regarding food poisoning : powdered arsenic is used particular in India. This has extreme lethal effect.

Bacteria : barbosa bacteria takes hardly 2-3 minutes for the terminal lethal effect.

commonly used drugs for operation related matters takes 10-11 minutes for terminal lethal effect.

Fungi has ergot of rai that is so lethal that one small drop brings terminal lethal end - it can be made in punjab haryana and rajasthan by locals.