Lutfullah and colleagues measured ten metals (calcium, magnesium, copper, zinc, iron, manganese, lead, cadmium, chromium, and nickel) in 46 samples of dried and liquid cow milk collected from retail markets in Peshawar, Pakistan in 2009. Samples were divided into four groups: infant formula powder (dried), powdered milk (dried), fresh milk (liquid), and processed milk (liquid). All toxic metal concentrations were reported to be below the international permissible limits cited by the authors (CE Regulation No. 2001/466, Codex Alimentarius, and Food Standards Agency UK). Cadmium showed the largest between-group differences, with dried milk groups reporting means roughly 5 to 10 times higher than liquid milk groups.
Key numbers
Values are reported in ppm (mg/kg wet weight) as mean + SD and range. All 46 samples are pooled in the total row; subgroup sample counts are not disaggregated by the authors.
Table 1: Essential mineral elements (ppm, wet weight)
| Milk group | Calcium | Magnesium | Copper | Zinc | Iron | Manganese |
|---|---|---|---|---|---|---|
| All samples (n=46) | 2106 + 954 (970-3825) | 349 + 205 (110-875) | 0.59 + 0.59 (0.10-2.37) | 4.79 + 4.03 (0.09-12.80) | 1.67 + 2.08 (0.02-7.54) | 0.0267 + 0.02 (0.01-0.09) |
| Infant formula (dried) | 3081 + 277 NS (2475-3600) | 540 + 206 NS (250-825) | 1.00 + 0.76 NS (0.11-2.37) | 8.97 + 2.35 NS (4.69-11.34) | 4.33 + 2.22 NS (1.33-7.54) | 0.0318 + 0.02* (0.01-0.07) |
| Powdered milk (dried) | 3092 + 502 NS (2075-3825) | 480 + 173 NS (225-875) | 0.90 + 0.41 NS (0.10-1.40) | 7.31 + 4.20 NS (2.22-12.80) | 2.42 + 0.99 NS (1.30-4.30) | 0.0400 + 0.02* (0.02-0.09) |
| Fresh milk (liquid) | 1333 + 142 NS (1050-1580) | 240 + 106 NS (120-425) | 0.15 + 0.01 NS (0.12-0.17) | 1.93 + 1.45 NS (0.69-5.01) | 0.17 + 0.12 NS (0.02-0.43) | 0.0215 + 0.01* (0.01-0.04) |
| Processed milk (liquid) | 1228 + 204 NS (970-1725) | 185 + 50 NS (110-250) | 0.46 + 0.52 NS (0.11-1.70) | 1.97 + 1.73 NS (0.09-4.84) | 0.25 + 0.11 NS (0.06-0.43) | 0.0166 + 0.01* (0.01-0.03) |
NS = nonsignificant vs. total group mean (ANOVA/LSD, P less than 0.05). * = significant at P less than 0.05 (Table 1).
Table 2: Toxic mineral elements (ppm, wet weight)
| Milk group | Lead | Cadmium | Chromium | Nickel |
|---|---|---|---|---|
| All samples (n=46) | 0.0091 + 0.01 (0.0001-0.03) | 0.1507 + 0.28 (0.01-1.20) | 0.0007 + 0.00 (0.0001-0.003) | 0.0146 + 0.01 (0.002-0.032) |
| Infant formula (dried) | 0.0177 + 0.01 NS (0.01-0.03) | 0.3545 + 0.40* (0.09-1.18) | 0.0015 + 0.00 NS (0.001-0.003) | 0.0277 + 0.00 NS (0.022-0.032) |
| Powdered milk (dried) | 0.0170 + 0.01 NS (0.01-0.03) | 0.2110 + 0.35* (0.04-1.20) | 0.0014 + 0.00 NS (0.001-0.002) | 0.0202 + 0.01 NS (0.002-0.032) |
| Fresh milk (liquid) | 0.0035 + 0.01 NS (0.0001-0.015) | 0.0408 + 0.07* (0.01-0.25) | 0.0001 + 0.00 NS (0.0001-0.0003) | 0.0065 + 0.00 NS (0.003-0.009) |
| Processed milk (liquid) | 0.0006 + 0.00 NS (0.0001-0.0015) | 0.0325 + 0.02* (0.01-0.09) | 0.0001 + 0.00 NS (0.0001-0.0003) | 0.0066 + 0.00 NS (0.004-0.009) |
NS = nonsignificant vs. total group mean (ANOVA/LSD, P less than 0.05). * = significant at P less than 0.05 (Table 2).
Converted to ppb (ug/kg): infant formula lead mean approximately 17.7 ppb (range 10 to 30 ppb); cadmium mean approximately 354.5 ppb (range 90 to 1180 ppb); chromium mean approximately 1.5 ppb (range 1.0 to 3.0 ppb); nickel mean approximately 27.7 ppb (range 22 to 32 ppb).
Methods (brief)
A total of 46 samples were collected from retail markets in Peshawar in 2009. The dried group comprised infant formula powder and powdered milk; the liquid group comprised fresh milk and processed milk. Individual samples were 50 g (dried) or 100 mL (liquid), sealed in sterile plastic containers and stored at 0 to 5 degrees C prior to analysis. Digestion used a nitric acid/perchloric acid (HNO3/HClO4) wet digestion procedure following AOAC 2000. Detection was by flame atomic absorption spectrophotometry on a Perkin Elmer Double Beam 2380 instrument. Temperature-time conditions were optimized per element. Reagent blanks were run in parallel. All samples were prepared in triplicate. Statistics used one-way ANOVA with LSD post-hoc testing and Pearson correlation coefficients (SPSS version 17).
Limits of detection and limits of quantification are not reported. Certified reference material or spike recovery data are not reported. The paper does not specify whether the instrument calibration used aqueous or matrix-matched standards.
Evidence fitness
This source provides mean and range values for ten metals across four milk product groups from a single retail market in Peshawar, Pakistan. It is usable as contextual occurrence evidence for infant formula powder and powdered milk in a low-income South Asian market context. The infant formula group is not separated by soy versus non-soy formulation; the paper does not specify whether brands were cow-milk-based or soy-based. Per-sample data are not available; only group means and ranges are reported, so no percentile distribution can be reconstructed.
The cadmium values in the dried milk groups are substantially elevated relative to other published datasets for this product class (mean 354.5 ppb in infant formula, with an upper range of 1180 ppb). This warrants caution in weighting these figures: the paper reports no certified reference material, recovery, or LOD data, and the cadmium levels exceed published EU maximum levels for infant formula by a wide margin. This source does not provide evidence suitable for establishing occurrence percentiles or certification limit inputs. It is appropriate as contextual signal for the cadmium and nickel ranges in Pakistani retail infant formula.
Limitations
The infant formula subset is not disaggregated by soy versus non-soy formulation, so it cannot be directly assigned to either product subcategory. Sample counts per subgroup are not reported individually. The market is a single city (Peshawar) in Pakistan; jurisdiction and market conditions differ substantially from EU, US, or Codex-regulated markets. The cadmium mean in infant formula powder (354.5 ppb) substantially exceeds EU and Codex maximum levels for this product class, which raises the possibility of either elevated local contamination, analytical artifacts due to absence of certified reference materials, or formulation differences. The paper does not distinguish between fortified and unfortified products within the dried milk groups, which is relevant for interpreting iron, zinc, and copper values. Manganese and cadmium showed statistically significant between-group differences (ANOVA, P less than 0.05); lead, chromium, and nickel differences were nonsignificant.
Related evidence
- Infant Formula Powder
- Infant Formula
- Milk powders (whole, skim, specialty)
- Lead
- Cadmium
- Chromium
- Nickel
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