Just bought a house and discovered afterwards that the house was once upon a time treated for termites. But there are three very bizarre aspects to this treatment:
First, the house is on a concrete slab.
Second, there are plugged drill holes in two rooms, but not in the remaining rooms around the perimiter of the house.
Third, some of the holes penetrate under-floor heating vents.
The time of the treatment cannot be established, but is probably at least ten years earlier because last owner (of ten years) has no knowledge or documentation.
So, there appears to be a SLIM chance that some very bad termiticide was injected directly into an air vent and might still be there, making the air very dangerous to breathe.
But it seems far more probable that someone began drilling to inject, but then stopped upon realizing they were drilling thru vents and plugged up and quit, without actually injecting anything.
I guess an air quality test would settle the matter? Should I even worry about this?