Jan 1978 Hyperkinesis and diet: a double-blind crossover trial with a tartrazine challenge https://pubmed.ncbi.nlm.nih.gov/349320/
Jan-Feb 1982; 'Sulfanilic acid: behavioral change related to azo food dyes in developing rats' 'While our work suggests a significant effect of azo food dyes on the developing rat central nervous system, species differences in parameters such as absorption, metabolism, and blood-brain barrier properties do not permit any extrapolation of these observations to proposed effects in children.'
But now we know the blood-brain barrier imagined in 1982 was not accurate so...
https://pubmed.ncbi.nlm.nih.gov/6803178/ From 1998 'Synthetic food colourings and 'hyperactivity': a double-blind crossover study' https://pubmed.ncbi.nlm.nih.gov/3395307/
From 6 September 2007 'Major study indicates a link between hyperactivity in children and certain food additives'
https://www.southampton.ac.uk/news/2007/09/hyperactivity-in-...
From 10 April 2008 'Food Standards Agency cites Southampton study in new recommendation on food additives'
https://www.southampton.ac.uk/news/2008/04/food-standards-ag...
21 August 2014 'Effects of a textile azo dye on mortality, regeneration, and reproductive performance of the planarian, Girardia tigrina' https://enveurope.springeropen.com/articles/10.1186/s12302-0...
Then from Aug 18, 2021 'The FDA says they’re safe in moderation. But some experts say their guidelines are outdated and need changes to account for the possibility that dyes affect children's brains and behaviour'
https://www.discovermagazine.com/health/is-it-time-to-rethin...
The jury is still out, hopefully continuous array's together with fast and high resolution non-invasive brain scans will be able to revisit all this stuff I'd imagine?
With regards the quantity and effect quandary 'Threshold effects can be felt with as little as 25 micrograms of LSD' so who knows.
Finally it's a petrochemical derivative, just mentioning that, here, at the bottom.
The second one talks about allergens, noted though not particularly relevant, and does this have amounts anywhere?
And the third one seems to be mentioning other mechanisms to get the same effects, but is not classifying the actual danger levels based on dose? Interesting but it's not helping me figure out if the additives are safe in small amounts.