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The spread of dioxins through Thermphos : Deposition, concentration in the air and exposure

De verspreiding van dioxinen rond Thermphos : Depositie, concentratie in de lucht en blootstelling


For some emission scenarios, the National Institute for Public Health and the Environment (RIVM) has calculated the degree to which people will be exposed to dioxins in the next five years as a result of emissions by the Dutch Phosphorus plant Thermphos in Zeeland. The starting point of the most realistic emission scenario is that of the average emission concentration for 2010 of 2 nanograms per cubic metres air. The daily exposure of people living in the neighbourhood of the plant is then increased by one third. The total daily intake of dioxins does not exceed the accepted standard level. In the worst case scenario, this exposure will double compared with the current situation. The exposure will then be approximately the level of the accepted standard for daily intake. This is based on emission levels over a period of five years that is equal to the highest emission measured in 2010 (5 nanograms per cubic metres air). This is clear from an RIVM risk assessment based on the available data and the scenarios that have been set. People living in the area of the plant are exposed to dioxins either through the air or through the consumption of crops that have absorbed the dioxins. The assumptions made regarding the degree of dioxin consumption? through crops is such that the level of people's exposure to dioxins is more likely to be overestimated than underestimated. In order to estimate the level of exposure, dispersion models were used to calculate the concentration in the air, the deposition on the ground and on crops as well as the soil concentration after five years. These data are subsequently converted into the amount of dioxins that are ingested through respiration, contact with ground, e.g., hand-to-mouth behaviour by children, and through the consumption of crops. This concerns crops that contain dioxins due to deposition of particles or because the crops have absorbed dioxins through the soil. The extra exposure to dioxins is determined by the consumption of locally cultivated and contaminated crops.

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