A new report, in the journal Environmental Science & Technology, says that titanium dioxide nanoparticles (nTiO2) can stress photosynthetic organisms, potentially leading to the disruption of nitrogen and carbon cycles in aquatic ecosystems. Since the 1990s, titanium dioxide nanoparticles have been used in a wide range of consumer products, such as cosmetics, paints, sunscreens, and foods, due to the fact that products coated in the substance shine pure white. Researchers at Northeastern University, United States, wanted to study how the nanomaterial affects a model organism – Anabaena variabilis, a common blue-green algae - in an aquatic ecosystem, as nTiO2 often discharge into open waterways through treated sewage effluent. The researchers found that the growth of the algae dropped by 90 percent at nTiO2 levels similar to those found in wastewater effluent. The presence of nTiO2 also caused changes in cell growth and structures. The findings, say the authors, suggest that nTiO2 could disrupt the carbon and nitrogen cycles in an aquatic ecosystem.