Rao & Edmondson, 1990: "Tissue reaction to an implantable identification device in mice." Toxicologic Pathology. 1990;18(3):412–416.

Summary: 140 mice were implanted with subcutaneous microchips and evaluated for adverse reactions after periods ranging from three months to two years. No neoplastic (abnormal tissue) reactions were observed.

Author(s)

Species

# Animals

Length of Microchip Exposure

Developed Cancer

Rao & Edmondson, 1990

mice

10

3 months

none observed

10

15 months

74

2 years

39

Less than 2 years

Note: When Le Calvez et al. (2006) later studied a larger sample (n=1,260) of the same breed of mouse, they found a 4.1% incidence of microchip-induced tumors.