Are Clear Plastic Cups Suitable for Cold Drinks Only?
author: Iris
2025-12-09
I. Basic Characteristics Analysis of PP and PET Materials
1.1 Molecular Structure and Thermal Properties of PP Material
PP (polypropylene) is a semi-crystalline thermoplastic polymer made from propylene monomers through addition polymerization. It is a white, waxy solid, non-toxic and odorless. Its molecular structure contains methyl groups. Because the volume of the methyl group is larger than that of the hydrogen atom, the steric hindrance is greater, making the glass transition temperature of PP higher than that of polyethylene. This unique molecular structure gives PP excellent heat resistance.
From the perspective of thermal performance parameters, PP material has significantly high-temperature resistance. Its melting point ranges from 164-176℃, and the melting point of some high-purity isotactic PP can reach 176℃. In terms of heat distortion temperature, the heat distortion temperature of PP is 114℃ (under 1.82MPa conditions), and the Vicat softening point is greater than 140℃. These data show that PP material can maintain good structural stability even in high-temperature environments.
According to national standards and industry research, the operating temperature range of PP material is -20℃ to 120℃, and it can withstand high temperatures of 150℃ without deformation under no external force. In practical applications, PP material can be used above 100℃, up to 120℃ under light load conditions, and the maximum continuous use temperature under no load is 120℃, with a short-term use temperature of up to 150℃. This excellent heat resistance makes PP an ideal material for making hot drink plastic disposable cups and microwaveable food containers.
From the perspective of thermal performance parameters, PP material has significantly high-temperature resistance. Its melting point ranges from 164-176℃, and the melting point of some high-purity isotactic PP can reach 176℃. In terms of heat distortion temperature, the heat distortion temperature of PP is 114℃ (under 1.82MPa conditions), and the Vicat softening point is greater than 140℃. These data show that PP material can maintain good structural stability even in high-temperature environments.
According to national standards and industry research, the operating temperature range of PP material is -20℃ to 120℃, and it can withstand high temperatures of 150℃ without deformation under no external force. In practical applications, PP material can be used above 100℃, up to 120℃ under light load conditions, and the maximum continuous use temperature under no load is 120℃, with a short-term use temperature of up to 150℃. This excellent heat resistance makes PP an ideal material for making hot drink plastic disposable cups and microwaveable food containers.
1.2 Molecular Structure and Thermal Properties of PET Material
PET (polyethylene terephthalate), commonly known as polyester resin, is a crystalline saturated polyester, a milky white or light yellow, highly crystalline polymer. The PET molecular chain structure contains benzene rings and ester bonds, and this special chemical structure determines its unique physicochemical properties.
The thermal performance of PET material differs significantly from that of PP. Its glass transition temperature (Tg) is approximately 70-80°C, which is a key parameter determining whether PET can hold hot beverages. Although the melting point of PET is as high as 250-260°C, far higher than that of PP and PE-HD, its glass transition temperature is the main factor limiting its high-temperature use.
In practical applications, the operating temperature range of PET material is -20°C to 68°C. Beyond this temperature range, PET material undergoes significant physicochemical changes. When the temperature exceeds 70°C, PET begins to show significant thermal deformation, and the molecular chain movement intensifies, leading to a decrease in material rigidity; in the 85-100°C range, PET undergoes a glass transition, changing from a glassy state to a highly elastic state, and the bottle body is prone to deformation.
The thermal performance of PET material differs significantly from that of PP. Its glass transition temperature (Tg) is approximately 70-80°C, which is a key parameter determining whether PET can hold hot beverages. Although the melting point of PET is as high as 250-260°C, far higher than that of PP and PE-HD, its glass transition temperature is the main factor limiting its high-temperature use.
In practical applications, the operating temperature range of PET material is -20°C to 68°C. Beyond this temperature range, PET material undergoes significant physicochemical changes. When the temperature exceeds 70°C, PET begins to show significant thermal deformation, and the molecular chain movement intensifies, leading to a decrease in material rigidity; in the 85-100°C range, PET undergoes a glass transition, changing from a glassy state to a highly elastic state, and the bottle body is prone to deformation.
1.3 Comparison of Chemical Stability of the Two Materials
In terms of chemical stability, PP and PET exhibit different characteristics. PP material has excellent chemical stability, is insoluble in any solvent at room temperature, and is resistant to acids, bases, salts, and most organic solvents except for strong oxidizing agents, concentrated sulfuric acid, and concentrated nitric acid. It remains stable in concentrated phosphoric acid, hydrochloric acid, 40% sulfuric acid, and their salt solutions at 100°C, and only a few strong oxidizing agents, such as fuming sulfuric acid, may cause changes.
PET material exhibits good resistance to heat, oxidation, reduction, and acidic environments at room temperature, making it suitable for most food and beverage packaging applications. However, under high temperature, strong oxidizing, or strong acidic extreme conditions, its performance will significantly decrease. Especially under high-temperature conditions, the ester bonds in PET molecules are prone to hydrolysis, especially in the presence of trace amounts of water.
PET material exhibits good resistance to heat, oxidation, reduction, and acidic environments at room temperature, making it suitable for most food and beverage packaging applications. However, under high temperature, strong oxidizing, or strong acidic extreme conditions, its performance will significantly decrease. Especially under high-temperature conditions, the ester bonds in PET molecules are prone to hydrolysis, especially in the presence of trace amounts of water.
1.4 Standards and Specifications for Food Contact Applications
In China, the food contact applications of PP and PET materials must comply with strict national standards. According to GB 4806.7-2016 "National Food Safety Standard for Plastic Materials and Articles Intended for Food Contact," both materials are listed as plastic materials suitable for food contact. This standard specifies the scope, terminology, basic requirements, technical requirements, migration test procedures, and labeling requirements for plastic materials and articles intended for food contact.
For PP material, the standard requires it to pass a 100℃ heat resistance test, remaining undeformed in 100℃ hot water. This requirement ensures the safety of the PP material when containing hot beverages. For PET material, the Chinese group standard T/ZZB 0915-2018 "Polyethylene Terephthalate (PET) Disposable Cups" explicitly specifies its operating temperature range as -20℃ to 68℃, a temperature limit that reflects the limitations of PET material's heat resistance.
In terms of international standards, the US FDA 21 CFR 177.1520 specifies the food contact requirements for PP materials, including testing items such as hexane migration not exceeding 6.40%, xylene migration not exceeding 9.80%, and a melting point within the range of 160-180℃. For PET material, FDA 21 CFR 177.1630 specifically regulates polyethylene terephthalate polymers, requiring acetaldehyde migration not exceeding 50 ppb, and total migration (10% ethanol, 40℃ × 10 days) not exceeding 0.5 mg/in².
The EU standard EU 10/2011 also regulates the food contact applications of these two materials, requiring all plastic materials to comply with overall migration limits and specific migration limits. The development and implementation of these international standards provide important guarantees for the safe application of PP and PET materials in the food contact field.
For PP material, the standard requires it to pass a 100℃ heat resistance test, remaining undeformed in 100℃ hot water. This requirement ensures the safety of the PP material when containing hot beverages. For PET material, the Chinese group standard T/ZZB 0915-2018 "Polyethylene Terephthalate (PET) Disposable Cups" explicitly specifies its operating temperature range as -20℃ to 68℃, a temperature limit that reflects the limitations of PET material's heat resistance.
In terms of international standards, the US FDA 21 CFR 177.1520 specifies the food contact requirements for PP materials, including testing items such as hexane migration not exceeding 6.40%, xylene migration not exceeding 9.80%, and a melting point within the range of 160-180℃. For PET material, FDA 21 CFR 177.1630 specifically regulates polyethylene terephthalate polymers, requiring acetaldehyde migration not exceeding 50 ppb, and total migration (10% ethanol, 40℃ × 10 days) not exceeding 0.5 mg/in².
The EU standard EU 10/2011 also regulates the food contact applications of these two materials, requiring all plastic materials to comply with overall migration limits and specific migration limits. The development and implementation of these international standards provide important guarantees for the safe application of PP and PET materials in the food contact field.
II. Mechanism of Temperature's Influence on Material Properties
2.1 Changes in Physical Properties of PP Material at Different Temperatures
PP material exhibits significant changes in physical properties under different temperature conditions. In the temperature range of 0-100℃, the crystalline structure of PP is stable, and the molecular chain segments in the amorphous region also maintain rigidity, thus exhibiting excellent heat resistance. This characteristic allows PP material to maintain good shape stability and mechanical strength when containing hot beverages.
At temperatures of 100-120℃, PP material can still be used normally under light load conditions, and the maximum continuous use temperature under no load can reach 120℃. In this temperature range, the movement of PP molecular chains intensifies, but the overall structure remains stable, without significant deformation or softening.
When the temperature exceeds 120℃, PP begins to face problems such as thermal aging, thermal deformation, and stress cracking. Under high-temperature conditions, the molecular chains of PP are prone to movement, leading to a gradual decrease in its mechanical properties. Although the melting point of PP is between 160-170℃, prolonged use at temperatures close to the melting point will accelerate the thermal aging process of the material.
When the temperature reaches 150℃, the PP material will not deform even without external force, but the thermal motion of the molecular chains is already very intense. When the temperature exceeds 220℃, PP undergoes significant degradation reactions, mainly manifested as molecular chain breakage and the generation of volatile substances. At high temperatures, antioxidants, stabilizers, and other additives in PP will decompose, leading to a significant decrease in the physical properties of the material.
Thermogravimetric analysis studies show that the thermal deformation temperature of PP material at high temperatures can be increased by about 20℃ by optimizing processing conditions. This finding provides a technical path for improving the heat resistance of PP material. By adding nanofillers, copolymer modification, and other methods, the thermal stability of PP material can be further improved, allowing it to maintain good performance at higher temperatures.
At temperatures of 100-120℃, PP material can still be used normally under light load conditions, and the maximum continuous use temperature under no load can reach 120℃. In this temperature range, the movement of PP molecular chains intensifies, but the overall structure remains stable, without significant deformation or softening.
When the temperature exceeds 120℃, PP begins to face problems such as thermal aging, thermal deformation, and stress cracking. Under high-temperature conditions, the molecular chains of PP are prone to movement, leading to a gradual decrease in its mechanical properties. Although the melting point of PP is between 160-170℃, prolonged use at temperatures close to the melting point will accelerate the thermal aging process of the material.
When the temperature reaches 150℃, the PP material will not deform even without external force, but the thermal motion of the molecular chains is already very intense. When the temperature exceeds 220℃, PP undergoes significant degradation reactions, mainly manifested as molecular chain breakage and the generation of volatile substances. At high temperatures, antioxidants, stabilizers, and other additives in PP will decompose, leading to a significant decrease in the physical properties of the material.
Thermogravimetric analysis studies show that the thermal deformation temperature of PP material at high temperatures can be increased by about 20℃ by optimizing processing conditions. This finding provides a technical path for improving the heat resistance of PP material. By adding nanofillers, copolymer modification, and other methods, the thermal stability of PP material can be further improved, allowing it to maintain good performance at higher temperatures.
2.2 Changes in Physical Properties of PET Material at Different Temperatures
The physical properties of PET material are extremely sensitive to temperature changes, especially near its glass transition temperature. Below 60℃, PET has excellent stability and can maintain good mechanical strength and dimensional stability. This temperature range is the safe operating range for PET material, suitable for containing cold drinks and beverages at moderate temperatures.
When the temperature reaches 70℃, PET begins to show significant thermal deformation, and the movement of molecular chains intensifies, leading to a decrease in material rigidity. This is because 70℃ is close to the glass transition temperature (Tg) of PET, at which point the molecular chain segments begin to gain enough energy to move, and the material transitions from a glassy state to a highly elastic state. In the temperature range of 85-100℃, PET undergoes a complete glass transition, transforming from a glassy state to a highly elastic state, making the bottle body prone to deformation. Differential scanning calorimetry (DSC) tests show that the most significant feature of the PET DSC curve is a high glass transition temperature (Tg ≈ 75℃). Although its melting point is approximately 250℃, much higher than PP and PE-HD, its glass transition temperature is the key factor determining whether it can hold hot water.
When the temperature exceeds 150℃, PET molecular chains begin to break down significantly, producing low-molecular-weight compounds. This thermal degradation leads to material performance degradation, such as decreased mechanical strength and yellowing. At higher temperatures (>1600K), the thermal degradation mechanism is dominated by free radical reactions, with EG (ethylene glycol) cracking into formaldehyde or acetaldehyde, leading to the formation of small molecular gases (such as CO₂).
The thermal shrinkage of PET material is also an important characteristic at high temperatures. Because the molecular chains of PET are stretched and oriented during blow molding, when heated again, the molecular chains tend to return to a disordered state, causing the product to shrink. This characteristic is widely used in PET heat-shrink labels, but it may lead to container deformation or even rupture when holding hot beverages.
When the temperature reaches 70℃, PET begins to show significant thermal deformation, and the movement of molecular chains intensifies, leading to a decrease in material rigidity. This is because 70℃ is close to the glass transition temperature (Tg) of PET, at which point the molecular chain segments begin to gain enough energy to move, and the material transitions from a glassy state to a highly elastic state. In the temperature range of 85-100℃, PET undergoes a complete glass transition, transforming from a glassy state to a highly elastic state, making the bottle body prone to deformation. Differential scanning calorimetry (DSC) tests show that the most significant feature of the PET DSC curve is a high glass transition temperature (Tg ≈ 75℃). Although its melting point is approximately 250℃, much higher than PP and PE-HD, its glass transition temperature is the key factor determining whether it can hold hot water.
When the temperature exceeds 150℃, PET molecular chains begin to break down significantly, producing low-molecular-weight compounds. This thermal degradation leads to material performance degradation, such as decreased mechanical strength and yellowing. At higher temperatures (>1600K), the thermal degradation mechanism is dominated by free radical reactions, with EG (ethylene glycol) cracking into formaldehyde or acetaldehyde, leading to the formation of small molecular gases (such as CO₂).
The thermal shrinkage of PET material is also an important characteristic at high temperatures. Because the molecular chains of PET are stretched and oriented during blow molding, when heated again, the molecular chains tend to return to a disordered state, causing the product to shrink. This characteristic is widely used in PET heat-shrink labels, but it may lead to container deformation or even rupture when holding hot beverages.
2.3 Effects of High Temperature on the Chemical Properties of Materials
High temperature not only affects the physical properties of plastic materials, but more importantly, it can trigger complex chemical changes. For PP material, oxidative degradation reactions occur under high-temperature conditions. High temperature accelerates PP oxidation, producing free radicals and low-molecular-weight byproducts, leading to material aging and surface corrosion. If the temperature remains too high, it may lead to complete decomposition, generating harmful small molecular compounds.
After prolonged heating at high temperatures, the molecular chains of PP material will break down, producing low-molecular-weight degradation products. These degradation products may include volatile organic compounds, small molecular hydrocarbons, etc., some of which may have adverse effects on human health. Studies have shown that PP decomposes into propylene monomers at temperatures exceeding 150℃. Although PP itself is heat-resistant and non-toxic, when used at temperatures exceeding 140℃ for extended periods, additives (such as certain plasticizers or colorants) may release harmful substances.
For PET material, the chemical changes at high temperatures are even more complex. The thermal degradation mechanism of PET is primarily molecular heterolysis, i.e., the molecule breaks in the middle, taking away an electron. Due to the nucleophilic effect of the carbonyl oxygen on the hydrogen atom at the β-position, coupled with the polarity of the bond connecting the α-carbon atom to the ester oxygen and the attraction of the positively charged carbonyl carbon, a change in the electron cloud distribution in the molecule occurs, leading to the cleavage of the hydrogen at the β-carbon atom.
At lower temperatures (usually below 200℃), PET molecular chains mainly degrade through main chain scission. The chain reaction causes the PET molecular chains to gradually break down, ultimately producing terephthalic acid (TPA) and ethylene glycol (EG). Under high-temperature conditions (>1600K), the thermal degradation mechanism shifts to a free radical-dominated process, where EG is cleaved into formaldehyde or acetaldehyde, leading to the formation of small gaseous molecules.
The influence of temperature on the molecular chain scission process is highly sensitive. Studies show that at 1400K, long PET chains (initially 100 monomers) degrade slowly, maintaining high molecular weight fragments; while at 1800-2000K, the chain length drops sharply within 200 ps, accelerating fragmentation. This finding indicates that small changes in temperature can lead to a dramatic deterioration of PET material properties.
After prolonged heating at high temperatures, the molecular chains of PP material will break down, producing low-molecular-weight degradation products. These degradation products may include volatile organic compounds, small molecular hydrocarbons, etc., some of which may have adverse effects on human health. Studies have shown that PP decomposes into propylene monomers at temperatures exceeding 150℃. Although PP itself is heat-resistant and non-toxic, when used at temperatures exceeding 140℃ for extended periods, additives (such as certain plasticizers or colorants) may release harmful substances.
For PET material, the chemical changes at high temperatures are even more complex. The thermal degradation mechanism of PET is primarily molecular heterolysis, i.e., the molecule breaks in the middle, taking away an electron. Due to the nucleophilic effect of the carbonyl oxygen on the hydrogen atom at the β-position, coupled with the polarity of the bond connecting the α-carbon atom to the ester oxygen and the attraction of the positively charged carbonyl carbon, a change in the electron cloud distribution in the molecule occurs, leading to the cleavage of the hydrogen at the β-carbon atom.
At lower temperatures (usually below 200℃), PET molecular chains mainly degrade through main chain scission. The chain reaction causes the PET molecular chains to gradually break down, ultimately producing terephthalic acid (TPA) and ethylene glycol (EG). Under high-temperature conditions (>1600K), the thermal degradation mechanism shifts to a free radical-dominated process, where EG is cleaved into formaldehyde or acetaldehyde, leading to the formation of small gaseous molecules.
The influence of temperature on the molecular chain scission process is highly sensitive. Studies show that at 1400K, long PET chains (initially 100 monomers) degrade slowly, maintaining high molecular weight fragments; while at 1800-2000K, the chain length drops sharply within 200 ps, accelerating fragmentation. This finding indicates that small changes in temperature can lead to a dramatic deterioration of PET material properties.
2.4 Temperature Dependence of Additive Migration Behavior
The migration behavior of additives in plastic materials under high-temperature conditions is an important factor affecting food safety. Studies have shown that temperature has a significant promoting effect on additive migration. When the temperature is increased from room temperature to 40℃, the migration amount of antioxidants increases by about 50%; further increasing to 60℃, this proportion rises to over 70%.
For PP materials, high temperature accelerates molecular motion, and high humidity increases the swelling degree of polypropylene and provides more reaction medium. The combined effect of both greatly promotes the migration of antioxidants. In an environment with a temperature of 40℃ and a humidity of 85%, the migration amount of antioxidants is several times higher than under normal temperature and humidity conditions, and the migration rate is also significantly faster.
Plasticizers are another important class of additives, and their migration behavior is also significantly affected by temperature. Plasticizers have a weak binding force with polymers, and as temperature increases, molecular motion intensifies, making them easily migrate out of the plastic. Phthalate plasticizers are prone to migrating into food at high temperatures, and long-term ingestion may have adverse effects on human health.
For PET materials, substance migration at high temperatures mainly involves substances such as acetaldehyde and antimony. PET materials may release trace amounts of antimony at high temperatures, which is a residue of the catalyst used in the PET production process. Studies have found that when PET plastic bottles were filled with 4% acetic acid, 10% ethanol, and 20% ethanol, respectively, the migration amount of the harmful substance antimony in the bottle containing acetic acid was significantly higher than in the other two. This indicates that the properties of the food simulant also affect the migration behavior of substances.
The Arrhenius equation model shows that for every 10℃ increase in temperature, the migration rate increases by 2.3 times, and a decrease of 1 pH unit accelerates antimony release by 40%. This finding provides a quantitative basis for evaluating the safety of plastic materials under high-temperature conditions and also reminds consumers to pay special attention to temperature control when using plastic containers.
For PP materials, high temperature accelerates molecular motion, and high humidity increases the swelling degree of polypropylene and provides more reaction medium. The combined effect of both greatly promotes the migration of antioxidants. In an environment with a temperature of 40℃ and a humidity of 85%, the migration amount of antioxidants is several times higher than under normal temperature and humidity conditions, and the migration rate is also significantly faster.
Plasticizers are another important class of additives, and their migration behavior is also significantly affected by temperature. Plasticizers have a weak binding force with polymers, and as temperature increases, molecular motion intensifies, making them easily migrate out of the plastic. Phthalate plasticizers are prone to migrating into food at high temperatures, and long-term ingestion may have adverse effects on human health.
For PET materials, substance migration at high temperatures mainly involves substances such as acetaldehyde and antimony. PET materials may release trace amounts of antimony at high temperatures, which is a residue of the catalyst used in the PET production process. Studies have found that when PET plastic bottles were filled with 4% acetic acid, 10% ethanol, and 20% ethanol, respectively, the migration amount of the harmful substance antimony in the bottle containing acetic acid was significantly higher than in the other two. This indicates that the properties of the food simulant also affect the migration behavior of substances.
The Arrhenius equation model shows that for every 10℃ increase in temperature, the migration rate increases by 2.3 times, and a decrease of 1 pH unit accelerates antimony release by 40%. This finding provides a quantitative basis for evaluating the safety of plastic materials under high-temperature conditions and also reminds consumers to pay special attention to temperature control when using plastic containers.
III. Safety Assessment and Health Risk Analysis
3.1 Safety Assessment of PP Material
The safety of PP material in food contact applications has been widely recognized. According to the GB 4806.7-2016 standard, the total migration of PP material should not exceed 10 mg/dm², and the migration at 100℃ should be controlled within 8 mg/dm². This limit ensures that PP material will not pose a health hazard under normal use conditions.
Regarding specific migrating substances, the main substances that need to be controlled in PP material include heavy metals and additives. The standard stipulates that the migration of lead should not exceed 0.01 mg/kg, the migration of cadmium should not exceed 0.002 mg/kg, and the migration of formaldehyde should not exceed 15 mg/kg. These limits for heavy metals and formaldehyde reflect the strict protection of consumer health and safety.
Additive migration is an important aspect of PP material safety assessment. The migration of the antioxidant BHT (butylated hydroxytoluene) should not exceed 0.05-0.5 mg/kg, and the migration of the plasticizer DEHP (di(2-ethylhexyl) phthalate) should not exceed 0.3 mg/kg. Although these additives do not pose a health hazard under normal use conditions, they may migrate under high temperature or prolonged contact conditions, so their migration levels need to be strictly controlled.
A study by a European research institution showed that the crystallinity of PP plastic disposable cups changes significantly after preheating at different temperatures, which in turn affects the migration behavior of additives. The study found that after preheating at 70℃ for 2 hours, the migration of additives such as 1-palmitoylglycerol, FCM No. 500, and FCM No. 808 increased with the extension of preheating time. This finding suggests that even heat-resistant materials like PP still require attention to the risk of additive migration under high-temperature conditions.
It is particularly important to note that although PP itself is heat-resistant and non-toxic, if the processing temperature far exceeds its tolerance range (e.g., consistently above 140℃), additives (such as certain plasticizers or colorants) may release harmful substances (such as bisphenol A analogs). Therefore, when using PP containers for hot beverages, prolonged contact with liquids exceeding 120℃ should be avoided.
Regarding specific migrating substances, the main substances that need to be controlled in PP material include heavy metals and additives. The standard stipulates that the migration of lead should not exceed 0.01 mg/kg, the migration of cadmium should not exceed 0.002 mg/kg, and the migration of formaldehyde should not exceed 15 mg/kg. These limits for heavy metals and formaldehyde reflect the strict protection of consumer health and safety.
Additive migration is an important aspect of PP material safety assessment. The migration of the antioxidant BHT (butylated hydroxytoluene) should not exceed 0.05-0.5 mg/kg, and the migration of the plasticizer DEHP (di(2-ethylhexyl) phthalate) should not exceed 0.3 mg/kg. Although these additives do not pose a health hazard under normal use conditions, they may migrate under high temperature or prolonged contact conditions, so their migration levels need to be strictly controlled.
A study by a European research institution showed that the crystallinity of PP plastic disposable cups changes significantly after preheating at different temperatures, which in turn affects the migration behavior of additives. The study found that after preheating at 70℃ for 2 hours, the migration of additives such as 1-palmitoylglycerol, FCM No. 500, and FCM No. 808 increased with the extension of preheating time. This finding suggests that even heat-resistant materials like PP still require attention to the risk of additive migration under high-temperature conditions.
It is particularly important to note that although PP itself is heat-resistant and non-toxic, if the processing temperature far exceeds its tolerance range (e.g., consistently above 140℃), additives (such as certain plasticizers or colorants) may release harmful substances (such as bisphenol A analogs). Therefore, when using PP containers for hot beverages, prolonged contact with liquids exceeding 120℃ should be avoided.
3.2 Safety Assessment of PET Material
The safety assessment of PET material is more complex, mainly involving the various harmful substances it may release at high temperatures. According to national standards, the key substances that need to be controlled in PET materials include acetaldehyde, antimony, terephthalic acid, and ethylene glycol.
Acetaldehyde is one of the main substances released from PET materials at high temperatures. The standard stipulates that the migration amount of acetaldehyde shall not exceed 50 μg/L. Acetaldehyde has an irritating odor, and high-concentration ingestion may have adverse effects on the human body. Studies have shown that PET bottles easily decompose and release trace amounts of acetaldehyde under high temperatures or sunlight exposure, and long-term accumulation may increase the risk of cancer.
Antimony is a catalyst used in the production of PET and is biologically toxic. The GB 4806.7-2016 standard clearly stipulates that the migration amount of antimony in PET beverage bottles shall not exceed 0.05 mg/L. Antimony can enter the human body through the skin, digestive tract, etc., causing damage to tissues and organs such as the skin, heart, liver, and kidneys. Studies have found that at 60℃ and when migration equilibrium is reached, the migration amount of antimony from recycled PET (rPET) chips to different food simulants is increased compared to original PET beverage bottles.
Terephthalic acid and ethylene glycol are constituent units of the PET molecular chain and are released when degraded at high temperatures. The standard stipulates that the migration amount of terephthalic acid shall not exceed 7.5-30 mg/kg, and the migration amount of ethylene glycol shall not exceed 10-30 mg/kg. These substances may have irritating effects on the human body at high concentrations.
The safety of PET material is also closely related to its usage conditions. Studies have shown that PET materials may release trace amounts of antimony at high temperatures, while PP materials, after prolonged heating at high temperatures, undergo molecular chain breakage, producing low-molecular-weight degradation products. As long as the PET plastic products on the market comply with national standards and are stored under appropriate conditions and for appropriate periods, the migration amount of harmful substances will be lower than the standard amount and will not pose a health risk to the human body. However, if reused repeatedly, or if the contents are changed, or if stored under unsuitable conditions, the otherwise safe plastic bottles may become unsafe.
Acetaldehyde is one of the main substances released from PET materials at high temperatures. The standard stipulates that the migration amount of acetaldehyde shall not exceed 50 μg/L. Acetaldehyde has an irritating odor, and high-concentration ingestion may have adverse effects on the human body. Studies have shown that PET bottles easily decompose and release trace amounts of acetaldehyde under high temperatures or sunlight exposure, and long-term accumulation may increase the risk of cancer.
Antimony is a catalyst used in the production of PET and is biologically toxic. The GB 4806.7-2016 standard clearly stipulates that the migration amount of antimony in PET beverage bottles shall not exceed 0.05 mg/L. Antimony can enter the human body through the skin, digestive tract, etc., causing damage to tissues and organs such as the skin, heart, liver, and kidneys. Studies have found that at 60℃ and when migration equilibrium is reached, the migration amount of antimony from recycled PET (rPET) chips to different food simulants is increased compared to original PET beverage bottles.
Terephthalic acid and ethylene glycol are constituent units of the PET molecular chain and are released when degraded at high temperatures. The standard stipulates that the migration amount of terephthalic acid shall not exceed 7.5-30 mg/kg, and the migration amount of ethylene glycol shall not exceed 10-30 mg/kg. These substances may have irritating effects on the human body at high concentrations.
The safety of PET material is also closely related to its usage conditions. Studies have shown that PET materials may release trace amounts of antimony at high temperatures, while PP materials, after prolonged heating at high temperatures, undergo molecular chain breakage, producing low-molecular-weight degradation products. As long as the PET plastic products on the market comply with national standards and are stored under appropriate conditions and for appropriate periods, the migration amount of harmful substances will be lower than the standard amount and will not pose a health risk to the human body. However, if reused repeatedly, or if the contents are changed, or if stored under unsuitable conditions, the otherwise safe plastic bottles may become unsafe.
3.3 Health Risk Assessment of Long-Term Use
The health risks associated with the long-term use of disposable clear plastic cups are a major concern for consumers. Studies show that prolonged exposure to disposable plastic products can alter gut microbiota, trigger inflammatory responses and oxidative stress, leading to myocardial damage and cardiovascular disease. Endocrine-disrupting chemicals commonly found in plastic products, such as bisphenol A (BPA) and phthalates (PAEs), can also disrupt hormonal balance and affect cardiovascular health.
Animal experiments provide more direct evidence. Studies have found that leachates from plastic exposed to hot water caused significant pathological damage to the myocardial tissue of rats and increased inflammatory responses. Although there are currently no clear safety intake standards, animal experiments suggest that long-term low-dose exposure may lead to metabolic disorders, organ damage, and inflammation.
The health risks of microplastics and nanoplastics should also not be ignored. Studies show that microplastics and nanoplastics invading carotid artery tissue increase the risk of heart disease, stroke, and death. These tiny particles may cross the blood-brain barrier, inducing brain inflammation; damage the intestinal mucosa, leading to microbial imbalance and digestive disorders; and long-term exposure may cause immune dysfunction, increasing the risk of autoimmune diseases.
For PET materials, the risks of long-term repeated use are even more pronounced. PET bottles are designed for single use, and repeated use may lead to wear or scratches, increasing the risk of bacterial growth or material degradation. Studies have found that PET plastic bottles may release the carcinogen DEHP after 10 months of use. This finding suggests that consumers should strictly follow the instructions for use and avoid long-term repeated use of disposable clear plastic cups made of PET material.
Animal experiments provide more direct evidence. Studies have found that leachates from plastic exposed to hot water caused significant pathological damage to the myocardial tissue of rats and increased inflammatory responses. Although there are currently no clear safety intake standards, animal experiments suggest that long-term low-dose exposure may lead to metabolic disorders, organ damage, and inflammation.
The health risks of microplastics and nanoplastics should also not be ignored. Studies show that microplastics and nanoplastics invading carotid artery tissue increase the risk of heart disease, stroke, and death. These tiny particles may cross the blood-brain barrier, inducing brain inflammation; damage the intestinal mucosa, leading to microbial imbalance and digestive disorders; and long-term exposure may cause immune dysfunction, increasing the risk of autoimmune diseases.
For PET materials, the risks of long-term repeated use are even more pronounced. PET bottles are designed for single use, and repeated use may lead to wear or scratches, increasing the risk of bacterial growth or material degradation. Studies have found that PET plastic bottles may release the carcinogen DEHP after 10 months of use. This finding suggests that consumers should strictly follow the instructions for use and avoid long-term repeated use of disposable clear plastic cups made of PET material.
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