S. H. Wakelin

The frequency of fragrance allergy in a patch-test population over a 17-year period

Fragrances are widely encountered in our daily environment and are known to be a common cause of allergic contact dermatitis. We have reviewed our patch test data from 1980 to 1996 to establish whether the pattern of fragrance allergy has changed with time. During this period, 25,545 patients (10,450 male, 15,005 female) were patch tested with the European standard series. The mean annual frequency of positive reactions to the fragrance mix was 8·5% in females (range 6·1–10·9) and 6·7% in males (range 5·1–12·9). Females were 1·3 times more likely to be allergic to fragrance (P < 0·001, 95% confidence interval, CI 1·17–1·41). Males with fragrance allergy were older than females by 5·6 years (mean age 48·2 vs. 42·6 years; P < 0·001, 95% CI 3·9–7·3). The incidence of a concomitant positive patch test to balsam of Peru in fragrance‐sensitive patients showed wide variation, suggesting that it is not a reliable marker of fragrance allergy. There was a positive correlation between the isomers isoeugenol and eugenol. Oak moss remained the most common overall allergen throughout the study, positive in 38·3% of females and 35·6% of males who were tested to the constituents of the fragrance mix. During the period of the study the incidence of positive tests to oak moss increased by 5% yearly (P = 0·001, 95% CI 2·2–8·7). The frequency of allergic reactions to eugenol and geraniol remained relatively constant. Isoeugenol and alpha‐amyl cinnamic aldehyde sensitivity increased and hydroxycitronellal showed a slow decline. There was a striking reduction in the frequency of sensitivity to cinnamic aldehyde (by 18% yearly; P < 0·001, 95% CI 14·3–21·0) and cinnamic alcohol (by 9% yearly; P < 0·001, 95% CI 5·2–12·9); these are now uncommon fragrance allergens. These data show temporal trends which may reflect the frequency of population exposure to individual fragrances.

Association of TNFA gene polymorphism at position -308 with susceptibility to irritant contact dermatitis.

Abstract Mechanisms underlying susceptibility to skin irritants are not clearly understood. Cytokines play a key role in inflammation, and functional polymorphisms in cytokine genes may affect responses to irritants. We investigated the relationship between polymorphism in the tumor necrosis factor (TNF) α-chain gene and responses to irritants. Volunteers (n=221) tested with sodium dodecyl sulfate (SDS) and benzalkonium chloride (BKC) were divided into responders and nonresponders and high and low irritant-threshold groups. DNA was assayed for the TNF-308 polymorphism by a polymerase chain reaction-restriction fragment length polymorphism method. There was a significant increase in the A allele (P=0.030) and AA genotype (P=0.023) in both the SDS low irritant-threshold group and in SDS responders (A allele P=0.022, AA genotype P=0.048). In the BKC low irritant-threshold group, we found a significant increase in the A allele (P=0.002) and AA genotype (P=0.016). Individuals with a low threshold to both irritants demonstrated a significant increase (P=0.002) in the A allele. This is the first description of a nonatopic genetic marker for irritant susceptibility in normal individuals. Genotyping for theTNF-308 polymorphism may thus contribute to screening of individuals deemed at risk of developing irritant contact dermatitis.

The effect of patch duration on the elicitation of para-phenylenediamine contact allergy

To study the length of exposure time required to elicit para‐phenylenediamine (PPD) allergic reactions, patients known to be allergic to PPD were recruited and patch tested. A group of 7 patients were patch tested with 1% PPD in pet. for 15 min, 30 min and for 120 min. The remaining 9 patients were patch tested with 1%, 0.3%, 0.1% and 0.01% PPD for 15 min, 30 min and for 120 min each. With exposure for 120 min, 11 of 16 subjects reacted to 1% PPD and 2 of 9 reacted to 0.01%. With exposure of 15 min, 6 of 16 reacted to 1% PPD and 0 of 9 reacted to 0.01% PPD. This study showed marked inter‐individual variability in eliciting a reaction to the PPD molecule on patch testing, with regard to both the exposure time and the concentration required.

A retrospective analysis of contact allergy to lanolin

Background Lanolin is often stated to be an important sensitizer but some of the available literature is based on the analysis of high‐risk patients.Objectives To analyse the frequency of contact allergy to lanolin (wool alcohols) in a central London teaching hospital patch‐test population.Methods Review of 24,449 patients recorded on our database during 1982–96 who were tested with a standard series containing 30% wool alcohols.Results The mean annual rate of sensitivity to this allergen was 1·7%. The wool alcohols‐allergic group contained a higher proportion of females (P < 0·05), and the mean age of both males and females (48·4 and 49·2 years) was higher than that of non‐wool alcohols‐allergic patients (41·4 and 35·9 years; P < 0·0005). There was no difference in atopic eczema status between these groups. The highest prevalence of allergy to wool alcohols was among patients with lower leg dermatitis (6·0%; 95% confidence interval, CI 4·46–7·54), followed by those with anogenital dermatitis (3·23%; 95% CI 1·81–4·65). There was an unexplained decline in the rate of positive patch tests to Amerchol® L‐101. However, some patients who reacted to this were negative with wool alcohols, so it may be a useful additional test reagent. The mean rates of allergy to Eucerin® (0·65% per annum) and 50% hydrogenated lanolin in petrolatum (1% per annum) were low, and we no longer use these as test reagents.Conclusions This study illustrates that lanolin sensitization has remained at a relatively low and constant rate even in a high‐risk population (i.e. patients with recent or active eczema).

Acute irritation thresholds in subjects with Type I – Type VI skin

It has long been recognized that human skin can be subdivided into simple categories based on their sensitivity to sunlight ‐ from Type I, never tans, always burns, to Type VI, marked constitutive pigmentation. There is also evidence that the more readily sunburnt type of skin is also more susceptible to the effect of irritants. In the present work, the irritancy threshold for sodium lauryl sulfate (SLS) has been assessed using a recently described 4‐h acute skin irritation patch test. A total of 110 subjects covering all 6 skin types were examined and their threshold for acute irritancy defined as the lowest concentration of SLS, applied under 4‐h occlusion, which would induce a clinically detectable irritant response. The SLS dose response generated using a range of concentrations (0.1%‐20%) demonstrated that there was no significant difference between the groups under these test conditions. Even for Type VI skin (n=25), the dose‐response curve fell within the general pattern. These results reinforce the general applicability of predictions of acute irritant potential made in groups of human volunteers.

Contact dermatitis from paraphenylenediamine used as a skin paint

Case Reports Case no. 1 A 32-year-old Somali Moslem woman developed an acute blistering eruption on the dorsum of her hands, forearms and feet 2 weeks after a friend had applied a PPD-containing black hair dye (BigenA) as a decorative skin paint Blistering was localized to areas of dye application (Fig. 1) and some areas showed additional pustulation. She had previously used henna-containing skin paints, but had never used chemical hair dye. The eruption resolved on treatment with potent topical corticosteroids, but marked post-inflammatory hyperpigmentation was evident on follow-up a year later. Patch testing to the standard series and a hairdressers series showed the following positive results.

Patch testing with natural rubber latex

Immediate‐type hypersensitivity to natural rubber latex (NRL) may be associated with chronic eczema, and it has recently been suggested that NRL should be used as a patch‐test allergen. However, a standardized preparation does not exist, and experience of patch testing with this substance is extremely limited. The aims of our study were to investigate the patch‐test response to different preparations of NRL amongst patients with suspected contact dermatitis. 608 patients were patch tested with a latex series which included wet and dry preparations of undiluted high‐ammonia (HA) NRL and low‐ammonia thiuram‐containing NRL. Cutaneous reactions to 1 or more NRL patches were noted in 24 patients. None of these were strong allergic reactions (> +), and in 15 patients, the responses were only doubtful (?+). Positive patch tests were observed in 9 patients, and were probably due to concurrent thiuram allergy in 6. In the remaining 3 patients, the reactions had subsided by the 2nd reading and may have represented false positives. None of the patients showed consistent allergic reactions to all NRL patches, and most of the doubtful readings had resolved within 4 days, suggesting that they were irritant rather than weak allergic responses. Patch testing to dry HA latex was associated with the least number of reactions. We conclude that allergic patch test reactions to NRL are uncommon, and as reactions are usually weak and difficult to interpret, we suggest that patch testing with NRL should remain experimental until further studies have been undertaken.

Contact allergy to PVP/eicosene copolymer.

Case Report A 32-year-old woman presented with 3 episodes of facial eczema, closely related to the use of a particular sunblock. Patch testing to the standard and a facial series, as well as her own sunblock, showed a ππ reaction to sunblock alone at 2 and 4 days. Photopatch testing was negative. Ingredient testing of the sunblock showed a ππ reaction to polyvinylpyrrolidone (PVP)/eicosene copolymer (10% pet.). 20 control patients tested to this ingredient were negative.