Determination of blood and urinary cadmium and urinary creatinine : Blood and urinary cadmium concentrations were quantified by graphite furnace atomic absorption spectrometry (GFAAS) with Zeeman-GFAAS background correction (Varian, SpectraA800Z) using 5% monobasic ammonium phosphate as a modifier. Blood samples were digested in 5% nitric acid solution with a ratio of 1:3 (v/v), then mixed, and centrifuged after standing for an hour. The supernatant was removed for analysis by GFAAS. Urine samples were diluted in 0.1% nitric acid solution with a ratio of 1:1 (v/v). Urinary creatinine levels were measured based on the Jaffe reaction