Overview
Nguyen and colleagues measured cadmium (flame AAS) and mercury (cold-vapor AAS) in 367 retail milk and dairy samples from six Vietnamese cities collected July 2019 to June 2020. Table 2 gives minimum, maximum and mean ± SD by product type, with the share exceeding national limits.
Key numbers
- Cheese (n=21): cadmium 115.81 ± 224.76 ppb, maximum 881.00; mercury 33.75 ± 26.72 ppb, maximum 112.50; 14.29% above the 50 ppb mercury limit (Table 2, p. 463).
- Milk cake (n=44, made from liquid milk, butter and sugar): cadmium 84.44 ± 126.67 ppb; mercury 18.08 ± 23.21 ppb (Table 2).
- Milk powder (n=30): mercury 43.21 ± 31.76 ppb, 22% above the limit; liquid milk (n=114): mercury 29.99 ± 26.07 ppb (Table 2).
Methods (brief)
Microwave digestion with HNO3/H2SO4/HClO4 (10:1:1) and H2O2; Hitachi AZ3000 AAS, flame for cadmium and cold vapor for mercury. LOD 1 ppb cadmium and 0.02 ppb mercury. Spike recoveries 93.0 to 94.0% (cadmium) and 92.5 to 95.5% (mercury); procedural blanks; five replicate measurements.
Evidence Fitness
Large multi-city retail survey with stated LODs and spike recoveries, but no certified reference material. Minimums printed as 0 are treated as below the LOD. For liquid milk the unit may be per litre. Flame AAS with a 1 ppb LOD is near its limit for dairy cadmium. Cheese and milk cake are proxies for the cheese-pizza and custard pages, which are not linked. Some authors also wrote the 2021 Ho Chi Minh City cheese survey; the cheese samples here differ in number and values and are not a reprint.