The Sino-American belt study: nickel and cobalt exposure, epidemiology, and clinical considerations.
BACKGROUND
Nickel and cobalt are common causes of metal allergy.


OBJECTIVE
The objective of this study was to investigate nickel and cobalt exposure in belt buckles by testing 701 belts purchased in China and the United States and to consider the prevalence of nickel allergy and its relevance among Chinese patients.


METHODS
Seven hundred one belt buckles purchased in China and the United States were tested for nickel and cobalt release. Six hundred thirty-one Chinese patients with suspected allergic contact dermatitis were patch tested and interviewed to determine clinical relevance of results. The Chinese and American literature was reviewed to investigate trends in nickel prevalence over the past decades.


RESULTS
Sixty percent (n = 219) of belts purchased in China (n = 365) released nickel, and 0.5% (n = 2) released cobalt; 55.7% (n = 187) in the United States (n = 336) released nickel, and 0.9% (n = 3) released cobalt. Belt dermatitis was a significant clinical finding in 34.8% of Chinese nickel-allergic patients. Literature review suggests increasing nickel allergy prevalence in the United States and China.


CONCLUSIONS
Metallic belt buckles are an important source of nickel exposure to consumers. Belts from lowest socioeconomic vendors were more likely to release nickel. Belts with silver color and dark metallic color were more likely to release nickel and cobalt, respectively. Clinical findings show belt dermatitis in China to be a problem.
University of Arizona College of Medicine-Phoenix, AZ 85004, USA. djhamann@email.arizona.edu
Dathan
D
Hamann
Carsten
C
Hamann
Lin-Feng
LF
Li
Hailian
H
Xiang
Kylin
K
Hamann
Howard
H
Maibach
James S
JS
Taylor
Jacob P
JP
Thyssen
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003020:Clothing / Q000009:adverse effects* / Q000191:economics; D003035:Cobalt / Q000009:adverse effects*; D017449:Dermatitis, Allergic Contact / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects*; D010328:Patch Tests; D012959:Socioeconomic Factors; D014481:United States; D055815:Young Adult
D003035:Cobalt; D009532:Nickel