Overview
Mensah and colleagues bought 40 baked clay balls sold for eating at eight Kumasi markets and measured pseudototal (aqua regia) and EDTA-available elements by AAS, then built near-infrared prediction models and estimated ingestion and dermal hazard quotients. Most per-market results are shown only in box plots and bar charts. The text reports cadmium contamination and lead well above food limits, with copper the largest contributor to the hazard index.
Key numbers
- Pseudototal cadmium “varied from 0.59 to 6.81 mg kg−1” across markets (Abstract; Section 3.3), but the text also gives a cadmium maximum of 27.00 ppm at Krofrom (Section 3.3).
- Lead: highest market average 17.7 ppm (Central market) (Section 3.3).
- Total arsenic: 0.20 to 0.24 ppm (Section 3.3).
- Table 1 prints iron, manganese and zinc per market (e.g. Mn mean 12.8 mg kg−1 at Tanoso), but these do not match the text’s total manganese of 256.4 to 302.0 ppm and may be available fractions (Table 1, p. 7).
Methods (brief)
Air-dried, crushed and 2 mm sieved clay was digested in aqua regia and analyzed on an Agilent 200 AAS; available elements were extracted with EDTA. Reference materials BRM No. 13 and 10a gave recoveries of 85 to 119 percent. NIR-PLSR models were fitted for arsenic, chromium, copper, manganese, lead and zinc.
Evidence Fitness
A reasonable market sample (40 clays, 8 markets) with reference-material QA, but most concentrations are figure-only and the printed cadmium and lead figures conflict between sections, so values should be used with caution. No mercury result is reported despite being in the methods. Direct evidence for clay-geophagy; the dermal pathway here is handling, not cosmetic use, so it is only a proxy for cosmetic-clay and not comparable with food bands.