For all metals, the transfer factors based on the HOAc-extractable
metal fraction are much higher than the TFtotal. In the studied soils this
does not result in a risk to human health due to the very low amounts
of soluble/exchangeable metal forms. Moreover, both TFtotal and TFHOAc
values decreasewith increasing total concentration ofmetals in the soil,
indicating that the proportion of soil metals taken up by the vegetables
does not increase with soil pollution. Thus, in the soils in question the
quantity of metals assimilated tends to remain under the control of
the plantmetabolismregardless of intensification of the totalmetal content.
Whether this actually occurs at higher levels of soil pollution
would require additional testing.
In polluted agricultural lands, soil-to-plant transfer factors for variousmetals
and formost commonly consumed vegetables could become
key components of human exposure to metals through the food chain.
Knowledge of such factors might help select the most appropriate
plant crops in relation to PTE bioavailability in soil.