Overview
This Research Square preprint reports lead, cadmium and arsenic measured by graphite furnace AAS in four composite samples each of basil, leek, spinach, mint and parsley grown with treated municipal wastewater in the Zabol agribelt, followed by a Monte Carlo risk model. Mint and leek carried the most lead, basil the most cadmium, and one spinach sample carried much more arsenic than the rest. A journal version appeared later in Exposure and Health; the filed PDF is the preprint.
Key numbers
- Lead: mint 2.23 ± 0.21, leek 2.12 ± 0.21, basil 1.63 ± 0.60, parsley 1.31 ± 0.04, spinach 0.725 ± 0.054 µg/g dry weight (Table 1).
- Cadmium: basil 0.178 ± 0.025 µg/g; spinach 0.0061 ± 0.0008 µg/g (Table 1).
- Arsenic: spinach samples 0.01, 0.023, 0.035 and 0.30 µg/g (Table 1).
Methods (brief)
Composite 2 kg samples were washed, dried at 65 °C, ground, digested by EPA 3051A microwave method and analyzed by GF-AAS. Detection limits were 0.01 (lead) and 0.001 (cadmium, arsenic) µg/g. NIST spinach leaves recovered 91 to 94%. Per-sample values are printed in Table 1.
Evidence Fitness
A preprint, not the peer-reviewed version; the journal version was not read. Field samples from wastewater-irrigated plots, so they represent a contaminated growing setting rather than retail produce. Only four samples per vegetable, on a dry-weight basis, and several cadmium and arsenic values fall below the stated quantification limit. The leafy herbs are a proxy for collard-greens and the vegetable set is a proxy for vegetables-mixed; neither is measured.