Assessment and management of risks arising from exposure to cadmium in fertilisers. I.

A risk assessment protocol has been developed for use by individual EU Member States with appropriate selection of input data, to assess the risks to humans and the environment arising from exposure to cadmium in fertilisers. The protocol comprises of three modules: (1) the accumulation module, in which the net accumulation of cadmium in soil and soil solution, resulting from the application of fertiliser, is computed over time. The accumulation module allows for a range of inputs from different sources (atmospheric deposition, sludge addition, manure and fertiliser application) as well as for average and extreme rates of fertiliser application. A critical parameter is the solid/liquid partition coefficient, which in turn is a function of soil properties such as pH and is highly variable depending on the algorithm selected as being representative of national conditions. (2) The exposure module, in which the uptake of cadmium from soil into plants and the subsequent intake of cadmium by humans is computed, using exposure parameters characterising both average and extreme exposure scenarios. The protocol focuses on food types known to be sensitive to cadmium uptake (grain, cereals, potatoes, root vegetables and leafy vegetables). Environmental exposure is also characterised. (3) The risk characterisation module, in which Member States may estimate the incidence and severity of the adverse effects likely to occur due to actual or predicted exposure to cadmium. This is undertaken by modelling the Predicted Environmental Concentrations (PECs) in humans and the environment using the accumulation and exposure modules, and then comparing these values against the relevant Predicted No Effect Concentrations (PNECs). A range of environmental PNEC values are reported in the literature; the European Commission recommends that normally the lowest No Observed Adverse Effect Level (NOAEL) should be used in the risk characterisation. For humans, the current WHO Provisional Tolerable Weekly Intake (PTWI) is equivalent to a daily intake of 70 microg Cd day(-1). Particular risk groups can be characterised, namely of: children; smokers; women with low iron stores; consumers of food items with high cadmium content; and extreme consumers of staple food items. At present, with the data available, it is not possible to characterise risk groups in detail, either at EU level or at Member State level. However, most Member States appear to have an average intake of cadmium which is lower than the WHO's PTWI.

Assessment and management of risks arising from exposure to cadmium in fertilisers--II.

A preliminary, illustrative human health risk assessment of exposure to cadmium in phosphate fertilisers was performed using typical UK data and a protocol previously developed for application by individual Member States in the European Union. The risk assessment indicated that the for the most pessimistic population exposures characterised by both extreme (97th percentile) cereal and potato consumption and high susceptibility to cadmium uptake, the estimated dose was under the WHO Provisional Tolerable Weekly Intake (PTWI) for fertiliser cadmium concentrations ranging from 15 to 100 mg Cd/kg P2O5 applied over 100 years. However, the low margin of safety for high risk groups and the uncertainties inherent in the overall risk assessment suggested that a prudent risk management strategy would involve maintenance of low levels of cadmium in fertilisers and/or conditions that permitted low accumulation of cadmium in soils. On this basis, two main risk reduction measures were developed and assessed: (a) imposition of limits on cadmium concentration in fertilisers; and (b) imposition of charges on levels of cadmium in phosphate fertilisers. An assessment of the economic impact of these risk reduction measures indicated that, at all price elasticities, the most significant impact in terms of changes in demand and changes in consumer expenditure on phosphate fertilisers will be seen with cadmium charges where no thresholds are defined. The impact on the consumer (i.e. farmer) will be an increase in spending of approximately US $4000 per year, which is considered significant, accompanied by a decrease in demand above 20%. If a threshold is set at 60 mg Cd/kg P2O5, the impact is significantly reduced, but stays relatively high compared to the other options. The analysis also indicates that the use of low-cadmium rock is the low cost option. At a likely rock price increase of approximately 5% and assuming a likely price elasticity of -0.2, the yearly costs to farmers will be approximately US $82 which is considered a minimal impact. In the worst case scenario (elasticity of -0.6 and a 10% increase in rock prices), the increase in spending by farmers will be of 3.9% or US $221 which is also considered to represent a minimal impact. At similar price elasticities, the use of decadmation technologies is predicted to be more costly than the use of low-cadmium rock but this option can still be considered as having a minimal impact on the consumer (increase in expenditure of 1.9-13.3% or US $106-748).