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Activity (Hands-On)Grades 7 - 8

Sunscreen Showdown: Engineering a Reef-Safe, Non-Carcinogenic Sunscreen

A photo of UV beads under 60 seconds of UV light exposure.Students design a reef-safe, non-carcinogenic mineral sunscreen


Students take on the role of chemical engineers tasked with designing a reef-safe, non-carcinogenic mineral sunscreen that rivals the effectiveness of leading commercial sunscreens. After learning about ultraviolet (UV) radiation, skin cancer, emulsions, and UV-filtering ingredients, students investigate the properties of different sunscreen components and use non-nano zinc oxide and non-nano titanium dioxide as mineral UV filters to formulate their own sunscreen prototypes. Working in teams, they establish design criteria and constraints, research ingredients, and create, test, and refine their formulations using UV-sensitive beads exposed to a UV lamp. Students compare the performance of their prototypes with a commercial sunscreen while also evaluating wearability, such as white cast and texture. Through iterative testing and redesign, they work to create a sunscreen that provides effective UV protection without relying on potentially more harmful chemical UV filters.

Chemical engineers use emulsion science to develop solutions for various problems. In cosmetic chemistry, emulsions are critical in skincare product design. Sunscreens are a type of emulsion (an immiscible mixture of oil and water). Similar to salad dressing, the oil forms small bubbles in the aqueous solution, which disperse UV filters and increase the surface area of skin covered in UV-reflecting metals. This dispersion is key for effective sunscreen in reducing the risk of skin cancer. However, nano UV filters such as nano-zinc oxide can harm coral reefs by damaging coral polyps, leading to bleaching and ecosystem disruption.

At the end of this activity, students should be able to:

  • Understand the science of UV radiation and how it causes DNA mutations that can lead to skin cancer.
  • Examine the environmental and health risks associated with common UV filters used in sunscreens, including their carcinogenic properties and harmful effects on coral reefs.
  • Design and create a stable sunscreen emulsion using mineral-based UV filters (non-nano zinc oxide and titanium dioxide), while ensuring it effectively prevents UV radiation and does not leave a white cast.
  • Identify and explain the function of each ingredient used in their sunscreen emulsions, particularly how they contribute to UV protection, texture, and stability.

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