Estimating the environmental risk of the societal stock of additives in plastics by a chemical footprint approach
Conference contribution, 2015
Environmental risk posed by additives in products in the technosphere in general and in consumer products in particular, is an important issue that has been, so far, investigated to a relatively limited extent. Previous estimates of the national stock and emissions are available on national scale [1,2,3] but the challenge has remained to understand how important or significant these stocks and emissions are from a risk perspective. The research presented here approaches the challenge by assigning risk characterisation scores to the additives and comparing the outcome with corresponding risk characterisation for biocides. We used the previous estimates om stock and emissions of plastic additives. Data for use of biocides were extracted from the Swedish Chemicals Agency The risk characterisation was carried out by applying USETox characterisation factors (CF), The amount of each substance, has been multiplied with its corresponding CF from USETox. These substance specific risk scores were then added to the overall risk score. It is clear that there are many uncertainties in the calculations. For example the emission calculations in the overall society example seem unreasonably high, in the order of 2 % annually of the total stock. In other work applying an advanced emission model to a limited sample of products, the emission rate is in the order of 0.02 % annually. This indicates that the overall society-wide emissions could be in the order of 500 tons rather than 47000 tons. For the risk scores, the uncertainty is even bigger, as the uncertainty of the CFs themselves come into play, as well as the incomplete availability of CFs. The total risk score for the National total use of biocides is 9.3E+09 CTU. This is to be compared with the risk scores as calculated for the additives, which is 1.3E+12 CTU for the total stock of additives and 3E+10 CTU for the emissions, or possible a factor 100 lower if assuming a similar overestimation as for emissions. The results are very sensitive to the identified uncertainties, and also to lack of CFs for possibly important substances, both among the additives and the biocides.