C.H.
My mom swears by vinager and water. but if you are really concerned, why not just use hot water and see how it turns out? Anything other than water and vinager is a chemical, therefore it will be toxic.
If you decide to do it yourself and use carpet shampoo, the most important thing to do is make sure you rinse it well. 3-4 times, if possible. If any soup is left on your rug, it's will make it 10 times worse AND you'll have to re-shampoo it quickly. My sister never realized she should rinse it afterwards and her carpet was filthy within 2 weeks.