Overview
Soltan and colleagues measured eight elements in raw camel and sheep milk, in the wild plants the animals grazed, and in the plants’ root-zone soils from Riyadh and Qassim regions of Saudi Arabia in spring 2016. They used plant bioaccumulation factors and milk-to-plant ratios to argue that soil and forage drive milk element levels. Only the milk values are findings; plants and soils are context.
Key numbers
- Camel milk lead “0.54” ppm (Riyadh) and “0.59” ppm (Qassim), mean of 5 samples (Table 1).
- Camel milk cadmium “0.013” ppm (Riyadh) and “0.026” ppm (Qassim); nickel “1.51” and “2.1” ppm (Table 1).
- Sheep milk lead “0.68” ppm (Riyadh) and “0.88” ppm (Qassim); nickel “0.80” and “2.21” ppm (Table 1).
- Forage plants carried 34.2 to 48.9 ppm lead and root-zone soils 19.6 to 31.8 ppm (Table 1).
Methods (brief)
Ten mL of milk was wet-oxidized with nitric, sulfuric and perchloric acids on a sand bath and made to 25 mL; elements were read by flame AAS (Solaar 969) with deuterium background correction. Results are means of five samples in ppm, with no SD, range or detection limit. Reference materials are said to have given acceptable results, but the cited NIST SRMs (2711, 2709) are soils, not milk.
Evidence Fitness
Moderate to weak. Sample sizes are small (5 per species per region), no dispersion or detection limits are printed, and the accuracy check relies on soil reference materials. Lead in camel milk at about 0.5 ppm is well above most published camel milk values, and the authors attribute it to roadside grazing. It measures raw camel milk directly. Feed, plant and soil results are not milk findings.