It was reported recently in this journal that UK occupational physicians have a positive attitude towards evidence-based guidelines and that the most common barriers to practising evidence-based medicine were lack of time and limited availability of guidelines . Guidelines should be of practical relevance to clinicians, employers and workers. When there are limited resources engaged in producing guidelines, the topics reviewed should be prioritized to focus on those diseases that have the biggest impact on individuals and which present the biggest burden to society.
Dermal and inhalational exposures represent the main pathways of exposure to hazardous substances at work. Occupational asthma is the commonest occupational respiratory disorder in western industrialized countries and has been addressed by systematic reviews, one being updated recently . Occupational skin diseases are the second commonest occupational diseases in the European Union  after musculoskeletal disorders and the third commonest in the UK after musculoskeletal and mental disorders . In 2008, dermatologists and occupational physicians participating in The Health and Occupation Reporting  network reported 2180 cases of occupational skin disease, of which 1573 (72%) were contact dermatitis .
There have been two known previous systematic reviews of contact dermatitis. The first reviewed the evidence for prevention and treatment, but did not produce accompanying evidence-based guidelines . The focus of the most recent review was health care workers and the risk of infection , so there remained a need for a new broad-based systematic review . While occupational contact urticaria accounts for only 1–8% of reported cases of occupational skin disease, both diseases have immunologic or non-immunologic causes. Thus the new British Occupational Health Research Foundation (BOHRF) systematic review aims to improve the prevention, identification and management of three diseases:
irritant occupational contact dermatitis, where agents have a direct toxic effect on the skin,
allergic occupational contact dermatitis involving a delayed or Type IV hypersensitivity reaction to skin sensitizers and
occupational contact urticaria that can be non-immunologic or immunologic involving an immediate or Type I hypersensitivity reaction.
The BOHRF review excluded studies concerned with latex since this had been addressed by a recent systematic review of latex allergy . The BOHRF guidelines development group included members of the recent contact dermatitis and latex allergy research working groups so as to ensure that the work was complementary and did not duplicate previous work. The methodology and full guidelines are described elsewhere . Essentially, Medline and Embase were searched systematically from 1950 and 1980 respectively to the end of September 2009 for original scientific studies published in English. A total of 3155 abstracts were identified and screened, 786 full papers were appraised and 119 studies were used towards the final evidence statements and recommendations.
Irritant occupational contact dermatitis is more common than allergic occupational contact dermatitis, although dermatologists see proportionately more patients with allergic contact dermatitis compared with occupational physicians. Most cases of irritant occupational contact dermatitis are caused by cumulative exposure to chemical agents. Physical irritants, e.g. friction and low humidity, can cause or contribute to the development of occupational contact dermatitis, but in little more then 1% of cases seen in contact dermatitis clinics.
Personal risk factors are often described by authors with references to narrative reviews and book chapters, yet there is little original direct scientific research. While atopy appears to be an independent risk factor for the development of occupational contact urticaria, the evidence for occupational contact dermatitis is inconsistent. However, a history of atopic dermatitis, particularly in adulthood, does appear to be an independent risk factor for the development of occupational contact dermatitis.
Occupational skin disease can be prevented by applying the normal hierarchy of controls. Substitution is the most effective intervention. Cement dermatitis has become much less common among construction workers since chromate was substituted with ferrous sulphate. Likewise substituting latex gloves with powder-free, low-protein latex gloves has reduced the incidence of occupational contact urticaria . Protective gloves are less effective than substitution. They can help to reduce the incidence of irritant occupational contact dermatitis, but only when coupled with other preventive measures. Prolonged wearing of occlusive gloves can of itself have a ‘wet work’ effect, in which case cotton liners should be worn to prevent the development of impaired skin barrier function .
Good hand care is important. The regular application of emollients helps to prevent the development of occupational contact dermatitis , but there is mixed evidence for the effectiveness of pre-work (barrier) creams . Some pre-work creams may help to prevent the development of dermatitis, but they are not generally effective as a preventative measure , although they may improve skin condition when used in combination with cleansing and after-work creams. Pre-work creams are not recommended for people who wear latex gloves, since they may favour the uptake of allergens from gloves .
There is no direct evidence for anyone to be able to recommend health surveillance for the early detection of occupational contact dermatitis or occupational contact urticaria nor has there been any comparison of the effectiveness of different screening methods . However, there is evidence that employee education and training programmes help to reduce the incidence of occupational contact dermatitis and that educational interventions induce important behavioural changes in latex glove use among health care workers .
If a worker should present with a rash, care must be taken to distinguish between occupational and non-occupational disease and between irritant and allergic dermatoses, since the occupational management will differ. Occupational dermatoses most commonly affect exposed areas of skin, i.e. the hands followed by the wrists, arms and face. Occupational contact dermatitis can be present at any stage in a worker's career, including apprenticeship. Studies have noted an increased risk of occupational contact dermatitis within the first months of employment. This may be attributable to the tasks that trainee workers are asked to perform, e.g. trainee hairdressers perform more frequent wet work. A temporal relationship with work and/or the presence of a rash on exposed areas of skin only raise suspicion of an occupational disease and do not confirm an occupational causation. Diagnosis is an iterative process that involves fastidious history taking and clinical examination. Identifying any responsible allergen by patch or prick tests is a major objective, since avoidance of further exposure can contribute to clinical recovery in the individual worker and may help to avoid new cases if exposure to the cause can be controlled.
Avoidance of further exposure can lead to recovery from occupational contact dermatitis and occupational contact urticaria in a number of patients, particularly with natural rubber latex. A small number of workers suffer from persistent dermatitis even after years of allergen/irritant avoidance. This is particularly marked for allergic occupational contact dermatitis to chromate and other metal salts. Overall, the prognosis of occupational contact dermatitis varies widely and, in some occupational settings, reasonable control of symptoms and job retention is possible. Redeployment to a low-exposure area or the introduction of exposure controls may lead to improvement or resolution of occupational contact dermatitis and occupational contact urticaria in some workers, but is not always effective. Similarly, the enhanced use of gloves may improve or prevent symptoms in some but not all workers who continue to be exposed to the causative agent.
As is the case with primary prevention, worker education and conditioning creams appear to offer some benefits as a tertiary preventive measure among workers who have developed occupational contact dermatitis whereas pre-work creams do not improve skin condition in workers with damaged skin .
What then are the implications for practice? First and foremost occupational health and safety professionals need to work with employers so as to ensure employers understand their responsibility to manage risk correctly. Even with familiar hazards that have ready solutions, there continue to be instances where employers have not managed the risk of staff being exposed to causes of occupational dermatitis .
When someone has been offered a job that places them at risk of developing occupational contact dermatitis, they should be asked if they have a personal history of dermatitis, particularly in adulthood, and advised of their increased risk and how to care for and protect their skin. When someone has been offered a job that places them at risk of developing occupational contact urticaria, they should be asked if they have a personal history of atopy, and similarly advised of their increased risk and how to care for and protect their skin.
Providing workers with health and safety education and training appears to be where we should focus our efforts, rather than on health surveillance, which currently has no evidence base.
After-work creams should be made readily available in the workplace and workers should be encouraged to use them regularly. However, pre-work (barrier) creams should not be promoted, since this may encourage workers to be complacent in following more effective preventative measures.
Should a worker develop clinical features suggestive of dermatitis or urticaria they should be referred for a diagnosis of an occupational cause to be excluded or confirmed objectively (patch tests and/or skin prick tests) and not on the basis of a compatible history alone because of the implications for future employment.
Conflicts of interest
P.J.N. chaired the guidelines development group that produced the systematic review.