An example of the sort of biochemical engineering research underway in this field: "the quest to create artificial blood is big business, with more than one billion pounds being spent over the last 20 years in an attempt to create a true alternative to blood. Among those around the globe seeking a viable blood alternative are scientists at the University of Essex who have just submitted a worldwide patent for their engineered hemoglobin. ... to date the world's scientists have failed to produce a safe alternative to blood. The reason for this failure, according to [the University of Essex researchers] lies in hemoglobin, the red molecule inside blood cells that carries oxygen around the body. Outside the protective environment of the red cell, hemoglobin can be toxic. Hemoglobin normally changes color from red to claret as it transfers oxygen around the body. However, when it is damaged the iron in hemoglobin is oxidized (like a car rusting) to produce dysfunctional brown and green products. ... Basically, hemoglobin produces free radicals that can damage the heart and kidneys. ... The trick with artificial blood is to modify the molecule to be less toxic, but still perform the vital role of carrying oxygen around the body."