Getting the council involved might be helpful, but there's such a wide range
of possible contaminants I doubt they could test for everything that might
have been there. That would need a very extensive and expensive analysis.
You mention plastic and if that's been burned you can get all sorts of
compounds including cyanide. There's only one way to be really safe and
that's not to eat food grown just there.

Arthur


"David Hill" wrote in message
...
"........ the soil is a lot darker with some red lumps which break up when
crushed .........."

This is the result of having bonfires on the soil, in it's self no
problem.
If you are worried contact the Council from whom you are renting the
allotment and ask them to test the soil for contamination. They should do
this for you ASAP and will either give it a clean bill of health, or offer
you a new allotment.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk