None of the substance was found at the scene of the stabbings in Southport and police said the poison they did discover presented a low risk to the public.
Dr Renu Bindra, senior medical advisor at the UK Health Security Agency, said: “There has been no evidence of ricin poisoning in anyone involved or connected to this incident.”
The charges which have been added do not require a motive to be established.
In order for the incident to be classed as a terrorist incident, motive would need to be established.
The teenager has already been charged with murdering Bebe King, six, Elsie Dot Stancombe, seven, and Alice da Silva Aguiar, nine, at a Taylor Swift-themed dance class.
He is also charged with ten counts of attempted murder and possession of a knife.
A trial is expected to begin in January.
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Caption: Alan Shearer?s Premier League predictions credit: Getty / Metro After some impressive results for English sides in Europe the focus is