Don't get me wrong David....in no way am I playing down the hazards of OP.....my point is that while acute and chronic poisoning on an airline flightdeck may occur with situations of leaky bearings as you describe, I am not sure that data can be tranferred to Jet Modelers directly......

There is no question that acute and chronic OP poisoning happens quite frequently in agricultural workers, either professionals or backyard gardeners who use Malathion or it's more potent relative Parathion in a careless fashion while spraying their fruit trees...or my wife using powdered Diazinon on her roses on a windy day...the serious acute poisoning produces some dramatic symptoms of nausea, vomiting, diarrhea, asthma, delerium, motor weakness, all due to the sudden inhibition of acetylcholinesterase by the OP........but these reactions almost always occur with a massive inhalational overdose of one of the aerosol pesticides....

The chronic reactions can be more subtle, but often can be non-reversible...producing a chronic neuropathy and mental deterioration due to the chronic overstimulation of the nerve synapses by acetylcholine, one of the most important neurotransmitters we have.....

The fact that turbine modelers have been using OP oils for at least 12-15 years, with few if any 100% documented cases of acute or chronic poisoning, supports the manufacturer's position of recommending it for use in their engines.......one could do a tough calculation of what the ppm of the OP is in, say, a volume of space behind a turbine of 100 feet on a side......corrected for density altitude and wind speed behind the turbine, and using the volume of oil and mass air-flow thru the motor.....I suspect that the resultant ppm would be quite small, probably below the safe levels recommended by health and environmental agencies since there have not been a significant number of documented poisoning events.....

So be cautious while pouring the stuff....use gloves.....and don't stand behind a turbine, huffing the exhaust......until we all feel comfortable using non-OP oils in all our pricey turbines......

Tom