"It is not yet known if the reactions being observed are due to chemicals in the ink itself or to other chemicals, such as preservatives or brighteners, added to them, or to the chemicals' breakdown over time," said Leger.
"It is not yet known if the reactions being observed are due to chemicals in the ink itself or to other chemicals, such as preservatives or brighteners, added to them, or to the chemicals' breakdown over time," said Leger.