Several studies of possible toxic effects of quantum dots on humans have been done using cell cultures in petri dishes or rodents, usually white lab rats. But lab rats are related to humans only in that both are mammals.
In a recently published letter in Nature Nanotechnology,"A pilot study in non-human primates shows no adverse response to intravenous injection of quantum dots", published online 05/20/2012, Ling Ye and other authors based at PLA General Hospital in Beijing, SUNY-Buffalo, Nanyang Technological University, and Changchun University of Science and Technology, report the results of experiments where quantum dots where injected into male rhesus monkeys. Rhesus monkeys were chosen for this experiment since they are genetically and physiologically closer to humans than rodents and are less endangered than chimpanzees.
The authors report that the rhesus monkeys did not exhibit any ill effects from the injections:
A complete blood count (cbc) was performed at regular intervals and the results did not suggest any acute toxicity.
After 90 days, the study did find that quantum dots had accumulated in the liver, spleen, and kidneys and in lesser amounts in the heart, lungs, and other organs. Examinations of tissues from these organs found no abnormalities.
In conclusion, rhesus macaques intravenously injected with ~ 25 mg of a cadmium based quantum dot formulation survived without any evidence of toxicity. All measured biochemical markers were in the normal range. . . .However, given the persistence of elevated cadmium and selenium levels in organs after three months, longer term studies will be required to determine the ultimate fate of these heavy metals and any ill effects arising due to their presence. All data obtained in this pilot study suggest that the phospholipid micelle encapsulated quantum dot formulation has very low tosicity on the timescale considered. This suggests a potential role for quantum dots in human clinical applications, such as image guided surgery for tumour removal, where the advantages provided for quantum dots can outweigh the potential risk associated with accumulation of their constituent elements in the body.