I am attempting to research the results of case studies regarding polytetrafluoroethylene [PTFE] (commercially known as Teflon). More specifically I am attempting to make sense of this Abstract on Acute pulmonary effects of ultrafine particles in rats and mice. Not being a chemist I'm having a hard time understanding the results and hoping someone can explain in laymens terms. More specifically, the abstract mentions;
We used ultrafine Teflon (polytetrafluoroethylene [PTFE]*) fumes (count median diameter [CMD] approximately 18 nm) generated by heating Teflon in a tube furnace to 486 degrees C to evaluate principles of ultrafine particle toxicity that might be helpful in understanding potential effects of ambient ultrafine particles. Teflon fumes at ultrafine particle concentrations of approximately 50 micrograms/m3 are extremely toxic to rats when inhaled for only 15 minutes.
That seems straight forward enough. They heated up Teflon in a tube, and made rats inhale it, who subsequently died. Then it goes on to say;
We found that neither the ultrafine Teflon particles alone when generated in argon nor the Teflon fume gas-phase constituents when generated in air were toxic after 25 minutes of exposure. Only the combination of both phases when generated in air caused high toxicity, suggesting the existence of either radicals on the particle surface or a carrier mechanism of the ultrafine particles for adsorbed gas-phase compounds.
This is the part thats unclear to me. The Teflon particles alone, I think means the compound before they heat it, but what is the 'fume gas-phase when generated in air'? How is that different then the fumes they made the rats inhale (from which they died after 15 minutes)? What does the 'combination of both phases when generated in air' mean?
Aging of the fresh Teflon fumes for 3.5 minutes led to a predicted coagulation resulting in particles greater than 100 nm that no longer caused toxicity in exposed animals.
How would coagulation affect the toxicity of the fumes? Does it change the chemical structure of what the animals inhale somehow making it less toxic? Naturally speaking, I would assume 'more' particles would result in higher levels of toxicity, not less.