Introduction to Life Cycle Assessment

Initial objective of the study : evaluate which brush has less environmental impacts.

According to the previous results, the manual toothbrush has less impact in four of the five categories evaluated. As far as climate change is concerned, the difference is too small to be conclusive.

The graph below details the stages in an iterative approach to investigating the sources of impacts

The graph below shows the main contributors to the cost of electric toothbrushes.

The ‘Toothbrush’ and ‘Brushhead’ categories cover the materials, manufacturing processes and transport required for each.

The manufacture of the brush is significant in all impact categories. It is even the main source of contribution in four of the five categories (except freshwater ecotoxicity): between 46% and 98%.

The end-of-life phase is a significant contributor (54%) to the freshwater ecotoxicity category.

The use phase, although less impactful, is also significant for three of the five impact categories (around 20-30%).

The ‘Toothbrush’ and ‘Brushhead’ categories cover the materials, manufacturing processes and transport required for each.

The interpretation phase is used to compare the assumptions made throughout the LCA.

It is necessary to assess the quality of the dataset used and the robustness of these assumptions, in particular through sensitivity analyses.