In this study, an argon plasma jet was made for therapeutic purposes. Although cold plasma jet (CAPJ) is considered a safe device, its risk assessment is essential to be approved for a clinical trial. To this end, the safety parameters of the CAPJ were evaluated from both aspects associated with the instrument such as design, construction, and environmental conditions, and also function on living organisms. It was shown that the device is physically safe for the user and the animal. In continue, healthy rats were treated by the plasma at two modes of streamer and plume mode at two distances of 20 and 25 mm from the nozzle for 2, 5, and 10 minutes of exposure time. In the study of blood serum biochemistry, the strongest deviation from the average is observed at alkaline phosphatase in the plume mode in the 10min (P10) group. Also, the amount of Aspartate transaminase (AST) in the blood serum of rats is lower than the control group for all groups except streamer mode at 10 min exposure (S10). And, the mean ALT enzyme in the serum of the S5 group is significantly higher compared to the plume mode in the 5 min (P5) group. The histopathology of the liver is studied to support these results. Shrinkage of the nucleus, cell swelling, and hyperemia are observed in the liver tissue for streamer mode, while in the plasma plume mode, these changes are not tangible. No significant difference is observed in the mean value of total Bilirubin, Direct Bilirubin, Albumin, Na, and K factors in the different groups after the plasma treatment and the histopathology of kidney tissue is performed for all the groups to support this conclusion and it did not show any damage to the kidney tissue. As a result of risk assessment in this study, the treatment with a duration of 2 to 5 minutes is safe with the specifically designed CAPJ nozzle head at a distance of 25 mm from the nozzle.
