Sweden's Department of Energy and Environment studied the available information on graphene, and came up with the conclusion that the new material may have potentially adverse environmental and health risks. Graphene could exert a considerable toxicity and it is also suggested that graphene is both persistent and hydrophobic (graphene is a very effective water repellent).
There are still many risk-related knowledge gaps to be filled, according to the researchers as "Considerable" emissions of graphene from electronic devices and composites are possible in the future.
Back in 2012 researchers from the University of Edinburgh said that graphene nanoplatelets could post health risks as the can accumulate in the lungs and cause damage. Researchers from Singapore's A*STAR have published a study on how graphene based materials may effect bacteria.