Hazardous substances present in cold food can originate from food additives and poor water quality.

1. Food additives: In order to increase the taste, color, shelf life, etc. of cold food, manufacturers usually add some food additives, such as preservatives, pigments, sweeteners, etc. If these additives are used improperly or exceed safe usage levels, they may cause harm to the human body.

2. Poor water quality: Water in cold food is a very important raw material. If the water quality is poor, it may contain a large amount of bacteria, viruses, heavy metals and other harmful substances, which may cause harm to human health.