Robyn

I was involved in this a couple of years ago. University based using OP's in greenhouses. The end result of all of our iunvestigation was that unless you mesured immediately before and after the results were too variable. There isn't a tight "normal" range for any of the blood results.

Our workers used the OP's a couple of times a year and we investigated the "engineering out" of the problem and monitoring to ensure that no one entered the greenhouses and that  dispersal had occured. It was a case of lots of people using their expertise to ensure the safety of the staff. There had been some blood testing by  aprevious OH provider but the results had such a huge range that it was impossible to tell whether exposure had occurred.

Regards

Jean