Nanosized titanium dioxide UV filter increases mixture toxicity when combined with parabens

Area of Science:

• Environmental toxicology
• Nanomaterial safety
• Ecotoxicology

Background:

• Personal care and hygiene products (PCPs) often contain engineered nanoparticles and UV filters.
• Concerns exist regarding the environmental impact of these chemicals on aquatic ecosystems.
• Titanium dioxide (TiO2) nanoparticles are widely used as UV filters in PCPs.

Purpose of the Study:

• To assess the environmental toxicity of nano-TiO2, oxybenzone (BP3), and parabens found in PCPs.
• To determine the EC50 values for these compounds on aquatic species.
• To investigate the combined toxic effects of these substances in mixtures.

Main Methods:

• Standardized toxicity bioassays were performed on Daphnia magna and Phaeodactylum tricornutum.
• EC50 values (concentration causing 50% mortality/effect) were determined for individual compounds.
• Binary mixtures of nano-TiO2, BP3, and benzylparaben (BzP) were tested for synergistic or antagonistic effects.

Main Results:

• Nano-TiO2 showed significant toxicity to D. magna (48h EC50 = 3.09 mg/L) and algae (72h EC50 = 2.27 mg/L).
• Parabens exhibited toxicity ranging from 1.35 to 32.52 mg/L on D. magna.
• Mixtures of nano-TiO2 with BP3 or BzP demonstrated synergistic toxicity, while BP3 and BzP showed antagonism.

Conclusions:

• Nano-TiO2, a common UV filter, poses a significant ecotoxicological risk to aquatic organisms.
• The combination of nano-TiO2 with other PCP ingredients can enhance overall aquatic toxicity.
• Further research is needed to understand the environmental fate and risks of nanoparticles in consumer products.