April 1, 2009 Your sunscreen might be preventing damage to your skin, but it may also be causing untold damage to the environment. A study carried out by scientists in Ohio has reported that nanoparticles now being added to cosmetics, sunscreens, and hundreds of other personal care products may be harmful to the environment by negatively affecting beneficial bacteria.
The study by Cyndee Gruden, Ph.D. and Olga Mileyeva-Biebesheimer focused on nano-titanium dioxide (nano-TiO2) particles added to cosmetics, sunscreens, and other personal care products for their highly beneficial effects in blocking ultraviolet light in sunlight. Hundreds of products utilizing these microscopic particles - 1/5,000th the diameter of a human hair – are already on the market and with many more poised for debut, scientists are seeking to avoid unwanted health and environmental effects in advance.
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Using aquatic microbes as their "canary-in-a-cage," the scientists studied the survival of Escherichia coli (E. coli) bacteria when exposed in laboratory cultures to various amounts of nano-TiO2. They found surprisingly large reductions in survival in samples exposed to small concentrations of the nanoparticles for less than an hour. The findings open the door to future research, including studies to determine whether the same effects occur in the natural environment. Gruden explained that the particles are washed down the drain in homes as people bathe and end up in municipal sewage treatment plants. From there, they can enter lakes, rivers, and other water sources where microorganisms serve essential roles in maintaining a healthy environment.
The report was part of symposia that included almost two dozen papers at the 237th National Meeting of the American Chemical Society where scientists grappled to understand the environmental and human health effects of nanotechnology. In a second study on nanotoxicity at the ACS National Meeting, scientists from Utah described development of a new biosensor that flashes like a beacon upon detecting nanoparticles in the environment. Their study found that Pseudomonas putida (P. putida) - a beneficial soil microbe - cannot tolerate silver, copper oxide and zinc oxide nanoparticles. Toxicity occurred at levels as low as micrograms per liter. That's equivalent to two or three drops of water in an Olympic-sized swimming pool, which could spell danger for aquatic life.
Although the public is ultimately responsible for understanding the risks of consumer products, Gruden said, science plays a large role in highlighting possible hazards. "It is the scientist's job to perform good research and let the findings speak for themselves," she said. And so far the promises of nanotechnology need more evaluation. "To date, it's unclear whether the benefits of nanotech outweigh the risks associated with environmental release and exposure to nanoparticles." Let’s hope we discover the dangers before we’ve already caused irreversible damage to the environment.