Food packaging is the final stage of the modern food industry. It plays a vital role in protecting, promoting, and facilitating the storage, transportation, and sale of food. To a certain extent, it has a direct or indirect impact on food quality, which not only endangers consumer health but also affects the healthy development of my country’s entire food packaging industry and even the food industry as a whole. Food packaging is closely linked to food safety. Food packaging must ensure the sanitation and safety of packaged food. Currently, the food containers and packaging materials approved for use in my country can be categorized as follows: plastic products; natural and synthetic rubber products; ceramic and enamel containers; aluminum, stainless steel, and iron containers; glass containers; food-grade paper; composite film and composite film bags; bamboo and wood; cotton and linen; and others.
Safety Analysis of Food Packaging Materials
Plastic
Plastic is a polymer material consisting of high-molecular-weight polymer resin as its basic component, with its performance enhanced by the addition of various additives. As an emerging trend among packaging materials, plastic packaging has become one of the fastest-growing packaging materials in the world over the past 40 years due to its abundant raw materials, low cost, excellent performance, light weight, and attractive appearance. The migration and leaching of toxic and harmful substances from plastic packaging can lead to food contamination, particularly in the following cases:
Toxicity of the resin itself
Unpolymerized free monomers, cracking products (vinyl chloride, styrene, phenols, nitrile rubber, formaldehyde), degradation products, and toxic substances formed through aging in the resin all affect food safety. The U.S. Food and Drug Administration has pointed out that it is not polyvinyl chloride (PVC) itself, but rather the vinyl chloride (VCM) remaining in PVC that can cause cancer when ingested, and therefore prohibits the use of PVC products as food packaging materials. The free vinyl chloride monomer (VCM) in polyvinyl chloride has an anesthetic effect and can cause blood vessels in the human limbs to constrict, leading to pain. It also has carcinogenic and teratogenic effects. In the liver, it forms vinyl chloride oxide, which has a strong alkylating effect and can bind to DNA and form tumors [1]. Residues in polystyrene, such as styrene, ethylbenzene, toluene, and isopropylbenzene, pose a risk to food safety. Styrene can inhibit reproduction in rats and reduce the weight of the liver and kidneys. Low-molecular-weight polyethylene dissolves in oils and fats and produces a waxy odor that impairs product quality. The extent to which these contaminants affect food safety depends on their concentration in the material, the integrity of the seal, the type of food coming into contact with the material, as well as time, temperature, and solubility in the food.
Surface Contamination of Plastic Packaging
Because plastics become easily charged, they can readily attract dust and microorganisms, thereby contaminating food.
Toxicity of additives such as stabilizers, plasticizers, and dyes that are added during the manufacturing process of plastic products
A scientific study conducted by Professor Li Shuguang of the Basic Medical College at Tongji University and his research team showed that plasticizer contamination in food in my country is widespread. The study found that nearly all brands of plastic barrels of cooking oil contain two plasticizers, “dibutyl phthalate (DBP)” and “dioctyl phthalate (DOP),” while iron barrels of cooking oil contain almost none. .
Contamination of food by a variety of toxic additives, heavy metals, pigments, viruses, etc., found in illegally used recycled plastics
Recycling and reusing plastics are all the rage. Due to the complexity of recycling processes, harmful substances often remain in recycling bins, making it difficult to thoroughly clean and process the materials. To mask quality defects in recycled products, large amounts of dye are often added, leading to color pigment residues that contaminate food. For regulatory reasons, even large quantities of medical plastic waste are recycled, posing a hidden threat to food safety.
Ink Spills
The main components of ink are pigments, resins, additives, and solvents. Ink manufacturers often consider the impact of resins and additives on safety but ignore the indirect risks to food posed by pigments and solvents. Some inks contain adhesion promoters such as siloxanes to improve adhesion. At certain drying temperatures, these substances cause bonds to break down and form compounds such as methanol, which can damage the human nervous system. The ink printed on plastic food bags has a greater impact on food safety, as some toxic substances, such as benzene, are difficult to volatilize. In recent years, the failure rate of plastic food bags in various countries has been low overall, at only 50 to 60 percent. The main causes of this are excessive benzene residues. The primary reason for the excessive benzene content is the use of benzene-containing solvents to dilute the ink when printing on plastic packaging.
Adhesives for Composite Films
Adhesives can be broadly classified into polyether and polyurethane adhesives. Polyether adhesives are increasingly being phased out, while polyurethane adhesives are available in two types: aliphatic and aromatic. Depending on the application, a distinction is made between water-based, solvent-based, and solvent-free adhesives. Although water-based adhesives do not have a major impact on food safety, they are not yet widely used in my country due to functional limitations [4]. Solvent-based adhesives are still predominantly used in my country [5]. With regard to food safety, most people believe that a low solvent residue does not compromise food safety. In fact, however, this assumption is one-sided. 99% of the solvent-based adhesives used in my country are aromatic adhesives [6]. They contain aromatic isocyanates. After food is packaged in such bags and subsequently subjected to high-temperature steam, these substances can migrate into the food and hydrolyze, producing aromatic amines that are carcinogenic. In my country, there is currently no national standard for adhesives in food packaging, and the corporate standards of various manufacturers and suppliers do not specify heavy metal content. However, strict limits apply to aromatic amines in food packaging from other countries. The EU, for example, stipulates that their migration level must be below 10 ppb.
Paper
Paper packaging plays a very important role in food packaging due to its unique advantages. In some industrialized countries, paper packaging accounts for 401 to 501 metric tons of total packaging material; in my country, the figure is approximately 401 metric tons. National standards regulate the hygiene indicators, physical and chemical indicators, and microbial indicators of raw paper used for food packaging. Pure paper is hygienic, non-toxic, and safe, and can be broken down by microorganisms under natural conditions without harming the environment. The sources of harmful substances in paper and their impact on food safety are primarily related to the following aspects.
Pollution caused by the raw materials used in paper production itself
Raw materials used in the production of food packaging paper include pulp, straw pulp, etc., which contain pesticide residues. Some manufacturers use a certain percentage of recycled waste paper in paper production; although the waste paper has been bleached, this process only removes the ink pigment, while harmful substances such as lead, cadmium, and polychlorinated biphenyls may remain in the pulp. Some manufacturers use moldy raw materials in production, resulting in the finished product containing a large amount of mold.
Additives in the Paper Manufacturing Process
In paper manufacturing, chemicals such as impregnating agents, sizing agents, fillers, bleaching agents, dyes, etc., must be added to the pulp. Most of the substances leached out of paper originate from the additives, dyes, and inorganic pigments in the pulp. Various metals are often used that can dissolve even at concentrations in the mg/kg range and may cause illness [2]. For example, during paper processing—particularly in chemical pulp production—paper and cardboard typically contain certain chemical residues, such as alkalis and salts from the sulfate pulp process. The Food Safety and Hygiene Act stipulates that the use of fluorescent dyes and brighteners in food packaging is prohibited, as these are carcinogenic [7]. Antifungal agents or formaldehyde from resin processing can also leach out of paper products.
Ink Stains
In my country, there are no special printing inks for food packaging. The inks used on paper packaging are mostly organic, solvent-based gravure inks that contain toluene and xylene. Benzene-containing solvents are often used to thin the ink, resulting in excessive benzene residues. Although the use of benzene solvents is prohibited under the GB9685 standard, they are still used in large quantities. Second, the pigments and dyes used in the printing inks contain heavy metals (lead, cadmium, mercury, chromium, etc.), aniline or fused-ring compounds that cause heavy metal contamination, and aniline or fused-ring dyes are clearly carcinogenic. During printing, they accumulate, causing the unprinted surface to come into contact with the ink and resulting in secondary contamination. Therefore, the harmful substances in printing inks for paper packaging have serious implications for food safety. To ensure the safety of food packaging, the use of benzene-free printing is becoming a growing trend.
Contamination During Storage and Transport
The surface of paper packaging becomes contaminated with dust, impurities, and microorganisms during storage and transport, which compromises food safety.
Metal
Metal packaging is one of the traditional packaging materials and has been used for food packaging for nearly 200 years. Metal packaging is processed into various container shapes, with sheet metal or metal foil serving as the raw materials for food packaging. Due to its high barrier properties, resistance to high and low temperatures, and ease of recycling, metal packaging is increasingly being used for food packaging. The main disadvantage of metal as a food packaging material is its low chemical stability and poor resistance to acids and alkalis. It corrodes easily, particularly when in contact with highly acidic foods, and metal ions can readily leach into the food, affecting its taste. The biggest safety concern with iron containers is that zinc can leach into food upon contact with the galvanized coating, potentially causing food poisoning. Aluminum contains elements such as lead and zinc, the long-term consumption of which can lead to chronic, cumulative poisoning. Aluminum has low corrosion resistance and is prone to chemical reactions in which harmful substances are deposited or released. Impurities and harmful metals in recycled aluminum are difficult to control. Stainless steel products contain high levels of nickel, which causes the container’s surface to turn black at high temperatures. At the same time, rapid heat transfer promotes the gelation and denaturation of unstable substances in food and may also have carcinogenic effects. Stainless steel should not come into contact with ethanol, as this can dissolve nickel and cause chronic poisoning. Therefore, it is generally necessary to coat the inner and outer walls of metal containers. The inner wall coating is an organic coating applied to the inside of metal cans. It protects the contents from direct contact with the metal, prevents electrochemical corrosion, and extends the shelf life of food. However, during the processing and storage of the cans, harmful chemicals from the coating leach into the contents, causing contamination. These substances include BPA (bisphenol A), BADGE (bisphenol A diglycidyl ether), NOGE (phenolic lacquer glycerol ether), and their derivatives. Bisphenol A epoxide derivatives are an environmental hormone that enters the body through canned food and causes endocrine disruption and genetic mutations.
Glass
Glass is an ancient packaging material. The Egyptians first produced glass containers over 3,000 years ago, and since then, glass has been used as a packaging material for food and other items. Glass is a molten product made from silicates, metal oxides, and other substances. It is an inert material that is non-toxic and safe. The most important properties of glass as a packaging material are: high barrier properties, clarity and transparency, good chemical stability, and ease of forming. Its consumption accounts for approximately 10% of total packaging material.
Dissolution of Toxic Substances During Melting
In general, the ions within glass are firmly bound. After being melted at high temperatures, most of them form insoluble salts with excellent chemical inertness, which do not react with the packaged food and ensure a high level of packaging safety. However, in glass products that are not properly melted, toxic substances may leach out of the glass raw materials. Therefore, glass products should not be soaked in water or heated with diluted acid. Foods and medications with strict packaging requirements can be packaged in borosilicate glass instead of soda-lime glass. At the same time, attention should be paid to the quality of the glass melting and molding processes to ensure the safety of the packaged food.
Excessive Heavy Metal Content
Lead compounds are often added to high-quality glassware, such as wine glasses with tall stems. The amount added is typically up to 30 % of the glass. This poses a significant safety concern for glassware.
Safety Risks Posed by Dyes in Colored Glass
To prevent harmful light from damaging the contents, various dyes are used to color the glass. The greatest safety risk associated with added metal salts is the migration of substances dissolved from the glass. For example, added lead compounds can leach into wine or beverages, and silicon dioxide can also leach out.
Ceramics
Compared to containers made of metal, plastic, and other packaging materials, ceramic containers are better at preserving the flavor of food. For example, fermented tofu stored in ceramic containers is of higher quality than fermented tofu stored in plastic containers, since ceramic containers are airtight, yet the arrangement of the ceramic molecules is not very dense, so air cannot be completely blocked—which promotes the continued fermentation of the tofu.
The hygiene and safety issues associated with ceramic packaging materials for food packaging are primarily related to the leaching of the heavy metals lead and cadmium from the glaze layer on the surface of glazed ceramics. Ceramic packaging is generally considered nontoxic, hygienic, and safe, and it interacts harmlessly with the packaged food. However, long-term studies have shown that glazes consist primarily of various metal oxides and their salts—such as lead, zinc, cadmium, antimony, barium, copper, chromium, and cobalt—most of which are harmful. Ceramics are fired at 1000–1500 °C. At lower firing temperatures, the colored glaze does not form insoluble silicates. Toxic and harmful substances easily leach from ceramic containers and contaminate food. For example, these substances easily leach into acidic foods (such as vinegar and juice) and wine, entering the food and leading to safety concerns. Both domestic and foreign regulations have established permissible limits for the amount of lead and cadmium that may leach from ceramic packaging containers.
The above is a brief introduction to the safety of food packaging materials and the main materials used. With the development of the national economy, policy adjustments, and changes in consumer attitudes, we have begun to establish a scientific, targeted, and practical food packaging safety control system based on the experience of developed countries; gradually establish and improve new regulations on food packaging materials; and formulate a food packaging quality standard system in line with international standards. As consumers, it is particularly important to increase their awareness of self-protection. A survey on consumers’ trust in the hygiene and safety of food packaging materials shows that people believe glass, ceramics, and metals are safer [9], but these materials also pose safety risks. Consumers lack safety knowledge—for example, they are unable to interpret the information on labels—which affects their acceptance of safety information. .
Trends in Food Packaging Materials
For low-carbon and eco-friendly packaging
In the food production chain, the general trend is toward environmental protection and CO2 reduction. The environmental pollution and waste of resources caused by discarded packaging are increasingly coming into focus. Packaging reduction, resource efficiency, environmental sustainability, low CO2 emissions, safety, and the reuse of packaging have become established practices. The experiences of Europe and the U.S. with food packaging are worth examining. Sweden and other countries, for example, have implemented the reuse of polyester PET beverage bottles and PC milk bottles more than 20 times. The Dutch Wellman Company and the American Johnson Company use 100% recycled PET containers, and some paper packaging can be recycled after use. Any consumer product that is not handled properly causes environmental pollution.
Establishment of a sensible consumption and usage system to reduce environmental pollution
In the field of packaging materials, polymer materials are advancing more rapidly than glass, metal, and paper. The main reason for this is the excellent properties of polymers.
After my country joins the WTO, due to the reduction in tariffs, the import tax on plastic resins will drop by 60%, and my country’s plastic packaging industry will have greater room for development. According to reports, the annual growth rate of paper containers in the United States over the past five years was 3.2%, the annual growth rate of metal containers was 2.5%, the annual growth rate of glass containers was 0.5%, and the annual growth rate of plastic containers was 5.5%. Food packaging materials need to be evaluated throughout the entire process. From an economic standpoint, the transportation and storage costs of biodegradable materials are relatively high. For consumers, paper packaging costs more than plastic packaging (about twice as much). It is clear that plastic will continue to be the most commonly used and most convenient packaging material in the food industry. Therefore, it is necessary to establish a reasonable consumer usage system to reduce and gradually eliminate its environmental impact.
Strengthening Research and Development and Safety Assessment of Functional Packaging Materials
In the future, greater emphasis will be placed on functionality in food packaging from a safety perspective. Paper food packaging offers improved features such as moisture resistance, freshness retention, sterilization, antimicrobial properties (antioxidants), resistance to water, acids, and oils, as well as odor neutrality. For biodegradable packaging materials, systematic research and evaluation of their stability, biodegradability, and cost-effectiveness are being intensified—for example, regarding safety at different temperatures, humidity levels, pH levels, and oxygen content, as well as when used with oil-containing foods and in microwave ovens. Therefore, scientific research departments should intensify their systematic research into food packaging and develop products that meet food hygiene requirements and are non-toxic and safe for both humans and the environment.
Accelerate the revision and drafting of standards and establish a quality standards system in line with international standards
Currently, some of my country’s food packaging hygiene standards and routine sampling criteria were established in the early 1990s. The existing outdated standards cannot accommodate testing of new materials and are no longer suitable for product safety requirements. Given the current situation of outdated standards, regulatory agencies should refer to advanced international standards to accelerate the revision, improvement, and updating of existing standards. My country lags behind developed countries in safety assessment and testing technology, which affects our ability to evaluate new substances and materials. Some monomers and additives cannot be detected, and even when they are detected, the sensitivity of the methods is very limited. Therefore, we should strengthen the development of detection and evaluation capabilities at technical support institutions, conduct research on trace detection technology and ultra-trace detection technology for certain monomers and additives, establish methods for detecting multiple types of chemical substances, improve various detection standards, and develop fast and effective detection methods and equipment as soon as possible. At the same time, we should continue to strengthen cooperation with international organizations, such as the Codex Alimentarius Commission (CAC), the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO), etc., and formulate and improve the safety evaluation procedures, evaluation mechanisms, and management methods for food packaging materials as soon as possible.
Improving the Safety Assurance System for Food Packaging Materials
Accelerate the promotion of the market access system for packaging material quality and safety, and actively implement mandatory certification. For enterprises that have obtained production licenses, post-certification oversight should be strengthened, and a sound long-term safety mechanism should be established. The relatively successful experience of Europe and the United States is worth learning from, and we should establish a sound food packaging market access system and regulatory measures, such as a food and packaging quality and safety certification system, a food and packaging recall system, and a traceable food and packaging safety database. GMP and HACCP systems are currently recognized worldwide as the most effective and economical food safety systems [14]. My country should implement the mandatory GMP and HACCP certification system in the food packaging materials industry as soon as possible to build a strong safeguard for my country’s food packaging safety.
Strengthening Entrepreneurial Self-Discipline and Social Responsibility
It is very difficult for the average consumer to determine whether food packaging poses safety risks. The relevant authorities should take appropriate measures to regulate companies’ production and ensure the safety of food packaging materials at the manufacturer level. Manufacturers’ legal awareness, self-discipline, and social responsibility are directly linked to food safety issues. As a key component of food processing, the food packaging industry should gradually introduce annual inspections, regular checks and audits, as well as random spot checks, and strengthen oversight of small and family-run businesses while imposing penalties on illegal companies. Furthermore, unclear responsibilities of regulatory authorities, repetitive inspections, and regulatory loopholes should be addressed to improve management efficiency and encourage companies to produce in accordance with standards and operate in compliance with the law. Food packaging materials are not only linked to environmental protection but, above all, to issues of public health and safety. The safety of food packaging materials is synonymous with food safety. Improving the quality and safety of food packaging materials not only ensures food safety but also safeguards consumer health as well as social stability and harmony.
Graduation
Food packaging materials are essential not only for preserving food quality but also for public health and safety. Although materials such as plastic, paper, metal, and glass are widely used, each poses its own risks, including contamination, migration of toxic substances, and environmental concerns. To address these challenges, it is essential to further improve safety standards, conduct thorough research, and establish rigorous testing protocols. Furthermore, promoting environmentally friendly and functional packaging materials, as well as strengthening regulatory frameworks and corporate self-regulation, are crucial for improving food packaging safety. Through these measures, we can protect both consumer health and the future of the food packaging industry.
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