Overview
Sadeghi and colleagues measured zinc, copper, lead and cadmium by anodic stripping voltammetry in raw milk from 22 Tehran districts and in packaged milks of 15 brands at three fat levels and four flavors. Raw milk had higher levels than packaged milk for all four metals, significantly so for lead, zinc and copper. Tables 2 to 7 give means and SDs in mg/kg; Table 1 summarises raw and packaged milk.
Key numbers
- Packaged vs raw milk: lead “0.048±0.033” vs “0.271±0.640”; cadmium “0.049±0.037” vs “0.099±0.116” (Table 1, p. 179; µg/mL per the abstract).
- Low fat packaged milk, by brand: lead means 0.02 to 0.08 mg/kg and cadmium 0.01 to 0.12 mg/kg (Table 3, pp. 179-180).
- Raw milk district means: cadmium up to “1.31±2.34” mg/kg (Region 21) and lead up to “0.66±0.65” mg/kg (Region 17) (Table 2).
Methods (brief)
Milk was analysed by differential pulse anodic stripping voltammetry on a hanging mercury drop electrode with standard addition and three readings per sample. Stated limits are 0.005 mg/kg for lead and cadmium. Precision was 3.5% (lead) and 4.5% (cadmium); no reference material or recovery is reported.
Evidence Fitness
The low and semi fat packaged milks are direct measurements for reduced-fat-milk. Sample counts per row are not given, and the stated totals (30 raw, 26 packaged) do not fit the tables. Many SDs exceed their means. Table 6 (coffee milk) repeats the Table 5 (honey milk) means row for row, so those rows are flagged. The text says all lead values were below 20 µg/kg, which contradicts the tables. Peer review is unverified. Brand names are replaced by numbers in the extraction.