That's not toxic at all.
I've also tried this and you need way more petrol than you think. I'm not sure if it's a good idea.
ps , If glueing slabs of foam together to make a board , choose your glue carefully . I once used expanda foam in a can because it is cheap , sticks well and thought it isn't too hard for shaping . But it did leave a hard layer that made shaping ****ty. In the end all went well , board was finished. Left it in the sun for one minute and it blew up like a balloon. Totally ruined .

It was the expanda foam . It off gassed a huge amount when it got warm . Won't be doing that again . If I was to glue slabs of foam together now I would use a thick q cell thickened resin . It surprisingly shapes OK against soft eps . You have to be careful and it's still a bit ****ty .