Overview
Oladapo and colleagues measured arsenic, nickel, cadmium, lead and mercury by MP-AES in 10 tomato pastes and 6 tomato ketchups, half Nigerian-made and half imported, bought in markets in southwest Nigeria. Per-product means are printed for cadmium, nickel and lead; arsenic and mercury were below detection. Domestic and imported products did not differ significantly.
Key numbers
- Lead: tomato paste means 0.128 mg/kg (imported) and 0.121 mg/kg (domestic); ketchup 0.136 and 0.102 mg/kg; highest single product 0.2418 mg/kg (domestic paste DTP4) (Table 2.3).
- Cadmium: 0.066 to 0.107 mg/kg across products; paste means 0.078 (imported) and 0.088 (domestic) mg/kg (Table 2.1).
- Arsenic and mercury below the detection limit in all samples (Results, p. 534).
Methods (brief)
One gram of sample was digested with hydrogen peroxide and nitric acid at 70 °C and analyzed on an Agilent 4200 MP-AES, with hydride generation for arsenic and mercury. Calibration used five standards from 0.2 to 4.0 mg/L. No reference material, recoveries or numeric detection limits are reported.
Evidence Fitness
A small market sample (16 products) with per-product means but no replicate counts. The nickel table’s unit scale conflicts with the text and the abstract, so nickel values are not usable. The text’s cadmium exceedance statement contradicts its own table. This paper measures tomato paste and ketchup directly; it is only a proxy for the barbecue-sauce, canned-spaghetti, pasta-sauce and tomato-soup pages, none of which is linked.