“…This probably cannot be answered forthrightly, but here is what I mean: at pH 5.5 and a temperature of 4°C, foot and mouth disease virus has been inactivated a millionfold within 30 minutes, 9 7 while poliovirus type 3 was inactivated at a rate which apparently would have required 11 weeks to produce the same result. 103 These two viruses, at pH 7 and 4°C, would show only limited inactivation over a period of months. I suggest that at pH 5.5, the foot and mouth disease virus is being inactivated chemically (by the acid) at a rate determined by the temperature, whereas the poliovirus is being inactivated thermally at a rate determined by the pH.…”