I built models and dioramas as well for two years. I've breathed in airbrush cleaner, paints,spray adhesive,polystyrene dust and many other toxic things by accident. As long as you don't breath this stuff in regularly youll be fine, I know dozens of people who work in auto shops, manufacturing plants, water plants and many other places where they breathe in fumes all of the time. Most of these people will never get cancer, and if they do its probably not caused by the fumes theyve breathed in. In China people breathe in toxins and fumes 24/7 with no break, there cancer rates are no higher than North Americas. You'll be fine, enjoy your hobby. If it concerns you buy a respirator.