Wong S S, Chan M T, Gan S L, Ng S K, Goh C L
National Skin Centre, Singapore.
Am J Contact Dermat. 1998 Mar;9(1):1-5.
The prevalence of chromate allergy among all patients tested at the Contact and Occupational Dermatoses Clinic at the National Skin Centre in Singapore had fallen progressively from 1983 to 1989. Chromate has also become a less common occupational allergen because of the decline in the number of cases of allergic contact dermatitis from cement.
The aim of this report was to study and update the epidemiology of occupational chromate allergy among workers seen in a tertiary dermatology referral centre in Singapore from 1990 to 1995 and to review the changing trends of occupational chromate allergy in our local setting since 1983. The occurrence of concomitant contact allergens among was also studied.
All patients diagnosed to have occupational allergic contact dermatitis together with positive reactions to chromate, at the Joint Occupational Dermatosis Clinic at the National Skin Centre in Singapore, between January 1990 to December 1995, were included. Causes of chromate allergy and frequency of occurrence of concomitant contact allergens among construction and nonconstruction workers were compared.
Eight hundred and fifty workers were seen during the 6-year-study period. Six hundred and thirty three (74.5%) were diagnosed to have occupational contact dermatitis, of which 257 (40.6%) had allergic contact dermatitis. Eighty-seven (33.8%) of these workers had positive reaction to chromate on patch testing. Ninety-five percent of these workers were men with a mean age of 33.4 years. The construction industry contributed 59% of the workers with chromate allergy. Cement (61%) remained the most common source of chromate allergy in our workers, and chromate from sources other than cement (39%) accounted for the rest. Of workers allergic to chromate from cement, 96% (51 of 53) came from the construction industry. Sixty percent of the workers with chromate allergy had concomitant contact allergens and the coexistence of two or more allergens was significantly more common among nonconstruction workers (53%) than construction workers (22%). The three most common concomitant contact allergens were cobalt (28%), rubber chemicals (21%) and nickel (18%). Nonconstruction workers had significantly higher rates of nickel allergy (36% v 6%) than construction workers (P < .03). Simultaneous reactivity to cobalt and nickel was also significantly more common among nonconstruction workers (22%) than construction workers (6%) (P < .03).
Chromate has progressively become a less common occupational allergen at the National Skin Centre in Singapore from 1983 to 1989, because of a progressive fall in the number of cases of allergic contact dermatitis from cement. However, our study showed that occupational chromate allergy had now increased from 1990 to 1995, because of an increase in chromate allergy from sources other than cement. Chromate allergy from cement is declining, although still frequent, and sources other than cement are increasing in recent years. Concomitant nickel allergy, as well as simultaneous nickel and cobalt allergies, were more common among nonconstruction workers than construction workers.
1983年至1989年期间，新加坡国立皮肤中心接触性和职业性皮肤病诊所检测的所有患者中，铬酸盐过敏的患病率逐渐下降。由于水泥引起的过敏性接触性皮炎病例数量减少，铬酸盐也已成为一种不太常见的职业过敏原。
本报告旨在研究并更新1990年至1995年在新加坡一家三级皮肤科转诊中心就诊的工人中职业性铬酸盐过敏的流行病学情况，并回顾自1983年以来我们当地环境中职业性铬酸盐过敏的变化趋势。同时还研究了伴随接触过敏原的发生情况。
纳入1990年1月至1995年12月期间在新加坡国立皮肤中心联合职业性皮肤病诊所被诊断为职业性过敏性接触性皮炎且对铬酸盐呈阳性反应的所有患者。比较了建筑工人和非建筑工人中铬酸盐过敏的原因以及伴随接触过敏原的发生频率。
在为期6年的研究期间共诊治了850名工人。其中633人（74.5%）被诊断为职业性接触性皮炎，其中257人（40.6%）患有过敏性接触性皮炎。这些工人中有87人（33.8%）在斑贴试验中对铬酸盐呈阳性反应。这些工人中95%为男性，平均年龄33.4岁。建筑业贡献了59%对铬酸盐过敏的工人。水泥（61%）仍然是我们工人中铬酸盐过敏的最常见来源，来自水泥以外来源的铬酸盐（39%）占其余部分。对水泥中铬酸盐过敏的工人中，96%（53人中的51人）来自建筑业。60%对铬酸盐过敏的工人有伴随接触过敏原，两种或更多过敏原共存的情况在非建筑工人（53%）中比建筑工人（22%）中更为常见。三种最常见的伴随接触过敏原是钴（28%）、橡胶化学品（21%）和镍（18%）。非建筑工人对镍过敏的发生率（36%对6%）显著高于建筑工人（P <.03）。非建筑工人中同时对钴和镍呈反应性的情况（22%）也比建筑工人（6%）更为常见（P <.03）。
1983年至1989年期间，由于水泥引起的过敏性接触性皮炎病例数量逐渐减少，铬酸盐在新加坡国立皮肤中心已逐渐成为一种不太常见的职业过敏原。然而，我们的研究表明，1990年至1995年期间职业性铬酸盐过敏有所增加，原因是水泥以外来源的铬酸盐过敏增加。来自水泥的铬酸盐过敏虽仍很常见但在下降，近年来水泥以外的来源在增加。非建筑工人中伴随镍过敏以及同时对镍和钴过敏的情况比建筑工人更为常见。
