There is no scientific evidence that olive oil breaks down into toxic components.
note that the experiments were carried out without food being cooked. While cooking, the water and steam which comes from the food being cooked aids the process of hydrolysis. The absence of food in these trials may have allowed for a greater impact of oil oxi- dation when compared with other deterioration reactions
They didn't test the affects of water and food contact on stability and note the potential significance of hydrolysis.
But just going by that, I'd avoid all refined oils and heating/frying.