Overview
Qin and colleagues bought two commercial whole milks in Suzhou, China and two in Yamanashi, Japan every six weeks for a year and analyzed them, with raw milk from Inner Mongolia, for macroelements, trace elements and the toxic metals arsenic, cadmium, mercury and lead. Lead and cadmium were two to three times higher in the Chinese milks than in the Japanese milks, and arsenic and mercury were not detected in any sample.
Key numbers
- Lead: 35.01 ± 8.63 and 32.97 ± 11.24 µg/kg in the Chinese commercial milks vs 11.98 ± 3.27 and 12.95 ± 2.94 µg/kg in the Japanese milks; raw milk 28.15 ± 11.23 µg/kg (Table 3).
- Cadmium: 4.53 and 4.25 µg/kg (China) vs 1.13 and 2.01 µg/kg (Japan) (Table 3).
- Arsenic and mercury not detected (detection limits 0.06 and 0.015 µg/kg) (Table 3, p. 303).
- One sample in each Chinese milk exceeded the Chinese 50 µg/kg lead tolerance limit (p. 303).
Methods (brief)
About 10 g of milk was microwave-digested; lead, cadmium, chromium, copper and molybdenum were measured by graphite furnace AAS and arsenic, mercury and selenium by atomic fluorescence. The milk powder reference material GBW10017 recovered lead exactly (0.07 mg/kg) but has no certified cadmium value.
Evidence Fitness
Small study (four products, eight samplings each) with good time coverage and a matrix reference material for lead. Rubidium and strontium unit labels look doubtful and were flagged. The commercial milks are whole milk, so this is a proxy for reduced-fat milk and the reduced-fat milk page is not linked.