The skin is the human’s armour. It provides a relative protection against microorganisms, minor traumas, electricity and irritants and it represents the first line in the body’s response to infections. The skin is an organ in itself and consists of three layers: The epidermis is a stratified squamous epithelium composed of proliferating basal and differentiated suprabasal keratinocytes. The epidermis acts as the body's major barrier against an inhospitable environment. The top of the epidermis is the stratum corneum, a thin keratin layer of dead cells. The dermis contains blood and lymphatic vessels, nerves, sebaceous glands and sweat glands. The hypodermis consists mainly of fat and is separated from the underlying muscles by a tough fascia (Figure 1). Each of the three layers is subject to pathology from exogenous or endogenous afflictions. The skin is colonized with a variety of microorganisms that may become invasive in case of breaches in the skin barrier between the host and the environment.
Figure 1. Composition of the skin
It is not within the scope of this chapter to present a detailed overview of dermatology, but rather to describe selected dermatological conditions that may occur in workers at sea and interfere with the work aboard. Some of these may be caused by exposures in the maritime setting.
Vulnerability in the context of work of the outer surfaces of the body may manifest itself by contact dermatitis and other diseases of the skin including infections and neoplastic disorders. Skin conditions may also occur as part of a more generalized disease.
Little is known about the prevalence and types of skin disease in seafarers. However, while it is generally assumed that contact dermatitis is the dominant occupational dermatosis, there is evidence that skin infections are more frequent1 because of the high incidence of wounds among seafarers and their likeliness of becoming infected in the marine environment.2
Skin disorders ranged second and third, respectively, of the most important groups of diseases in a survey among Polish fishermen and seafarers3. An increased prevalence of dry skin, dermatitis, and acne found among Norwegian machine crew was found to be related to the exposure to oil and solvents although the latter was not significant.4 Questionnaire screening of 81 fishermen revealed a high percentage of dermatological conditions including histories on actinic keratosis (33%), actinic cheilitis (1%), basal cell carcinoma (19%), squamous cell carcinoma (9%), malignant melanoma (4%), eczema (37%), superficial fungal infections (30%), bacterial infections (58%), bites/stings (85%), and fish shocks (15%). On examination, actinic keratosis and cheilitis were present in 60% and 15%, respectively, and basal and squamous cell carcinoma in 9% and 6%, respectively.5
Based on telemedical case logs, Lucas et al. have recently characterized the types of skin disorders at sea that require acute treatment. Out of a total number of 1.844 calls, 10% (n = 183) were due to skin disorders. Sixty-eight percent of these (n = 125) were infections, 14% (n = 25) inflammatory, 7% (n = 13) environmental, and 11% (n = 20) non-specific rashes. Cutaneous abscesses and cellulitis (n = 84) were the most common acute skin disorders encountered. In some cases digital photographs helped in the diagnostics.1 Skin disorders accounted for a comparable fraction (8%) of the contacts with the Danish Radio Medical. In a study by Dahl, dermatological conditions accounted for 29% of the crews´ and 13% of the passenger consultations and were the largest group of contacts to a cruise ship´s medical centre.6 In a similar more recent study, the crews´ skin disorders constituted 27% of contacts.7 The wide spectrum of work-related dermatological conditions notified to the authorities has been demonstrated in a review by Loddé et al.8