Headline: Whats worse for the environment?

I was in the local 'organic supermarket' shopping for the Spagetti Bolognaise I was going to make.
I needed Tomatoes, and because there wasn't enough time, was going to use a tin of tomatos.....
I wonder, whats worse, tinned tomatoes from Italy, tinned tomatoes from South America or tinned Tomatoes from the USA. There are of course none from Australia.
In the end, I bought the South American ones. Not only is their eonomic need greater, they are less likely to have government protections on them.
But really. When is it going to become mandatory to add an envronmental impact statement to goods? It'd be really useful to know... did these tons go via the US, which way around the world did they go......
Its a shame that Sydney's so environmentally broken, that getting locally produced food, directly from the farmer, involves driving.