this is complete and utter horseshit..
how can you tell from the amount of something present in a urine sample how much was actually administered?
the answer is, in 99.999999999999% of cases YOU CANT
If I take 100mcg of Nandrolone today, there will be certain levels of nandralone or its metabolites in my urine...
In 3 days time there will be less Nandrolone or its metabolites in my urine
In 7 days time there will even less Nadrolone or its metabolites in my urine
If you tested me in 10 days, and you discovered a miniscule amount of nandrolone or its metabolites in my urine you have absolutely zero way of knowing if its a miniscule amount because i only took a miniscule amount, or if its a miniscule amount because i took a larger amount ten days ago.
You are talking bollocks
What USADA will on occasion say is that the "amount detected is consistent with accidental contamination" but that will be coupled with OTHER EVIDENCE. For example, dietery habits or evidence in teh case of clenbuterol positives etc.
The other exception is if you have earlier samples that are negative for the substance. That can help you pinpoijnt when it was administred and from that you can work out the likely excretion rate and determine if the levels are consistent with contamination.
But there is no possible, scientific way of establishing, purely from the levels of something in a urine sample, if it is the result of contamination or not.