# Comprehensive methodology for standardized ecotoxicological assessment of TiO2-based sunscreen leachates in aquatic environment

## TL;DR

This study assesses the environmental impact of titanium dioxide in sunscreens by simulating their release into freshwater and seawater and testing their effects on aquatic organisms.

## Contribution

A novel ecosafety-oriented methodology integrating leaching protocols and multi-species testing for realistic ecotoxicological assessment of TiO2-based sunscreens.

## Key findings

- Toxic effects were observed in microalgae and crustaceans exposed to TiO2 active ingredients.
- Sunscreens formulations showed no toxicity, but algal growth inhibition was linked to TiO2 size.
- The study provides realistic ecotoxicological evidence for freshwater and marine environments.

## Abstract

This study evaluates the ecotoxicity of micro- and nano-sized titanium dioxide (TiO2), either as active ingredients or incorporated into sunscreen formulations in the aquatic environment, by proposing a leaching protocol simulating a realistic scenario of human immersion in freshwater and seawater.

To this aim, an ecotoxicological screening of micro- and nano-TiO2 active ingredients and incorporated into sunscreens was applied, by evaluating acute and sub-acute responses (bioluminescence and growth inhibition, immobilization, behaviour) in freshwater and marine bacteria, microalgae and crustaceans. Then, Ti concentration was measured in the leachates of sunscreens through Inductively Coupled Plasma mass spectrometry (ICP-MS).

Toxic effects (EC50s) were only found in microalgae and crustaceans exposed to TiO2 active ingredients. No toxicity occurred with sunscreens formulations, although significant algal growth inhibition was determined, likely due to TiO2 size rather than Ti concentration. By integrating a sunscreen leachate based methodology with a multi-species and multi-endpoint approach, this study introduces a novel ecosafety-oriented assessment of TiO2 providing realistic ecotoxicological evidence relevant to freshwater and marine environments.