A proposal for a diet-based local PCDD/F deposition limit.

This study proposes a method to estimate the maximal tolerable value for the atmospheric deposition of dioxins (PCDD/Fs) to soil. The case study for the application of this methodology is an Alpine valley where a steel production plant is present. In order to estimate the limit value for the PCDD/F deposition, consolidated food chain models were applied, but were adapted to be run backwards with respect to their original formulation, by starting from the diet of people living in the region and from the PCDD/F Tolerable Daily Intake value proposed by the World Health Organization. For this case study, the estimated limit value was 2.30 pg WHO-TEQ m(-2) d(-1) when only local diary products were taken into account and 1.91 pg WHO-TEQ m(-2) d(-1) when also the role of local cereals and vegetables was considered. The average PCDD/F deposition measured in the same region during a monitoring campaign was lower than the above limit values (1.40 pg WHO-TEQ m(-2) d(-1)). Indications on how to consider the contribution of meat and fish are provided too. The approach proposed in this paper represents a useful tool to assess the acceptable overall deposition for a specific region.