If the fridge is really ancient it is possible that there could be some ammonia, it was used as a refrigerant back in the days of the wild west, not sure when it stopped, probably the 50's but not too sure.
In some parts of Europe they are not up with the state of the art equipment that we are used to and take for granted, so it could be possible that some are still using ammonia as a refrigerant.
I remember in Italy years ago you could see some of the fastest cars on the street (Ferrari, Maserati etc) and still have raw sewerage running down the gutters in some large towns.
The Blue Danube is pretty brown in places too and pollution is not a high priority on some countries agenda.