Decreasing allergic contact dermatitis frequency through dermatotoxicologic and epidemiologic based intervention?

Factors influencing field testing of alcohol-based hand rubs

BACKGROUND

According to the World Health Organization guidelines, field tests, in the context of a bid for the supply of alcohol-based hand rubs, should take into account climatic region, test period, products already in use, and type of use (hygienic or surgical) when assessing tolerance. This laborious method is often contested.

OBJECTIVE

To conduct a post hoc analysis of the data of a large bid, including 5 factors, to validate the relevance of their inclusion.

METHODS

For the purposes of the bid, products were compared in terms of the 4 World Health Organization tolerance criteria (appearance, intactness, moisture content, sensation) during product testing and were separated into groups on the basis of the studied factors. The post hoc analysis method included (1) comparison of the mean before-and-after difference based on the self-evaluation of the skin with the 4 World Health Organization tolerance criteria, between climatic regions, periods, products in use, test product, and the type of use; (2) generalized linear models, taking into account all studied factors.

RESULTS

The analysis included data for 1,925 pairs of professionals. The means of the differences observed were independently and significantly associated with the test period (P<.001), the hygienic or surgical use (P=.010 to .041, not significant for appearance), the product already in use (significant for appearance P=.021), and the test product (P<.001). The association with climatic region was found to be significant only in the nonadjusted analysis.

CONCLUSION

The type of use, the test period, and the product in use should be taken into account when designing field tests of alcohol-based hand rubs.

In vitro release dynamics of thiram fungicide from starch and poly(methacrylic acid)-based hydrogels

In order to make the judicious use of pesticide/fungicide and to maintain the environment and ecosystem we have developed the starch and poly(methacrylic acid)-based agrochemical delivery system for their controlled and sustained release. The delivery device was prepared by using N,N'-methylenebisacrylamide (N,N'-MBAAm) as crosslinker and was characterized with FTIR, TGA and with swelling studies as a function of time and crosslinker concentration. This article discusses the swelling kinetics of polymer matrix and release dynamics of thiram (fungicide) from hydrogels for the evaluation of the diffusion mechanism and diffusion coefficients. The values of the diffusion exponent 'n' for both cases, that is the swelling of hydrogels and for the release of thiram from the hydrogels have been observed between 0.7 and 0.9 when the concentration of the crosslinker in the polymers were varied from 6.49x10(-3) to 32.43x10(-3) moles/L. It is inferred from the values of the 'n' that Non-Fickian diffusion mechanism has occurred in both the cases.

Prevalence of patch test results from 1970 to 2002 in a multi-centre population in North America (NACDG)

BACKGROUND

The North American Contact Dermatitis Group (NACDG) has members who assess subjects with suspected allergic contact dermatitis (ACD) and patch tests them with the same screening allergens using a standardized procedure permitting analysis of long-term trends in patch test reactions.

OBJECTIVE

This study reports the trends in prevalence patch test positivity of allergens by pooling data collected by the NACDG between 1970 and 2002.

PATIENTS/METHODS

Patients were tested with the screening series of allergens, using a standardized technique. Data from these patients were recorded on a standard computer entry form and analysed. More than 100 allergens were tested on over 34,000 patients during several patch studies between the period. The Cochran-Armitage test of trend is used to evaluate changes in prevalence over time.

RESULTS

4 trends are noticed: (1) The incidence of presumed allergic nickel (P < 0.0001) and quaternium-15 (P < 0.0001) reactions rose with consistency over the years. (2) While that of cinnamic aldehyde (P = 0.21) and p-phenylenediamine (P < 0.0001) decreased. (3) The prevalence of positive reactions for potassium dichromate (P < 0.0001) shows an initial steady decrease but then a sharp increase starting from the 1996 period. (4) In contrast, thiuram (P = 0.0008) and neomycin (P < 0.0001) show an initial general increase, with a sharp decrease between 1998 and 2002.

CONCLUSION

Implications for opportunities to prevent ACD by utilizing less-allergenic alternatives appear robust; however, we do not wish to over generalize interpretations because of important limitations.

Controlled release of thiram fungicide from starch-based hydrogels

In order to make the judicious use of thiram fungicide and to exploit the potential of agri-polymers, we have developed the starch- poly(acrylamide) and starch-poly(acrylic acid) based agrichemical delivery system (hydrogels) for its controlled and sustained release. Polymeric networks have been prepared by using N,N'-methylenebisacrylamide (N,N-MBAAm) as crosslinker and ammonium persulfate (APS) as initiator and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and swelling studies. Release dynamics of thiram fungicide from polymeric matrices has been studied for the evaluation of the diffusion mechanism and diffusion coefficients. It has been established that Non-Fickian diffusion mechanism has occurred for the release of thiram from these polymeric matrices. Furthermore, the initial rate of diffusion of thiram from these polymeric matrices is more as compared to the late stages of diffusion, which is analogous to the trends obtained for the diffusion of water molecules from these polymer matrices.

Effect of glutathione depletion on apoptosis induced by thiram in Chinese hamster fibroblasts

Fungicide thiram, which is also known as an inducer of allergic contact dermatitis (ACD), was used as a model compound of thiuram chemicals, and its cellular effects were investigated in cultured Chinese hamster V79 cells. The level of intracellular reduced glutathione (GSH), protein sulfhydryl (PSH) groups, protein carbonyls (PC), membrane lipid peroxidation reflected by enhanced thiobarbituric acid reactive substrates (TBARS) production, as well as apoptotic effect were determined. The apoptosis induction was determined by assessing DNA fragmentation by TUNEL, annexin V binding, and caspases activation assays, using fluorescent microscope or flow cytometry, respectively. The concentrations of thiram required to induce cellular GSH depletion (by 40-50%), protein, and membrane lipid peroxidation (2-fold, and 1.7-fold, respectively), as well as to induce apoptosis in V79 Chinese hamster fibroblasts without causing necrosis through cytotoxic effects were between 50-100 microM. To investigate the role of decreased GSH content in the toxicity of thiram, GSH level was modified prior to exposure. Pretreatment of V79 cells with N-acetyl-L-cysteine (NAC), a GSH biosynthesis precursor, prevented GSH decrease, PC and TBARS production, as well as caspases activation induced by thiram exposure. On the other hand, thiram effects were enhanced by the previous depletion of cellular GSH by L-buthionine-(S,R)-sulfoximine (BSO).

Thresholds of elicitation depend on induction conditions. Could low level exposure induce sub-clinical allergic states that are only elicited under the severe conditions of clinical diagnosis?

While numerous studies have examined dose/response relationships occurring in the experimental induction of contact allergic dermatitis, fewer have examined the effects of varying the doses of both induction and challenge. Recently published studies have however done this and they all show the same remarkable observation: the threshold of elicitation decreases as the doses used to induce the allergy increase. This has important implications. One is that it may be more complicated to determine clear threshold doses below which allergic responses are not seen. It is also proposed that normal exposure to weak allergens such as some fragrance materials may induce "sub-clinical" allergic states which will not be elicited under these same exposure conditions but which may become apparent under the more severe conditions of clinical diagnosis. This may explain why the prevalence of Patch test reactions to some fragrance materials is apparently increasing in the absence of any clearly documented "epidemic" of consumer complaints.

Frequency of contact allergy in German children and adolescents patch tested between 1995 and 2002: results from the Information Network of Departments of Dermatology and the German Contact Dermatitis Research Group

Allergic contact dermatitis (ACD) affects approximately 7% of the general population. To evaluate the frequency of ACD in children, we analysed patch test results collected by the Information Network of Departments of Dermatology between 1995 and 2002. Data of 285 children (6-12 year) and 2175 adolescent patients (13-18 year) were analysed to determine the frequency of sensitization to the 30 most common contact allergens, adjusting for age and sex. As control group, we defined adult patients (60-66 year, n = 7904). The top allergens in children were thimerosal, gentamicin sulphate, nickel-II-sulphate, ammoniated mercury, cobalt-II-chloride, fragrance mix, bufexamac, Compositae mix, propylene glycol and turpentine. The overall proportion of sensitized patients according to the patch test results was 52.6% in the children group compared to 49.7% in the adolescent group. These findings were similar in the adult group at 52.2%. The detailed analysis regarding sex, occupation, atopy, site of eczema and age showed distinct patterns in each group indicating age-specific exposures. Atopy-related diseases were more common in children compared to adults. On the basis of the data of this study, the relationship between atopy and the risk of development of ACD, at least in children, needs further investigation.

Contact allergy to fragrances: frequencies of sensitization from 1996 to 2002. Results of the IVDK*

Increasing frequencies of sensitization to the fragrance mix (FM) have been acknowledged as a serious problem for many years. It is well known that the single compounds (SCs) of the FM contribute differently to the FM patch rest reactions. In this study, we were interested in the time trends of the FM, the SCs, Myroxylon pereirae resin (MP; balsam of Peru) and oil of turpentine (OT) as possible further indicators of perfume allergy and analysed the data collected by the Information Network of Departments of Dermatology multicentre project from 1996 to 2002. During the study period (1996-2002), the FM [8% petrolatum (pet.)], MP (25% pet.) and OT (1% pet.) were tested in 59,298, 59,334 and 59,478 patients, respectively. SCs were tested in a selected group of patients, ranging from n = 1083 to n = 1924 per year. A significant increase in the proportions of patients with positive reactions to FM, MP and OT between 1996 and 1998 is noted, and a significant decline from 1999 to 2002 (Cochrane Armitage trend test, P < 0.0001). The highest frequency of sensitization to the FM was 13.1% in 1999, and the lowest 7.8% in 2002. The number of concomitant reactions to OT, a surrogate marker for terpenes, in FM-positive patients was significantly increased between 1997 and 1999. Reactions to SCs in FM-positive patients were observed in 29.9% (oak moss absolute) to 5.9% (geraniol). There was no time trend in reactions to SCs, although the relative share was increased for isoeugenol, cinnamic aldehyde and geraniol in 1999. In summary, we report for the first time, a significant decline in sensitization to the FM, very probably due to a reduced exposure (less potent allergens used in fine fragrances, possibly less use of natural ingredient-based cosmetics and lowered use concentration of important fragrance allergens). The differences in ranking of SCs could stimulate (a) a redefinition of the FM and (b) a differentiated preventive and regulatory approach, with oak moss and isoeugenol being regulated strictly by prohibition, concentration limits further reconsidered and/or health warnings and clearly less noxious substances like geraniol treated less restrictively.