My guess is that yr query is not readily answerable in an absolute sense because mould is not a species and not all genera of moulds produce mycotoxins.
An additional factor is that the scope and official tolerance limits for specific mycotoxins globally vary, eg –
The most conservative viewpoint (ie highly Risk Averse) would presumably adopt a "zero tolerance" type logic and test any detection. This is equivalent to the strictest limit in my previous post or the (parenthesis) limit in example No.2 in this attached file.
dairy specs-controls.doc 316KB
I have yet to see any opinion or detailed analysis of a specific “safety” relationship between a positive “mould count" and “mycotoxins”.
Nonetheless, there do seem to have been very few reported instances of proven mould-related mycotoxins causing health-related incidents for dairy yoghurts. For mould growing on the surface of yoghurt this (2009) observation might be an explantion but it looks a bit too convenient IMO –
since mycotoxin production would be expected to coincide with visible growth, and visibly spoiled products are unlikely to be consumed, this does not seem to be a serious hazard.
(the comment does not exclude the possibility of direct toxin contamination via the original milk, or later additions.
It is obviously crucial to control any items added post-pasteurization, eg see the puree comments in No.(3) of attached file.
As a possible caveat to assuming mold on yoghurt has only non-safety significance, this later (2013) incident has become globally well-known –
Further speculation over Yoghurt X welcomed.