As part of a multiyear study involving teams across 16 institutions, spearheaded by Professor Clare Mahon from Durham University’s Department of Chemistry, researchers have discovered a striking connection. Some chemical sunscreens are ruining white laundry with horrible red stains. American and Brazilian researchers recently published their novel approach in the journal Chemical Communications. They demonstrated how DHHB, an active chemical compound ingredient, reacts with bleach to form a different molecule that changes the dyed fabric color.
To recreate the investigation, we tested 11 different non-toxic sunscreens. They found that only those containing DHHB, a common ingredient in sunscreens, produced a distinctive red coloration when exposed to bleach. This caused a surprising reaction in seven of the tested sunscreens. This creates a huge threat of harm to consumers who may unknowingly ruin their clothes.
The principle is that DHHB reacts with bleach to form a new compound. This new molecule absorbs the shorter and medium-range wavelengths of visible light, so only the longer red wavelengths can get through. The synthesis of this new molecule breaks longstanding rules of chemistry, as its molecular shape strays from typical guidelines.
To gain a deeper understanding of the resulting molecular structures produced by this reaction, the research team used advanced nuclear magnetic resonance experiments. These experiments yielded new information on the structure of both the starting molecules and the reaction products arising from their interaction. Beyond that, Professor Mark Wilson ran computational simulations to study the properties of the molecule they had just made.
The full implications of this study are incredibly important, not just for the health and safety of consumers, but to the manufacturers of sunscreen products. Professor Mahon advised everyone to be careful of how everyday items, such as bleach, can mix with personal care products. It’s not their fault—these interactions can have unintended consequences, including some really ugly stains.
The innovative research team included world-class scientists. Other famous members included Professor Andy Beeby, Dr Alan Kenwright, and Dr Eric Hughes. Together, their long plight and tireless work have begun focusing the public’s attention on one often overlooked and accepted everyday interaction with chemicals – exposure.