Hi Mano,
Health & Safety aspects are usually down to national legislation first, normally one would consider the time people were exposed to the set temperature and also provide appropriate protective clothing.
From a food safety perspective, one would consider the maximum time the product was exposed to the packing temperature conditions and the maximum possible temperature rise in this period. Typically, I see a maximum product temperature of -12 °C quoted for frozen products. Obviously you will want to reduce this temperature again after after packing if it does rise that high.
Kind regards,
Tony