Overview
Zhou and colleagues sampled raw milk from 60 individual Holstein cows on five farms in the industrial city of Tangshan and one control farm in agricultural Qiqihar, and measured lead, arsenic, chromium and cadmium by ICP-MS alongside the cows’ water, silage and soil. Lead and cadmium in milk were significantly higher on industrial-area farms, while arsenic was higher on the control farm and tracked drinking-water arsenic.
Key numbers
- Lead in milk, all 60 cows: mean 1.22 ± 1.62 µg/L, range 0.03 to 10.46 µg/L (Table 1).
- Lead by area: 0.16 µg/L unpolluted vs 1.43 µg/L industrial; cadmium 0.04 vs 0.10 µg/L (Table 2).
- Arsenic, all cows: mean 0.06 ± 0.20 µg/L, maximum 1.53 µg/L (Table 1).
- Chromium, all cows: mean 0.87 ± 1.02 µg/L (Table 1).
Methods (brief)
One millilitre of milk was microwave-digested in nitric acid and hydrogen peroxide and analyzed by ICP-MS in helium mode. Milk detection limits were 0.050 (lead), 0.004 (arsenic), 0.035 (chromium) and 0.001 µg/L (cadmium); values below the limit were set to half the limit. Accuracy was checked with spiked samples; no certified reference material is reported.
Evidence Fitness
Sixty individual-cow raw milk samples with farm-level statistics, reported per litre on a wet-weight basis. Five of six farms are in an industrial area, so the data describe a polluted setting rather than ordinary retail supply. Minimum values below the detection limit are half-limit substitutes. This is a proxy for reduced-fat milk (raw whole milk, not a fat-reduced retail product), so the reduced-fat milk page is not linked.