Improved prediction of the bioconcentration factors of organic contaminants from soils into plant/crop roots by related physicochemical parameters.

There has been an on-going pursuit for relations between the levels of chemicals in plants/crops and the source levels in soil or water in order to address impacts of toxic substances on human health and ecological quality. In this research, we applied the quasi-equilibrium partition model to analyze the relations for nonionic organic contaminants between plant/crop roots and external soil/water media. The model relates the in-situ root concentration factors of chemicals from external water into plant/crop roots (RCF) with the system physicochemical parameters and the chemical quasi-equilibrium states with plant/crop roots (α ≤1). With known RCF values, root lipid contents (f), and octanol-water K's, the chemical-plant α values and their ranges of variation at given fK could be calculated. Because of the inherent relation between α and fK, a highly distinct correlation emerges between log RCF and log fK (R = 0.825; n = 368), with the supporting data drawn from 19 disparate soil-plant studies covering some 6 orders of magnitude in fK and 4 orders of magnitude in RCF. This correlation performs far better than any relationship previously developed for predicting the contamination levels of pesticides and toxic organic chemicals in plant/crop roots for assessing risks on food safety.