Overview
Amer and colleagues measured lead, cadmium and aluminum by flame AAS in 75 raw cow milk samples sold by artisanal producers in Alexandria, Egypt, and followed the metals through laboratory-made cream, skim milk, butter, ghee, two traditional soft cheeses, whey and yogurt. Most milk samples had no detectable metal, but 13 percent exceeded the Egyptian lead limit of 20 ug/l. Skimming, churning and boiling to ghee lowered concentrations, while cheese making concentrated them.
Key numbers
- Raw milk lead: mean 45.06 (SD 128.9) ug/l, maximum 630; among the 10 positive samples mean 338.0 ug/l (Table 1, p. 457).
- Raw milk cadmium: mean 4.77 (SD 14.79) ug/l, maximum 80 (Table 1).
- Laboratory skim milk lead 173.66 ± 15.96 ug/kg versus 431.46 ± 120.12 in its source milk (-59.75 percent) (Table 2, p. 459).
Methods (brief)
Two grams of milk or product wet-digested in nitric acid and hydrogen peroxide and analysed by flame AAS; blanks subtracted. Detection limits 8 to 40 ppb for lead. No reference material or recovery data. Processing products were made from one 20 L batch of farm milk.
Evidence Fitness
The survey is reasonably sized, but flame AAS detection limits are high for milk, so most results are zeros and the means are driven by a few positives. Survey results are per litre and are not converted. The processing experiment uses a single batch, and its unit label (ug/kg) conflicts with the text (ug/l). For semi-skimmed-milk and milkshake this is a proxy: raw whole milk and laboratory skim milk, not semi-skimmed milk or a milkshake, so those pages are not linked.