Phytotoxicity and bioconcentration of microcystins in agricultural plants: Meta-analysis and risk assessment

Highlights: • Microcystins phytotoxicity in agricultural plants was studied by meta-analysis. • Greater phytotoxicity of microcystins is from natural bloom extract. • Durum wheat, corn, white mustard and garden cress exhibited the most phytotoxicity. • Leafy vegetables could bioconcentrate ∼3 times more microcystins than other plants. • Human health risk from ingesting microcystins could be greater for leafy vegetables. Microcystins are cyanotoxins produced by many species of cyanobacteria. They are specific inhibitors of serine/threonine protein phosphatases and are phytotoxic to agricultural plants. This study used a formal meta-analysis to estimate the phytotoxicity and bioconcentration rates of agricultural plants exposed to microcystins, and the human health risk from consuming microcystin-contaminated plants. Among the 35 agricultural plants investigated, microcystins were most phytotoxic to durum wheat, corn, white mustard and garden cress. Leafy vegetables such as dill, parsley and cabbage could bioconcentrate ∼3 times more microcystins in their edible parts than other agricultural plants. Although the human health risk from ingesting microcystins could be greater for leafy vegetables than other agricultural plants, further work is needed to confirm bioconcentration of microcystins in realistic water-soil-plant environments. Still, we should avoid growing leafy vegetables, durum wheat and corn on agricultural land that is irrigated with microcystins-contaminated water and be attentive to the risk of microcystins contamination in the agricultural food supply.