Ecotoxicity in LCA – A review of methods and an assessment of the ecotoxic impact of pesticide use in Swedish winter wheat and Brazilian soybean production

This study gave a review of some of the existing life cycle assessment (LCA) methods focusing on ecotoxicity, and made assessments of the ecotoxic impact of pesticide use in an example Swedish winter wheat field from a 2005 inventory and an example Brazilian soybean production field. Pesticides are used worldwide within agriculture and are under constant development aiming to increase the control of unwanted weeds, fungi and insects etc. Regulation occurs worldwide at various levels but the global usage of herbicides and insecticides etc. brings concern for the health of the environment from exposure to toxic substances. Although human toxicity is of equal importance, this thesis looked at ecotoxicity as an impact category within LCA. Currently ecotoxicity impact assessment within LCA is a difficult task due to a multitude of factors to consider, such as the vast number of active ingredients, which can cause impacts at a single organismal level or communal level, acting individually or synergistically. The consensus of a single method and subsequent impact unit to use has not been met globally, making ecotoxicity evermore harder to assess. In this thesis, assessment methods were compared on several aspects with the aim to choose one for use on the following two case studies. The results from the comparison and other factors presented USEtox as the method to continue with for the two case studies. A field in Egonsborg was chosen as the example Swedish wheat field as farmer practices were known, giving realism to the assessment on pesticide use and dosage. For the Brazilian soybean assessment the area of Mato Grosso, known for its extensive soybean farms and production was chosen. Although dosages were known for the Mato Grosso area, confidentiality in farmer practices meant an estimate on the combination of pesticides used had to be applied for the assessment. Results of this report bring to light the difficulty in directly comparing LCA methods showing how the number of active substances each method can assess differs greatly as well as the characterised unit and how the characterisation factors are derived. Points where LCA lacks and improvements could occur would be e.g. the assumption of linearity of substance exposure as background volumes or potential threshold levels of substances in the environment are not currently considered. The toxicity of winter wheat and soybean production is presented as 0.28 CTUe/kg and 1.3 CTUe/kg respectively although these results are not intended to be …