Overview
This study measured lead, cadmium, zinc, copper, iron and manganese by ICP-MS in leafy vegetables, tomatoes and soft fruits grown in 16 Warsaw allotment gardens and in rural control gardens. Leafy vegetables carried far more lead and cadmium than fruits, and lettuce grown along streets had the highest levels. Lead and cadmium in the fruits were printed only as below the detection limit.
Key numbers
- Lettuce (n = 33): lead mean 11.1 mg/kg DM (range 1.0 to 21.0), cadmium mean 1.36 mg/kg DM (range 0.10 to 2.70) (Table 1, p. 6).
- Beet greens (n = 26): lead mean 10.0 mg/kg DM, cadmium mean 1.03 mg/kg DM (Table 1).
- Lettuce along the street: lead “16.0 ± 4.43”, cadmium “2.81 ± 0.72” mg/kg DM; furthest from the street: lead “7.3 ± 3.32”, cadmium “0.25 ± 0.15” (Table 3, p. 10).
- Control vegetables: lead mean 0.2 mg/kg DM, cadmium below LOD; cherries, gooseberries and red currants: lead and cadmium “LOD” (Tables 1-2).
Methods (brief)
Mixed samples from 5 to 7 sites were washed, dried at 60 and then 105 °C, dry ashed at 480 °C, dissolved in hydrochloric acid and analyzed by ICP-MS following US EPA Method 6020B in an accredited laboratory. Analyses were in duplicate, and certified soil and tobacco reference materials were used, but recoveries are not reported. All results are on a dry-matter basis.
Evidence Fitness
A garden-grown (not retail) urban survey with moderate sample sizes and dry-weight results that are not comparable with fresh-weight limits. Some printed statistics are internally inconsistent (cherries copper mean below its minimum, a control fruit iron minimum above its maximum, and lettuce location counts that sum to 53 rather than 33); these are flagged in the extraction. No collard greens were measured; the leafy vegetables here are only a proxy for collard-greens, so that page is not linked.