I have no Idea of any details of the lights you are speaking of.
If you are worried that it may not be safe, you might like to try and take it apart and seal it some how, or even put some extra grease on the O Ring seals if it uses them.

The manifacturer may make the entire range technically intrinsically safe, but for cost reasons they may have only tested 1 model to be certified, therefor covering themselves in case of a lawsuit.

I have a friend who works in those environments, and they will not allow anything without the certification to be used even if it is safe.
I cant remember the brand, but one of the lights they use is exactly the same as the off the shelf model except but it uses a different colour plastic and cost 3 times the price because it has a certificate to say its safe.