Zinc oxide, a material commonly used in sunscreen, may be toxic to humans, according to a study published in the ACS’ Chemical Research in Toxicology. Scientists in the study report that the particle size of zinc oxide – specifically those that are smaller than 100 nanometers – are toxic to colon cells.
Researchers found that the chemical properties of smaller particles are significantly different than larger particles, and since nanoparticles are commonly used in foods, cosmetics and other consumer products, they may have some harmful toxic effects.
Many sunscreen formulations contain a significant concentration of nanopoarticles of zinc oxide. Philip Moos and scientists in the study indicated that, “unintended exposure to nano-sized zinc oxide from children accidentally eating sunscreen products is a typical public concern, motivating the study of the effects of nanomaterials in the colon.” (Source: MedicalNewsToday.com)
The American Chemical Society experimented with cell cultures of colon cells and compared them with the effects of zinc oxide nanoparticles, and zinc oxide in powder form. The results of the study indicate that the nanoparticles were twice as toxic as the cells of the larger particles, and especially damaging to the colon cells when ingested. The study did not look at the effects of these particles as they passed through the digestive tract.
Researchers report that further research needs to be done to determine whether the zinc nanoparticle toxicity effects occur only in people or also in laboratory animals, and to what extent.
Common sunscreen ingredients are known carcinogens and some have strong estrogenic actions that can interfere with sexual development and cause reproductive problems. Common sunscreen ingredients include diethanolamine, triethanolamine, padimate, octyl dimethyl PABA, oxybenzone, homosalate, salicylates and parabens.
Another popular ingredient in sunscreen is Benzophenone. While this compound is effective at warding off UVA and UVB rays, it is also a free radical generator which can initiate a reaction that causes melanoma or other types of skin cancer.