Epidemiology of occupational contact dermatitis in a North Italian population

ARTICLE

Occupational skin diseases represent approximately 40% of all occupational illnesses; different percentages from one country to another are determined by the extent and the type of industrialization and also by the knowledge of the physician.

Contact dermatitis (CD), allergic or irritant, accounts for more than 90% of all occupational skin diseases [1].

In Italy contact dermatitis accounts for more than 50% of occupational disease workers' compensation [2]. Adequate preventive measures are necessary for the protection of worker's health as well as to avoid loss of productivity and medical and disability costs.

Increasing industrialization, the use of new materials and the production of new substances require the constant education of dermatologists who are the best qualified clinicians to diagnose and treat this kind of illness [3].

For the best approach to occupational contact dermatitis the dermatologist should work in collaboration with occupational physicians in order to know the working environment better and to provide adequate preventive measures.

Materials and methods

We considered 1,565 subjects affected by dermatitis which was suspected of having a professional origin by a dermatologist on the basis of clinical and anamnestic data. All patients were tested with the standard series GIRDCA (Italian Group of Research in Environmental and Contact Dermatitis) and with other specific allergens on the basis of their kind of work and contacted substances.

In our study we examined the more numerically significant occupations: employees; housewives; cleaners; hairdressers; mechanics; hospital, construction, food service, textile and bar workers.

For each profession we considered: positive reactions which were relevant to the job of the patient, sex, age, allergological anamnesis, localization of lesions and kind of dermatitis (clinical aspects of irritant rather than allergic ones).

Results

838 (645 females and 193 males) of the 1,565 patients tested (1,056 females and 509 males) are included in the occupational groups examined: 281 employees, 245 housewives, 71 hospital personnel, 53 cleaners, 43 construction workers, 41 hairdressers, 40 workers in the catering industry, 32 mechanics, 16 textile workers and 16 bar workers. 727 patients are not included in examined groups. They are students, pensioners, unemployed persons and a few workers in different occupations (goldsmith, lithographer and workers in the rubber industry or in paper manufacture).

Employees

Among the 281 patients tested, 220 were females (78.3%) and 61 were males (21.7%). Occupational allergic contact dermatitis (OACD) was diagnosed in 7 females (2.4%). Patch test showed positive reactions to potassium dichromate (1.4%), phenolformaldehyde resin (0.7%), formaldehyde (0.7%), p-phenylenediamine (0.3%). The age-groups most concerned were 21-30 years (42.8% of patients) and 41-50 years (42.8%). The lesions involved the hands in all subjects.

13 subjects (4.6%) had an occupational irritant contact dermatitis (OICD), 10 of whom were females and 3 males. 69.2% of these patients were in third and fourth decades. The lesions were only on the hands.

Housewives

Among the 245 housewives, 18 (7.3%) had a OACD with positive patch test to nickel sulphate (4.8%), cobalt chloride (1.2%), fragrance mix (0.8%), balsam of Perù (0.8%), potassium dichromate (0.8%), formaldehyde (0.4%), p-phenylenediamine (0.4%) and thiuram mix (0.4%). 66.6% of patients were in the third and fourth decades. The lesions involved the hands in 17 patients, the forearms in 3 and the wrists in 1 case.

OICD was diagnosed in 20 subjects (8.1%). 60% of them were between 41 and 60 years old. The lesions were located on the hands in 19 patients, on the wrists in 1 and on the forearms in 1.

Hospital workers

Among the 71 hospital workers, 17 (24.0%) were males and 54 (76.0%) were females.

Seven patients (9.8%), 6 women and 1 man, had an OACD. We saw positive patch test reactions to thiuram mix (2.8%), diaminodiphenylmethane (2.8%), mercury ammonium chloride (2.8%), kathon CG (1.4%), latex (1.4%). The age ranged mainly from 21 to 30 years. The eczema was located on the hands (6 cases), on the wrists (2 cases) and on the eyelids (1 case).

Nine patients (12.6%), 3 males and 6 females, had a OICD. 71.4% of these subjects were in the third decade. The lesions were mostly localized on the hands (7 cases), on the forearms (1 case) and on the wrists (1 case).

Cleaners

In this group there were 53 subjects, 11 males (20.8%) and 42 females (79.2%).

Two females (3.7%) had a OACD with positive reactions to diaminodiphenylmethane (1.8%), p-phenylenediamine (1.8%) and tegobetaine L7 (1.8%). 1 patient was 19 years old, the other one was 27 years old. Both of them had lesions on the hands.

OICD occurred in 16 cases (30.1%), 13 females and 3 males. 62.5% of these patients were between 21 and 40 years old and all had lesions on the hands, 2 of them also on the forearms.

Construction workers

We examined 43 male construction workers.

Ten patients (23.2%) had an OACD with positive patch test reactions to potassium dichromate (11.6%), epoxy resin (6.9%), carba mix (2.3%), diaminodiphenylmethane (2.3%) and phenol formaldehyde resin (2.3%). 2 (4.6%) of these cases were airborne allergic contact dermatitis due to epoxy resin. 60% of subjects with OACD were in the fourth and fifth decades. The eczema was located on the hands (7 patients), on the face (2 patients), on the feet (2 patients), on the forearms (1 patient), on the legs (1 patient), on the trunk (1 patient) and diffusely (1 patient).

In 8 cases (18.6%) there was an OICD on the hands. 75% of this group of patients were in the fifth and sixth decades.

Hairdressers

We patch tested 41 hairdressers, 34 females (83.0%) and 7 males (17.0%).

Sixteen patients (39.0%), 12 females and 4 males, suffered from OACD with positive patch test to p-phenylenediamine (36.5%), ammonium persulphate (12.1%), diaminotoluene sulphate (7.3%), o-nitro-p- phenylenediamine (4.8%), balsam of Perù (4.8%) and potassium dichromate (2.4%). Ammonium thioglycolate reacted positively only in one patient (2,4%).

68.7% of patients were in the second decade. The lesions were localized on the hands in each patient, 1 on the wrists and on the forearms.

Four were OICD, 3 females and 1 male aged between 11 and 30 years. The lesions were located on the hands.

Workers in the food industry

We patch tested 40 workers in the food industry, 14 males (35.0%) and 26 females (65.0%). OACD was diagnosed in 4 women who had dermatitis on the hands. 2 of them (50%) were between 31 and 40 years old. They showed positive patch test reactions to thiuram mix (5.0%) and to balsam of Perù (5.0%).

The diagnosis of OICD was established in 6 patients (15%), 4 males and 2 females. 83.3% of these subjects were between 31 and 50 years old. The OICD were localized on the hands in all patients and on the forearms in 2.

Mechanics

Among the 32 patients of this group 29 were men (90.6%) and 3 women (9.4%).

Two males (6.2%), 25 and 41 years old, had an OACD. Patch testing showed positive reactions to lubricating oil (6.2%) and to potassium dichromate (3.1%). Both patients had dermatitis only on the hands.

Five men (15.6%) showed an OICD on the hands. 80% of these patients were between 31 and 50 years old.

Textile workers

We examined 16 textile workers, 4 males (25.0%) and 12 females (75.0%).

The diagnosis of OACD was established in 5 subjects (31.2%), 4 women and 1 man. They showed positive patch test reactions to disperse blue 124 (18.7%), disperse yellow 3 (12.5%), formaldehyde (12.5%), disperse orange 3 (6.2%) and disperse red 1 (6.2%). All patients with OACD were aged between 41 and 50. The dermatitis was localized on the hands (4 cases), on the eyelids (3 cases), on the wrists (1 case) and on the forearms (1 case).

OICD was diagnosed in 2 subjects (12.5%), 1 woman 55 years old and 1 man 21 years old.

Bar workers

Among the 16 workers of this group, 7 were males (43.7%) and 9 were females (56.3%).

We diagnosed no OACD, but we examined 6 patients (37.5%) suffering from OICD, 3 females and 3 males. These 6 patients showed dermatitis on the hands and 83.3% of them were aged between 21 and 40.

Altogether we found 71 cases of OACD and 89 cases of OICD.

Personal and/or familial allergological anamnesis was found positive only in 21 out of 71 patients (29.57%) affected by OACD.

Discussion

The results of this study show that contact dermatitis is a very frequent occupational skin disease, in fact we diagnosed contact dermatitis in 19% of patients within a non selected group (among 838 patients examined 160 had a contact dermatitis). The irritant type of eczema is more frequent than the allergic type. This agrees with other reports [4]. OICD is more common in bar workers (37.5%), in cleaners (30.1%) and in construction workers (18.6%) (Table I). In fact the subjects engaged in these trades handle chemical and physical substances that are very irritant to the skin [4]. OACD is more common in hairdressers (39.0%), in textile workers (31.2%) and in construction workers (23.2%) (Table I). These data show that allergic contact dermatitis is more frequent in a workplace with both irritant and allergic factors. This situation is mostly present for hairdressers. In our study the 39.0% of these workers had an OACD and only 9.7% an OICD. In agreement with other reports [5].

None of the bar workers showed ACD, but only ICD and this is probably due to their frequent handling of water and other irritants, but only few allergenic factors.

For employees the OICD is generally due to repeated contact with dusty paper and other skin drying factors. With regard to housewives, hospital workers, cleaners, food services and bar workers the irritant factors are represented by frequent contact with water and detergents that can alter the hydrolipidic film.

For construction workers and mechanics the irritant factors are mainly chemical substances together with atmospheric factors (open air, cold temperature, wind).

75% of patients with OACD and 65% of OICD are females. This might be due to their using, not only in workplace but also in the home, more irritant factors and sensitizing substances than males and/or their greater predisposition to develop an irritative or an allergic reaction.

The hairdressers develop a contact dermatitis at a younger age than other workers. 68.7% of them show an ACD between 14 and 20 years and 100% of ICD between 14 and 30 years (Table II). This probably occurs because the apprentices handle strong allergenic products, such as dyes and permanent wave solutions, together with irritants, such as water and shampoos, from the early stages of their work. The frequent washing of hands with shampoos could be a cause of irritant contact dermatitis among apprentices in hairdressing.

In the group of textile workers we saw 100% of OACD between 41 and 50 years, later than in other professions (Table II). This probably depends on the lack of strong irritants excluding water and dampness.

In all professions the allergic and irritant lesions are mainly located on the hands (94.4%). Another location to point out is the face, diffusely in construction workers and particularly on the eyelids in textile workers. This localization may be due to airborne dermatitis with accumulation of the allergens in the palpebral fold where the horny layer is thinner than in other portions of the face.

We observed that the patch test reactions are mainly caused by p-phenylenediamine with 18 cases (25.3%), 15 of whom were found in hairdressers. Other allergens with positive test reactions are, in order of frequency, potassium dichromate (18.3%), mainly present in building workers and employees, nickel sulphate (16.9%) in housewives and balsam of Perù (8.4%) in hairdressers, housewives and workers in the food industry. On the contrary if we analyse the data pertinent to the groups of allergens, we find that metal reactions are more frequent, with 28 cases (39.4%), than dye reactions, with 25 cases (35.2%), and than the rubber and preservative reactions, with 9 cases (12.6%).

Metal sensitization was mainly present in housewives but also in construction workers and in employees. The housewives' dermatitis from metals was due to contact with nickel sulphate contained in different kinds of domestic tools and to contact with nickel sulphate, cobalt chloride and potassium dichromate present in detergents and cleaners [5, 6]. These metals derive from systems of production, particularly during the grinding with metallic wheels and the transit at high speed into steel pipes, hoppers and tinners [6]. In building workers the allergic contact dermatitis to metals is caused by potassium dichromate present in cement [7], because it produces an alkaline environment making this allergen soluble. In employees the allergic contact dermatitis is due to potassium dichromate contained in inks and in rubber articles such as pigment [8].

The reactions to rubber allergens (thiuram mix, carba mix) occur mainly among construction workers, hospital personnel, workers in the food industry and cleaners with their frequent use of rubber gloves [9].

Positive patch test reactions to preservatives occurred in textile workers, who use formaldehyde during the finishing processes and among hospital personnel, housewives and cleaners, who handle tegobetaine L7 and kathon CG which is mostly contained in detergents.

Positive patch test reactions to dyes are mainly caused by p-phenylenediamine among the hairdressers and by dispersion among the textile workers, as is reported in other studies [5]. We have seen that of the 15 hairdressers sensitized to p-phenylenediamine, 8 (53.3%) subjects also showed positive reactions to textile dyes, while no textile worker presented the same concomitant sensitivity. Probably, it is a false cross-sensitivity because the p-phenylenediamine remained as an impurity during the cycle of production [9] and it is not present in textile workers because the percentage of p-phenylenediamine in cloth is not sufficient to sensitize and there are not so many irritant factors.

It is interesting to note that we found a relatively low frequency of sensitization to ammonium thioglicolate in hairdressers compared with other authors [5], but we have no data about glycerylmonothioglycolate which was not tested in our group.

Generally, nickel sulphate is the commonest cause of positive patch test reactions. However it is difficult to know if this allergen is the cause of occupational dermatitis because it is ubiquitous. We saw 7 (17.0%) young hairdressers with acute eczema and with patch test reactions caused only by nickel sulphate. This datum would prove that this allergen is occupationally relevant in these patients, as cited in another report [5]. Furthermore the hairdressers are in contact with permanent wave liquids which contain ammonium thioglycolate and nickel sulphate is easily released from utensils in the presence of this substance [10].

The standard series GIRDCA proved to be suitable to recognize an OACD. Only in a few patients did we decide to integrate the standard series with other substances specific to a particular work situation. The possibility of false negative reactions has also to be considered because the workers handle a large number of substances which are often unknown. This possibility can be reduced with a better specificity of Professional Series and with the help of an occupational physician in order to recognize the work haptens.

Our study shows that OCD is very frequent and has a public health importance, as the prognosis is poor and it is often difficult to change work. Approximately 75% of patients have chronic eczema or recurrences of dermatitis, sometimes despite job modification or optimum medical treatment [1]. It is necessary to reduce occupational skin diseases by education and motivation of workers, who often have no knowledge of the dermatological hazards of their workplace [5], and by suitable and continuous epidemiological studies.

Article accepted on 25/10/99

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