Let's say I have a document, a specification for a vitamin mix for addition into animal fodder. This document has a table listing the maximum permitted contents of bacteria in the mix.

The first line reads: "Maximum overall bacterial count, in cells/g: 500 000".

The second, third, and fourth to tenth lines read "E.Coli and coliform bacteria", "Proteus", etc. The column value is "not allowed" for each of these, meaning that it's a no-no to have any such bacteria in the mix.

Is "not allowed" a proper combination of words? I came up with "not permitted" as an alternative, but there could be more idiomatic word combinations.

The Russian original is "не допускаются" ('are not admitted', in a blunt translation; meaning the very existence of such bacteria in a sample of the product is a no-no)

  • I don't think there's anything wrong with 'not allowed'.
    – Varun Nair
    Commented May 11, 2016 at 10:04
  • You could use 'forbidden', although that sounds very commanding and strict.
    – Varun Nair
    Commented May 11, 2016 at 10:06
  • 1
    I would prefer not allowed to not permitted, but I would prefer the numeral 0 over either one.
    – Adam
    Commented May 11, 2016 at 15:06
  • 1
    The U.S. EPA uses zero in its drinking water contaminant tables: epa.gov/ground-water-and-drinking-water/…
    – Adam
    Commented May 11, 2016 at 15:14
  • 2
    You could also say "None permitted" or "None allowed" if you are using a count. How many red ones are allowed? None (are allowed).
    – ColleenV
    Commented May 11, 2016 at 15:55

2 Answers 2


There are many similar examples out there:

The United States EPA sets standards for drinking water contaminants:

Di(2-ethylhexyl) phthalate zero

I have seen this switched to the numeral 0 in city water quality fact sheets.

In strict terms, though, we can't say that a concentration is zero - only that it cannot be detected. So some standards will say non-detectable. That invites the question of how hard one has to look before declaring something non-detectable.

The U.S. FDA sets limits for bacteria in animal-sourced fertilizer with that issue specifically adressed:

L. monocytogenes Not detected using a method that can detect one CFU per five gram analytical portion

Not permitted would be well understood by the public, but doesn't really specify how to determine the absence.

The examples above reflect the usage when issuing regulations. If you are looking for a way to provide testing results, it is common to report non-detects as being less than the detect threshold. For instance, if your test can detect 0.1 ppm listeria, you could report a non-detect as:

Listeria <0.1 ppm


Not allowed is a more informal way of saying not permitted. Not permitted is more formal, as shown by the definition - officially allow (someone) to do something.

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