The refrigerator needs to be integrated in the maintenance program. By doing so, the volume of gas can be monitored frequently. Leakage of gas shall be avoided by:
- Making sure that the fragile parts of the installation can't be damaged by movement in the refrigerator (with forklift trucks for example). The fragile parts are normally in a technical room, where only dedicated personnel has acces
- Maintenance is done by qualified personnel only
You can work this out in your risk assessment. Freon is toxic and is a dangerous good, however it's not likely that it reacts with your product. For freon there is more an environmental risk than a food safety risk. Which means that the risk shall be worked out in your Human Health, Safety and Environmental plan and that leakage shall be avoided.
For the association of refrigerators and food risk; it are the refrigeration liquids (such as glycol when these are not food grade) that can pose a food safety risk, in case of a leakage. There was a case in the 80's. This kind of things has been sorted out in the food industry, but one needs always to be aware.
I hope to have informed you sufficiently.