore. The duct will then leak, emitting sweat into the living cells in the lower epidermis where they will cause a reaction which reduces the barrier properties of the skin once the gloves are removed.
What is needed is a layer on top of the skin that traps and retains any moisture emitted from the skin. A separate cotton glove, worn underneath the chemical protective glove has been shown to be effective at doing this.
“The negative effect on skin barrier function from occlusive gloves was prevented by the use of a cotton glove.” – Effect of glove occlusion on human skin – Long-term experimental exposure, Ramsing DW, Agner T, Contact Dermatitis 1996, 34, 258-262.
The cotton gloves will ultimately become saturated and need changing. However, they can be rinsed, dried and reused. In Germany the regulation regarding hazardous substances stipulates that where occlusive gloves are worn for more than two hours in total in a single shift cotton gloves must be worn. The UK Personal Protective Equipment regulations also require action to minimise the effect of occlusion.
With regard to allergic reactions to gloves, provided that good quality gloves are used allergic reactions are relatively rare.
How should we use gloves?
Having decided that there is a need to use gloves to protect against one or more chemical hazards in our working environment, how should we use them?
The selection of chemical protection gloves
The diagram on the next page shows the elements of the comprehensive approach adopted by EnviroDerm Services. It is beyond the scope of these notes to deal with each of the elements in depth.
Each element in this system has its own particular sub-elements that are not shown in the overview, but that will need to be considered if the correct conclusion about which glove to use and how it should be used is to be reached.
It should be obvious from this that it is rare to find a situation in which one chemical protective glove can be worn that will provide protection across the entire workplace. Each task requires that the glove to be used is selected to match the conditions stipulated in the risk assessment for that task. Different tasks, using the same chemicals, may require different gloves (or possibly no gloves at all) or the same gloves changed at different intervals.
What is important is to recognise that the selection and protocol for the use of a chemical protective gloves must be based on the real chemical hazard arising when one or more chemicals are used for a particular task and the nature of the exposure that does, or might, occur when the task is carried out.
Thus it is essential that the risk assessment reflects the real hazard encountered when a task is carried out if the glove is to provide the protection required. The starting point for any glove selection and use system should be a check to ensure that the risk assessments are valid. Those based solely on the information from the safety data sheets may not meet this condition.
Paragraph 10 of the sixth edition of the Approved Code of Practice for COSHH states:
“Employers should regard a substance as hazardous to health if it is hazardous in the form in which it may occur in the work activity. A substance hazardous to health need not be just a chemical compound, it can also include mixtures of compounds, micro-organisms, or natural materials such as flour, stone or wood dust.”
In other words, it is not the hazard shown on the safety data sheet but that which is present when the chemical is actually used – regardless of whether it is even on a safety data sheet – that the protection is needed for.
As a result, the selection and the way in which it is used, e.g. how often the gloves must be changed, is specific to that task for which the glove is provided. The data on which the selection and use is originally based is indicated by the risk assessment after all other practicable exposure management methods have been implemented. Basing the selection and use on the information on the safety data sheet creates a significant risk that the glove will not provide adequate protection and may actually increase the potential for damage to health.
In many cases it may be advantageous to provide one or more glove manufacturers with a detailed set of data about the task, the chemical hazards arising when chemicals are used during the task (very often not the same as what is stated on the safety data sheet), the extent and frequency of contact between glove and chemical, and relevant environmental conditions that may affect glove performance, etc. The manufacturer is requested to make an appropriate recommendation as to glove type and performance, including the anticipated time before permeation breakthrough can be expected. However, caution when evaluating the information provided is recommended, as experience suggests that the quality of manufacturers’ advice can vary considerably.
Based on these recommendations we can then decide which glove should be used for the specific task, how frequently it should be changed and how it should be disposed of. In other words, for the particular task there will be a protocol regarding glove use which can then form part of the method statement/working practice for that task.
The flow diagram shows two elements that, in our experience, are often overlooked. These are training and skin health surveillance. Unless glove users are trained in the correct procedure for donning and, in particular, removing gloves, there is a very real possibility that hands will become contaminated with the very chemicals against which the gloves are supposed to be protecting.
Gloves can also cause skin damage due to the hyperhydration that can occur. Also if they fail to provide the protection needed damage to health can occur. Thus skin health surveillance should be introduced wherever chemical protective gloves are to be used.
In the UK, according to the current Approved Code of Practice for the Control of Substances Hazardous to Health regulations this is essentially a requirement if compliance is to be achieved when gloves are worn for protection against chemical hazards, as the following extract shows.
“Examples where health surveillance is appropriate under the criteria in regulation 11(2)(b) are: where there have been previous cases of workrelated ill health in the workforce/ place; where there is reliance on PPE, eg gloves or respirators, as an exposure control measure; eg printers wearing gloves to protect against solvents used during press cleaning, or paint sprayers using two-pack paints wearing respirators to prevent asthma. Even with the closest supervision there is no guarantee that PPE will be effective at all times; where there is evidence of ill health in jobs within the industry; eg frequent or prolonged contact with water (termed ‘wet-working’) causing dermatitis in hairdressers and healthcare workers, or breathing in mists from chrome plating baths causing chrome ulcers in platers.” (Approved Code of Practice for COSHH, 6th edition.)
Hopefully this overview will make clear the need for a careful and fully informed approach to the selection and use of gloves for protection against chemical hazards. What this article has not attempted is to provide a step-by-step guide to this process. Unless the approach does include the many factors not explained here, the risk of damage to health from wearing gloves may actually be increased, as should the gloves fail to prevent exposure the result may be an increase in the level and severity of the damage to health that occurs.
“Wearing internally contaminated gloves led to higher systemic absorption than was gained from the equivalent skin contamination when not wearing gloves.” (Rawson BV, Cocker et al.: “Internal Contamination of Gloves: Routes and Consequences”, Annals of Occupational Hygiene, 49, 6, 535541, 2005.)