Single-species tests fall short: broadening toxicity assessments of organic UV filters on marine microalgae.

Summary

Across seven marine microalgae species, growth rate was the most sensitive endpoint and revealed substantial interspecies variability to six sunscreen UV filters. 2-ethylhexyl salicylate and homosalate were most toxic, and standard reliance on Phaeodactylum tricornutum may underestimate risks, supporting multi-species, multi-endpoint testing.

Key Findings

• Growth rate was the most sensitive endpoint across species for UV filter toxicity.
• Tisochrysis lutea was more sensitive than the commonly used Phaeodactylum tricornutum.
• 2-ethylhexyl salicylate and homosalate were the most toxic among six UV filters tested.
• Growth inhibition often coincided with increased fluorescence, indicating compensatory responses.

Clinical Implications

Dermatology and public health messaging may consider environmental impacts when advising on UV filter choices; regulators can refine risk assessment by including sensitive species and endpoints.

Limitations

• Short-term (72 h) laboratory exposures may not reflect chronic or real-world mixture effects.
• Limited to microalgae; broader trophic levels were not assessed.
• Chemical transformation and environmental fate were not evaluated.

Future Directions

Adopt multi-species, multi-endpoint test batteries in standardized guidelines; extend to chronic exposures and mixture toxicity; integrate sensitive species in high-throughput platforms.