Yes, Freon is toxic at certain levels. Overexposure causes central nervous system depression and possibly cardiac arrhythmia. Depending on the type of freon, it is also extremely cold and can cause...
Not all non-Newtonian fluid is toxic. A good example of this would be the synovial joints such as your knee making use of a non-Newtonian fluid (synovial fluid) There are a few that would be...