Ecotoxicity impact assessment of laundry products: a comparison of USEtox and critical dilution volume approaches

There is an increasing interest in the assessment and comparison of the environmental impacts of consumer products. Schemes such as Grenelle de l’Environnement, currently under development in France, aim to assess and communicate the life cycle impacts of consumer products. Freshwater ecotoxicity is one of the impact categories under consideration. This paper presents the results of a comparison of USEtox and critical dilution volume (CDV) approaches for assessing laundry products.

The study focused only on the end-of-life stage, i.e. when the products are discharged after use into a sewage treatment plant and the environment. Two independent case studies were performed, in parallel, on three laundry product formats: powder, dilute liquid and concentrated liquid. For the USEtox assessment, new characterization factors (ChF) were calculated for all ingredients.

The relative ranking of the laundry product formats was consistent across the two studies but not with the two methods. The dilute liquid format had the highest ecotoxicological impact potential with the CDV method, whereas the powder format was ranked highest with the USEtox method. A comparison was also made between published USEtox factors and those used in this work, suggesting that the published ones should be seen primarily as screening level values.

While risk assessment is the recommended method for evaluating the safety of chemicals, the potential use of the CDV and USEtox methods for ranking products on their environmental ecotoxicity profile was evaluated. The two methods showed a lack of agreement, which can be attributed to their different conceptual approaches. The lack of concurrence between the methods raises the issue of whether either method is suitable for environmental product labelling. In addition, the current USEtox database does not cover many laundry ingredients, and furthermore, the USEtox method does not satisfactorily address inorganic chemicals, which are important ingredients in laundry products. The calculation of additional or revised ChFs for USEtox is a time-consuming task. In comparison, the CDV method covers most laundry ingredients, but its lack of comprehensive environmental fate modelling is an inherent weakness. A common limitation for both methods is the level of uncertainty in the impact scores, which can make it difficult to identify statistically significant differences between product scores.