A list member asked me off-list about milligrams versus parts
per billion and parts per million, so I guess I should lay this
out, since contamination claims are clearly going to become more
and more common.

The highest number I could find in was from Louisiana's (USA)
testing of imported honey from China:

   "The highest concentration the lab found in the
    3 honey samples was 5.46 parts per billion."

I should list a few standard conversions for those who think that if God
intended us to use the metric system, there would have been 10 Disciples.
In my view, if God had wanted us to use the metric system, he would have
given us ten fingers.   :)

A "billion" in science is a "USA-style" billion, 10 to the 9th, so one has
8 zeroes after the decimal point, and then the first digit.

So, "5.46 parts per billion" is a fractional value of 0.000000005460

  1 gram is 10 to the -3 kilos           (There are a thousand grams in a kilo)
  1 milligram is 10 to the -6 kilos      (There are a million milligrams in a kilo)
  1 microgram is 10 to the -9 kilos      (There are a billion micrograms in a kilo)

  1 milligram is 10 to the -3 grams      (There are a thousand milligrams in a gram)
  1 microgram is 10 to the -3 milligrams (There are a thousand micrograms in a milligram)

As an easy way to remember, "parts per million" is like saying "milligrams
per kilo" and "parts per billion" is like saying "micrograms per kilo".
(Try to convert this to ounces and pounds, and your calculator may melt.)

So, one kilo of honey would contain 5.46 micrograms of the
contaminating antibiotic as a worst-case estimate.

So, how much honey would I have to eat to get a (completely ineffective)
1 milligram "dose" of the antibiotic if all the honey was equally
contaminated at 5.46 ppb?

One milligram is 1000 micrograms, so:

   1000 / 5.46 = 183.15  kilos of honey would contain 1 milligram
                    that's 403.85 pounds of honey.

Just to be silly, if I wanted a 250mg "dose" which is a common dose
in pills, I'd need to eat 250 times as much honey, or 45,787 kilos,
which would be 100,961 pounds of honey.

...but I have no idea what level of dose over what period of time
would be required to increase one's chances of getting aplastic
anemia, but I don't think I'd have ANY form of "anemia" if I
was eating several hundred pounds of honey a year, would I?

And just how does this sort of thing happen?

The Chinese Ministry of Agriculture's view is in their critique
of the "Draft Report for the Residue control in Live Animals and
Animal Products by EC Inspection Mission to China" at
http://www.agri.gov.cn/english/e02.htm :

In this document it is claimed that an investigation into the
contamination of the shrimp and prawns revealed:

        "The prawn peeling workers had not worn protective
        gloves in the past, causing itchy symptoms on their
        hands, so some of the workers used chloromycetin
        (chloramphenicol) to treat their hands in order to
        avoid the itching, and as a result, the prawns were polluted."

But they don't explain anything about the honey.

I guess the bottom line is that antibiotics that should not be used
at all outside of human medicine have no business showing up at any
level in food, but it is important to see how tiny the amount of
a "parts per million" or "parts per billion" contamination really is.

But I WASN'T kidding about washing your hands with anti-bacterial soap
before loading the uncapper.  Not one little bit.  Back to plain old
Dial and Lava soaps in the honey room.  (Lava gets off the propolis
better than anything else I have tried.)

The best example of a conversion challenge I have
ever seen was in a British description of heat loss
through an insulating barrier:

        BThU/hour/sq ft/cm/degree F

... which makes my head hurt.