Study on standard limits of cadmium in urine for chronic cadmium poisoning diagnostic in China

Objective To study the standard limits of urinary cadmium for chronic cadmium poisoning diagnostic in China. Methods  In five non-environmental cadmium pollution areas, Randomly selected non-occupational cadmium exposed population 1369 people (male 644, female 752) with each gender and 25-54 age, questionnaire surveyed and collected random urine. Urinary cadmium and urinary creatinine(Cr) concentration were tested, excluding urinary Cr <0.3 g/L and >3 g/L. Stratified by influence factors of urinary cadmium, reference limits of cadmium poisoning are proposed by 95% quantile (P95) of urinary cadmium of general population after correction by urinary Cr. Results  Urinary cadmium increased with age and showed an upward trend. Women significantly higher than male, and smokers significantly higher than non-smokers (P<0.01) in male. According to gender, smoking and 25～34 and 35～54 years of age, analysis the upper limit of cadmium in urine, the 95% upper limit of urinary cadmium of female (<9.73μg/gCr) and 35～54 male smokers (8.08 μg/gCr) was significantly higher than other populations (<6.0 μg/gCr). In addition to the 25～34 year-old non-smoker male, the 95% upper limit of urinary cadmium exceeded the urinary cadmium limits (5 μg/gCr) of Diagnosis of Occupational Cadmium Poisoning (GB Z17—2015) in China, but below the kidney damage biological threshold value (10 μg/gCr) recommended by WHO, and also below the criteria of health hazard area of environmental cadmium pollution (GB / T 17221-1998) (15 μg/gCr). Conclusion Suggest to universalize two standard limits of urine cadmium of GBZ17-2015 and GB / T 17221-1998, and adjust to <10 μg / gCr. But for smoking women over 30 year-old it needs more research to explore.