Photolysis and Cellular Toxicity of the Organic Ultraviolet Filter Chemical Octyl Dimethyl Para-Aminobenzoic Acid (OD-PABA) and its Photoproducts

Date of Award


Document Type

Restricted (Opt-Out)

Degree Name

Bachelor of Science



First Advisor

Laura MacManus-Spencer

Second Advisor

Margot Paulick




OD-PABA, uvfc, sunscreen, toxicity, breakdown, cell culture, ultraviolet, photolysis


Organic ultraviolet filter chemicals (UVFCs) are the active ingredients used in many sunscreens to protect the skin from UV light. These chemicals have been found in numerous aquatic environments, leading to concerns about how they might affect aquatic organisms and humans. UVFCs have also been known to penetrate the skin and act as endocrine-disrupting compounds. Many personal care products like lip balms and makeups contain the UVFC octyl dimethyl para-aminobenzoic acid (OD-PABA), also known as Padimate O. Upon exposure to UV light, OD-PABA degrades into numerous photoproducts. Some of these photoproducts have been previously identified, whereas others have not. Furthermore, the cellular toxicity of OD-PABA and its photoproducts are not well-established. In this study, we have isolated and characterized the major products of OD-PABA photolysis. We have also determined the cellular toxicities of OD-PABA and some of its isolated photoproducts to mammalian cells in vitro. It was found that OD-PABA is toxic to mammalian cells at micromolar concentrations, which are relevant to current human usage. Additionally, the OD-PABA complete photolysate was shown to exhibit higher toxicity than that of the parent compound itself; photoproduct IV had comparable toxicity to OD-PABA. As OD-PABA is a commonly used UVFC, results from this study provide us with an enhanced understanding of OD-PABA photolysis and its potential human and environmental health effects, which will allow us to better evaluate the suitability of this UVFC as a sunscreen agent.

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