Effects of the Sunscreen UV Filter, Oxybenzone, on Green Microalgae
Ming-Li TEOH1,2,3*, Nur Suhaida SANUSI1, Ching-Yee WONG1, and John BEARDALL4
1School of Biosciences, Taylor's University, Lakeside Campus, 47500 Subang Jaya,
Selangor Darul Ehsan, Malaysia;
2Institute of Ocean and Earth Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia;
3National Antarctic Research Centre, Institute of Graduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia;
4School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
Abstract: UV filters are widely used in sunscreen and personal care products due to their ability to give protection to our skin from UV radiation. Oxybenzone, commonly known as benzophenone-3, is one type of UV filter found as the active ingredient in many pharmaceutical products. Although oxybenzone has been extensively studied as an environmental toxicant in the ecosystem, little is known about its toxicity effects on microalgae. The effects of oxybenzone on growth (measured as OD620, chl ɑ and carotenoids) and macromolecular composition of polar microalgae (Chlorella UMACC 400 and Chlorella UMACC 401) and temperate microalgae (Chlorella sp., Chlamydomonas reinhardtii, Scenedesmus quadricauda) were investigated. These microalgae were cultured in triplicate and exposed to different oxybenzone concentrations (0, 100, 200, 300 and 400 mg·L−1), at 4 ºC and 18 ºC for polar and temperate species respectively, for 96 h. The oxybenzone concentrations used represent a range from environmental to extreme concentrations to understand the impact of this toxicant on microalgae. The results showed that the highest concentration of oxybenzone (300 and 400 mg·L−1) had adverse effects on growth rate and biomass of these microalgae. However, exposure to oxybenzone concentrations ranging from 200 mg·L−1 to 400 mg·L−1 did not have significant effects on S. quadricauda growth. The exposure to oxybenzone at higher concentrations also led to changes in cell structure after 96 h. Generally, protein and carbohydrate content of all microalgae except S. quadricauda increased with increasing oxybenzone concentrations. Protein content increased significantly when cells were exposed to oxybenzone, though effects were greater in the polar species, suggesting that it could be one of the adaptive strategies that enabled these microalgae to tolerate oxybenzone. Further investigation is required to determine the effects of oxybenzone on other features of microalgal performance at relevant environmental concentrations.
Keyword: Polar algae, temperate algae, Chlorella, benzophenone-3, emerging contaminants