I didn't find any good data on real-world use either, but wiki had a little info on why it is used:
http://en.wikipedia.org/wiki/Azodicarbonamide
"Azodicarbonamide is used in food industry as a food additive, a flour bleaching agent and improving agent. It reacts with moist flour as an oxidizing agent.[2] The main reaction product is biurea,[3] a derivative of urea, which is stable during baking. Secondary reaction products include semicarbazide[4] and ethyl carbamate.[5] The United States permits the use of azodicarbonamide at levels up to 45 ppm.[6] In Australia[citation needed] and Europe[7] the use of azodicarbonamide as a food additive is not approved"
This study seems to say it's harmless instead of deadly:
http://www.inchem.org/documents/jecfa/jecmono/40abcj28.htm
"The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
13-20 December, 19651 Geneva, 11-18 October, 19662"
"Biochemical aspects
When azodicarbonamide reacts with flour, it behaves as a hydrogen
acceptor and it is rapidly and completely converted into biurea, which
is stable under baking conditions. Reaction between azodicarbonamide
and flour only occurs on wetting. Forty-five minutes after treatment
of a flour with 8.25 ppm of azodicarbonamide, less than 0.1 ppm of
azodicarbonamide could be detected in the dough. When 14C-labelled
azodicarbonamide was used for breadmaking, the activity remained in
the bread and there was no liberation of labelled carbon dioxide.
Biurea labelled with 14C was unaffected by pepsin or trypsin
in vitro. When administered orally to rats in doses of 33 mg,
labelled biurea was recovered quantitatively within 120 hours from
faeces and urine. Absorption from the intestinal tract was about 20
per cent. No radioactivity was detectable in the blood after 24 hours;
no tissues were found to accumulate biurea (Joiner et al., 1963; Oser
et al., 1965)."
So far it looks like
Agent11 bit on a FUD email forward from some food-purity group. I'm not against food purity (my peanut butter is Adams. Ingredients: Peanuts.) but I'll buy "impure" food too without thinking it will deplete my vital essences or harsh my mellow.