The Skin You're In
Published: 10th Oct 2005
Skin should help to keep our insides in, and the outside out. It should also be one of the ways in which we perceive the pleasurable sensations and enjoyments of the world. Too often, it can become an instrument of torture.
More years ago than one of your authors cares to remember, when he was an innocent little cherub, there was an advertising campaign for a particular type of kitchen worktop material which stated enigmatically that it was "the second most interesting surface in the world". It had to be explained to him that the implied most interesting surface was skin, and a number of years passed before blossoming amateur interest led him to agree. Professional interest, related to keeping skin and what it surrounds in pristine condition through the use of personal protective equipment (PPE), came much later.
The range of assaults and abuses which we inflict on this delicate layer in the course of a typical day, every day, involve many different factors:
- Mechanical attack in the form of rubbing, cuts, stabs and stretching
- Thermal attack by both hot and cold contact, air blasts, and radiant heat
- Exposure to damaging radiation from the sun or artificial sources
- Contact with damaging substances and / or infectious agents
- Prolonged and repeated contact with water
The skin is a remarkable organ, and its ability to cope with any exposure to this array of challenges is extraordinary. This is reflected in the widely different skin textures and properties to be found on different parts of the same body (compare your thigh with the palm of your hand), between the same parts of different bodies (compare the hands of a manual worker with those of an office worker), or even the same parts of the same body over time. Hands that are unused to the rigours of heavy work will temporarily toughen up considerably in response to protracted bouts of self-inflicted DIY or gardening. The "healthy tan" and the rugged weather-beaten features so beloved of romantic fiction are further manifestations of this phenomenon.
However, this self-preservation adaptive mechanism of the skin, in response to repeated exposure to the above factors, is all too easily overwhelmed by both short-term and long-term attacks, particularly in occupational settings. The intensity and duration of the exposures in these situations often defeat our natural defences, resulting in damage and disease. Normally, more than one of the factors mentioned will be present at any given time, and the combined effect is often greater than the sum of its parts.
What seems to be the problem?
Ailments arising as a result of subjecting the skin to these factors range from the relatively mild (superficial grazes and cuts, minor burns which heal spontaneously without complications), to the debilitating (dermatitis or eczema, major cuts and burns, infections), to the potentially fatal (cancers, or skin sensitisation, or other disease caused by absorption of substances through the skin). The most insidious hazards are those which are not immediately apparent, and which may only develop after prolonged and repeated exposures, or with a delay between exposure and the appearance of disease. Chemical exposure frequently falls into this category. The key message here is that if you can prevent contact between these substances and the skin, you will also prevent skin-related problems.
Chemical substances capable of causing a reaction on the skin can be divided into four groups:
- Those that cause acute effects such as acid or alkaline burns, and essentially destroy the structure of the skin, e.g. contact with wet cement
- Those that cause irritation to the skin leading to irritant contact dermatitis, e.g. solvents and detergents, which strip out the skin's natural protective oils and moisture
- Those that sensitise the skin causing allergic contact. This condition involves the body's immune system, and once a person is sensitised to a given chemical, any subsequent exposure will produce an allergic reaction, possibly elsewhere in the body. There is no cure once sensitisation has occurred, and the only solution is to avoid all exposure to the causative agent, which may be more difficult than it sounds
- Those that can cause other skin disease such as skin cancer and skin discolouration (depigmentation) at the site of contact, e.g. some components of cutting oils and coal tar pitch
Many chemical substances can penetrate the skin and are capable of causing diseases elsewhere in the body, or even of affecting reproductive health.
If your skin is compromised by any of the above ailments, or simple mechanical damage, its barrier properties against these substances will be reduced. Similarly, damaged and irritated skin can make you more susceptible to opportunistic infections by bacteria, fungi and viruses, the effects of which may be either local (gangrene; necrotising fasciitis) or systemic (MRSA; hepatitis).
Harmful substances come in just about any form. Solid particles and liquids are common, but some gases and vapours are also potentially a problem, particularly if they are soluble in water or natural skin oils. Micro-organisms, while usually invisible are almost ubiquitous. Macro-organisms, (whole plants and animals, components of them, or substances exuded by them) will also be a problem to some people.
Cost and value
The Health and Safety Executive (HSE) estimates that around one million people in the UK regularly handle chemicals as part of their work. There are around 26,000 people who are known to have occupational dermatitis, and around 4,000 new cases are diagnosed by skin specialists every year. This number is known to underestimate the true scale of the problem, because of underreporting. A quarter of those occupationally exposed to chemicals rely on personal protective equipment to control this exposure, with a total annual purchase cost of £300 million. Gloves alone account for more than £30 million annually.
The financial cost of work-related skin disease to UK industry is put at £200 million per year, and includes loss of production, sickness absence, compensation payments, rehiring and retraining of staff. There are no estimates available of the costs associated with the burden that occupational skin disease places on our already stretched health service. Added to all these are the human costs associated with the pain and suffering caused to those affected and their families. Many are unable to continue to work and lose their livelihoods. It is impossible to put a price tag on these aspects.
The different forms of contact dermatitis account for eighty percent of reported occupational skin disease, and because of the nature of work, the great majority of this disease occurs or originates on the hands.
It may come as a surprise to learn who are most commonly affected by these skin problems. Industrial users of noxious chemicals do not feature as highly as might be expected, for these situations are generally recognised as hazardous, and treated accordingly. Instead, there is a tendency for habitual users of common and less obviously harmful substances or products to be the most affected; printing workers, agricultural workers, hairdressers, florists, health-care workers and cleaning staff. A recurring theme here is frequent exposure to water and detergents / cleaning agents, which uninformed users may be unlikely to recognise as potentially hazardous.
As we have already said, work-related dermatitis is due to contact with harmful agents. There are lots of simple and positive approaches you can take to prevent this contact and the unnecessary suffering and costs it brings.
Safe working distance
Assuming it is not possible to use a less harmful chemical, or totally separate people from it, there are a number of simple measures which can usually be introduced to reduce and control their exposure before finally surrendering to the temptations of protective equipment. A little thought or re-training may be all that is required.
Most people are familiar with the concept of "safe working load" as applied to cranes and lifting gear. Consider now the concept of "safe working distance" (SWD), which can take the form of maintaining either spatial or physical separation between people and the substances they should not be contaminated with.
Let's use the analogy of a simple meal to illustrate SWD. Unless this is to degenerate into a Tom Jones-like (Fielding, not Swansea, although the difference here may be negligible - allegedly) gorging session, you might choose to use cutlery of some sort as tools to access and handle the food on your plate. Similarly, there is often no need to risk direct contact between hands (whether gloved or not) and chemicals or contaminated surfaces; don't dip your hands into the chemical vat to retrieve items, use tongs or a simple hook. Rather than grab lumps of meat, dripping with succulent juices and luscious sauces, carve them and place them between slices of crusty bread so you can handle them cleanly.
Similarly, don't decant or weigh out from bulk quantities of hazardous chemicals if you can use machine-pre-packaged soluble sachets to add these substances to a process. Health and safety law is quite categorical that all practicable alternatives must be used before turning to PPE as a control measure.
If control of exposure to chemicals really cannot be achieved without use of protective equipment, it is essential that this equipment be chosen carefully, so that it matches the hazards, the demands of the working environment, and the needs of the individual user. Fundamental to this matching is an understanding of what properties are required of protective equipment to be able to protect against the substances in the environment.
The protective equipment must first and foremost provide a barrier that prevents direct contact between the substance and the skin of the wearer. It must completely cover the vulnerable area of the body, and have no holes in it that would allow the substance through; this is known as penetration. The tests used to certify this type of product do not guarantee complete protection:
- Statistically representative samples of production batches of protective gloves are tested for freedom from holes by filling them with air or water and looking for leaks. But only a small proportion of product is sampled, and a small proportion of this is permitted to have holes in it. There is no water-tight guarantee that an untested item will have no holes in it
- Chemical protective clothing is tested for barrier performance by one of a range of different methods, appropriate to the type of protection claimed (Table 1). Liquid-protective clothing passes the test if less than 0.3 ml of liquid gets inside the garment. Clothing for use against airborne particles can allow up to 30% of the challenge cloud inside
So at best, the barrier performance of the equipment may be imperfect. In practice, these small quantities of permitted leakage will generally pale into insignificance when compared with the exposures which will occur if the equipment is not worn and used correctly. Simply leaving a suit fastening undone, or allowing chemical to splash into an open glove cuff will lead to significant and avoidable exposure.
Time marches on
All protective clothing is a compromise. The level of protection provided has to be balanced against the restriction the equipment imposes on the user and their ability to do their job. The need for dexterity and freedom of movement restrict the weight, thickness and materials which can realistically be used in protective equipment. Because of this conflict, practical protective equipment invariably has limitations on the length of time it can be expected to be effective.
It is a simple fact of life, and a consequence of the molecular nature of matter, that given time a substance on one side of a barrier will find its way through to the other side. Just how long this will take depends on many complex factors, including the molecular sizes of the substance and the material of the barrier, the barrier thickness, the temperature, the volatility of the substance, and any chemical affinity (or otherwise) between the substance and barrier material. The process by which this transportation takes place is known as permeation.
Performance standards for chemical protective clothing and gloves recognise this phenomenon, and classify products in terms of how long they can prevent a range of chemical substances from reaching the unexposed side of the material, often referred to as breakthrough time, under defined laboratory conditions. Classification times range from 10 minutes to eight hours (Table 2). This classification system is largely the reason why PPE manufacturers will almost invariably not quote breakthrough times in excess of eight hours for any product against any chemical.
However, only a relatively small number of substances, taken to be fairly representative of different classes of chemical (like inorganic acids or aromatic hydrocarbons), are called up in the certification process for protective gloves and clothing. If you want to use the PPE to protect against any other chemical, you should confirm its permeation time with the PPE manufacturer.
Permeation can be likened to the Viking raids on Britain during the Dark Ages. The Scandinavian fjords, populated by aggressive and battleaxe-laden Vikings, are the exposed side the PPE barrier, which is itself represented by the broad North Sea. The soft and vulnerable British coast represents the PPE wearer. Hoards of Vikings set off across the sea in their longships, intent on rape and pillage, and will continue on this voyage to wreak havoc on our peaceful shores, even if those they have left at home are suddenly wiped out by the Black Death.
So it is with chemical PPE. Once the protective material has been exposed on one surface, there is a pulse of contamination making its way through the thickness of the material even if the contaminant is removed from contact with the outside face. A significant proportion of users of chemical protection, probably the majority, fail to recognise this fact. They expect the equipment to work as long as it remains intact.
If the contaminant does reach the internal face of the PPE material, it finds itself in an enclosed, moist, warm environment, in intimate contact with the wearer's skin; this is a condition called "occluded exposure", and it is particularly effective in enhancing both the local effects of chemicals on the skin, and their ability to be absorbed through the skin into the body. Genetically and culturally, the Vikings are still here.
Clothing or gloves which have broken through in this way will look and feel no different from clean unused items. It will not be apparent to the wearer that they are being exposed until the chemicals begin to have their evil way.
Prevention of this type of exposure is simple. Once the equipment has been exposed, remove and change it at least before the relevant breakthrough time given by the manufacturer.
All the right moves
Selection of the best protection for the skin against harmful contact is not easy, but with the right approach you can avoid many of the pitfalls. Simple guidance in support of the UK Control of Substances Hazardous to Health (COSHH) Regulations has been produced by HSE through COSHH Essentials (www.coshh-essentials.org.uk), including the basics of using PPE as a control measure. Think about:
Body parts - What form of protection you need. Which parts of the body might be exposed to contact? Do you need just gloves, or aprons, coveralls, boots, faceshield as well? Coverage should be no more and no less than is necessary. Remember too that each item you wear will add to your encumbrance, the effort required to work, and your potential for heat stress. There is a time and place for hot sweaty bodies, but it is not at work, while wearing chemical protective equipment. (Sweat itself can be an irritant and cause skin rashes and dermatitis.) If you are heavily protected, you may have to strictly limit your working durations through planned work-rest schedules incorporating regular cool-down and rehydration breaks.
Making contact - How might the substance come into contact with your skin? Direct contact or immersion; squirting, spraying or settling from the air; accidentally touching contaminated surfaces? This dictates the type of protective clothing you need (e.g. Table 1), or the length of gloves.
What is it? - What substances are involved? This restricts the materials from which the PPE can be made, and how long it will protect (e.g. Table 2). Consult the manufacturers' chemical performance data.
Up to the job? - What other hazards are involved in the job and the working environment? This will tell you what additional strength and protective capabilities the PPE must have, and how different items have to work together. The equipment has to withstand the physical and mechanical stresses of the working environment without damage. Separate suites of standards and classifications apply to these properties, which will be described in the information provided with the equipment by the manufacturer, and this has to be matched to the demands of the job. You will rarely use one item of PPE in isolation, and you must manage the interfaces between them properly to ensure that none of the individual items are compromised - gloves and cuffs; suit legs and boots; coverall hoods and respirators.
Get it on - Can you get the right sizes? You are unlikely to wear badly fitting PPE correctly, and it will be uncomfortable. It may also become a hazard in itself, snagging on obstructions, reducing dexterity, or causing you to trip. Some people may become sensitised to the PPE materials themselves (particularly residual latex protein from glove manufacturing processes, or additives used in stabilisation of rubbers). If so, they will have to find alternative PPE made from other suitable materials.
But selecting the right PPE is only one small step in the process of achieving protection. You have to use and maintain it correctly, through supporting activities which have equal importance in the overall programme:
- Ensure that the right types and sizes of equipment are correctly stored and available for individual users
- Arrange training in when and how to put on the equipment correctly. There is no benefit in putting on gloves if your hands are already contaminated
- Arrange training in how to safely remove contaminated equipment and look for evidence of failure or symptoms of exposure
- Arrange training in how to recognise when equipment needs to be changed or replaced
- Decide how to dispose of the equipment, or clean it. (There is considerable debate over whether contaminated equipment can ever be cleaned properly and safely - the longships are still in mid-ocean, and may arrive at any time). The safest course of action is to dispose of it appropriately rather than set up systems to re-use it - either course of action has cost and environmental implications
- Ensure training is followed through effective supervision
- Review of the entire working process and controls in place, to ensure that exposure to the hazards really is minimal and at acceptable levels
- Monitor the effectiveness of the programme through health surveillance of the workforce, by skin examinations or biological monitoring
For the whole thing to be effective, there must be no weak links in the chain. If one link fails, the whole system falls down.
A brief word about skin care products:
- Pre-work creams are formulated to provide a semi-resistant barrier between the chemicals and the skin, but are no substitute for protective gloves and are not classed as PPE
- Skin cleansers help remove contaminants from the skin. Use the least aggressive cleanser that will do the job. Using the SWD principle for handling chemicals will help to reduce the need for excessive use of skin cleansers
- After-work creams (moisturisers) restore the moisture content of the skin and are best used at the end of each work shift or after washing the hands
In all cases, you should seek expert help or medical advice if skin problems do materialise.
Healthy skin is both strong and vulnerable; it is both a right and a privilege. You owe it to yourself and others to keep it that way.
Nick Vaughan Health and Safety Laboratory Harpur Hill, Buxton, Derbyshire SK17 9JN, UK
Bob Rajan-SithamparanadarajahHealth and Safety Executive Magdalen House, Stanley Road, Bootle L20 3QZ, UK
Published: 10th Oct 2005 in Health and Safety International