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Giornale Italiano di Dermatologia e Venereologia 1999 August;134(4):299-302


language: English

Contact sensitization to Thimerosal. Relationship with atopy

Ingordo V. 1, D’Andria C. 2, D’Andria G. 1, Tamburelli A. 3, Maffeo N. 4

1 Italian Navy Main Hospital “M. O. G. Venticinque”, Department of Dermatology, Aerobiologic Testing Station, Taranto, Italy; 2 ”S. Maugeri” Foundation, Medical Center, Taranto, Italy; 3 Italian Navy Autonomous Infirmary, Service of Surgery; 4 Medical-Surgical Department, Rome, Italy


Background. The reported sensitization rates to Thimerosal (TS) vary widely among the published studies in a review of the literature. A significant frequency of positive reactions to patch test to TS has been reported in young people and other groups with no history of exposure to this aptene. On this basis, epidemiological study has been carried out on a sample group of subjects (predominantly young sailors and soldiers) who underwent patch testing, in order to evaluate the frequency of contact sensitivity to TS and its association with atopy.
Methods. GIRDCA series patch tests have been performed in 58 male patients affected by Atopic Dermatitis (AD), diagnosed on the basis of the Hanifin-Raijka criteria. Moreover, two groups of military volunteers were subjected to patch testing with TS (0.1% in pet.): 34 atopic subjects (skin prick test positive for pneumoallergens and high level of total serum IgE), with no history of dermatitis (atopic group); 40 healty subjects (skin prick test negative for pneumoallergens and normal level of total serum IgE), with no history of dermatitis (healty group). The concentration of TS contained in the G.I.R.D.C.A. series and employed for testing the control groups was of 0.1%.
Results. The overall TS-positivity within the AD sample was 15.5% (9/58). The mean age of the TS-positive subjects was similar (21.1 years; 18-26 years) to that of the TS-negative subjects (21.3 years; 17-33 years). The TS-positivity was not clinically relevant in any case. The TS-positive test of the AD sample was stratified according to the final diagnosis obtained from: collected clinical histories, results of patch test, skin prick tests for pneumoallergens/foods and total serum IgE. The following data resulted: TS-pos./allergic contact dermatitis associated to atopic dermatitis (ACD+AD) 3/17 (17.6%); TS-pos./atopic dermatitis 6/41 (14.6%), (AD). The two control groups demonstrated the following TS-positivities: 2/34 (5.8%) in the atopic group and 1/40 (2.5%) in the healthy group. In none of the total three TS-positive subjects the sensitization was clinically relevant. The higher prevalence rate of TS-positivity in subjects with AD and with ACD+AD was statistically significant when compared with that of the group of healty controls (p<0.05).
Conclusions. The conclusion is drawn that AD is statistically related to positive reactions to TS, tested in concentration of 0.1%. This relationship may be explained by these considerations: 1. dysfunctional lymphocytes wich are present in AD may play a role in the development of sensitization; 2. the frequent use by atopic individuals, with coexistent rhinoconjunctivitis or asthma, of extracts for specific hyposensitization terapy and such topical preparations results in increased exposure to TS; 3. the hyperreactivity of the skin of AD patients may explain the positivity to TS in the high concentration of 0.1%; 4. tetanus toxoid vaccination in atopic military personnel could be expected to lean more frequently to sensitization to TS. Moreover, it may be necessary to test for TS-positivity in AD patients using the optimal eliciting patch test concentration of 0.05%.

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