137 15 Occupational Irritant Dermatitis – Metal Workers Undine Berndt, Peter Elsner Contents tates the skin by denaturating keratin, defatting and dehydrating the stratum corneum [6, 7]. In addition, References . 138 frequent wetting and drying cycles contribute to the skin-damaging effect. An above-average incidence of irritant contact dermatitis in those machinists who work at machines with short running periods and do Although computerized tooling operations are in- mechanical work in between has been observed [8]. creasing, the metalworking industry is a trade that Within the phase of manual work, the cutting fluid continues to have a great deal of work done by hand. that the workers are exposed to during machine oper- Consequently, the parts of the body which are pre- ating dries on the skin surface, thus reaching a higher, dominantly affected by occupational skin disease are and thus, irritant concentration. the hands and forearms. Among the frequently ob- served cases of hand dermatitis in metalworkers, the vast majority is of irritant origin [1, 2] (Fig. 1). This condition is closely related to exposure to metalwork- ing fluids. These liquids are sprayed or flow over the Number of case work piece that is being shaped by different mechani- cal means, such as turning, drilling, grinding, or plan- ing. Thus, cutting fluids carry away the produced heat and decrease its production by lubricating the area Observation period (years) between the tool and the metal so as to minimize fric- Fig. 1. Cumulative incidence of irritant hand dermatitis dur- tion. Secondly, they wash away metal chips, reduce ing the observation of 201 trainee metal workers over a period strain hardening, and protect the workpiece against of 2.5 years [9] rusting [3,4]. Handling the workpiece and operating the machine, the metal worker’s skin is frequently or Manual work, which is usually done at the work- even permanently exposed to metalworking fluids. bench to prepare the raw material as well as to put These substances are classified as insoluble or neat oils the finishing touches to the manufactured product, and water-based fluids. Especially with the increasing is also considered a challenging activity for the skin. use of the latter, contact dermatitis has become the Thus, the use of hand tools such as files and scrap- most common occupational skin disease in this pro- ers involves friction and pressure on the worker’s fession. Water-based metalworking fluids are complex hands, which promote the development of hand ec- mixtures which include emulsifiers, extreme pressure zema by injuring the horny layer. There is a high ex- additives, corrosion inhibitors, coupling agents, stabi- posure to mechanical hazards, especially within the lizers, biocides, antifoam agents, dyes and fragrances first months of a metalworker’s apprenticeship of [9]. together with (soluble oils) or without (synthetic During this time, the trainees are mainly involved in fluids) mineral oils [5]. Each single ingredient may manual jobs at the workbench, becoming acquainted already have an irritant effect on the skin, which is to the work environment yet insufficiently skilled to often followed by sensitization to one or various of operate machines. The sudden intensive demands on the numerous additives. Metalworking fluids tend to the barrier function of the skin contribute to its early be alkaline, and the pH value even increases due to decompensation in persons with sensitive skin condi- the concentration of the product in use, which irri- tions. Additionally, metal shavings may cause micro- 138 Undine Berndt, Peter Elsner traumas that allow chemical irritants to enter the skin ditionally, instructions for the correct dilution of the more easily. originally concentrated metalworking fluid has to be After finishing the process, machines need clean- followed. Rags to wipe the fluids from the skin must ing, maintenance and lubrication. Swarf must be re- be renewed at short intervals. moved from the working zone. Solvents are used to When handling aggressive solvents and degreasers, clean processed metal products and skin of mineral gloves should be worn. Cleaning hands with water oils. Thus, workers may be exposed both to deter- and mild syndets and regular use of skin care prod- gents and solvents, which has been shown to lead to ucts and barrier creams are recommended, but even an overadditive irritant effect [10]. A significant irri- those substances as well as frequent water contact tant interaction of the combined exposure to oils and may cause irritation. Additives in creams and soaps solvents has also been reported [11] (Fig. 2). may be sensitizers. Atopics, in particular, should be thoroughly in- formed about their increased risk of becoming af- fected by hand eczema in this profession and about preventive measures to avoid its occurrence. Hours per day References 1. Goh CL, Yuen R. A study of occupational skin disease in the metal industry (1986–1990). Ann Acad Med Singapore 1994; 23:639–644 pressure and friction metal dust 2. De Boer EM, van Ketel WG, Bruynzeel DP. Dermatoses in oil-based MWF cleanser with solvent cleanser without solvents water-based MWF metal workers (I). Irritant contact dermatitis. Contact Der- Fig. 2. Average daily exposure to irritants per workday in a co- matitis 1989; 20:212–218 hort of 201 trainee metal workers during an observation period 3. Alomar A. Occupational skin disease from cutting fluids. of 2.5 years [9] Dermatol Clin 1994; 12:537–534 4. Crow KD. The engineering and chemical aspects of soluble Occupational hand eczema in metalworkers is of- oils. Brit J Dermatol 1981; 105 [Suppl 21]:11–18 5. Grattan CEH, English JSC, Foulds IS, Rycroft RJG. Cutting ten a mixture of endogenous and exogenous dermati- fluid dermatitis. Contact Dermatitis 1989; 20:372–376 tis. There are several published studies indicating that 6. Zugerman C. Cutting fluids. Their use and effects on the irritant dermatitis in metalworkers is significantly skin. Occup Med 1986; 1:245–258 more common in individuals with an atopic back- 7. De Boer EM, Bruynzeel DP. Occupational dermatitis by ground [12, 13, 14]. metalworking fluids. In: Menné T, Maibach HI (eds). Hand The prognosis of hand dermatitis in metalwork- eczema. CRC Press, Boca Raton, 1994; pp 217–230 ers is guarded and the condition may persist, despite 8. Krbek F, Schäfer T. 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