Overview
Sani and colleagues measured lead, cadmium and chromium by flame AAS in unbranded raw cow milk from eight milk markets and in branded supermarket cow milk in Kaduna, Nigeria. The tables print three replicate values and a mean for each market and for five of the fifteen brands. All reported values are in the low parts-per-billion range and were judged within Nigerian limits. Arsenic and mercury were not measured. Fat content is not stated, so the paper is a proxy for semi-skimmed-milk, not direct evidence for it.
Key numbers
- Lead, unbranded milk: market means 0.000733 ppm (Kasuwar Barchi) to 0.003133 ± 0.000808 ppm (Panteka) (Table 2, p. 2).
- Lead, branded milk: brand means 0.0009 ± 0.0001 to 0.001933 ± 0.000306 ppm (Table 1.1, p. 2).
- Cadmium, unbranded milk: market means 0.000657 to 0.0032 ± 0.003315 ppm; highest single value 0.007 ppm (Railway Market) (Table 4, p. 4).
- Cadmium, branded milk: brand means 0.0007 to 0.003267 ± 0.003272 ppm (Table 3, p. 4).
- Chromium, unbranded milk: market means 0.0009 to 0.004567 ± 0.002491 ppm (Table 6, p. 5).
Methods (brief)
One cubic centimeter of milk was wet-digested with hydrochloric and perchloric acids, diluted and read by flame AAS. Digestion was done in triplicate with reagent blanks. No detection limit, certified reference material or recovery is reported.
Evidence Fitness
Small sample (39 milks, only 5 brands tabulated) with no detection limits or reference material. Values near 0.001 ppm are well below what flame AAS usually detects, so the absolute numbers are uncertain. The abstract means do not match the tables, and the text reports a cadmium exceedance that the printed values and the stated 0.2 ppm limit do not support. Fat level is not given: this is a proxy for semi-skimmed-milk and does not link that page.