Apparently not much has been published about the mutagenicity of propidium iodide beyond the abstract below. However, it is of the same chemical class as ethidium bromide (a diaminophenanthridium dye) and deserves to be handled very carefully. Apparently its polar nature does keep it from having highly significant mutanenicity, at least under the Ames test conditions under which ethidium is highly mutagenic. One of the other compounds in the abstract is ethidium monoazide, which is also sometimes used in flow for viability assessment. However, I feel that the concern expressed by the nuclear medicine doctor about propidium because it is an "iodide" is unfounded because the iodide (actually two of them) is only a counterion to the cations of propidium. As such, they will instantaneously dissociate away from the dye in the body's buffering capacity. Even the amount of iodide that could be introduced by ingesting a mL of the typical micromolar solution of propidium iodide seems infinitesimal and is likely lower than one would get from eating a single grain of iodized table salt, which is 0.006% to 0.01% KI. Mutat Res 1983 Aug;121(2):89-94 Structure-function characterization of phenanthridinium compounds as mutagens in Salmonella. Fukunaga M, Yielding LW. The mutagenic activity of some phenanthridinium compounds was examined by using Salmonella typhimurium strain TA98. Microsomal enzyme activation of the compounds was necessary for the detection of frameshift mutagenesis. Amino and/or azido functions at both R3 and R8 were structural requisites for significant mutagenic activity, although mutagenicity was severely reduced for the diazido analog. When an azido or amino group was substituted by hydrogen at either R3 or R8, mutagenic activities were minimal, and the deaminated compound (3,8-dihydro derivative) was not mutagenic. Propidium was only slightly more mutagenic than the monoamino and monoazido analogs. Relationships between mutagenic activity and chemical structure of phenanthridinium compounds are discussed. propidium [Structure: 3KB] ethidium [Structure: 2KB] Leslie Armstrong-Lea wrote: > Hi, > Seeing these posts about safety precautions to be used while > pregnant and working in flow cytometry prompted me to send a word of > caution to ALL flow cytometrists, pregnant or not. We all need to be > careful when using toxic, carcinogenic, pathologic, etc. samples or > chemicals. We tend to get so used to working with this stuff, that I > think we forget to respect the potential hazards. > I was diagnosed with thyroid cancer last year, and although the > only "known" cause of thyroid cancer is radiation exposure (which I > have not had), the nuclear medicine doctor that administered my > ablative dose of I131 following my surgery was curious about my > exposure to propidium iodide for 15 years. Even though it is not > supposed to be taken up by live tissue,, he did wonder if it could > cause thyroid cancer, as the thyroid has such an affinity for iodine of > any sort. I don't know if anyone would have any answers to this, but I > just wanted to make sure everyone, not just pregnant ladies, respects > the warnings to use caution when dealing with dyes, chemicals, body > fluids, etc. Be safe out there!! > > ==================================== > Leslie Armstrong-Lea > Radiological Health Sciences (RHS) > Colorado State University > Ft. Collins, CO 80523-1673, USA > voice:(970)491-1347 > fax:(970)491-0623 > > leslie.armstrong-lea@colostate.edu > ====================================
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