Overview
Onwordi and colleagues measured lead, cadmium, nickel, copper, cobalt, zinc, iron, sodium, magnesium and calcium by flame atomic absorption in 18 biscuit products (three each of six types) bought in Lagos. Lead was present in every type at levels the authors judge above EU limits; cadmium was below detection throughout. Results are on a dry-weight basis.
Key numbers
- Lead: crackers 2.3 ± 1.3 mg/kg (range 0.7 to 4.3), digestives 1.80 ± 0.65 mg/kg, shortcakes 0.83 ± 0.76 mg/kg (Table 4, p. 7).
- Cadmium below detection (<0.02 mg/kg) in all biscuit types (Table 4, p. 7).
- All 18 biscuits: lead 1.49 ± 0.92 mg/kg, nickel 0.12 ± 0.15 mg/kg (Table 5, p. 10).
Methods (brief)
Samples pulverised, dried 1 h at 60 °C, wet-digested with nitric acid, hydrogen peroxide and perchloric acid; flame AAS, in duplicate. CRM BCR-191 brown bread checked copper, iron, zinc, calcium and magnesium only (Table 3); no lead recovery is reported.
Evidence Fitness
Direct biscuit data from a small sample (three products per type). Lead by flame AAS without a lead CRM is uncertain at these levels, and the cookie calcium mean falls outside its range. The products are generic biscuit types, so they are proxies for cheese-crackers, sugar-cookies, wheat-cereal-biscuits and white-cake, which are not linked.