Overview
Klavins and colleagues measured up to 24 elements by ICP-OES in freeze-dried berries: eight highbush blueberry cultivars grown at one Latvian farm, supermarket blueberries from nine origin countries and wild bilberries from Latvia, Lithuania, Finland and Norway. They also measured carbon, nitrogen and oxygen isotope ratios for origin testing. Results are dry-weight means with SD (Tables 1 to 3). The authors judge all levels low.
Key numbers
- Wild bilberry, Lithuania: lead “0.456 ± 0.023” mg/kg, cadmium “0.033 ± 0.002” mg/kg (Table 3, p. 7).
- Commercial blueberries labelled Argentina: cadmium “0.073 ± 0.006” mg/kg, lead “0.16 ± 0.031” mg/kg (Table 2, p. 5).
- Cultivar Duke: arsenic “0.31 ± 0.01” mg/kg (Table 1, p. 4).
- Chile blueberries: cadmium, lead and selenium “<LOD” (Table 2).
Methods (brief)
Frozen berries were lyophilized, digested by microwave in nitric acid and hydrogen peroxide and analyzed by ICP-OES. Accuracy was checked with a blueberry fruit certified reference material (within 15 percent). Detection limits are stated only for the digest solution.
Evidence Fitness
Broad geographic coverage with SDs and a matrix-matched reference material. Values are dry weight, so they read several times higher than fresh fruit. The bilberry table gives n = 9 for every country although Latvia had 26 sites, and sample-basis detection limits are not stated. Arsenic is total arsenic. Blueberry is an ingredient proxy for blueberry-muffin; no baked product was measured.