Meral I, Mert H, Mert N, Deger Y, et al. (2007):
Meral and colleagues exposed guinea pigs to 890-915 MHz EMF (SAR 0.95 W/kg) from a cellular phone for 12 h/day (45 minutes stand-by and 15 minutes spiking mode) for 30 days. Fourteen animals were randomly divided into exposed and sham groups.
At the end of the experiment blood was taken by cardiac puncture and brain samples were also obtained. Brain tissue levels of MDA (indicating oxidative stress) increased, and levels of the antioxidant enzymes GSH and CAT decreased. Levels of vitamins A, D3, and E did not change. Blood levels of MDA, vitamins A, D3, and E, and CAT increased, while GSH decreased.
The authors suggested that the increased levels of MDA indicated a higher rate of oxidative metabolic activity, while decreased GSH levels and CAT brain levels indicate antioxidant, i.e. protective, activity. The increased blood CAT activity and blood vitamin levels may result from the attempts of these substances to scavenge reactive oxygen species.
The details of the exposure system are scanty, and it is not clear whether the study was blinded.