Kochia (syn Bassia) seems to be of low toxicity. The only references I've got to it are to do with poisoning in cattle and sheep but even here most of the cattle fed it, in trials, just didn't do well rather than suffering severe poisoning.

Most of my library has no mention of it.

First ive heard of that !!! We've used it in our summer bedding displays on Brighton parks for many years.

It is invasive in warmer parts of the world, but in the UK, this plant is a half hardy annual, or at least, the 'burning bush' Bassia scoparia (previously Kochia scoparia) is, which is the only one that thrives in Britain anyway. So here, no, it's not invasive at all, it'll be dead by December most years. It's also not poisonous.

Thankyou to you all