Overview
Somda and colleagues harvested tomatoes in October 2018 from two peri-urban plots in Ouagadougou irrigated with industrial wastewater. They measured arsenic, cadmium, chromium, copper, mercury, nickel, selenium and zinc by graphite furnace AAS in fruit, soil and water, and also tested microbial quality. Table 2 gives one mean ± SD per metal per site. Lead was not measured.
Key numbers
- Tomato, Boulmiougou: arsenic 17.80 ± 0.32, cadmium 2.71 ± 0.02, mercury 15.13 ± 0.30 mg/kg (Table 2, p. 948).
- Tomato, Kossodo: arsenic 3.47 ± 0.15, cadmium 2.78 ± 0.01, mercury 14.86 ± 0.10 mg/kg (Table 2, p. 948).
- Transfer factors are 0.86 to 0.87 at Boulmiougou and 0.79 to 0.80 at Kossodo for every metal (Table 3, p. 950).
Methods (brief)
Fruit was washed, dried at 105 °C and powdered, digested with nitric, perchloric and sulfuric acids, and read on a Shimadzu 6800 AAS with graphite furnace. No detection limit, reference material, recovery or sample count is reported.
Evidence Fitness
Not reliable as occurrence data. At each site every tomato value is a fixed fraction of the soil value (0.87 and 0.80), so the transfer factor is the same for all eight metals. Independent measurements would not do that, and the values may have been derived rather than measured. Mercury near 15 mg/kg and arsenic near 18 mg/kg in tomato are implausible. The text also mixes up table cells, and the microbial table is titled “lettuce”. All findings carry integrity flags. Fresh tomato is a proxy for barbecue-sauce, pasta-sauce and tomato-soup; those pages are not linked.