COD
Contact Dermatitis • Original Article
Contact Dermatitis
Occupational contact dermatitis in blue-collar workers: results from a multicentre study from the Danish Contact Dermatitis Group (2003–2012) Jakob F. Schwensen1 , Torkil Menne´ 1 , Niels K. Veien2 , Anne T. Funding2 , Christian Avnstorp3 , Morten Østerballe4 , Klaus E. Andersen5 , Evy Paulsen5 , Charlotte G. Mørtz5 , Mette Sommerlund6 , Anne Danielsen7 , Bo L. Andersen8 , Jens Thormann9 , Ove Kristensen10 , Berit Kristensen10 , Susanne Vissing11 , Niels H. Nielsen12 , Jacob P. Thyssen1 and Jeanne D. Johansen1 1 Department of Dermato-Allergology, National Allergy Research Centre, Copenhagen University Hospital Gentofte, 2900 Hellerup, Denmark, 2 Dermatology Clinic, Fyrkildevej 7, 9220 Aalborg Øst, Denmark, 3 Dermatology Clinic, Roskildevej 264, 2610 Rødovre, Denmark, 4 Dermatology Clinic, Bredgade 30, 7400 Herning, Denmark, 5 Department of Dermatology and Allergy Centre, Odense University Hospital, 5000, Odense C, Denmark, 6 Department of Dermatology,
˚ 1, 1570 Copenhagen, Denmark, 8 Dermatology Clinic, Aarhus University Hospital, 8000 Aarhus, Denmark, 7 Dermatology Clinic, Banegardspladsen Havnepladsen 3A, 5700 Svendborg, Denmark, 9 Dermatology Clinic, Skovgade 23C, 7100 Vejle, Denmark, 10 Dermatology Clinic, Bredgade 50, 4400 Kalundborg, Denmark, 11 Dermatology Clinic, Gl. Hovedgade 14, 2970, Hørsholm, Denmark, and 12 Dermatology Clinic, Bindeleddet 15, 2880, Bagsværd, Denmark doi:10.1111/cod.12277
Summary
Background. Blue-collar workers have a high risk of occupational contact dermatitis, but epidemiological studies are scarce. Objectives. To investigate allergic contact dermatitis in blue-collar workers with dermatitis registered by the Danish Contact Dermatitis Group. Methods. A retrospective analysis of patch test data from 1471 blue-collar workers and 1471 matched controls tested between 2003 and 2012 was performed. A logistic regression was used to test for associations. Results. The blue-collar workers often had occupational hand dermatitis (p < 0.001). Atopic dermatitis was less commonly observed among blue-collar workers (19.6%) than among controls (23.9%) (p = 0.005). Allergens with a statistically significant association with the occupational group of blue-collar workers were epoxy resins, methyldibromo glutaronitrile, 2-bromo-2-nitro-1,3-propanediol, potassium dichromate, and methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI). The following occupations were additionally identified as risk factors for contact sensitization to MCI/MI and MI, epoxy resins, and potassium dichromate, respectively: painting, construction work, and tile setting/terrazzo work. Conclusion. Contact allergy is a major problem among blue-collar workers. The data indicate a healthy worker effect among blue-collar workers diagnosed with dermatitis, as blue-collar workers were diagnosed significantly less often with atopic dermatitis than were controls. Key words: allergic contact dermatitis; atopic dermatitis; blue-collar workers; construction workers; epidemiology; occupational; painters; patch test; terazzo; workers/tile setters.
Correspondence: Jakob F. Schwensen, Department of Dermato-Allergology, National Allergy Research Centre, Copenhagen University Hospital Gentofte, Niels Andersens Vej 65, 2900 Hellerup, Denmark. Tel: +45 39777303; Fax: +45 39777118. E-mail: [email protected] Conflict of interests: The authors declare no conflict of interests. Accepted for publication 20 May 2014
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© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
In spite of epidemiological studies reporting high incidence rates of occupational contact dermatitis among bluecollar workers, patient-based epidemiological studies on allergic contact dermatitis in blue-collar workers are scarce as compared with those on other highrisk occupations, for example hairdressing (1–3). Furthermore, the few studies on blue-collar workers that exist are often not fully comparable, as the definitions of blue-collar worker vary. A blue-collar worker is a highskilled or low-skilled working class person performing manual work involving the following fields: construction, oil extraction, mining, mechanics, machine operation, metal processing, agriculture, and fishing (4). The prevention of allergic contact dermatitis among groups of blue-collar workers has been a priority over the years. After restriction of the level of hexavalent chromium in cement, a significant decrease in allergic cement dermatitis among Danish tile setters was observed (5), and later this was also observed in German construction workers following the implementation of EU law (6). In recent years, sensitization to epoxy resin has increased among workers, for example in the construction industry (6). Despite efforts to lower the incidence of sensitization to epoxy resins in blue-collar workers by a compulsory educational programme before they commenced work with epoxy resins, this is still insufficient, and the incidence of sensitization to epoxy resins is increasing (7, 8). The aim of this study was to conduct a retrospective epidemiological analysis among Danish blue-collar workers with dermatitis evaluated in our clinics.
Methods The Danish Contact Dermatitis Group established the National Database for Contact Allergy in October 2002. Since then, it has monitored contact allergy prevalence rates. Contributors to the database are dermatology departments and private dermatology clinics throughout Denmark. Blue-collar workers
Patch test data for blue-collar workers were extracted from the database by means of the Danish version of the International Standard Classification of Occupation (DISCO88). Consequently, the definition of the blue-collar worker in this study is as follows: a working class person, skilled or unskilled, performing manual work involving the following fields – construction, oil extraction, mechanics, machine operation, and metal processing. DISCO-88 divides occupations into 10 major groups (one digit code). Each major group is further organized
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
into sub-major groups (two digits), minor groups (three digits), and unit groups (four digits). The entire major groups 7 and 8 were extracted and used for the analysis. Unit groups included in the analysis were, for example, ‘painters’ (DISCO-88 code 7141), ‘blacksmiths’ (7220), and ‘mechanics’ (7230). Major group 6, defined as skilled agricultural and fishery workers, was excluded from this analysis. ‘Elementary occupations’ and the minor group ‘mining’ define major group 9, and ‘construction labour’ (931) fulfilled the definition of a blue-collar worker and was included. A total of 86 unit groups were extracted, making a total of 12 occupational groups in the analysis (Table 1). The aggregated occupational classification was made on the basis of well-known subgroups. The occupational group of machine operators was, for example, composed of 16 unit groups from DISCO-88 (Table 1).
Study population and controls
The study population comprised 1471 consecutively registered cases of contact dermatitis among blue-collar workers, registered between January 2003 and December 2012. The control group was based on a 1:1 case–control match. Each blue-collar worker was matched with a patient with dermatitis, that is, a control, not registered as a blue-collar worker in the database. Matching criteria were gender, age, and test year. A total of 1471 controls were included. Data concerning painters registered in the database have been published previously (9). In the analysis by Mose et al., patch test data for painters were extracted from the database by means of DISCO-88 codes 7141 and 7142, between 2001 and 2010.
Demographics and patch test results
Information available from the database included age, occupation, MOALHFA index (Male, Occupation, Atopic dermatitis, Leg dermatitis, Hand dermatitis, Facial dermatitis and Age > 40 years), and patch test results. The diagnosis of atopic dermatitis included past and present atopic dermatitis. All contributors to the database, either dermatologists or physicians supervised by dermatologists, were following uniform guidelines (10). All blue-collar workers and controls were patch tested with the European baseline series. Allergens of potential relevance in relation to occupational exposures of bluecollar workers were, for example metals or allergens used in metalworking fluids, detergent products, and paints. Additionally, it should be noted that not all blue-collar
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
Table 1. The occupational classification of the blue-collar workers based on the DISCO classification 88 Occupation
Unit groups in DISCO-88
Blacksmiths Carpenters Construction workers Drivers of heavy equipment Electricians Machine operators
7213, 7220, 7221, 7223 7121, 7124, 7420, 8285 7129, 7130, 7132, 7134, 9300, 9311, 9312, 9313 8300, 8310, 8320, 8330, 8340 7136, 7137, 8282, 8283 8100, 8140, 8150, 8160, 8170, 8200, 8210, 8220, 8224, 8230, 8231, 8240, 8250, 8260, 8281, 8290 7230 7200, 7210, 7212, 7214, 7222, 7223, 7224, 7240, 7311, 8122, 8123 7140, 7141, 7142 7122, 7123, 7211 7411, 7412, 7413, 7414, 8271, 8272, 8274, 8275, 8276, 8278, 9320 7110, 7113, 7135, 7143, 7150, 7310, 7312, 7313, 7320, 7321, 7323, 7324, 7341, 7343, 7344, 7345, 7346, 7400, 7416, 7432, 7433, 7434, 7435, 7436, 7437, 7440, 8113, 8221, 8223, 8232, 8251, 8252, 8253, 8263, 8264, 8265, 8280, 8284, 8286, 9330
Mechanics Metal-processing workers Painters Tile setters/terazzo workers Workers in the food industry Others
% (n/total blue-collar workers) 6.0 (88/1471) 5.5 (81/1471) 2.9 (43/1471) 7.3 (10/1471) 6.0 (88/1471) 13.9 (205/1471) 10.6 (156/1471) 8.2 (121/1471) 8.4 (124/1471) 3.3 (48/1471) 11.2 (165/1471) 16.6 (244/1471)
DISCO, Danish version of the International Standard Classification of Occupation.
workers were tested with the allergens in the special series, for example methylisothiazolinone (MI). Patch tests were applied to the upper back. The occlusion time was 48 hr, and readings were performed at least once on D3 and D4, and often also on D2 and D7, in accordance with the recommendations of the ICDRG (11). Reactions of strength 1+, 2+ and 3+ were interpreted as positive responses. Irritant reactions, doubtful reactions and negative reactions were interpreted as negative responses. In cases of retesting, patch test data obtained at the first visit were included in the analysis. The concentration of the allergen in the vehicle at the time of patch testing may have varied between the centres and throughout time in specific centres.
Statistics
The data were processed with spss™ (SPSS™ Statistics, Chicago, IL, USA; IBM PASW Statistics) for Windows™, edition 20.0. The chi-square test was applied for analysis of the MOAHLFA index. Associations between occupation and positive patch test reactions to allergens from the European baseline series were expressed as crude odds ratios (ORs) with 95% confidence intervals (CIs). Allergens associated with the occupations of bluecollar workers were selected, and analysed with logistic regression analyses, with the allergen’s positive patch test result as the dependent variable, and with study year (2003–2007 or 2008–2012), gender, atopic dermatitis, occupational relationship, age group (age of ≤ 35 years or age of > 35 years) and occupations (e.g. painter or not painter) as the explanatory variables. Prevalence and
350
asymptotic 95% CIs were calculated for selected allergens that the blue-collar workers were additionally tested with. All p-values are two-sided, and 0.05 was chosen for statistical significance.
Results A total of 1471 blue-collar workers (1148 males and 323 females) were patch tested between 2003 and 2012. Blue-collar workers were defined according to selected unit groups from the International Standard Classification System (Table 1). The mean age of the group of blue-collar workers was 41.9 years (95% CI 41.3–42.6). At the time of patch testing, the youngest blue-collar worker tested was 15 years of age and the oldest tested was 77 years of age. The findings according to the MOAHLFA index (Table 2) show that the contact dermatitis more often had occupational relevance among blue-collar workers than among controls (p < 0.001). For the blue-collar workers, the contact dermatitis was more commonly located on the hands (73.3%) than on the face (18.8%) and legs (7.2%). Blue-collar workers had facial dermatitis (p < 0.001) and atopic dermatitis (p = 0.005) less often than controls. Table 3 shows positive patch test reactions in blue-collars workers and controls regarding selected allergens in the European baseline series. Allergens associated with the occupational group of blue-collar workers were potassium dichromate (OR 1.51; 95% CI 1.02–2.24), epoxy resin (OR 3.87; 95% CI 2.22–6.75), 2-bromo-2-nitropropane-1,3-diol (OR 3.76; 95% CI 1.63–8.71), methyldibromo glutaronitrile (OR 1.40; 95% 1.01–1.94), and methylchloroisothiazolinone
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
Table 2. The distribution of the MOALHFA index of total cases of
contact dermatitis in blue-collar workers and controls Blue-collar workers (n = 1471), % (n) Male Occupation Atopic dermatitis Hand eczema Leg dermatitis Facial dermatitis Age > 40 years
78.0 (1148) 42.1 (620) 19.6 (288) 73.3 (1078) 7.2 (106) 18.8 (276) 58.7 (864)
Controls (n = 1471), % (n) 78.0 (1148) 18.6 (273) 23.9 (351) 58.1 (855) 8.6 (126) 24.5 (360) 58.4 (859)
p-value∗ 1.000 35 years of age) (OR 2.31; 95% CI 1.18–4.52). Moreover, individuals sensitized to potassium dichromate often had atopic dermatitis (OR 2.38; 95% CI 1.35–4.20). Tile setters/terrazzo workers more often had contact allergy to potassium dichromate than other occupational groups (OR 3.47; 95% CI 1.14–10.54) (Table 4). Sensitization to 2-bromo-2-nitropropane-1,3-diol was associated with the occupation of painting (OR 4.09; 95% CI 1.18–14.21).
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
Blue-collar workers were tested with additional selected allergens of occupational relevance, as described in the ‘Methods’ section. All selected allergens were individually analysed with logistic regression, as described in ‘Methods’, and only significant results for the allergens are presented. Frequent allergens were bisphenol F and MI. Bisphenol F gave the most positive reactions in the occupational groups of the blue-collar workers (21.4, 95% CI 11.6–31.3). Of the 15 patients who reacted to bisphenol F, all had a concomitant reaction to epoxy resin. Moreover, the logistic regression analysis of bisphenol F showed that sensitization to bisphenol F was occupationally related (OR 28.58; 95% CI 1.52–537.35). Contact allergy to MI was seen in 5.7% (46/809) (95% CI 4.1–7.3) of the blue-collar workers. Of the 46 patients who reacted to MI, 22 did not have a concomitant reaction to MCI/MI. Contact allergy to MI was often associated with hand dermatitis (OR 3.64; 95% CI 1.03–12.81) and was occupationally related (OR 3.63; 95% CI 1.59–8.23), and painters were at high risk of developing contact allergy to MI (OR 4.87; 95% CI 1.84–12.89). In the first study period, sensitization to MI was seen in 4.6% (10/219) of the blue-collar workers, as compared with 6.2% (36/580) in the second study period, with no significant increase in the prevalence between the two study periods (OR 1.54; 95% CI 0.71–3.32).
Discussion We evaluated the prevalence of contact allergy to various allergens among blue-collar workers in a database of consecutive Danish dermatitis patients patch tested during 2003–2012. The blue-collar workers often have occupational related hand dermatitis, with contact allergy to MCI/MI, methyldibromo glutaronitrile, epoxy resin, 2-bromo-2nitro-1,3-propanediol, and potassium dichromate. Those with contact allergy to epoxy resin had occupationally related dermatitis, and the dermatitis was often seen in construction workers. Contact allergy to MCI/MI and MI was often located on the hands, the dermatitis was occupationally related, and painters, in particular, had a high risk of sensitization to MCI/MI and MI. As expected, the male/female ratio was high (1148 males and 323 females) (6). The blue-collar workers were patch tested at a mean age of 41.9 years (95% CI 41.3–42.6), which correlates with previous findings (6, 9). Moreover, the blue-collar workers were diagnosed significantly less often with atopic dermatitis than were controls (p = 0.005). It is tempting to speculate that a healthy worker effect exists among blue-collar workers,
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
Table 3. Positive patch test reactions in blue-collar workers and controls to allergens included in the European baseline series Blue-collar workers, % (n/total tested) Potassium dichromate Neomycin sulfate Thiuram mix p-Phenylenediamine Cobalt chloride Benzocaine Formaldehyde Colophonium Myroxylon pereirae N-Isopropyl-N -phenyl-p-phenylenediamine Lanolin alcohol Epoxy resin p-tert-Butyl formaldehyde resin Fragrance mix II Sesquiterpene lactone mix Quaternium-15 Nickel sulfate Methylchloroisothiazolinone/methylisothiazolinone Mercaptobenzothiazole Primin Clioquinol Parabens mix Mercapto mix Quinoline mix 2-Bromo-2-nitropropane-1,3-diol Iodopropynyl butylcarbamate Hydroxyisohexyl 3-cyclohexene carboxaldehyde Methyldibromo glutaronitrile Fragrance mix II
4.4 (64/1468) 1.2 (17/1468) 2.5 (36/1468) 2.7 (40/1467) 4.6 (68/1468) 0.3 (2/692) 4.2 (61/1468) 4.4 (64/1468) 2.0 (30/1469) 0.9 (7/750) 0.5 (7/1469) 4.1 (60/1469) 1.2 (17/1469) 6.6 (97/1467) 1.0 (15/1467) 2.0 (29/1468) 12.2 (178/1463) 4.2 (61/1469) 1.1 (16/1468) 0.2 (3/1467) 0.9 (6/694) 0.7 (10/1469) 0.9 (13/1469) 1.2 (18/789) 1.8 (26/1459) 1.2 (17/1452) 2.3 (34/1457) 6.1 (89/1466) 4.0 (49/1231)
Controls, % (n/total tested) 2.9 (43/1471) 1.5 (22/1471) 2.5 (37/1471) 3.0 (44/1469) 3.4 (50/1471) 0.3 (2/772) 2.9 (43/1471) 4.4 (64/1470) 2.4 (35/1471) 0.6 (5/792) 0.7 (11/1470) 1.1 (16/1471) 1.8 (27/1471) 7.8 (115/1470) 1.5 (22/1469) 1.4 (20/1471) 12.0 (176/1467) 1.6 (24/1471) 1.0 (14/1471) 0.3 (4/1471) 1.4 (11/788) 0.3 (4/1471) 0.9 (13/1471) 0.9 (13/703) 0.5 (7/1457) 0.6 (8/1451) 2.3 (33/1461) 4.4 (65/1469) 4.4 (54/1233)
OR (95% CI) 1.51 (1.02–2.24) 0.77 (0.41–1.46) 0.97 (0.61–1.55) 0.91 (0.59–1.40) 1.38 (0.95–2.00) 1.12 (0.16–7.94) 1.44 (0.97–2.14) 1.00 (0.70–1.43) 0.86 (0.52–1.40) 1.48 (0.47–4.47) 0.64 (0.25–1.64) 3.87 (2.22–6.75) 0.63 (0.34–1.15) 0.83 (0.63–1.10) 0.68 (0.35–1.32) 1.46 (0.82–2.60) 1.01 (0.81–1.27) 2.61 (1.62–4.21) 1.15 (0.56–2.36) 0.75 (0.17–3.36) 0.62 (0.23–1.67) 2.51 (0.79–8.03) 1.00 (0.46–2.17) 1.24 (0.60–2.55) 3.76 (1.63–8.71) 2.14 (0.92–4.97) 1.03 (0.64–1.67) 1.40 (1.01–1.94) 0.91 (0.61–1.34)
OR, crude odds ratio; 95% CI, 95% confidence intervals. Significant values are in bold type.
and that preventive measures such as career guidance for individuals with atopic dermatitis have worked. Before a final conclusion regarding a healthy worker effect can be drawn, it is important for a similar analysis to be performed among blue-collar apprentices (12). The prevalence rates of contact allergy to MCI/MI and MI were 4.2% (61/1469) and 5.7% (46/809), respectively, which is in accordance with other studies (13, 14). Furthermore, both contact allergy to MCI/MI and contact allergy to MI were significantly associated with the group of painters. A German study investigated the development of contact allergy to MI among workers in high-risk occupations, and, within the groups of blue-collar workers, painters were the only ones with a significantly increased risk of developing MI allergy (13), as previously reported (10). Surprisingly, contact allergy to MCI/MI was not associated with the second study period (2008–2012). Previous studies have found epidemic increases in contact allergy to both MCI/MI and MI (13–16). The lack of a time trend for contact allergy to MCI/MI, is probably attributable to the setup of this study, as only blue-collar workers were included in the analysis.
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The increased incidence of MCI/MI and MI contact allergy in recent years is mainly a result of the increased use of MI as a preservative in cosmetics (13, 14, 16), but a reasonably high number of occupational cases have been reported (13). Of the blue-collar workers with positive patch test reactions to MI, 52% (24/46) had a concomitant reaction to MCI/MI. These findings correlate with recent epidemiological studies on the increasing trend of MI allergy (13–16), and further supports the idea that MI is an independent sensitizer (14). The development of allergic dermatitis caused by MI in blue-collar workers could be the result of the increased use of MI in the industry, for example in paints. Moreover, ingredient lists and Material Safety Data Sheets are often incomplete. A recent Danish study found that systemic stepwise exposure assessment should be prioritized, as it can increase the number of patients diagnosed with occupational allergic contact dermatitis through the study of ingredient lists and Material Safety Data Sheets (17). The preservative 2-bromo-2-nitro-1,3-propanediol is widely used in cosmetics and in industry. Our data indicate
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355 3.3 (44/1345)
4.3 (56/1305) 3.0 (5/164)
Yes
2.8 (3/108)
No
4.3 (58/1361)
Yes
6.3 (3/48)
No
4.1 (58/1421)
Yes
0.0 (0/81)
No
4.4 (61/1388)
Yes
1.1 (1/88)
Yes
No
4.3 (60/1381)
No
4.0 (55/1381) 6.8 (6/88)
No
Yes
Yes
4.1 (54/1313) 4.5 (7/156)
No
4.2 (56/1349)
1.20 (0.37–3.94)
1.26 (0.31–5.16)
2.26 (0.54–9.55)
–
0.44 (0.05–3.68)
2.57 (0.80–8.29)
1.86 (0.60–5.74)
0.88 (0.25–3.12)
3.7 (6/163)
6.4 (83/1303)
2.4 (4/164)
4.3 (56/1305)
6.1 (83/1358)
12.5 (6/48)
5.9 (83/1418)
4.9 (4/81)
6.1 (85/1385)
5.7 (5/88)
6.1 (84/1378)
8.0 (7/87)
5.9 (82/1379)
3.8 (6/1310)
6.3 (83/1310)
6.7 (8/120)
6.0 (81/1346)
9.8 (20/204)
5.5 (69/1262)
0.0 (0/43)
6.3 (89/1423)
4.8 (6/124)
6.2 (83/1342)
4.5 (37/816)
8.0 (52/650)
4.2 (12/288)
6.5 (77/1178)
7.8 (78/1006)
2.4 (11/460)
6.2 (67/1074)
5.6 (22/392)
5.9 (67/1145)
6.9 (22/321)
7.3 (45/619)
5.2 (44/847)
% (n/total tested)
5.6 (6/108)
1.52 (0.42–5.54)
4.45 (1.35–14.73)
2.21 (0.59–8.28)
–
0.70 (0.14–3.60)
1.52 (0.47–4.86)
1.12 (0.31–4.00)
1.19 (0.41–3.44)
4.83 (1.36–17.17)
2.70 (0.97–7.51)
0.76 (0.44–1.31)
0.47 (0.19–1.14)
1.69 (0.86–3.32)
0.41 (0.23–0.75)
0.80 (0.40–1.60)
3.82 (2.08–7.02)
OR (95% CI)
0.70 (0.26–1.87)
1.01 (0.37–2.77)
2.25 (0.79–6.45)
1.05 (0.32–3.39)
1.10 (0.38–3.21)
1.36 (0.51–3.59)
0.82 (0.30–2.26)
1.12 (0.45–2.77)
1.55 (0.75–3.18)
–
0.83 (0.31–2.22)
0.58 (0.37–0.90)
0.82 (0.43–1.56)
3.24 (1.67–6.29)
1.13 (0.67–1.92)
0.72 (0.41–1.24)
1.49 (0.94–2.36)
OR (95% CI)
Methyldibromo glutaronitrile
3.7 (4/108)
4.1 (56/1361)
12.5 (6/48)
3.8 (54/1421)
4.9 (4/81)
4.0 (56/1388)
0.0 (0/88)
4.3 (60/1381)
2.3 (2/88)
4.2 (58/1381)
3.8 (6/156)
4.1 (54/1313)
3.3 (4/120)
4.3 (58/1349) 2.5 (3/120)
No
Yes
0.84 (0.21–3.39)
4.4 (9/205)
4.1 (52/1264) 3.9 (8/205)
4.1 (52/1264)
11.6 (5/43)
3.9 (55/1426)
8.1 (10/124)
3.7 (50/1345)
3.8 (31/817)
4.4 (29/652)
2.1 (6/288)
4.6 (54/1181)
4.8 (48/1008)
2.6 (12/461)
3.5 (38/1077)
5.6 (22/392)
4.1 (47/1147)
4.0 (13/322)
6.5 (40/620)
2.4 (20/849)
% (n/total tested)
Yes
1.58 (0.57–4.42)
–
5.52 (2.16–14.13)
1.16 (0.67–2.01)
0.60 (0.25–1.44)
3.43 (1.55–7.56)
2.02 (0.92–4.45)
0.71 (0.37–1.39)
2.38 (1.34–4.23)
OR (95% CI)
Epoxy resin
No
4.3 (61/1426) 0.0 (0/43)
No
13.7 (17/124)
Yes
Yes
No
3.7 (24/652) 4.5 (37/817)
2003–2007
2008–2012
4.7 (55/1181) 2.1 (6/288)
5.3 (53/1008)
Age > 35 years
Yes
1.7 (8/461)
Age ≤ 35 years
No
2.0 (8/392) 4.9 (53/1077)
No
4.0 (46/1147)
Yes
4.7 (15/322)
Female
6.6 (41/620)
Yes
Male
2.4 (20/849)
No
% (n/total tested)
MCI/MI
3.1 (5/163)
4.5 (59/1303)
8.4 (9/107)
4.0 (55/1359)
12.5 (6/48)
4.1 (58/1418)
4.9 (4/81)
4.3 (60/1385)
4.5 (4/88)
4.4 (60/1378)
3.4 (3/88)
4.4 (61/1378)
1.9 (3/156)
4.7 (61/1310)
4.2 (5/120)
4.4 (59/1346)
3.4 (7/205)
4.5 (57/1261)
7.0 (3/43)
4.3 (61/1423)
3.2 (4/124)
4.5 (60/1342)
4.2 (34/815)
4.6 (30/651)
7.0 (20/287)
3.7 (44/1179)
5.2 (52/1005)
2.6 (12/461)
4.8 (52/1075)
3.1 (12/391)
4.2 (48/1144)
5.0 (16/322)
4.4 (27/618)
4.4 (37/848)
% (n/total tested)
0.76 (0.26–2.28)
2.24 (0.86–5.86)
3.47 (1.14–10.54)
1.47 (0.43–5.03)
1.12 (0.34–3.73)
0.86 (0.23–3.30)
0.53 (0.14–2.01)
0.99 (0.33–3.01)
0.78 (0.29–2.10)
1.91 (0.49–7.47)
0.77 (0.24–2.51)
0.83 (0.49–1.38)
2.38 (1.35–4.20)
2.31 (1.18–4.52)
1.94 (0.99–3.78)
0.66 (0.34–1.27)
1.04 (0.60–1.79)
OR (95% CI)
Potassium dichromate
1.2 (2/163)
1.9 (24/1296)
2.8 (3/108)
1.7 (23/1351)
2.1 (1/48)
1.8 (25/1411)
0.0 (0/80)
1.9 (26/1379)
0.0 (0/86)
1.9 (26/1373)
2.3 (2/88)
1.8 (24/1371)
0.0 (0/154)
2.0 (26/1305)
0.0 (0/118)
1.9 (26/1341)
3.0 (6/203)
1.6 (20/1256)
0.0 (0/43)
1.8 (26/1416)
6.5 (8/124)
1.3 (18/1335)
1.2 (10/816)
2.5 (16/643)
2.4 (7/287)
1.6 (19/1172)
2.2 (22/1002)
0.9 (4/457)
1.9 (20/1069)
1.5 (6/390)
1.8 (20/1139)
1.9 (6/320)
2.3 (14/615)
1.4 (12/844)
% (n/total tested)
0.86 (0.15–4.85)
1.80 (0.38–8.64)
1.04 (0.11–9.94)
–
–
1.23 (0.21–7.16)
–
–
1.56 (0.42–5.76)
–
4.09 (1.18–14.21)
0.48 (0.21–1.09)
2.11 (0.84–5.33)
2.80 (0.89–8.84)
1.35 (0.51–3.58)
1.10 (0.41–2.94)
1.58 (0.69–3.65)
OR (95% CI)
2-Bromo-2-nitropropane-1,3-diol
CI, confidence interval; OR, odds ratio; MCI/MI, methylchloroisothiazolinone/methylisothiazolinone. Logistic regression analysis was used to calculate ORs and 95% CIs. Significant values are in bold type. For each allergen included in the analysis, a logistic regression analysis was conducted. Only significant results are presented. The prevalence within each background variable for the selected allergen is presented with ORs and 95% CIs, for example MCI/MI with a prevalence of 6.6% for an occupational contact dermatitis and OR (95% CI) of 2.38 (1.34–4.23).
Workers in the food industry
Drivers of heavy equipment
Tile setters/terazzo workers
Carpenter
Electricians
Blacksmiths
Mechanics
Workers in metal processing
Machine operators
Construction workers
Painters
Test years
Atopic dermatitis
Age group
Hand dermatitis
Sex
Occupational
occupational classification
Table 4. Percentages of positive reactions to selected allergens of special interest included in the European baseline series in subgroups of patients defined by background variables and
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
that contact allergy to 2-bromo-2-nitropropane-1,3-diol is significantly associated with the group of blue-collar workers (Table 3). Painters are mainly affected by it (OR 4.09; 95% CI 1.18–14.21), and, to our knowledge, this is the first study describing a significant association between contact allergy to 2-bromo-2-nitropropane-1,3diol and painters. The Danish Contact Dermatitis Group has previously pointed out that a high prevalence of sensitization to 2-bromo-2-nitropropane-1,3-diol is found in painters (9). The prevalence of contact allergy to epoxy resin for blue-collar workers was 4.1% (60/1469), and was associated with the occupational group of blue-collar workers (OR 3.87; 95% CI 2.22–6.75). Other studies have presented prevalence rates of contact allergy to epoxy resin ranging from 0.9% to 12.4% for selected occupational groups and in larger patient-based studies (6–9, 18, 19). The prevalence of contact allergy to epoxy resin in blue-collar workers was found to be higher among older individuals (4.8%) than among younger individuals (2.6%). This may be explained by the fact that bluecollar workers working with epoxy resin need special skills, and therefore the blue-collar workers are better educated and older than less skilled manual workers and younger employees. A recent Danish study illustrated the problems with working with epoxy resin, as only onethird of patients with contact dermatitis caused by epoxy resin used protective gloves, only half of patients had participated in a compulsory educational programme, and over half of the workers commencing work with epoxy resin had developed contact dermatitis within 1 year (7). Our data did not show any significant increase in contact allergy to epoxy resin over the time period of the study (OR 0.76; 95% CI 0.44–1.31) (Table 4). A recent German study, on the other hand, found an alarming and increasing trend for contact allergy to epoxy resin among workers in the building trades (6). This is probably attributable to differences in the study periods, as our data are relatively new. Contact allergy to epoxy resin was observed significantly more often in construction workers and tile setters/terrazzo workers, which is in accordance with previous studies (7, 9). A limitation is that only patch test data for epoxy resin in the European baseline series were included. A previous study found that up to 17% of epoxy-allergic patients were not found by testing only with the European baseline series (19). Diglycidyl ether of bisphenol F is less often used as a chemical to produce epoxy resin than, for example, bisphenol A. Some 95% of all epoxy resins consist of a glycidyl ether group formed by the reaction of bisphenol A with epichlorohydrin (20). In blue-collar workers,
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the prevalence of bisphenol F allergy was 21.4% (95% CI 11.6–31.3), and was associated with occupational dermatitis (OR 28.58; 95% CI 1.52–537.35). Often, the allergen of bisphenol F is not included in epidemiological analyses (6, 7, 9). A high prevalence of 6.1% (89/1466) of contact allergy to methyldibromo glutaronitrile was found among blue-collar workers (Table 3). Since 2008, no cosmetics available for the European consumer have contained the preservative methyldibromo glutaronitrile. Hence, a decreasing time trend for contact allergy to methyldibromo glutaronitrile has been observed since the imposition of the regulatory intervention (21). Contact allergy to methyldibromo glutaronitrile was significantly associated with the group of blue-collar workers as compared with controls (OR 1.40; 95% CI 1.01–1.94). Among blue-collar workers, a significantly decreasing time trend for sensitization to methyldibromo glutaronitrile was observed (OR 0.58; 95% CI 0.37–0.90). This study did not present any data on occupational exposures to methyldibromo glutaronitrile, but the association between the group of blue-collar workers and sensitization to methyldibromo glutaronitrile may reflect the fact that methyldibromo glutaronitrile is still allowed for use in industry, for example car care products, detergent products, polishing preparations for floors, adhesives, paints, and metalworking fluids (22). Contact allergy to chromium is, surprisingly, still associated with the blue-collar workers (OR 1.51; 95% CI 1.02–2.24) (Table 3) (5) and is significantly associated with tile setters/terrazzo workers (OR 3.47; 95% CI 1.14–10.54). Since the imposition of the regulatory intervention on restricting chromium in cement, a significant decrease in the prevalence of allergic chromium dermatitis has been observed (5, 6). The intervention prescribes that all manufacturers have to add a reducing agent, for example ferrous sulfate, to their products to reduce the concentration of hexavalent chromium to the permitted level of two parts per million (23). Furthermore, manufacturers should provide information on safe shelf-life, as the reducing agent is effective for only a limited period. Cement products used in controlled and closed systems are not covered by the regulation (23). The association between contact allergy to chromium and tile setters and terrazzo workers may be attributable to previous hexavalent chromium exposure before the control, exposure to cement products not covered by the restriction, or increased leather exposure, for example to leather work gloves. Recently, the EU has introduced a regulation on chromium release from leather articles, in an attempt to halt the increasing trend for chromate dermatitis (24–26).
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
The conclusions to be drawn from this retrospective epidemiological analysis are that blue-collar workers are often affected by occupational related hand dermatitis at a relatively older age. Moreover, the results presented indicate a healthy worker effect among blue-collar workers diagnosed with dermatitis. Allergens such as epoxy resin, MCI/MI, methyldibromo glutaronitrile, 2-bromo-2-nitropropane-1,3-diol and potassium dichromate from the European baseline series are significantly associated with blue-collar workers. Even though the prevalence of contact allergy to methyldibromo glutaronitrile has decreased over time,
owing to regulatory interventions regarding cosmetic products, blue-collar workers still have a high prevalence of sensitization to methyldibromo glutaronitrile. Before possible regulatory interventions regarding the use of methyldibromo glutaronitrile in industry are discussed, it is necessary to determine the current use of methyldibromo glutaronitrile in industry e.g. by studying ingredient lists and Material Safety Data Sheets. Furthermore, it is important to remember that MCI/MI and MI are not only preservatives used in cosmetics with a risk for female consumers, but are also preservatives used in industry with a risk for blue-collar workers.
References 1 Bock M, Schmidt A, Bruckner T, Diepgen T L. Occupational skin disease in the construction industry. Br J Dermatol 2003: 149: 1165–1171. 2 Schwensen J F, Friis U F, Menn´e T, Johansen J D. One thousand cases of severe occupational contact dermatitis. Contact Dermatitis 2013: 68: 259–268. 3 Dickel H, Kuss O, Blesius C R, Schmidt A, Diepgen T L. Occupational skin diseases in Northern Bavaria between 1990 and 1999: a population-based study. Br J Dermatol 2001: 145: 453–462. 4 Eurofound. EWCS. Coding and Classification Standards, 2005. Available at: hhtp://www.eurofound.europa.eu/ surveys/ewcs/2005/classification.htm (last accessed 18 February 2014). 5 Zachariae C O, Agner T, Menn´e T. Chromium allergy in consecutive patients in a country where ferrous sulfate has been added to cement since 1981. Contact Dermatitis 1996: 35: 83–85. 6 Geier J, Krautheim A, Uter W, Lessmann H, Schnuch A. Occupational contact allergy in the building trade in Germany: influence of preventive measures and changing exposure. Int Arch Occup Environ Health 2011: 84: 403–411. 7 Bangsgaard N, Thyssen J P, Menn´e T et al. Contact allergy to epoxy resin: risk occupations and consequences. Contact Dermatitis 2012: 67: 73–77. 8 Rietschel R L, Mathias C G, Fowler J F Jr et al. Relationship of occupation to contact dermatitis: evaluation in patients tested from 1998 to 2000. Am J Contact Dermat 2002: 13: 170–176. 9 Mose A P, Lundov M D, Zachariae C et al. Occupational contact dermatitis in painters: an analysis of patch test data from the Danish Contact Dermatitis Group. Contact Dermatitis 2012: 67: 293–297.
10 Menne T, Johansen J D, Sommerlund M, Veien N K, Danish Contact Dermatitis Group. Hand eczema guidelines based on the Danish guidelines for the diagnosis and treatment of hand eczema. Contact Dermatitis 2011: 65: 3–12. 11 Wilkinson D S, Fregert S, Magnusson B et al. Terminology of contact dermatitis. Acta Derm Venereol 1970: 50: 287–292. 12 Bregnhoj A, Sosted H, Menn´e T, Johansen J D. Healthy worker effect in hairdressing apprentices. Contact Dermatitis 2011: 64: 80–84. 13 Uter W, Geier J, Bauer A, Schnuch A. Risk factors associated with methylisothiazolinone contact sensitization. Contact Dermatitis 2013: 69: 231–238. 14 Lundov M D, Opstrup M S, Johansen J D. Methylisothiazolinone contact allergy – growing epidemic. Contact Dermatitis 2013: 69: 271–275. 15 Geier J, Lessmann H, Schnuch A, Uter W. Recent increase in allergic reactions to methylchloroisothiazolinone/methylisothiazolinone: is methylisothiazolinone the culprit? Contact Dermatitis 2012: 67: 334–341. 16 Urwin R, Wilkinson M. Methylchloroisothiazolinone and methylisothiazolinone contact allergy: a new ‘epidemic’. Contact Dermatitis 2013: 68: 253–255. 17 Friis U F, Menn´e T, Flyvholm M A, Bonde J P, Johansen J D. Occupational allergic contact dermatitis diagnosed by a systematic stepwise exposure assessment of allergens in the work environment. Contact Dermatitis 2013: 69: 153–163. 18 Amado A, Taylor J S. Contact allergy to epoxy resins. Contact Dermatitis 2008: 58: 186–187. 19 Romyhr O, Nyfors A, Leira H L, Smedbold H T. Allergic contact dermatitis caused by
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epoxy resin systems in industrial painters. Contact Dermatitis 2006: 55: 167–172. Andersen K E, White I R, Goossens A. In: Allergens from the European Baseline Series, 5th edition, Johansen J D, Frosch P J, Lepoittevin J P (eds): Berlin, Heidelberg, Springer-Verlag, 2011: pp. 545–591. Johansen J D, Veien N, Laurberg G et al. Decreasing trends in methyldibromo glutaronitrile contact allergy – following regulatory intervention. Contact Dermatitis 2008: 59: 48–51. European Commission, Scientific Committee on Consumer Products. Opinion on Methyldibromoglutaronitrile (sensitisation only), 2006. Available at: http://ec.europa.eu/health/ph_risk/ committees/04_sccp/docs/sccp_o_060.pdf (last accessed 18 February 2014). European Union. Directive 2003/53/EC of the European Parliament and of the Council on Cement, 2003. Available at: http://eur-lex.europa.eu/LexUriServ/ LexUriServ.do?uri=OJ:L:2003:178: 0024:0027:EN:PDF (last accessed 18 February 2014). Thyssen J P, Jensen P, Carlsen B C, Engkilde K, Menne T, Johansen J D. The prevalence of chromium allergy in Denmark is currently increasing as a result of leather exposure. Br J Dermatol 2009: 161: 1288–1293. Nguyen S H, Dang T P, MacPherson C, Maibach H, Maibach H I. Prevalence of patch test results from 1970 to 2002 in a multi-centre population in North America (NACDG). Contact Dermatitis 2008: 58: 101–106. Thyssen J P, Menn´e T, Johansen J D. Hexavalent chromium in leather is now regulated in European Union member states to limit chromium allergy and dermatitis. Contact Dermatitis 2014: 70: 1–2.
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Contact Dermatitis • Original Article
Contact Dermatitis
Occupational contact dermatitis in blue-collar workers: results from a multicentre study from the Danish Contact Dermatitis Group (2003–2012) Jakob F. Schwensen1 , Torkil Menne´ 1 , Niels K. Veien2 , Anne T. Funding2 , Christian Avnstorp3 , Morten Østerballe4 , Klaus E. Andersen5 , Evy Paulsen5 , Charlotte G. Mørtz5 , Mette Sommerlund6 , Anne Danielsen7 , Bo L. Andersen8 , Jens Thormann9 , Ove Kristensen10 , Berit Kristensen10 , Susanne Vissing11 , Niels H. Nielsen12 , Jacob P. Thyssen1 and Jeanne D. Johansen1 1 Department of Dermato-Allergology, National Allergy Research Centre, Copenhagen University Hospital Gentofte, 2900 Hellerup, Denmark, 2 Dermatology Clinic, Fyrkildevej 7, 9220 Aalborg Øst, Denmark, 3 Dermatology Clinic, Roskildevej 264, 2610 Rødovre, Denmark, 4 Dermatology Clinic, Bredgade 30, 7400 Herning, Denmark, 5 Department of Dermatology and Allergy Centre, Odense University Hospital, 5000, Odense C, Denmark, 6 Department of Dermatology,
˚ 1, 1570 Copenhagen, Denmark, 8 Dermatology Clinic, Aarhus University Hospital, 8000 Aarhus, Denmark, 7 Dermatology Clinic, Banegardspladsen Havnepladsen 3A, 5700 Svendborg, Denmark, 9 Dermatology Clinic, Skovgade 23C, 7100 Vejle, Denmark, 10 Dermatology Clinic, Bredgade 50, 4400 Kalundborg, Denmark, 11 Dermatology Clinic, Gl. Hovedgade 14, 2970, Hørsholm, Denmark, and 12 Dermatology Clinic, Bindeleddet 15, 2880, Bagsværd, Denmark doi:10.1111/cod.12277
Summary
Background. Blue-collar workers have a high risk of occupational contact dermatitis, but epidemiological studies are scarce. Objectives. To investigate allergic contact dermatitis in blue-collar workers with dermatitis registered by the Danish Contact Dermatitis Group. Methods. A retrospective analysis of patch test data from 1471 blue-collar workers and 1471 matched controls tested between 2003 and 2012 was performed. A logistic regression was used to test for associations. Results. The blue-collar workers often had occupational hand dermatitis (p < 0.001). Atopic dermatitis was less commonly observed among blue-collar workers (19.6%) than among controls (23.9%) (p = 0.005). Allergens with a statistically significant association with the occupational group of blue-collar workers were epoxy resins, methyldibromo glutaronitrile, 2-bromo-2-nitro-1,3-propanediol, potassium dichromate, and methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI). The following occupations were additionally identified as risk factors for contact sensitization to MCI/MI and MI, epoxy resins, and potassium dichromate, respectively: painting, construction work, and tile setting/terrazzo work. Conclusion. Contact allergy is a major problem among blue-collar workers. The data indicate a healthy worker effect among blue-collar workers diagnosed with dermatitis, as blue-collar workers were diagnosed significantly less often with atopic dermatitis than were controls. Key words: allergic contact dermatitis; atopic dermatitis; blue-collar workers; construction workers; epidemiology; occupational; painters; patch test; terazzo; workers/tile setters.
Correspondence: Jakob F. Schwensen, Department of Dermato-Allergology, National Allergy Research Centre, Copenhagen University Hospital Gentofte, Niels Andersens Vej 65, 2900 Hellerup, Denmark. Tel: +45 39777303; Fax: +45 39777118. E-mail: [email protected] Conflict of interests: The authors declare no conflict of interests. Accepted for publication 20 May 2014
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© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
In spite of epidemiological studies reporting high incidence rates of occupational contact dermatitis among bluecollar workers, patient-based epidemiological studies on allergic contact dermatitis in blue-collar workers are scarce as compared with those on other highrisk occupations, for example hairdressing (1–3). Furthermore, the few studies on blue-collar workers that exist are often not fully comparable, as the definitions of blue-collar worker vary. A blue-collar worker is a highskilled or low-skilled working class person performing manual work involving the following fields: construction, oil extraction, mining, mechanics, machine operation, metal processing, agriculture, and fishing (4). The prevention of allergic contact dermatitis among groups of blue-collar workers has been a priority over the years. After restriction of the level of hexavalent chromium in cement, a significant decrease in allergic cement dermatitis among Danish tile setters was observed (5), and later this was also observed in German construction workers following the implementation of EU law (6). In recent years, sensitization to epoxy resin has increased among workers, for example in the construction industry (6). Despite efforts to lower the incidence of sensitization to epoxy resins in blue-collar workers by a compulsory educational programme before they commenced work with epoxy resins, this is still insufficient, and the incidence of sensitization to epoxy resins is increasing (7, 8). The aim of this study was to conduct a retrospective epidemiological analysis among Danish blue-collar workers with dermatitis evaluated in our clinics.
Methods The Danish Contact Dermatitis Group established the National Database for Contact Allergy in October 2002. Since then, it has monitored contact allergy prevalence rates. Contributors to the database are dermatology departments and private dermatology clinics throughout Denmark. Blue-collar workers
Patch test data for blue-collar workers were extracted from the database by means of the Danish version of the International Standard Classification of Occupation (DISCO88). Consequently, the definition of the blue-collar worker in this study is as follows: a working class person, skilled or unskilled, performing manual work involving the following fields – construction, oil extraction, mechanics, machine operation, and metal processing. DISCO-88 divides occupations into 10 major groups (one digit code). Each major group is further organized
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
into sub-major groups (two digits), minor groups (three digits), and unit groups (four digits). The entire major groups 7 and 8 were extracted and used for the analysis. Unit groups included in the analysis were, for example, ‘painters’ (DISCO-88 code 7141), ‘blacksmiths’ (7220), and ‘mechanics’ (7230). Major group 6, defined as skilled agricultural and fishery workers, was excluded from this analysis. ‘Elementary occupations’ and the minor group ‘mining’ define major group 9, and ‘construction labour’ (931) fulfilled the definition of a blue-collar worker and was included. A total of 86 unit groups were extracted, making a total of 12 occupational groups in the analysis (Table 1). The aggregated occupational classification was made on the basis of well-known subgroups. The occupational group of machine operators was, for example, composed of 16 unit groups from DISCO-88 (Table 1).
Study population and controls
The study population comprised 1471 consecutively registered cases of contact dermatitis among blue-collar workers, registered between January 2003 and December 2012. The control group was based on a 1:1 case–control match. Each blue-collar worker was matched with a patient with dermatitis, that is, a control, not registered as a blue-collar worker in the database. Matching criteria were gender, age, and test year. A total of 1471 controls were included. Data concerning painters registered in the database have been published previously (9). In the analysis by Mose et al., patch test data for painters were extracted from the database by means of DISCO-88 codes 7141 and 7142, between 2001 and 2010.
Demographics and patch test results
Information available from the database included age, occupation, MOALHFA index (Male, Occupation, Atopic dermatitis, Leg dermatitis, Hand dermatitis, Facial dermatitis and Age > 40 years), and patch test results. The diagnosis of atopic dermatitis included past and present atopic dermatitis. All contributors to the database, either dermatologists or physicians supervised by dermatologists, were following uniform guidelines (10). All blue-collar workers and controls were patch tested with the European baseline series. Allergens of potential relevance in relation to occupational exposures of bluecollar workers were, for example metals or allergens used in metalworking fluids, detergent products, and paints. Additionally, it should be noted that not all blue-collar
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
Table 1. The occupational classification of the blue-collar workers based on the DISCO classification 88 Occupation
Unit groups in DISCO-88
Blacksmiths Carpenters Construction workers Drivers of heavy equipment Electricians Machine operators
7213, 7220, 7221, 7223 7121, 7124, 7420, 8285 7129, 7130, 7132, 7134, 9300, 9311, 9312, 9313 8300, 8310, 8320, 8330, 8340 7136, 7137, 8282, 8283 8100, 8140, 8150, 8160, 8170, 8200, 8210, 8220, 8224, 8230, 8231, 8240, 8250, 8260, 8281, 8290 7230 7200, 7210, 7212, 7214, 7222, 7223, 7224, 7240, 7311, 8122, 8123 7140, 7141, 7142 7122, 7123, 7211 7411, 7412, 7413, 7414, 8271, 8272, 8274, 8275, 8276, 8278, 9320 7110, 7113, 7135, 7143, 7150, 7310, 7312, 7313, 7320, 7321, 7323, 7324, 7341, 7343, 7344, 7345, 7346, 7400, 7416, 7432, 7433, 7434, 7435, 7436, 7437, 7440, 8113, 8221, 8223, 8232, 8251, 8252, 8253, 8263, 8264, 8265, 8280, 8284, 8286, 9330
Mechanics Metal-processing workers Painters Tile setters/terazzo workers Workers in the food industry Others
% (n/total blue-collar workers) 6.0 (88/1471) 5.5 (81/1471) 2.9 (43/1471) 7.3 (10/1471) 6.0 (88/1471) 13.9 (205/1471) 10.6 (156/1471) 8.2 (121/1471) 8.4 (124/1471) 3.3 (48/1471) 11.2 (165/1471) 16.6 (244/1471)
DISCO, Danish version of the International Standard Classification of Occupation.
workers were tested with the allergens in the special series, for example methylisothiazolinone (MI). Patch tests were applied to the upper back. The occlusion time was 48 hr, and readings were performed at least once on D3 and D4, and often also on D2 and D7, in accordance with the recommendations of the ICDRG (11). Reactions of strength 1+, 2+ and 3+ were interpreted as positive responses. Irritant reactions, doubtful reactions and negative reactions were interpreted as negative responses. In cases of retesting, patch test data obtained at the first visit were included in the analysis. The concentration of the allergen in the vehicle at the time of patch testing may have varied between the centres and throughout time in specific centres.
Statistics
The data were processed with spss™ (SPSS™ Statistics, Chicago, IL, USA; IBM PASW Statistics) for Windows™, edition 20.0. The chi-square test was applied for analysis of the MOAHLFA index. Associations between occupation and positive patch test reactions to allergens from the European baseline series were expressed as crude odds ratios (ORs) with 95% confidence intervals (CIs). Allergens associated with the occupations of bluecollar workers were selected, and analysed with logistic regression analyses, with the allergen’s positive patch test result as the dependent variable, and with study year (2003–2007 or 2008–2012), gender, atopic dermatitis, occupational relationship, age group (age of ≤ 35 years or age of > 35 years) and occupations (e.g. painter or not painter) as the explanatory variables. Prevalence and
350
asymptotic 95% CIs were calculated for selected allergens that the blue-collar workers were additionally tested with. All p-values are two-sided, and 0.05 was chosen for statistical significance.
Results A total of 1471 blue-collar workers (1148 males and 323 females) were patch tested between 2003 and 2012. Blue-collar workers were defined according to selected unit groups from the International Standard Classification System (Table 1). The mean age of the group of blue-collar workers was 41.9 years (95% CI 41.3–42.6). At the time of patch testing, the youngest blue-collar worker tested was 15 years of age and the oldest tested was 77 years of age. The findings according to the MOAHLFA index (Table 2) show that the contact dermatitis more often had occupational relevance among blue-collar workers than among controls (p < 0.001). For the blue-collar workers, the contact dermatitis was more commonly located on the hands (73.3%) than on the face (18.8%) and legs (7.2%). Blue-collar workers had facial dermatitis (p < 0.001) and atopic dermatitis (p = 0.005) less often than controls. Table 3 shows positive patch test reactions in blue-collars workers and controls regarding selected allergens in the European baseline series. Allergens associated with the occupational group of blue-collar workers were potassium dichromate (OR 1.51; 95% CI 1.02–2.24), epoxy resin (OR 3.87; 95% CI 2.22–6.75), 2-bromo-2-nitropropane-1,3-diol (OR 3.76; 95% CI 1.63–8.71), methyldibromo glutaronitrile (OR 1.40; 95% 1.01–1.94), and methylchloroisothiazolinone
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
Table 2. The distribution of the MOALHFA index of total cases of
contact dermatitis in blue-collar workers and controls Blue-collar workers (n = 1471), % (n) Male Occupation Atopic dermatitis Hand eczema Leg dermatitis Facial dermatitis Age > 40 years
78.0 (1148) 42.1 (620) 19.6 (288) 73.3 (1078) 7.2 (106) 18.8 (276) 58.7 (864)
Controls (n = 1471), % (n) 78.0 (1148) 18.6 (273) 23.9 (351) 58.1 (855) 8.6 (126) 24.5 (360) 58.4 (859)
p-value∗ 1.000 35 years of age) (OR 2.31; 95% CI 1.18–4.52). Moreover, individuals sensitized to potassium dichromate often had atopic dermatitis (OR 2.38; 95% CI 1.35–4.20). Tile setters/terrazzo workers more often had contact allergy to potassium dichromate than other occupational groups (OR 3.47; 95% CI 1.14–10.54) (Table 4). Sensitization to 2-bromo-2-nitropropane-1,3-diol was associated with the occupation of painting (OR 4.09; 95% CI 1.18–14.21).
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
Blue-collar workers were tested with additional selected allergens of occupational relevance, as described in the ‘Methods’ section. All selected allergens were individually analysed with logistic regression, as described in ‘Methods’, and only significant results for the allergens are presented. Frequent allergens were bisphenol F and MI. Bisphenol F gave the most positive reactions in the occupational groups of the blue-collar workers (21.4, 95% CI 11.6–31.3). Of the 15 patients who reacted to bisphenol F, all had a concomitant reaction to epoxy resin. Moreover, the logistic regression analysis of bisphenol F showed that sensitization to bisphenol F was occupationally related (OR 28.58; 95% CI 1.52–537.35). Contact allergy to MI was seen in 5.7% (46/809) (95% CI 4.1–7.3) of the blue-collar workers. Of the 46 patients who reacted to MI, 22 did not have a concomitant reaction to MCI/MI. Contact allergy to MI was often associated with hand dermatitis (OR 3.64; 95% CI 1.03–12.81) and was occupationally related (OR 3.63; 95% CI 1.59–8.23), and painters were at high risk of developing contact allergy to MI (OR 4.87; 95% CI 1.84–12.89). In the first study period, sensitization to MI was seen in 4.6% (10/219) of the blue-collar workers, as compared with 6.2% (36/580) in the second study period, with no significant increase in the prevalence between the two study periods (OR 1.54; 95% CI 0.71–3.32).
Discussion We evaluated the prevalence of contact allergy to various allergens among blue-collar workers in a database of consecutive Danish dermatitis patients patch tested during 2003–2012. The blue-collar workers often have occupational related hand dermatitis, with contact allergy to MCI/MI, methyldibromo glutaronitrile, epoxy resin, 2-bromo-2nitro-1,3-propanediol, and potassium dichromate. Those with contact allergy to epoxy resin had occupationally related dermatitis, and the dermatitis was often seen in construction workers. Contact allergy to MCI/MI and MI was often located on the hands, the dermatitis was occupationally related, and painters, in particular, had a high risk of sensitization to MCI/MI and MI. As expected, the male/female ratio was high (1148 males and 323 females) (6). The blue-collar workers were patch tested at a mean age of 41.9 years (95% CI 41.3–42.6), which correlates with previous findings (6, 9). Moreover, the blue-collar workers were diagnosed significantly less often with atopic dermatitis than were controls (p = 0.005). It is tempting to speculate that a healthy worker effect exists among blue-collar workers,
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Table 3. Positive patch test reactions in blue-collar workers and controls to allergens included in the European baseline series Blue-collar workers, % (n/total tested) Potassium dichromate Neomycin sulfate Thiuram mix p-Phenylenediamine Cobalt chloride Benzocaine Formaldehyde Colophonium Myroxylon pereirae N-Isopropyl-N -phenyl-p-phenylenediamine Lanolin alcohol Epoxy resin p-tert-Butyl formaldehyde resin Fragrance mix II Sesquiterpene lactone mix Quaternium-15 Nickel sulfate Methylchloroisothiazolinone/methylisothiazolinone Mercaptobenzothiazole Primin Clioquinol Parabens mix Mercapto mix Quinoline mix 2-Bromo-2-nitropropane-1,3-diol Iodopropynyl butylcarbamate Hydroxyisohexyl 3-cyclohexene carboxaldehyde Methyldibromo glutaronitrile Fragrance mix II
4.4 (64/1468) 1.2 (17/1468) 2.5 (36/1468) 2.7 (40/1467) 4.6 (68/1468) 0.3 (2/692) 4.2 (61/1468) 4.4 (64/1468) 2.0 (30/1469) 0.9 (7/750) 0.5 (7/1469) 4.1 (60/1469) 1.2 (17/1469) 6.6 (97/1467) 1.0 (15/1467) 2.0 (29/1468) 12.2 (178/1463) 4.2 (61/1469) 1.1 (16/1468) 0.2 (3/1467) 0.9 (6/694) 0.7 (10/1469) 0.9 (13/1469) 1.2 (18/789) 1.8 (26/1459) 1.2 (17/1452) 2.3 (34/1457) 6.1 (89/1466) 4.0 (49/1231)
Controls, % (n/total tested) 2.9 (43/1471) 1.5 (22/1471) 2.5 (37/1471) 3.0 (44/1469) 3.4 (50/1471) 0.3 (2/772) 2.9 (43/1471) 4.4 (64/1470) 2.4 (35/1471) 0.6 (5/792) 0.7 (11/1470) 1.1 (16/1471) 1.8 (27/1471) 7.8 (115/1470) 1.5 (22/1469) 1.4 (20/1471) 12.0 (176/1467) 1.6 (24/1471) 1.0 (14/1471) 0.3 (4/1471) 1.4 (11/788) 0.3 (4/1471) 0.9 (13/1471) 0.9 (13/703) 0.5 (7/1457) 0.6 (8/1451) 2.3 (33/1461) 4.4 (65/1469) 4.4 (54/1233)
OR (95% CI) 1.51 (1.02–2.24) 0.77 (0.41–1.46) 0.97 (0.61–1.55) 0.91 (0.59–1.40) 1.38 (0.95–2.00) 1.12 (0.16–7.94) 1.44 (0.97–2.14) 1.00 (0.70–1.43) 0.86 (0.52–1.40) 1.48 (0.47–4.47) 0.64 (0.25–1.64) 3.87 (2.22–6.75) 0.63 (0.34–1.15) 0.83 (0.63–1.10) 0.68 (0.35–1.32) 1.46 (0.82–2.60) 1.01 (0.81–1.27) 2.61 (1.62–4.21) 1.15 (0.56–2.36) 0.75 (0.17–3.36) 0.62 (0.23–1.67) 2.51 (0.79–8.03) 1.00 (0.46–2.17) 1.24 (0.60–2.55) 3.76 (1.63–8.71) 2.14 (0.92–4.97) 1.03 (0.64–1.67) 1.40 (1.01–1.94) 0.91 (0.61–1.34)
OR, crude odds ratio; 95% CI, 95% confidence intervals. Significant values are in bold type.
and that preventive measures such as career guidance for individuals with atopic dermatitis have worked. Before a final conclusion regarding a healthy worker effect can be drawn, it is important for a similar analysis to be performed among blue-collar apprentices (12). The prevalence rates of contact allergy to MCI/MI and MI were 4.2% (61/1469) and 5.7% (46/809), respectively, which is in accordance with other studies (13, 14). Furthermore, both contact allergy to MCI/MI and contact allergy to MI were significantly associated with the group of painters. A German study investigated the development of contact allergy to MI among workers in high-risk occupations, and, within the groups of blue-collar workers, painters were the only ones with a significantly increased risk of developing MI allergy (13), as previously reported (10). Surprisingly, contact allergy to MCI/MI was not associated with the second study period (2008–2012). Previous studies have found epidemic increases in contact allergy to both MCI/MI and MI (13–16). The lack of a time trend for contact allergy to MCI/MI, is probably attributable to the setup of this study, as only blue-collar workers were included in the analysis.
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The increased incidence of MCI/MI and MI contact allergy in recent years is mainly a result of the increased use of MI as a preservative in cosmetics (13, 14, 16), but a reasonably high number of occupational cases have been reported (13). Of the blue-collar workers with positive patch test reactions to MI, 52% (24/46) had a concomitant reaction to MCI/MI. These findings correlate with recent epidemiological studies on the increasing trend of MI allergy (13–16), and further supports the idea that MI is an independent sensitizer (14). The development of allergic dermatitis caused by MI in blue-collar workers could be the result of the increased use of MI in the industry, for example in paints. Moreover, ingredient lists and Material Safety Data Sheets are often incomplete. A recent Danish study found that systemic stepwise exposure assessment should be prioritized, as it can increase the number of patients diagnosed with occupational allergic contact dermatitis through the study of ingredient lists and Material Safety Data Sheets (17). The preservative 2-bromo-2-nitro-1,3-propanediol is widely used in cosmetics and in industry. Our data indicate
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355 3.3 (44/1345)
4.3 (56/1305) 3.0 (5/164)
Yes
2.8 (3/108)
No
4.3 (58/1361)
Yes
6.3 (3/48)
No
4.1 (58/1421)
Yes
0.0 (0/81)
No
4.4 (61/1388)
Yes
1.1 (1/88)
Yes
No
4.3 (60/1381)
No
4.0 (55/1381) 6.8 (6/88)
No
Yes
Yes
4.1 (54/1313) 4.5 (7/156)
No
4.2 (56/1349)
1.20 (0.37–3.94)
1.26 (0.31–5.16)
2.26 (0.54–9.55)
–
0.44 (0.05–3.68)
2.57 (0.80–8.29)
1.86 (0.60–5.74)
0.88 (0.25–3.12)
3.7 (6/163)
6.4 (83/1303)
2.4 (4/164)
4.3 (56/1305)
6.1 (83/1358)
12.5 (6/48)
5.9 (83/1418)
4.9 (4/81)
6.1 (85/1385)
5.7 (5/88)
6.1 (84/1378)
8.0 (7/87)
5.9 (82/1379)
3.8 (6/1310)
6.3 (83/1310)
6.7 (8/120)
6.0 (81/1346)
9.8 (20/204)
5.5 (69/1262)
0.0 (0/43)
6.3 (89/1423)
4.8 (6/124)
6.2 (83/1342)
4.5 (37/816)
8.0 (52/650)
4.2 (12/288)
6.5 (77/1178)
7.8 (78/1006)
2.4 (11/460)
6.2 (67/1074)
5.6 (22/392)
5.9 (67/1145)
6.9 (22/321)
7.3 (45/619)
5.2 (44/847)
% (n/total tested)
5.6 (6/108)
1.52 (0.42–5.54)
4.45 (1.35–14.73)
2.21 (0.59–8.28)
–
0.70 (0.14–3.60)
1.52 (0.47–4.86)
1.12 (0.31–4.00)
1.19 (0.41–3.44)
4.83 (1.36–17.17)
2.70 (0.97–7.51)
0.76 (0.44–1.31)
0.47 (0.19–1.14)
1.69 (0.86–3.32)
0.41 (0.23–0.75)
0.80 (0.40–1.60)
3.82 (2.08–7.02)
OR (95% CI)
0.70 (0.26–1.87)
1.01 (0.37–2.77)
2.25 (0.79–6.45)
1.05 (0.32–3.39)
1.10 (0.38–3.21)
1.36 (0.51–3.59)
0.82 (0.30–2.26)
1.12 (0.45–2.77)
1.55 (0.75–3.18)
–
0.83 (0.31–2.22)
0.58 (0.37–0.90)
0.82 (0.43–1.56)
3.24 (1.67–6.29)
1.13 (0.67–1.92)
0.72 (0.41–1.24)
1.49 (0.94–2.36)
OR (95% CI)
Methyldibromo glutaronitrile
3.7 (4/108)
4.1 (56/1361)
12.5 (6/48)
3.8 (54/1421)
4.9 (4/81)
4.0 (56/1388)
0.0 (0/88)
4.3 (60/1381)
2.3 (2/88)
4.2 (58/1381)
3.8 (6/156)
4.1 (54/1313)
3.3 (4/120)
4.3 (58/1349) 2.5 (3/120)
No
Yes
0.84 (0.21–3.39)
4.4 (9/205)
4.1 (52/1264) 3.9 (8/205)
4.1 (52/1264)
11.6 (5/43)
3.9 (55/1426)
8.1 (10/124)
3.7 (50/1345)
3.8 (31/817)
4.4 (29/652)
2.1 (6/288)
4.6 (54/1181)
4.8 (48/1008)
2.6 (12/461)
3.5 (38/1077)
5.6 (22/392)
4.1 (47/1147)
4.0 (13/322)
6.5 (40/620)
2.4 (20/849)
% (n/total tested)
Yes
1.58 (0.57–4.42)
–
5.52 (2.16–14.13)
1.16 (0.67–2.01)
0.60 (0.25–1.44)
3.43 (1.55–7.56)
2.02 (0.92–4.45)
0.71 (0.37–1.39)
2.38 (1.34–4.23)
OR (95% CI)
Epoxy resin
No
4.3 (61/1426) 0.0 (0/43)
No
13.7 (17/124)
Yes
Yes
No
3.7 (24/652) 4.5 (37/817)
2003–2007
2008–2012
4.7 (55/1181) 2.1 (6/288)
5.3 (53/1008)
Age > 35 years
Yes
1.7 (8/461)
Age ≤ 35 years
No
2.0 (8/392) 4.9 (53/1077)
No
4.0 (46/1147)
Yes
4.7 (15/322)
Female
6.6 (41/620)
Yes
Male
2.4 (20/849)
No
% (n/total tested)
MCI/MI
3.1 (5/163)
4.5 (59/1303)
8.4 (9/107)
4.0 (55/1359)
12.5 (6/48)
4.1 (58/1418)
4.9 (4/81)
4.3 (60/1385)
4.5 (4/88)
4.4 (60/1378)
3.4 (3/88)
4.4 (61/1378)
1.9 (3/156)
4.7 (61/1310)
4.2 (5/120)
4.4 (59/1346)
3.4 (7/205)
4.5 (57/1261)
7.0 (3/43)
4.3 (61/1423)
3.2 (4/124)
4.5 (60/1342)
4.2 (34/815)
4.6 (30/651)
7.0 (20/287)
3.7 (44/1179)
5.2 (52/1005)
2.6 (12/461)
4.8 (52/1075)
3.1 (12/391)
4.2 (48/1144)
5.0 (16/322)
4.4 (27/618)
4.4 (37/848)
% (n/total tested)
0.76 (0.26–2.28)
2.24 (0.86–5.86)
3.47 (1.14–10.54)
1.47 (0.43–5.03)
1.12 (0.34–3.73)
0.86 (0.23–3.30)
0.53 (0.14–2.01)
0.99 (0.33–3.01)
0.78 (0.29–2.10)
1.91 (0.49–7.47)
0.77 (0.24–2.51)
0.83 (0.49–1.38)
2.38 (1.35–4.20)
2.31 (1.18–4.52)
1.94 (0.99–3.78)
0.66 (0.34–1.27)
1.04 (0.60–1.79)
OR (95% CI)
Potassium dichromate
1.2 (2/163)
1.9 (24/1296)
2.8 (3/108)
1.7 (23/1351)
2.1 (1/48)
1.8 (25/1411)
0.0 (0/80)
1.9 (26/1379)
0.0 (0/86)
1.9 (26/1373)
2.3 (2/88)
1.8 (24/1371)
0.0 (0/154)
2.0 (26/1305)
0.0 (0/118)
1.9 (26/1341)
3.0 (6/203)
1.6 (20/1256)
0.0 (0/43)
1.8 (26/1416)
6.5 (8/124)
1.3 (18/1335)
1.2 (10/816)
2.5 (16/643)
2.4 (7/287)
1.6 (19/1172)
2.2 (22/1002)
0.9 (4/457)
1.9 (20/1069)
1.5 (6/390)
1.8 (20/1139)
1.9 (6/320)
2.3 (14/615)
1.4 (12/844)
% (n/total tested)
0.86 (0.15–4.85)
1.80 (0.38–8.64)
1.04 (0.11–9.94)
–
–
1.23 (0.21–7.16)
–
–
1.56 (0.42–5.76)
–
4.09 (1.18–14.21)
0.48 (0.21–1.09)
2.11 (0.84–5.33)
2.80 (0.89–8.84)
1.35 (0.51–3.58)
1.10 (0.41–2.94)
1.58 (0.69–3.65)
OR (95% CI)
2-Bromo-2-nitropropane-1,3-diol
CI, confidence interval; OR, odds ratio; MCI/MI, methylchloroisothiazolinone/methylisothiazolinone. Logistic regression analysis was used to calculate ORs and 95% CIs. Significant values are in bold type. For each allergen included in the analysis, a logistic regression analysis was conducted. Only significant results are presented. The prevalence within each background variable for the selected allergen is presented with ORs and 95% CIs, for example MCI/MI with a prevalence of 6.6% for an occupational contact dermatitis and OR (95% CI) of 2.38 (1.34–4.23).
Workers in the food industry
Drivers of heavy equipment
Tile setters/terazzo workers
Carpenter
Electricians
Blacksmiths
Mechanics
Workers in metal processing
Machine operators
Construction workers
Painters
Test years
Atopic dermatitis
Age group
Hand dermatitis
Sex
Occupational
occupational classification
Table 4. Percentages of positive reactions to selected allergens of special interest included in the European baseline series in subgroups of patients defined by background variables and
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
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OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
that contact allergy to 2-bromo-2-nitropropane-1,3-diol is significantly associated with the group of blue-collar workers (Table 3). Painters are mainly affected by it (OR 4.09; 95% CI 1.18–14.21), and, to our knowledge, this is the first study describing a significant association between contact allergy to 2-bromo-2-nitropropane-1,3diol and painters. The Danish Contact Dermatitis Group has previously pointed out that a high prevalence of sensitization to 2-bromo-2-nitropropane-1,3-diol is found in painters (9). The prevalence of contact allergy to epoxy resin for blue-collar workers was 4.1% (60/1469), and was associated with the occupational group of blue-collar workers (OR 3.87; 95% CI 2.22–6.75). Other studies have presented prevalence rates of contact allergy to epoxy resin ranging from 0.9% to 12.4% for selected occupational groups and in larger patient-based studies (6–9, 18, 19). The prevalence of contact allergy to epoxy resin in blue-collar workers was found to be higher among older individuals (4.8%) than among younger individuals (2.6%). This may be explained by the fact that bluecollar workers working with epoxy resin need special skills, and therefore the blue-collar workers are better educated and older than less skilled manual workers and younger employees. A recent Danish study illustrated the problems with working with epoxy resin, as only onethird of patients with contact dermatitis caused by epoxy resin used protective gloves, only half of patients had participated in a compulsory educational programme, and over half of the workers commencing work with epoxy resin had developed contact dermatitis within 1 year (7). Our data did not show any significant increase in contact allergy to epoxy resin over the time period of the study (OR 0.76; 95% CI 0.44–1.31) (Table 4). A recent German study, on the other hand, found an alarming and increasing trend for contact allergy to epoxy resin among workers in the building trades (6). This is probably attributable to differences in the study periods, as our data are relatively new. Contact allergy to epoxy resin was observed significantly more often in construction workers and tile setters/terrazzo workers, which is in accordance with previous studies (7, 9). A limitation is that only patch test data for epoxy resin in the European baseline series were included. A previous study found that up to 17% of epoxy-allergic patients were not found by testing only with the European baseline series (19). Diglycidyl ether of bisphenol F is less often used as a chemical to produce epoxy resin than, for example, bisphenol A. Some 95% of all epoxy resins consist of a glycidyl ether group formed by the reaction of bisphenol A with epichlorohydrin (20). In blue-collar workers,
354
the prevalence of bisphenol F allergy was 21.4% (95% CI 11.6–31.3), and was associated with occupational dermatitis (OR 28.58; 95% CI 1.52–537.35). Often, the allergen of bisphenol F is not included in epidemiological analyses (6, 7, 9). A high prevalence of 6.1% (89/1466) of contact allergy to methyldibromo glutaronitrile was found among blue-collar workers (Table 3). Since 2008, no cosmetics available for the European consumer have contained the preservative methyldibromo glutaronitrile. Hence, a decreasing time trend for contact allergy to methyldibromo glutaronitrile has been observed since the imposition of the regulatory intervention (21). Contact allergy to methyldibromo glutaronitrile was significantly associated with the group of blue-collar workers as compared with controls (OR 1.40; 95% CI 1.01–1.94). Among blue-collar workers, a significantly decreasing time trend for sensitization to methyldibromo glutaronitrile was observed (OR 0.58; 95% CI 0.37–0.90). This study did not present any data on occupational exposures to methyldibromo glutaronitrile, but the association between the group of blue-collar workers and sensitization to methyldibromo glutaronitrile may reflect the fact that methyldibromo glutaronitrile is still allowed for use in industry, for example car care products, detergent products, polishing preparations for floors, adhesives, paints, and metalworking fluids (22). Contact allergy to chromium is, surprisingly, still associated with the blue-collar workers (OR 1.51; 95% CI 1.02–2.24) (Table 3) (5) and is significantly associated with tile setters/terrazzo workers (OR 3.47; 95% CI 1.14–10.54). Since the imposition of the regulatory intervention on restricting chromium in cement, a significant decrease in the prevalence of allergic chromium dermatitis has been observed (5, 6). The intervention prescribes that all manufacturers have to add a reducing agent, for example ferrous sulfate, to their products to reduce the concentration of hexavalent chromium to the permitted level of two parts per million (23). Furthermore, manufacturers should provide information on safe shelf-life, as the reducing agent is effective for only a limited period. Cement products used in controlled and closed systems are not covered by the regulation (23). The association between contact allergy to chromium and tile setters and terrazzo workers may be attributable to previous hexavalent chromium exposure before the control, exposure to cement products not covered by the restriction, or increased leather exposure, for example to leather work gloves. Recently, the EU has introduced a regulation on chromium release from leather articles, in an attempt to halt the increasing trend for chromate dermatitis (24–26).
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Contact Dermatitis, 71, 348–355
OCCUPATIONAL CONTACT DERMATITIS IN BLUE-COLLAR WORKERS • SCHWENSEN ET AL.
The conclusions to be drawn from this retrospective epidemiological analysis are that blue-collar workers are often affected by occupational related hand dermatitis at a relatively older age. Moreover, the results presented indicate a healthy worker effect among blue-collar workers diagnosed with dermatitis. Allergens such as epoxy resin, MCI/MI, methyldibromo glutaronitrile, 2-bromo-2-nitropropane-1,3-diol and potassium dichromate from the European baseline series are significantly associated with blue-collar workers. Even though the prevalence of contact allergy to methyldibromo glutaronitrile has decreased over time,
owing to regulatory interventions regarding cosmetic products, blue-collar workers still have a high prevalence of sensitization to methyldibromo glutaronitrile. Before possible regulatory interventions regarding the use of methyldibromo glutaronitrile in industry are discussed, it is necessary to determine the current use of methyldibromo glutaronitrile in industry e.g. by studying ingredient lists and Material Safety Data Sheets. Furthermore, it is important to remember that MCI/MI and MI are not only preservatives used in cosmetics with a risk for female consumers, but are also preservatives used in industry with a risk for blue-collar workers.
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