Summary
This study measured concentrations of copper, nickel, cobalt, zinc, manganese, cadmium, chromium, and lead in soils and coffee beans from the West Guji Zone of Ethiopia, one of the country’s major coffee-producing regions. Copper concentrations in coffee beans ranged from 20.20 to 22.44 mg/kg and zinc from 6.74 to 8.43 mg/kg, both below permissible limits. The carcinogenic risk (CR) for chromium was 8.7 × 10^-5, which falls within the USEPA acceptable lifetime risk range (10^-6 to 10^-4). ANOVA analysis found significant differences in copper, nickel, cobalt, zinc, manganese, and cadmium concentrations across sampling sites (p less than 0.001), reflecting variation in soil composition, agricultural practices, and environmental conditions.
Key numbers
| Measure | Value | Units | Matrix | Source location |
|---|---|---|---|---|
| Cu range in coffee beans | 20.20 to 22.44 | mg/kg | Roasted/processed coffee bean | p. 6 |
| Zn range in coffee beans | 6.74 to 8.43 | mg/kg | Roasted/processed coffee bean | p. 6 |
| CR for chromium | 8.7 × 10^-5 | dimensionless | Coffee consumption pathway | p. 1 |
| ANOVA significance for Cu, nickel (Ni), Co, Zn, Mn, cadmium (Cd) | p less than 0.001 | probability | Soil and bean samples | p. 5 |
| USEPA acceptable CR range | 10^-6 to 10^-4 | dimensionless | Reference | p. 1 |
Methods (brief)
Soil and coffee bean samples collected from West Guji Zone farming sites. Metal analysis by ICP-OES or AAS (specific instrument not stated in available pages). Health risk assessment using USEPA HQ and CR frameworks. ANOVA used to test significance of concentration differences across sites.
Evidence fitness
This study provides site-specific data on heavy metals in Ethiopian coffee beans from a commercially important origin. The carcinogenic risk from chromium is at the upper margin of the USEPA acceptable range but does not exceed it. The site-level ANOVA results confirm that contamination is heterogeneous across the zone, with significant variation tied to soil type and local practices. The study does not provide population-level dietary intake estimates beyond the coffee consumption pathway.
Limitations
Single-zone study; results may not represent other Ethiopian coffee-producing regions. Specific sample sizes and methods not fully detailed in the available pages. Coffee bean preparation stage (green versus roasted) affects metal concentrations and is not always consistent across sources.
Related evidence
Update history
No substantive edit history is available in this build. The full commit record is available in git.