The urban myth, that I refer to, is usually quoted along the lines of "a bowl of nuts from x was found to contain urine from over y number of individuals"
Finding the amount of urea on the nuts would tell you nothing. Assuming that any urea present has come from urine. It may have come from a single individual, or many. Also, since most men don't actually get their hands wet while passing water, (and those that do would have dried them before dipping into the nuts), the resultant urea concentration is going to measured in parts per billion.
It's also missing the point. A bit of urine is harmless. By far the biggest hazard would be from saliva. Someone taking a handfull of nuts may be inclined to lick their fingers. Saliva is loaded with all kinds of microbes. If the same individual were to now grab another few nuts, they could be passing on all kinds of nasties.
In fact, just the microbes landing on the nuts, from being exposed to the air, would pose a bigger threat than that of the urine.
Finding the amount of urea on the nuts would tell you nothing. Assuming that any urea present has come from urine. It may have come from a single individual, or many. Also, since most men don't actually get their hands wet while passing water, (and those that do would have dried them before dipping into the nuts), the resultant urea concentration is going to measured in parts per billion.
It's also missing the point. A bit of urine is harmless. By far the biggest hazard would be from saliva. Someone taking a handfull of nuts may be inclined to lick their fingers. Saliva is loaded with all kinds of microbes. If the same individual were to now grab another few nuts, they could be passing on all kinds of nasties.
In fact, just the microbes landing on the nuts, from being exposed to the air, would pose a bigger threat than that of the urine.