Our body creates its own chemical atmosphere around it. Because the fats of our skin react with the ozone to reactive OH-radicals, which in turn react with other substances in our immediate vicinity. However, if we apply cosmetic products such as perfume or body lotion, this effect is reduced, a study shows. Although it is still unclear how our body’s oxidation field affects our health, the results show that diverse influencing factors determine the air quality directly around us.
Our breathing air contains a mix of numerous chemical compounds. In interiors, this includes the evaporation of furniture, walls and floor coverings as well as substances that are released in everyday activities such as cooking or cleaning. Our own evaporation also change air chemistry in our immediate vicinity. The fats of our skin react with traces of ozone out of the air. This creates reactive hydroxyl radicals (OH), which in turn oxidize other chemicals near us in seconds.
Test under more realistic conditions
“Such a natural oxidation field can change our chemical exposure indoors,” reports a team led by Nora Zannoni from the Max Planck Institute for Chemistry in Mainz. In 2022, the research team demonstrated the existence of a personal oxidation field and informed the underlying chemical reactions on the skin. “At that time we examined test subjects under strictly controlled conditions, whereby the use of personal care products was prohibited before the tests,” explain the researchers. But how do perfume, body lotion and Co. affect our body’s atmosphere in the real world? Zannoni and her colleagues have now tested this in a recent study. Four volunteers either applied a odor -neutral body lotion or a perfume on uncovered areas of their skin before they went to a test chamber in which the air chemicals around them were measured.
The result: Both the body lotion and the perfume ensured a lower OH content in the air directly around the subjects. According to the researchers, this is due to the fact that the main component, ethanol, reacts with the hydroxyl radicals. Unlike the fats of our skin, however, it does not produce any new OH-radicals in the reaction with ozone, so that the supply is used more than filled up. The same effect also has components of body lotion, including the preservative phenoxyethanol. In addition, the cream acts as a physical barrier on the skin, reduces the reactions of ozone with skin fats, so that fewer OH radicals arise. “In a direct comparison, scents influence the OH reactivity and its concentration over a shorter period of time. In contrast, body lotion had a more persistent effect,” says Zannoni.
Effects still unclear
However, the researchers cannot yet answer whether this is positive or negative based on the previous knowledge. Because what influence the OH radicals have on the chemicals in our breathing air is mixed. “In some cases, the chemical conversions that result from increased OH concentrations can lead to products that are less toxic compared to their forerunners,” explain Zannoni and their team. “The bottom line is that increased OH concentrations seem to contribute to a less healthy interior air. Before a recommendation can be made, a more comprehensive assessment of the relative toxicity of the corresponding precursors and products is required.”
But even if the results have so far not been derived whether we should use more or less body lotion, the findings are relevant for risk reviews. “When we buy a sofa, it is checked for pollutants before the sale. But while we are sitting on the sofa, we change the evaporation of the sofa through our oxidation field,” explains Zannoni’s colleague Jonathan Williams. “This creates new chemical compounds in the immediate vicinity of our respiratory tract, the properties of which have so far been largely unknown and unexplored. Interestingly, we now know that both body lotion and perfume steam this effect.”
Source: Nora Zannoni (Max Planck Institute for Chemistry, Mainz) et al., Science Advances, Doi: 10.1126/sciadv.ads7908
