sustainability Article Life Cycle Assessment of a Plant-Based, Regionally Marketed Shampoo and Analysis of Refill Options Hanna Kröhnert and Matthias Stucki *   Citation: Kröhnert, H.; Stucki, M. Life Cycle Assessment of a Plant-Based, Regionally Marketed Shampoo and Analysis of Refill Options. Sustainability 2021, 13, 8478. https://doi.org/10.3390/su13158478 Academic Editor: Silvia Fiore Received: 9 June 2021 Accepted: 22 July 2021 Published: 29 July 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Institute of Natural Resource Sciences, Life Sciences and Facility Management, Zurich University of Applied Sciences (ZHAW), CH-8820 Wädenswil, Switzerland; hanna.kroehnert@gmail.com * Correspondence: matthias.stucki@zhaw.ch Abstract: The environmental impact of a plant-based shampoo produced and marketed in Zurich, Switzerland, was analyzed using the life cycle assessment method. Beside the identification of environmental hotspots and mitigation possibilities, the focus of the study was on the analysis and comparison of different refill offers. The results of the study show that one hair wash using the investigated shampoo is related to greenhouse gas emissions of 161 g CO 2 eq. For all investigated impact categories, the use phase represents the dominant life stage, except for land use, which is dominated by the production of the purely plant-based shampoo ingredients. The environmental impact related to the use phase is highly sensitive on the consumers’ showering habits, such as water consumption and water temperature, due to predominantly fossil-based heating in Zurich. On the producer’s side, a switch to renewable energy sources both for heating and electricity is identified as most effective measure to reduce the environmental impact of the manufacturing phase. As to the product end-of-life, the results suggest that emissions of the shampoo ingredients after wastewater treatment have a negligible impact on freshwater ecotoxicity. In this context, a need for further research is identified with respect to characterization factors and specific removal rates in wastewater treatment plants. From a life cycle perspective, packaging production and disposal have rather low contributions. Offering refill possibilities can reduce the packaging related contributions by several percentage points, however, higher mitigation potentials are found for use phase and manufacturing. Keywords: shampoo; natural ingredients; packaging; refill; LCA; environmental impact 1. Introduction Shampoo represents one of the most common personal care products: In European households, shampoo is used with an average application frequency of two to three times per week [1], amounting to about 2 kg of shampoo used per person each year [2]. While previously rather neglected as a research topic [3], the environmental impact of personal care products from a life cycle perspective has received increasing attention in the last decade. However, publications on life cycle assessment (LCA) of shampoo using a cradle- to-grave approach are still rare. At the European level, comprehensive LCA studies on representative products were conducted by Cosmetics Europe and Quantis [4,5] and by the Joined Research Centre of the European Commission [6], which considered ingredients compositions and packaging solutions most widely used on the European market. The two studies found various envi- ronmental hotspots for shampoo: climate change, water resource depletion, mineral and fossil resource depletion, eutrophication, particulate matter, human toxicity, and freshwater ecotoxicity. While the results for freshwater ecotoxicity are almost entirely dominated by the product disposal via wastewater treatment, the studies show that all other ecological hotspots contain a major contribution from the use stage of the shampoo, specifically the use of hot water while showering. In fact, the extent of the environmental impact of a shampoo is very sensitive towards consumer habits such as the water temperature and the Sustainability 2021, 13, 8478. https://doi.org/10.3390/su13158478 https://www.mdpi.com/journal/sustainability