Overview
This study examined how copper (Cu) coexposure affects the accumulation, translocation, and metabolism of the acaricide/insecticide tolfenpyrad in pea seedlings under soil-based and hydroponic cultivation. The study is primarily a pesticide residue and Cu interaction study, not a food survey. Its relevance to the pea heavy metals page is the documentation of copper uptake behavior and bioconcentration in pea seedling roots, stems, and leaves, and the effect of Cu on pesticide translocation.
Key numbers
Copper concentrations in soil-cultivated pea seedling tissues under low-dose treatment conditions (Table in Figure S3A, supplemental information):
- Roots: 0.392 to 0.552 mg/kg (without Cu addition), elevated to 0.462 to 0.649 mg/kg (with Cu addition)
- Stems: 0.248 to 0.580 mg/kg (without Cu addition), elevated to 0.281 to 0.605 mg/kg (with Cu addition)
- Leaves: 0.211 to 0.748 mg/kg (without Cu addition), elevated to 0.258 to 0.808 mg/kg (with Cu addition)
Bioconcentration factor (BCF) for tolfenpyrad: BCF less than 1 in soil-cultivated seedlings (indicating low root accumulation from soil); BCF greater than 1 in hydroponically grown seedlings (indicating ready absorption from nutrient solution). These are BCF values for the pesticide, not for Cu itself.
Limit of quantitation (LOQ) for tolfenpyrad: 0.01 mg/kg; limit of detection (LOD): 0.003 mg/kg (p.6, supplemental methods).
Half-lives for tolfenpyrad dissipation in soil-cultivated pea seedlings: 3.6 to 3.8 days (Table S2, supplemental information).
Methods (brief)
Soil cultivation and hydroponic cultivation experiments using pea seedlings (variety Zhongwan No. 6) in a greenhouse incubator (25 degrees C day, 15 degrees C night, 16 h light/8 h dark, 70% relative humidity). Single root application of tolfenpyrad at 50 mg/L (low dose) and 80 mg/L (high dose). Copper standard (99% purity, Ehrenstorfer GmbH) added at 10 mg/L. Roots, stems, leaves collected at 0, 1, 2, 3, 4, 6, 8, 10, 12, 14 days post-application. Cu concentrations by ICP-MS (Thermo Scientific iCAP Q). Tolfenpyrad by LC-MS/MS (Shimadzu LC-20AD XR system). Metabolites identified by UHPLC-HRMS (Shimadzu Nexera UHPLC with Q-Orbitrap). Recovery rates for tolfenpyrad: 82.71 to 102.5%, RSDs 0.74 to 3.32%.
Implications
Relevant to the frozen peas pathway section as evidence that copper is taken up by pea roots and distributed to stems and leaves, with Cu concentrations in pea seedling tissues in the range of 0.2 to 0.8 mg/kg (wet weight basis is not stated explicitly for the Cu tissue data; the paper reports these values alongside fresh-weight-basis tissue samples). The study confirms that the pea root system is a site of copper accumulation and that Cu levels in tissues are influenced by soil Cu concentration. This is a controlled greenhouse experiment, not a field or food survey, and the Cu concentrations applied (10 mg/L addition) represent elevated exposure rather than typical soil backgrounds.
Related evidence
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