There are numerous types of materials for food packaging bags. The composition, properties and other factors of different materials can affect their safety in multiple aspects, as follows:
Plastic packaging materials
The influence of the resin itself: Plastic resins are generally non-toxic, but their monomers, degradation products and substances produced by aging may be toxic. For instance, the vinyl chloride monomer used in the production of cling film, if not fully polymerized into polyvinyl chloride, the remaining vinyl chloride monomer has an anesthetic effect and can also cause cancer and birth defects. Bisphenol A is a raw material for many high-molecular materials such as polycarbonate. When heated, it can be dissolved in food, which may disrupt the human metabolic process, affect the development and immunity of infants, and even cause cancer.
The influence of additives: Additives are often used in the plastic production process, such as plasticizers, stabilizers, colorants, etc. Phthalates, plasticizers, are toxic, carcinogenic and difficult to degrade. Adhesives are mainly composed of aromatic isocyanic acid. After high-temperature steaming, they can form aromatic amines, which are carcinogens. In addition, if recycled plastic is directly used for food packaging, it is difficult to ensure that the residual harmful substances on the recycled containers are thoroughly cleaned. Moreover, some manufacturers add a large amount of paint to the recycled plastic, which may lead to a large amount of paint pigment residue and contaminate the food.
Paper packaging materials
The impact of raw materials: Some paper packaging materials are produced from waste paper. During the collection process, there may be moldy paper. After production, a large amount of mold and pathogenic bacteria will be generated, causing food to spoil and deteriorate. Recycled waste paper may also contain harmful substances such as lead, cadmium and polychlorinated biphenyls, which can pose a threat to human health.
The impact of ink: If food factories do not use special ink for food packaging, most non-special inks contain organic solvents such as toluene, which may cause excessive benzene solvents in food, endanger the human hematopoietic function, damage the nervous system, and even lead to leukemia.
The influence of additives: Additives such as sizing agents, bleaching agents, and dyeing agents added during the papermaking process may pose safety hazards. For instance, paper treated with fluorescent brighteners contains fluorescent chemical pollutants. These substances have a high solubility in water and are prone to migrate into the human body, increasing the burden on the liver. Excessive exposure may have carcinogenic effects.
Metal packaging materials
Non-coated metals: The main safety issue is the leaching of toxic and harmful heavy metals. For instance, when the galvanized layer in iron products comes into contact with food, zinc will migrate to the food, causing food poisoning. Aluminum products contain elements such as lead and zinc. Excessive intake can cause chronic accumulation poisoning.
Coated metals: The main safety issue lies in the leaching of free phenols, free formaldehyde and toxic monomers from the surface coating. Once these substances leach out, they may contaminate food and affect food safety.
Glass packaging materials: Generally, glass packaging materials are non-toxic, odorless and have good chemical stability. However, the high transparency of glass is detrimental to certain contents of food, as it is prone to chemical reactions and the production of toxic substances. However, relatively speaking, the toxic substances in glass packaging containers are relatively simple, mainly lead, arsenic and antimony, and usually the amount of their migration into food is very low, posing relatively little harm to humans.
Ceramic packaging materials: The main safety issues of ceramic packaging materials are the glaze on the ceramic surface and the content of lead and cadmium. The heavy metals lead and cadmium contained in various colored glazes can dissolve into food, and long-term intake can cause harm to human health.