The refrigerant gas R-123 has a low toxicity when inhaled in a single or short-term occurrence, according to the Environmental Protection Agency, after extensive testing as of March 2015. R-123 also has a very low toxicity if applied to the skin and is only a mild irritant to the eye.
Weakness, disorientation, or lack of coordination were seen in animal test subjects when the concentrations of R-123 were greater than 5,000 parts per million, or 0.5 percent. Testing on rats showed that inhaling R-123 long-term increased the occurrence of benign tumors in the liver, pancreas and testis.
Refrigerant manufacturers recommend long-term, occupational exposures should not be greater than 10 and 30 parts per million over an eight-hour period.