Rosales-Huamani et al. 2023 — PTEs in Quinoa Soils, Huacaybamba-Huánuco, Peru
This peer-reviewed study from the National University of Engineering (Lima) and National University of Callao measured potentially toxic elements (As, Pb, Cd, Cu, Zn) in 50 agricultural soil samples from a 4-hectare quinoa-producing area in the Huacaybamba-Huánuco Department of Peru, an Andean highland region adjacent to gold and copper mineralization zones. Analyzed by atomic absorption spectrophotometry (AAS, EPA 3050-B method). The study found that all As, Cu, and Zn concentrations were below Peruvian and European agricultural soil quality standards, but 46% of Pb samples exceeded standards and 100% of Cd samples exceeded Peruvian environmental soil quality standards.
Key numbers
Soil concentrations (50 samples, Huacaybamba-Huánuco quinoa area, mg/kg):
As (n=50): mean 2.01 ± 0.52 mg/kg; minimum 1.27 mg/kg; maximum 3.93 mg/kg. All values below Peruvian/EU standard. Distribution concentrated in first quartile (1.70 mg/kg).
Pb (from Table 1, individual samples): range approximately 28.14–324.00 mg/kg (extracting min/max from the tabulated data). 46% of samples exceeded the Peruvian quality standard for agricultural soils.
Cd (from Table 1, individual samples): range approximately 1.47–4.49 mg/kg. 100% of samples exceeded Peruvian environmental quality standard. Mean approximately 2.0–2.5 mg/kg based on table values (full statistical summary for Cd in results section beyond pages read).
Cu (n=50): range 30.36–92.61 mg/kg (from Table 1). All below standards.
Zn (n=50): range 60.30–243.78 mg/kg (from Table 1, excluding high outlier). All below standards.
Fe (from Table 1): range 35,190–85,646 mg/kg (high iron — consistent with Andean volcanic/mineralogical substrate).
Note on scope: This paper reports soil concentrations only, not quinoa grain concentrations. The relationship between these soil values and quinoa grain uptake requires application of transfer factors which are not reported in this paper.
Methods (brief)
50 soil samples from 50-point grid (20m × 20m spacing) in a 4-hectare quinoa cultivation area. Sampling depth: 30 cm side of 50 cm pits. AAS (GBC Scientific XplorAA) for all elements. EPA 3050-B acid digestion. Wavelengths: As 193.7 nm, Cd 228.8 nm, Pb 217.0 nm, Cu 324.7 nm, Zn 213.9 nm. Quality control: duplicates every 10 samples, blanks and internal standards every 25. Precision coefficient of determination: 99%.
Limitations
This study reports soil concentrations only, not quinoa grain metal content. The connection to food-safety risk requires knowledge of quinoa’s metal bioaccumulation from soil, which varies substantially and is not calculated here. The journal (International Journal of Membrane Science and Technology) is not the primary venue for food safety research; the study’s institutional affiliations and methodology appear credible but the venue is unexpected. The study area is a specific 4-hectare locality in a geologically complex Andean region; results may not generalize to other quinoa-growing areas in Peru or Bolivia.
Implications
- Certification: The 100% exceedance of Peruvian Cd standards in quinoa-growing soils in this locality is a significant finding: soils from Andean mining-adjacent regions can have elevated Cd and Pb. Any HMT&C certification of Peruvian quinoa should require soil characterization or direct grain testing.
- Courses: Good illustration of how natural geological mineralization (volcanic rocks, sulfide deposits in Andean regions) drives background metal levels in agricultural soils independently of anthropogenic contamination.
- App: No grain concentration data; not directly applicable to contamination_profile. Flags Peruvian origin as a geographic risk factor warranting supply-chain scrutiny.
- Microbiome: Not applicable.