Changing trends in the epidemiology of contact dermatitis in Singapore

A seven-year retrospective analysis of patch test data in a cohort of patients with contact dermatitis in Sri Lanka

Background

Patch testing with a baseline series is a common tool employed when the sensitizing agent in contact dermatitis is unclear. However, for Asian countries, there are no locally validated baseline series to utilize in screening.

Methods

We completed a retrospective analysis of all patients that had undergone patch testing with the European Baseline series, Shoe Series or Comprehensive International Baseline series, over 7 years from 2012 to 2018 in a tertiary care reference dermatology clinic in Sri Lanka to evaluate the suitability of these investigations to identify causes for contact dermatitis in the local study population.

Results

Out of 438 patients tested, 239 (54.8%) reacted to at least one substance in the series. The Shoe Series was significantly more likely to yield a positive result than the European Baseline Series (70.2% vs 46.9%, p < 0.05). The top three sensitizers identified by all series were nickel sulfate (16%, 70/438), p-phenylenediamine (12.3%, 54/438) and 2-mercaptobenzothiazole or mercapto mix (10.5%, 46/438).

Conclusion

Shoe series has a comparatively high yield in the local population compared to European Baseline series. Since little less than half of the study population did not have any reactivity to any of the allergens tested it is important to develop or modify and validate a locally relevant, more suitable baseline series which is based on the Shoe Series in Sri Lanka. This is further evidence for the continuously changing nature of allergens in the environment and the need to modify existing patch testing standards accordingly.

Electronic supplementary material

The online version of this article (10.1186/s12895-019-0090-8) contains supplementary material, which is available to authorized users.

Epidemiology of nickel sensitivity: Retrospective cross-sectional analysis of North American Contact Dermatitis Group data 1994-2014

BACKGROUND

Nickel is a common allergen.

OBJECTIVE

To examine the epidemiology of nickel sensitivity in North America.

METHODS

Retrospective, cross-sectional analysis of 44,097 patients patch tested by the North American Contact Dermatitis Group from 1994 to 2014. Nickel sensitivity was defined as a positive patch test for nickel. We evaluated the frequency of nickel sensitivity and patient demographics. For each positive reaction to nickel, we tabulated clinical relevance, occupational relatedness, and exposure sources.

RESULTS

The average frequency of nickel sensitivity was 17.5% (1994-2014). Nickel sensitivity significantly increased over time (from 14.3% in 1994-1996 to 20.1% in 2013-2014 [P < .0001]). Nickel-sensitive patients were significantly more likely to be female, young, nonwhite, and atopic (have eczema and asthma) and/or have dermatitis affecting the face, scalp, ears, neck, arm, or trunk (P values ≤ .0474). Overall, 55.5% of reactions were currently clinically relevant; this percentage significantly increased over time (from 44.1% in 1994-1996 to 51.6% in 2013-2014 [P < .0001]). The rate of occupational relatedness was 3.7% overall, with a significant decrease over time (from 7.9% in 1994-1996 to 1.9% in 2013-2014 [P < .0001]). Jewelry was the most common source of nickel contact.

LIMITATIONS

Tertiary referral population.

CONCLUSIONS

Nickel allergy is of substantial public health importance in North America. The frequency of nickel sensitivity in patients referred for patch testing has significantly increased over a 20-year period.

The human skin/chick chorioallantoic membrane model accurately predicts the potency of cosmetic allergens

The current standard method for predicting contact allergenicity is the murine local lymph node assay (LLNA). Public objection to the use of animals in testing of cosmetics makes the development of a system that does not use sentient animals highly desirable. The chorioallantoic membrane (CAM) of the chick egg has been extensively used for the growth of normal and transformed mammalian tissues. The CAM is not innervated, and embryos are sacrificed before the development of pain perception. The aim of this study was to determine whether the sensitization phase of contact dermatitis to known cosmetic allergens can be quantified using CAM-engrafted human skin and how these results compare with published EC3 data obtained with the LLNA. We studied six common molecules used in allergen testing and quantified migration of epidermal Langerhans cells (LC) as a measure of their allergic potency. All agents with known allergic potential induced statistically significant migration of LC. The data obtained correlated well with published data for these allergens generated using the LLNA test. The human-skin CAM model therefore has great potential as an inexpensive, non-radioactive, in vivo alternative to the LLNA, which does not require the use of sentient animals. In addition, this system has the advantage of testing the allergic response of human, rather than animal skin.

Epidemiological data on consumer allergy to p-phenylenediamine

Many women and men now dye their hair. p-Phenylenediamine (PPD) is a frequent and important component of permanent hair dye products; exposure to it may cause allergic contact sensitization, acute dermatitis, and severe facial oedema. To increase our understanding of PPD allergy, we reviewed published literature containing PPD patch test data from dermatitis patients and individuals in the general population. This was performed to estimate the median prevalence and the weighted average of PPD sensitization and thereby assess the burden of PPD-containing hair care products on health. Literature was examined using PubMed-MEDLINE, Biosis, and Science Citation Index. The median prevalence among dermatitis patients was 4.3% in Asia, 4% in Europe, and 6.2% in North America. A widespread increase in the prevalence of PPD sensitization was observed among Asian dermatitis patients. In Europe, a decrease in the 1970s was replaced by a plateau with steady, high prevalences ranging between 2% and 6%. The prevalence remained high in North America, although a decreasing tendency was observed. Contact allergy to PPD is an important health issue for both women and men. More stringent regulation and enforcement are required as public health measures to reduce the burden of disease that exposure to PPD has brought to populations.

Trends of contact allergy to fragrance mix I and Myroxylon pereirae among Danish eczema patients tested between 1985 and 2007

BACKGROUND

Fragrance contact allergy has for long been recognized as an important health issue. In Denmark, the frequency of fragrance mix (FM) I contact allergy increased between 1985-1986 and 1997-1998 among male and female dermatitis patients.

OBJECTIVES

To investigate the development of FM I and Myroxylon pereirae (MP) contact allergy between 1985 and 2007 with an emphasis on recent years.

METHODS

A retrospective analysis of all patch test data from our database was performed. Comparison of sensitivity rates was made using a chi-squared test for trend. Logistic regression analyses were used to test for associations.

RESULTS

Of 16,173 patients, 7.2% were sensitized to FM I and 4% to MP. FM I contact allergy was associated with female sex [odds ratio (OR) = 1.52; 95% confidence interval (CI) = 1.33-1.74] and age between 41 and 60 years (OR = 3.20; 95% CI = 1.98-5.21). Significant declines of FM I and MP reactions among women but not men were observed between 1999 and 2007.

CONCLUSIONS

Although the frequency of FM I contact allergy has decreased in Denmark in recent years, it is still high. Furthermore, fragrance contact allergy is caused by other important allergens not included in this analysis. Allergic contact reactions to the ingredients of FM I remain a problem in European consumers.

Allergic contact sensitization in the general adult population: a population-based study from Northern Norway

Few studies have so far addressed the prevalence and risk factors for contact sensitization in the general adult population; however, many such studies have been conducted in hospitals. We present the prevalence of contact sensitization in a general adult population and its relationship to potential risk factors like smoking, ear piercing and atopic diseases. 1236 adults (44.2% men and 55.8% women) were randomly selected from a cross-section of the population in Sør-Varanger municipality, Norway, and patch tested with TRUE Test (Pharmacia, Hillerød, Denmark). Contact sensitivity to at least 1 out of 24 allergens was found in 35.4% of the women and in 14.8% of the men. The most common allergens were nickel (17.6%), cobalt (2.8%), thiomersal (1.9%), fragrance mix (1.8%) and colophony (1.2%). All other allergens were observed in 1.0% or less. In women, ear piercing was an important risk factor for nickel sensitization. No such significant correlation was seen in men [in women relative risk (RR) = 3.30, 95% confidence interval (CI) = 2.01-5.43, and in men RR = 1.82, 95% CI = 0.66-5.00], and contact sensitivity was associated with atopic dermatitis (AD) [adjusted odds ratio (OR) = 1.58, 95% CI = 1.04-2.40] and smoking (adjusted OR = 1.42, 95% CI = 1.01-1.99) in women but not in men. The prevalence of contact sensitivity was common in this general population, especially in women. Smoking and AD might be a risk factor for contact sensitization.

Sensitization to nickel: etiology, epidemiology, immune reactions, prevention, and therapy

Nickel is a contact allergen causing Type I and Type IV hypersensitivity, mediated by reagins and allergen-specific T lymphocytes, expressing in a wide range of cutaneous eruptions following dermal or systemic exposure. As such, nickel is the most frequent cause of hypersensitivity, occupational as well as among the general population. In synoptic form, the many effects that nickel has on the organism are presented to provide a comprehensive picture of the aspects of that metal with many biologically noxious, but metallurgically indispensable characteristics. This paper reviews the epidemiology, the prognosis for occupational and non-occupational nickel allergic hypersensitivity, the types of exposure and resulting immune responses, the rate of diffusion through the skin, and immunotoxicity. Alternatives toward prevention and remediation, topical and systemic, for this pervasive and increasing form of morbidity are discussed. The merits and limitations of preventive measures in industry and private life are considered, as well as the effectiveness of topical and systemic therapy in treating nickel allergic hypersensitivity.

Patch testing of Singapore children and adolescents: our experience over 18 years

This is a retrospective epidemiologic study of allergic contact dermatitis in children and adolescents in Singapore who had undergone patch testing from January 1, 1986 to December 31, 2003. A total of 2,340 patients below the age of 21 years had undergone patch testing. Of these, 1,063 (583 girls, 480 boys) were positive to one or more allergens. The most common allergens were: nickel (40%), thimerosal (15%), colophony (9%), lanolin (8%), cobalt (8%), fragrance mix (5%), and neomycin (4%). Each of these allergens will be discussed individually. This is the first study with over 1000 patients on this subject from Asia.

Patch testing: a retrospective analysis of 103 patients with emphasis on practical aspects for the clinician

BACKGROUND

Allergic contact dermatitis is a common dermatologic disorder caused by small chemical molecules that can penetrate the skin barrier. Thousands of chemicals capable of inducing allergic contact dermatitis have been identified. To cure allergic contact dermatitis, the allergen should be identified and eliminated from the environment of the patient. Patch testing, utilizing a variety of standard panels of the most frequent allergens, is used to identify the allergen in question. Patch testing is still the gold standard tool used to identify one or more substances that may contribute to the etiology of allergic contact dermatitis.

OBJECTIVE

To determine the frequency of patch test positivity and to identify the most common allergens in patients with suspected allergic contact dermatitis.

METHODS

A retrospective analysis of files of 103 patients who have been clinically diagnosed to have allergic contact dermatitis and have been patch tested using a standard technique with a Northern American Contact Dermatitis Group series.

RESULTS

Sixty-two patients (60.2%) showed positive reactions to one or more substance. The most common allergens were nickel sulfate, fragrance mix, and neomycin sulfate. There was an increased frequency of positive reactions to fragrance mix and a significant decrease of frequency of thimerosal positive reactions.

CONCLUSIONS

Increased awareness of allergens and their potential sources may help to limit the usage of these chemicals in manufacturing consumer products. This may have contributed to decreased prevalence rates of certain allergens such as thimerosal and paraphenylenediamine.

Metal allergy in Singapore

This is a clinical epidemiologic study to determine the frequency of metal allergy among patch-tested patients in the years 2001-2003. The results are compared with those of previous studies. All patients diagnosed as having allergic contact dermatitis in the National Skin Centre, Singapore, from January 2001 to December 2003 were studied retrospectively. The frequency of positive patch tests to the following metals were nickel 19.9%, chromate 5.6%, cobalt 8.2% and gold 8.3%. The frequency of nickel allergy has been steadily rising over the last 20 years. The most common sources of nickel allergy are costume jewelry, belt buckles, wrist watches and spectacle frames. After declining from 1984 to 1990, chromate and cobalt allergies have also been steadily increasing subsequently. The most common sources of chromate allergy were cement, leather and metal objects. Most positive patch tests to cobalt are regarded as co-sensitization due to primary nickel or chromate allergies. There has been a steep increase in positive patch tests to gold from 2001 to 2003, which is difficult to explain because the relevance and sources of such positive patch tests can rarely be determined with certainty. There has been an overall rise in the frequency of metal allergy in the last 20 years.

Results of standard series patch testing in patients with occupational allergic contact dermatitis

BACKGROUND

In the workplace, the skin is at high risk of exposure to chemicals and other contaminants, and occupational dermatitis is an important field of study.

METHODS

We evaluated 230 patients referred to our clinic because they were affected by dermatitis suspected to be of occupational and allergic origin. They were tested with the allergens of the GIRDCA standard series, and with supplementary series when indicated.

RESULTS

Among the 230 subjects, 49 were positive only to supplementary series (26.3% of all allergic contact dermatitis), while 130 (69.9% of all allergic contact dermatitis) were considered to have an occupational allergic contact dermatitis diagnosed by the standard series alone. The most frequent occupations of the patients were health care workers and hairdressers/beauticians. The most common agents responsible for occupational allergic contact dermatitis were metals and para-phenylenediamine.

CONCLUSIONS

As the standard series detected a relatively low proportion of occupational allergic contact dermatitis, it is not adequate to recognize an occupational allergic contact dermatitis, certain supplementary series should also to be tested. However, even if such occupational series are used, we remain likely to continue to underestimate the frequency of occupational allergic contact dermatitis, because workers come into contact with a large number of substances that are often unknown.

Cultural aspects in the treatment of patients with skin disease

As the cultural distance between patient and physician widens, so does miscommunication. Negotiation between the belief systems of the physician and the patient may create a therapeutic environment of mutual trust and respect that increases the possibility of successful clinical outcomes.

The fragrance hand immersion study - an experimental model simulating real-life exposure for allergic contact dermatitis on the hands

Recently, we showed that 10 x 2% of consecutively patch-tested hand eczema patients had a positive patch test to a selection of fragrances containing fragrances relevant to hand exposure. In this study, we used repeated skin exposure to a patch test-positive fragrance allergen in patients previously diagnosed with hand eczema to explore whether immersion of fingers in a solution with or without the patch-test-positive fragrance allergen would cause or exacerbate hand eczema on the exposed finger. The study was double blinded and randomized. All participants had a positive patch test to either hydroxycitronellal or Lyral (hydroxyisohexyl 3-cyclohexene carboxaldehyde). Each participant immersed a finger from each hand, once a day, in a solution containing the fragrance allergen or placebo. During the first 2 weeks, the concentration of fragrance allergen in the solution was low (approximately 10 p.p.m.), whilst during the following 2 weeks, the concentration was relatively high (approximately 250 p.p.m.), imitating real-life exposure to a household product like dishwashing liquid diluted in water and the undiluted product, respectively. Evaluation was made using a clinical scale and laser Doppler flow meter. 3 of 15 hand eczema patients developed eczema on the finger immersed in the fragrance-containing solution, 3 of 15 on the placebo finger and 3 of 15 on both fingers. Using this experimental exposure model simulating real-life exposure, we found no association between immersion of a finger in a solution containing fragrance and development of clinically visible eczema on the finger in 15 participants previously diagnosed with hand eczema and with a positive patch test to the fragrance in question.

Comparative frequency of patch test reactions to topical antibiotics

BACKGROUND

Neomycin, clioquinol and fusidic acid are all topical antibiotics widely used in dermatological practice in the U.K., either as a single agent or in combination with topical corticosteroids. However, an adverse effect of topical antibiotics is contact sensitization.

OBJECTIVES

To examine the frequency of positive patch test reactions to fusidic acid, clioquinol and neomycin.

METHODS

To compare the frequency of allergic patch test reactions over 1 year, we patch tested all patients attending the St John's Institute of Dermatology contact dermatitis clinic for one calendar year with fusidic acid, neomycin and clioquinol.

RESULTS

We patch tested 1119 patients. Positive patch test reactions to neomycin were noted in 40 patients (3.6%), compared with eight patients (0.7%) to clioquinol and three patients (0.3%) to fusidic acid. The frequency of medicament allergy to neomycin was thus five times more common than to clioquinol and ten times more common than to fusidic acid. Although fusidic acid is not part of our extended standard series, it is in our medicaments series. Therefore, in the second part of our study, we reviewed all cases of positive patch test reactions to fusidic acid over the last 20 years. We found that the frequency of hypersensitivity has decreased since the early 1980s despite increasing usage; the current average frequency being 1.62 patch-tested patients per year (1.45%) of those patch tested to the medicaments series). The most common diagnosis in such patients was stasis dermatitis (54.2%).

CONCLUSIONS

The frequency of fusidic acid allergy in an eczema population is low and is comparable with published data from over 10 years ago.

Common contact sensitizers in Delhi

Seventy-five patients of both sexes with clinically suspected contact dermatitis were patch tested with the Indian Standard Series and indigenous antigens. The results were compared with the data from other centers. Most of these patients were young adults between 20 and 39 yrs old with the mean age of 36.63 +/- 5.6 yrs. Their occupational profiles included household workers (17.33%), masons (10.66%), farmers (6.66%), factory workers (4%), medical personnel (4%), lab workers (2.66%), and miscellaneous (17.33%). Itching and burning were two of the most common complaints, and chronic dermatitis was the predominant morphologic pattern of the lesions observed. Frequent sites involved included the hands (40.83%), airborne type (22.44%), hands and feet (12.24%), feet (12.24%), face (10.2%), and neck (2.04%). Patch test analysis of these patients revealed that, out of 75 subjects tested, 49 (65.3%) reacted to one or more allergens. Parthenium (20%) is the most common contact sensitizer followed by potassium dichromate (16%), xanthium (13.33%), nickel sulphate (12%), chrysanthemum (8%), mercaptobenzothiazole, and garlic (6.66% each). These findings are in broad conformity with those in other reports. We concluded that the Indian Standard Series of antigens with the addition of a few more (such as garlic, onion and chlorheximide of local relevance) is suitable for detecting the allergens responsible for the contact dermatitis prevailing in this region.

Changes in the pattern of sensitization to common contact allergens in denmark between 1985-86 and 1997-98, with a special view to the effect of preventive strategies

The objective of the present study is to describe any changes in the prevalence of sensitization to common contact allergens in patch-tested patients over a 12-year period. Attention is given to possible effects of preventive strategies introduced in Denmark regarding nickel and chromate sensitization during that period, and particular areas of concern are identified. Members of the Danish Contact Dermatitis Group collected patch-test results from consecutive eczema patients as well as information about exposures and demographic variables over a 6-month period in 1985-86. The investigation was repeated in 1997-98 in the same clinics, at the same time of year, using identical methods and patch-test substances, including nickel sulphate 5%, potassium dichromate 0.5% and fragrance mix 8%. Nickel was the most common contact allergen in both study periods, followed by the fragrance mix. In children 0-18 years of age, the frequency of nickel allergy decreased from 24.8% in the first study period to 9.2% in the second study period (P < 0. 0008). Fragrance mix allergy doubled in frequency from 4.1% in 1985-86 to 9.9% in 1997-98, an increase that affected all age groups. Contact allergy to potassium dichromate decreased significantly from 3.0% in the first period to 1.2% in the second period (P = 0. 001). The decrease was seen in both sexes and was most pronounced among those of working age. No other significant changes were found in the frequency of sensitization to common allergens over the 12-year observation period.

Patch testing in a British district general hospital

The results of patch testing in 753 patients attending a dermatology clinic in a British district general hospital over the period 1993-96 are presented. The frequency of positive reactions, and of the relative frequency of common allergens is broadly comparable to series published from specialist contact clinics. This study suggests that nonspecialist dermatology clinics can carry out routine patch testing adequately, although there are likely to be a number of cases which will require review in a specialist clinic or specialist advice.

Contact reactions to fragrances

BACKGROUND

The most common reaction to fragrances is contact dermatitis, a delayed hypersensitivity reaction; however, other reactions include immediate contact reactions (contact urticaria) and photo-allergic reactions. Fragrance mix (FM) and balsam of Peru (BP) are used to screen for fragrance allergy.

OBJECTIVE

To study the different types of allergic skin reactions to fragrance compounds.

METHODS

Delayed hypersensitivity reactions to FM and BP were studied in 4,975 patients with suspected contact dermatitis by routine patch testing interpreted at 48 and 96 hours. In 664 of the patients, patch tests were read at 30 minutes to evaluate for immediate (wheal-and-flare) contact reactions and again at 48 and 96 hours. Photopatch tests to FM were performed in 111 patients with suspected photo-allergic dermatitis.

RESULTS

Delayed contact reactions to FM occurred in 6.6% of females and 5.4% of males and to BP in 3.9% of females and 4.1% of males. Analysis of data over time (12 study years) showed an increased trend for reactions to fragrances, particularly in males. Sensitivity to other contact allergens (polysensitivity) was found in 62% of patients and polysensitivity presented more often with generalized contact dermatitis. The most sensitizing components of the fragrance mix that were tested in 38 patients were cinnamic alcohol, oak moss, and cinnamic aldehyde. There were 112 immediate patch test reactions to FM and 113 to BP in 664 patients. Immediate contact reactions were followed by delayed contact reactions in 13.4% of patients for FM and 8.8% for BP, representing a significant increase in the frequency of delayed contact reactions. Patients with immediate contact reactions to fragrances did not have a higher incidence of atopy (25.9%). No cases of positive photopatch test reactions to FM were seen.

CONCLUSION

Fragrances commonly cause both delayed and immediate patch test reactions and patients with immediate contact reactions have an increase in delayed contact reactions to the same allergen.

Common contact sensitizers in Chandigarh, India. A study of 200 patients with the European standard series

200 patients (122 male, 78 female) with suspected allergic contact dermatitis were patch tested with the European standard series (ESS) and the results compared with other Asian centres. 131 (65.5%) patients showed 1 or more patch test positives to the ESS. Patch tests were positive to all allergens except primin. Potassium dichromate was the most common allergen (20.5%) followed by nickel sulfate (16.5%), SQL mix (14%), PPD (11.5%), cobalt (8%), fragrance mix (7.5%), formaldehyde (6.5%), colophony (5.5%), neomycin sulfate and mercapto mix (5% each). In women, nickel sulfate was the commonest allergen (30.8%) followed by SQL mix (16.7%) and potassium dichromate (15.4%). In men, potassium dichromate was the commonest sensitizer (23.8%) followed by SQL mix and PPD (12.3% each). Our results are at variance with other centres in Asia. SQL mix was able to detect less than 1/2 (42.2%) of patients allergic to ethanolic dilutions of ether extracts of parthenium. We conclude that the European standard series, with exclusion of primin, is suitable for detection of allergic contact dermatitis in India. However, SQL mix is not a adequate screen for parthenium sensitivity and patch testing with extracts of the plant should be continued, wherever indicated.

Adverse reactions to fragrances. A clinical review

This article reviews side-effects of fragrance materials present in cosmetics with emphasis on clinical aspects: epidemiology, types of adverse reactions, clinical picture, diagnostic procedures, and the sensitizers. Considering the ubiquitous occurrence of fragrance materials, the risk of side-effects is small. In absolute numbers, however, fragrance allergy is common, affecting approximately 1% of the general population. Although a detailed profile of patients sensitized to fragrances needs to be elucidated, common features of contact allergy are: axillary dermatitis, dermatitis of the face (including the eyelids) and neck, well-circumscribed patches in areas of "dabbing-on" perfumes (wrists, behind the ears) and (aggravation of) hand eczema. Depending on the degree of sensitivity, the severity of dermatitis may range from mild to severe with dissemination and even erythroderma. Airborne or "connubial" contact dermatitis should always be suspected. Other less frequent adverse reactions to fragrances are photocontact dermatitis, immediate contact reactions and pigmentary changes. The fragrance mix, although very useful for the detection of sensitive patients, both causes false-positive and false-negative reactions, and detects only 70% of perfume-allergic patients. Therefore, future research should be directed at increasing the sensitivity and the specificity of the mix. Relevance is said to be established in 50-65% of positive reactions, but accurate criteria are needed. Suggestions are made for large-scale investigation of several fragrances on the basis of literature data and frequency of use in cosmetics. The literature on adverse reactions to balsam of Peru (an indicator for fragrance sensitivity), essential oils (which currently appear to be used more in aromatherapy than in perfumery) and on fragrances used as flavours and spices in foods and beverages is not discussed in detail, but pertinent side-effects data are tabulated and relevant literature is provided.

Patch testing of 490 patients in Hong Kong

Patch testing, using European standard allergens and suspected causative substances brought in by patients, was carried out in 490 patients with eczema in Hong Kong and 437 completed the test. Before patch testing, 244, 141 and 105 patients were diagnosed as having contact dermatitis, endogenous eczema and unclassified eczema, respectively. After patch testing, the diagnosis of the causal agent was changed in 54 contact dermatitis patients, and 18% of endogenous eczema patients and 34% of unclassified eczema patients were re-diagnosed as contact dermatitis. In the patients with a final diagnosis of contact dermatitis, 19.5% were positive to fragrance mix, followed by nickel sulfate (16.4%) and cobalt chloride (11.3%). The commonest causative agents for contact dermatitis were soap or detergent (22.0%) and traditional Chinese medicine (17.3%); the latter was a more common cause of contact dermatitis than Western medicine (9.0%) or metals (13.4%). The prevalence of allergic reaction to fragrance in Hong Kong was higher than among Chinese in Beijing, Shanghai, Taipei or Singapore (78% ethnic Chinese). Dermatologists should have a high index of suspicion about traditional medications and should patch test with the suspected substance when patients give a history of use.

Change in cement manufacturing process, a cause for decline in chromate allergy?

Hexavalent chromate in cement is the commonest cause of allergic contact dermatitis, especially among construction workers. Over the past decades, there has been a general decline in the prevalence of chromate allergy among construction workers. We suspect that a change in the constituents of cement, resulting in the lowering of hexavalent chromate, contributed to the decline. Slag (free from hexavalent chromate) from the iron-quenched, blast furnace process has been used as a substitute for clinker (which contains high hexavalent chromate) in manufacturing cement. As a result, the slag has diluted the hexavalent chromate content of cement. Our analytical study showed that slag is free from hexavalent chromate and that the hexavalent chromate of clinker ranged from 6-17 micrograms/g. Substituting slag for clinker resulted in dilution of hexavalent chromate in the cement. The hexavalent chromate content of cement declines proportionately with increasing proportion of slag, e.g., a cement containing 5% slag has a total hexavalent chromate concentration of 17.5 micrograms/g, whereas increasing the proportion of slag to 60% reduced the hexavalent chromate content to 7.1 micrograms/gm in the same cement.

The fragrance mix and its constituents: a 14-year material

Results from 14 years of patch testing with the fragrance mix and its constituents are reviewed. From 1979-1992, 8215 consecutive patients were patch tested with the fragrance mix and 449 (5.5%) had a positive reaction. An increase in the frequency of reactions to fragrance mix was seen from the first 5-year period to the last. Only 54.4% of the patients tested in the last 5-year period with the individual constituents of the mix had at least 1 positive reaction. The results of testing with the constituents are the basis for a discussion of methodological problems. A significant decrease in the frequency of reaction to cinnamic aldehyde was registered, at the same time as the test concentration was reduced from 2% to 1% pet. However, no significant variations in the frequency of reactions to oak moss were seen, notwithstanding a similar reduction in test concentration.