How do you know if the gloves you are providing your workforce as protection are really working? It may sound a simple question, but the answer is anything but simple. Indeed, it is common to find that, whilst the gloves appear to be working, the reality is that the wearers are actually being exposed to the very chemicals that the gloves are supposed to be protecting them against.
To understand why, we need first to appreciate how gloves work and can fail when used to protect against chemical hazards. In advance it is important to understand that this article does not in any way intend to disparage the use of gloves for this purpose. Whilst our aim must always be to organise the way work is carried out so that gloves are not required there are many situations where they are either the last resort or where other measures are simply not practicable and where gloves, if correctly selected and used, can provide excellent protection.
There are two main reasons why the way in which gloves, if not correctly selected and used within their real performance limits for the task for which they are being provided, may not provide the level of protection that the unwary believe they are achieving. These are misuse and permeation breakthrough. Furthermore, it must be recognised that all occlusive gloves, if worn for longer periods (or more frequently for shorter periods) will cause damage to the skin regardless of the material that the gloves are manufactured from.
Misuse can take several forms, some more obvious than others.
Using the wrong glove
It should be clear that a glove used as protection against a chemical hazard must be matched to the particular characteristics of the chemical as present during the task. Unfortunately, it is still common to find that a glove, shown in a manufacturer’s catalogue as suitable for solvents is used for a particular solvent for which the glove is not suitable. Furthermore, the glove must match the real chemical present during the execution of a specific task for which it is to be worn.
Far too many risk assessments for chemicals are based on the safety data sheet or sheets for the chemical or chemicals as delivered. The simple fact is that we purchase chemicals to use for a particular purpose. In using them we may change their properties and thus also change the hazard they present. Furthermore, many chemicals that have not been assigned a hazard statement can still be damaging to the skin. Water, in the form of wet work or long-term wearing of gloves, is the most common cause of occupational contact dermatitis.
It is essential that this is recognised in the risk assessment for the task so that the glove can be matched to the real chemical hazard that it needs to protect against for that particular task.
Using the glove beyond its performance limits
No glove will protect indefinitely against chemicals. The problem, as explained in the section on permeation breakthrough, is that determining the real length of time during which a glove will protect against a specific chemical, or mixture of chemicals, is often far from simple and may require in-use testing. Here, again, it is essential that the performance data relates to the specific hazard present during the task.
Not removing the gloves correctly
It is often not recognised that those required to wear gloves for chemical protection need to appreciate how to use them correctly. This applies particularly to the thin, single-use gloves which are usually fairly tight fitting. It is common to find that on removal the wearer will have contaminated their hands with the chemical against which the gloves have been protecting them, negating the benefit that the gloves will have provided. In one study with hairdressers it was found that without training on the correct technique for glove removal every single one of the forty-three participants in the study contaminated their hands with the shampoo they had been using as a result of incorrect removal technique. Having been shown the correct technique this was reduced to 55.8%.(Oreskov KW, Søsted H, Johansen JD, Glove use among hairdressers: difficulties in the correct use of gloves among hairdressers and the effect of education, Contact Dermatitis, 2015)
Different removal techniques apply for single-use gloves and for those which will be re-used. It is an essential element in any glove selection and use system that the correct technique is taught. Ideally the training will incorporate ‘hands-on’ testing using a chemical with a UV trace material to ascertain whether the person has been successful in removing their gloves without contaminating their hands.
Storing gloves incorrectly
All chemical protective gloves will have a shelf life. In addition, if stored incorrectly this can significantly affect the way in which the glove will perform. This applies both to storage prior to the glove being issued for use and for situations where gloves will be removed and redonned either during or between tasks.
When storing gloves prior to use it is important that a ‘first in – first out’ approach is adopted to ensure that gloves are rotated and not allowed to remain in stock for extended periods.
Where gloves are removed and redonned then arrangements should be made to ensure that they are stored correctly so that they do not become damaged in between uses.
“on removal the wearer will have contaminated their hands with the chemical against which the gloves have been protecting them”
Permeation is where a chemical migrates through a glove at a molecular level. There is no visible or sensory change in the glove itself so no visible indication that this is happening. As the chemical emerges from the interior surface of the glove as a vapour there is also no sensory indication for the wearer that they are no longer protected. The consequences can be minor, or in certain situations dramatic.
When working at a fume cabinet using dimethyl mercury, a researcher spilt a very small amount of this chemical on the thin, single-use gloves she was wearing. As there was no indication to her that the gloves were not protecting her, she finished the task then removed the gloves. Unknown to her the chemical had permeated through the glove and been absorbed into her blood. The consequences were severe brain damage leading to her death several months later.
In most countries those marketing gloves for chemical protection are required to provide permeation
breakthrough data for the chemical for which the gloves are being sold as protection. Unfortunately the standard test procedure does not provide reliable data on how the glove will perform under actual conditions of use. Nor, in many cases, are the data available for mixtures of chemicals. This can be important. As an example, data provided by a manufacturer showed that the particular glove from their range had a permeation breakthrough time in excess of four hours for toluene and a similar permeation breakthrough time for methyl-ethyl-ketone. However, when mixed together in equal amounts the permeation breakthrough time was measured at just nine minutes!
The standard permeation breakthrough time uses a sample of the glove clamped between two chambers. One contains the chemical under test, the other a detection medium. The permeation breakthrough time is usually that when a steady permeation rate is achieved in the detection medium. In use the glove will be subjected to many different factors that can significantly change the time recorded with the standard test. The table above illustrates some of these.
Unfortunately, there is no simple rule that can be applied that covers these factors and the effect that each will have on the real performance of a glove under actual in-use conditions.
Thus, where the consequences of failure would be significant, acute and irreversible damage to health in-use testing may be advisable in order to establish the exact permeation breakthrough time that will be achieved with the specific glove when used for that particular task.
Of course, this also indicates that where gloves are being provided for chemical protection the selection and use protocol must be matched to the conditions prevailing in the particular task. The concept that one glove can be used across a range of different tasks, even with the same chemical, could result in some wearers being exposed to an extent that significant damage to health occurs.
Gloves as a hazard to health
It is an inescapable fact that all occlusive gloves will cause reactions in the skin regardless of the material they are manufactured from. All too often, when a skin rash appears following extended glove use the automatic assumption is that this is an allergic reaction to the glove material. In the majority of cases this assumption will be incorrect. Far more common is an irritant contact dermatitis due not to the glove material but to the occlusion caused by the glove. In our case the term ‘occlusion’ refers to the prevention of the passage of water or other liquids. All chemical protective gloves will occlude the skin.
We often encounter the view that under such gloves the skin will become excessively moist due to sweat. Whilst sweat may contribute to the increase in skin hydration there is another, often more important factor, namely that of trans-epidermal water loss (TEWL). We all lose water all the time across our skin. This is essential as part of the natural functioning of our skin. A person with skin in reasonable condition can lose as much as 700ml each day due to TEWL. This moisture evaporates and is undetectable to the individual, although it can be measured. TEWL is considered a good indicator of the condition of the skin as a barrier.
When the surface of the skin become occluded, in our case by the glove, this moisture can no longer evaporate. It is then reabsorbed into the skin and absorbed initially by the cells (corneocytes) in the outermost layer of the skin (stratum corneum) and eventually reaches the living epidermis. TEWL alone can lead to hyperhydration. If conditions induce the glove wearer to sweat, then this will exacerbate the hyperhydration of the living epidermis.
In the hyperhydrated condition in the epidermis causes a reaction that results in the cells there producing less of what are called natural moisturising factors (NMFs). NMFs enable the corneocytes in the stratum corneum to bind the water they need to function effectively as a barrier.
“Increased water content will have a negative feedback response on the formation of natural moisturizing factors (NMFs) through the deactivation of keratohyalin granules degradation. Keratohyalin granules are the main source of NMFs. The skin surface becomes excessively dry after the removal of the occlusion.” – From:- Dermatotoxicology (second edition), Zhai H, Maibach HI (eds), CRC Press
This results in an impaired skin barrier that is less resistant to harmful chemicals (even water itself) and cannot function correctly to inhibit the colonisation of the skin by transient, potentially pathogenic, micro-organisms. It can take the skin several hours to recover. This effect may not be apparent to the person themselves but can be identified through skin hydration measurement.
Since it is a fundamental principle, in the U.K. enshrined in the regulations, that:
“The use of PPE must not increase the overall level of risk, i.e., PPE must not be worn if the risk caused by wearing it is greater than the risk against which it is meant to protect.” – From paragraph 35 of the guidance document to the U.K. Personal Protective Equipment at Work Regulations 1992
The long term wearing of occlusive gloves can actually result in what a leading dermatologist has termed hydration dermatitis. So where wearing of occlusive gloves for long periods is necessary for protection of the hands from chemical hazards action should be considered as to how to reduce the effect of hyperhydration.
One study illustrates how this might be achieved. The study showed that:
“Glove occlusion on normal skin 6 h/day for 14 days compromises skin barrier function, as measured by TEWL. Furthermore, occlusion caused dermatitis in 6 of the 37 volunteers participating in the study.”
It then went on to state that:
The irritant effect on the barrier function was prevented by the use of a cotton glove worn under the occlusive glove. – Ramsing DW, Agner T, Effect of glove occlusion on human skin (II) Long-term experimental exposure, Contact Dermatitis, 1996. 34, 25S-262
In Germany their guidance on hazardous substances (TRGS401 – Technische Regel für Gefahrstoffe) states that where occlusive gloves have to be worn for more than two hours in total in an eight-hour shift cotton gloves shall be worn.
Of course there will be the occasional case of an allergic reaction to one of the chemicals used in the manufacture of the glove. However, the good manufacturers make considerable efforts to keep such chemicals to a minimum.
What conclusions may we draw from this?
Gloves are a last resort
With the exceptions explained gloves should always be regarded as a last resort; other means of preventing exposure should be identified and implemented. Where the nature of the hazard is such that any glove failure would result in acute, irreversible and serious (potentially life changing) damage to health the appropriateness of relying on gloves should be questioned.
Selection and use of gloves must be task based.
Firstly determining which glove will provide adequate protection and for how long it can do this will depend on many factors in addition to the actual chemical against which it must protect. As a result the selection of the glove and the way in which it must be used will depend on the nature of the task. A generic approach, i.e. that one glove can be used across a range of dissimilar tasks, creates a high risk of worker exposure and consequent damage to health.
Gloves must not increase the probability of damage to health
The hazard that results from the wearing of the chemical protective glove must not present a greater hazard than exposure to the chemical by working without gloves.
Deciding how gloves will perform can be uncertain
The many ways in which glove performance can be affected by conditions prevailing during a task is frequently not easy to identify, even when a structured approach to the selection of the glove and how it should be used is adopted. Given such variability firstly it is important to err on the side of caution. Where the hazard is such that glove failure, probably due to permeation breakthrough, could result in acute, irreversible damage to health in-use testing should be considered. There are techniques by which this can be done.
Correct glove use
No-one should be expected to wear gloves to protect them from anything other than very mildly hazardous chemicals without having received appropriate training that they have a basic understanding of how gloves work and fail and have received practical training in the correct technique for glove removal.
Action to minimise hyperhydration
Where gloves have to be worn for long periods, or for shorter periods with only short breaks, action should be taken to ensure that the damage due to hyperhydration is minimised.
Skin health surveillance
All gloves will fail to danger. All occlusive gloves will damage the skin. Thus it is essential that effective skin condition assessment, preferably including the measurement of skin hydration, is carried out regularly.