In daily life, people like to pack rice cakes and rice flowers in plastic bags ... but we must understand that there are two kinds of plastic bags used in the market; Some are made of PVC, polystyrene and melamine plastic. When this chemical raw material is used to make membranes, additives are often added. Additives contain a variety of harmful substances, so this bag can't hold food. The chemical raw materials of plastic film used as food bag are polyethylene and polypropylene, which are non-toxic.
How to identify whether plastic bags are toxic or non-toxic?
First, put plastic bags at the bottom of the water. Because of the different specific gravity, polyethylene and polypropylene are non-toxic when floating on the water surface, while PVC and polystyrene are toxic when sinking into the water;
Secondly, from the appearance, polyethylene and polypropylene are relatively soft and basically transparent, but polyethylene is milky white and polypropylene is white; Plastic bags made of PVC are slightly yellow, less flexible than polyethylene and polypropylene, and taste slightly like plasticizers;
Third, non-toxic raw materials, polypropylene and polyethylene, have a sense of lubrication when touched by hand, and the surface looks like wax, which is flammable in case of fire. If used, it drips like candle oil, with yellow flame and paraffin smell. This canned food; For example, plastic bags made of toxic raw materials such as PVC, polystyrene and melamine are sticky by hand, and are not easy to burn. They go out immediately after leaving the fire, and the flame is green and has a choking smell, so it cannot be used to hold rice, food and so on.
Nowadays, plastic bags have replaced the previous Chinese cabbage seeds and have a wide range of applications, especially plastic bags for packaging food, which should attract our attention. Plastic bags are generally made of two kinds of plastic films: one is made of polyethylene, polypropylene and concentrated ammonia water; The other is made of polyvinyl chloride. The former is non-toxic; The latter is poisonous and cannot be used to package food.
The toxicity of plastic bags can be identified by the following simple methods:
Put the plastic bag into the water by water detection method, and the non-toxic plastic bag can float out of the water when it is put into the water; Toxic plastic bags will not float.
Hand-touch detection method is non-toxic if you touch the plastic bag with your hand. Otherwise, it is toxic.
Jitter detection method: grab one end of the plastic bag by hand and stir vigorously. What makes a crisp sound is non-toxic. On the contrary, it is toxic.
Fire detection method can cut off one side of plastic bag and burn it with fire, which is toxic and not easy to burn; Non-toxic, easy to burn in case of fire.
Water-soluble nontoxic plastic film
Water-soluble fully degradable nontoxic plastic film and its production technology are high-tech to completely eliminate "white pollution". It uses polymer materials, carbohydrates, modifiers and so on. Through special technology and method, water-soluble controllable fully degradable plastics are made. At present, it has obtained the national invention patent with the patent number of ZL96 10568.78, which has been highly valued by leading departments at all levels in the country. The plastic film produced by this patented technology and special equipment not only has the characteristics of ordinary plastics and starch plastics, but also has the main characteristics of controllable total degradation through different ways after use. Ordinary plastics are not degradable, and starch plastics can only be degraded by starch. First, it can be recycled after use, and the film can be made again after cleaning treatment, reducing the cost by nearly half; Second, it can be completely degraded in soil within a certain period of time according to the use requirements; It can be quickly dissolved in cold water and hot water respectively after use. With these three ways, the used water-soluble plastic film can be said to have nowhere to escape, which we call "water burial white pollution". In addition, according to the slogans of "vigorously developing green environmental protection industry" and "eliminating white pollution" put forward by the state to support the development of green environmental protection industry, it can also be seen that this technology conforms to the national industrial development policy. It is also an inevitable development trend that ordinary plastic products are replaced by degradable products. Degradable, pollution-free, non-toxic new environmental protection "plastic" will bring you a profit of 10 million yuan!
How to distinguish between toxic and non-toxic plastic bags? First, put plastic bags at the bottom of the water. Because of the different specific gravity, polyethylene and polypropylene are non-toxic when floating on the water surface, while PVC and polystyrene are toxic when sinking into the water; Secondly, from the appearance, polyethylene and polypropylene are relatively soft and basically transparent, but polyethylene is milky white and polypropylene is white; Plastic bags made of PVC are slightly yellow, less flexible than polyethylene and polypropylene, and taste slightly like plasticizers; Third, non-toxic raw materials, polypropylene and polyethylene, have a sense of lubrication when touched by hand, and the surface looks like wax, which is flammable in case of fire. If used, it drips like wax candle oil, with yellow flame and paraffin smell. This canned food; For example, plastic bags made of toxic raw materials such as PVC, polystyrene and melamine are sticky by hand, and are not easy to burn. They go out immediately after leaving the fire, and the flame is green and has a choking smell, so it cannot be used to hold rice, food and so on.
Quality standard of nontoxic plastic bags
Quality standard of nontoxic plastic bags
Scope of Application This standard is applicable to the inspection of non-toxic plastic bags for intermediate packaging in factories.
Material: high pressure polyethylene.
Specifications Measure the length and width of non-toxic plastic bags with a tape measure with accuracy of1mm..
The length should be 900 20 mm, the width should be 700 20 mm and the thickness should be 0.08 0.01mm.
The external surface of technical standard shall be clean and transparent, free from scratches and pinholes, mildew, unevenness or skew.
Sealing: Fill a certain amount of air into the plastic bag, tighten the mouth of the plastic bag by hand and squeeze it into the middle of the plastic bag to avoid air leakage or bursting.
The microbial limit should be ≤ 1000/100cm2 for bacteria and ≤ 100/100cm2 for molds, and Escherichia coli and live mites should not be detected.
No. B-024
Re-inspection cycle The first re-inspection cycle is 12 months, and the second re-inspection cycle is 12 months.
Composition of toxic plastic bags and its harm to the environment
Main hazards:
"White pollution" mainly refers to "visual pollution" and "potential harm" to the environment.
Effect.
"Visual pollution" refers to the plastic garbage scattered in the city and discarded by people, which is harmful to the city appearance and landscape.
The destruction of the landscape, such as a large number of polystyrene foamed plastic tableware scattered on both sides of the railway, rivers and lakes, and ultra-thin plastic bags flying all over the sky or hanging on branches, has brought people bad visual stimulation, and people have a strong reaction to it.
"Potential crisis" refers to the environmental problems caused by plastic waste entering the natural environment and being difficult to degrade.
Its hazards mainly include the following points:
Recycling is not easy, because the recycling cost is high, but the utilization rate is low, so businesses can say that it is unprofitable, and it is difficult to attract the general public to carry out "white recycling" because of the low recycling price. So it's hard to recycle.
Difficult to degrade. The recovered white waste is not easy to treat. At present, the main treatment methods are incineration and landfill. If burned, it will produce a lot of toxic smoke, pollute the atmosphere and promote the formation of acid rain. As for landfill, it will remain unchanged for 100 years and will not be absorbed by nature, which will do great harm to the land, change its pH value, affect the absorption of nutrients and water by crops, and lead to agricultural production reduction. As for plastic products discarded in water or land, it will not only affect the environment, but also cause great harm to the land. This destroys the ecological balance.
Toxic substances decompose at high temperature, and plastic products have no toxic substances. However, due to its imperfect recycling equipment and simple process, many manufacturers do not have legal business licenses. When the temperature reaches 65℃, toxic substances will precipitate and penetrate into food, causing harm to important parts of the human body such as liver, kidney, reproductive system and central nervous system.
Respondents: Black and White _ Milk Tea-Five Grades111118: 02.
"Potential crisis" refers to the environmental problems caused by the difficulty of degradation of plastic waste after it enters the natural environment.
Its hazards mainly include the following points:
Recycling is not easy, because the recycling cost is high, but the utilization rate is low, so businesses can say that it is unprofitable, and it is difficult to attract the general public to carry out "white recycling" because of the low recycling price. So it's hard to recycle.
Difficult to degrade. The recovered white waste is not easy to treat. At present, the main treatment methods are incineration and landfill. If burned, it will produce a lot of toxic smoke, pollute the atmosphere and promote the formation of acid rain. As for landfill, it will remain unchanged for 100 years and will not be absorbed by nature, which will do great harm to the land, change its pH value, affect the absorption of nutrients and water by crops, and lead to agricultural production reduction. As for plastic products discarded in water or land, it will not only affect the environment, but also cause great harm to the land. This destroys the ecological balance.
Toxic substances decompose at high temperature, and plastic products have no toxic substances. However, due to its imperfect recycling equipment and simple process, many manufacturers do not have legal business licenses. When the temperature reaches 65℃, toxic substances will precipitate and penetrate into food, causing harm to important parts of the human body such as liver, kidney, reproductive system and central nervous system.
Experts found that almost all plastic products contain a large amount of plasticizer, which is potentially harmful to human body.
"Plasticizer" (plastic bags and plastic products contain a kind of "phthalate" chemical composition, which can increase the plasticity and flexibility of plastics and improve the strength of plastic products), which triggered the safety crisis of supermarket plastic wrap last year, once again broke into people's lives. This time, the problem appeared in the plastic bucket of edible oil used by ordinary people for three meals a day.
Not long ago, Guangzhou Food Safety Information Network released a message saying that a study by Tongji University confirmed that the plasticizer in plastic barrels of edible oil was harmful to human body. "With plastic barrels of cooking oil, the cooking oil will dissolve into a plasticizer that is harmful to the human body." According to the news, the research group of Professor Li Shuguang from Tongji University School of Basic Medicine collected plastic barrels of soybean salad oil, blended oil, peanut oil and bulk soybean oil sold in the market with different brands and different factory dates. It was found that almost all brands of plastic barreled edible oil contained plasticizer "dibutyl phthalate". It is inferred that the plasticizer detected in edible oil mainly comes from plastic containers. This plasticizer is toxic to human reproductive system, especially to men.
In the past, people always thought that plasticizer compounds had low toxicity, good physical and chemical properties, convenient production and low price, so their production and use were almost unrestricted. At present, China has become a big user of plasticizers, producing about 300,000 tons of plasticizers every year.
The comparative study conducted by Professor Li shows that the plasticizer detected in edible oil mainly comes from its plastic container. Among the edible oil samples collected by the scientific research team, it was found that the content of plasticizer in a certain brand of plastic barrel edible oil samples was the highest, which were 2.98 mg/L and 24.16 mg/L, respectively. The researchers believe that this may be due to the high content of plasticizer in the plastic container of this brand, or it is polluted by plasticizer during production and processing.
At the same time, it was found that the content of phthalate plasticizers in the samples had no obvious correlation with storage time. There are many factors that affect the migration rate of plasticizer into edible oil. Besides storage time, mobility and storage temperature, there are also plastic packaging materials? Plasticizer content is related: the higher the storage temperature, the faster the migration speed; The higher the content of plasticizer in plastic, the worse the compatibility between plasticizer and resin, and the greater the percentage of plasticizer that may be dissolved out. The content of plasticizer in plastic packaging materials used for barreled edible oil produced by different manufacturers is different, and the storage temperature also changes with different environments. Therefore, the content of plasticizer in edible oil did not show an obvious trend of increasing with storage time without controlling other influencing factors. The content of plasticizer in edible oil residue accumulated on the kitchen lampblack machine is very high, which indicates that a large amount of plasticizer may be inhaled into the lungs with the lampblack during cooking.
The news also said that the researchers found that the acute toxicity of plasticizer is very low, and there will be almost no acute poisoning in a short time after human intake, but this does not mean that it is safe. On the contrary, its chronic toxicity is quite harmful to human body. The results of foreign animal research show that plasticizer can lead to animal survival rate, weight loss, liver and kidney function decline and red blood cell reduction, which is mutagenic and carcinogenic.
According to experts, PVC products containing DOP (dioctyl phthalate) plasticizer are also widely used in fields related to human medical care and life, and it is difficult to replace them with other materials. Such as latex gloves, plasma bags, some blood transfusions, transfusion, respirators, children's toys, artificial leather (used as clothing, shoes, handbags, sofa fabrics, etc. ), PVC products account for a large proportion. Some developed countries have made strict regulations or corresponding suggestions on plasticizers and other additives used in these products, while the main plasticizer for medical gloves and plasma bags in China is still DOP.
What is even more worrying is that plasticizer pollution is almost everywhere at present. As time goes on, the most commonly used raw materials in the chemical industry will slowly overflow from plastic products and enter the air, soil, water and even food. "It has a wide range of uses, a large pollution area and a large number of people, which is even more powerful than pesticides and DDT." Professor Li Shuguang pointed out that few people are aware of this at present. This is a very dangerous trend. If the relevant state departments do not give effective prevention and strong control, we will bear serious consequences for this phenomenon.
With the development of plasticizer and the increase of its application range, people pay more and more attention to its safety. Governments have begun to realize the potential threat of plasticizers to human health, such as Denmark's ban on the use of phthalate plasticizers in plastics for children's toys and care products. Because most children like to put toys in their mouths, plasticizers will endanger their health; The use of DOP in children's toys is also prohibited in Switzerland.
Although different countries have different restrictions on plasticizers, they basically follow two principles: first, limit the amount of plasticizers used in plastics; Second, limit the maximum allowable migration of food. Countries that adopt the first principle include the United States, Germany, Britain and Japan. , while the Netherlands, Italy, Spain and other countries will combine the above two principles.
According to reports, China has also formulated the Hygienic Standard for the Use of Additives for Food Containers and Packaging Materials (GB 9685-94), which stipulates the varieties, scope of application and maximum dosage of additives for food containers and packaging materials. The maximum allowable dosage of DBP (dibutyl phthalate) and DOP are 35% and 50% respectively, but the maximum allowable content in food has not yet been determined.
To this end, some experts suggest that China's food industry should vigorously advocate reducing the use of plastic packaging containers, especially to avoid direct contact between plastic products and various foods and prevent plasticizers from polluting food. At the same time, increase investment in scientific research, carry out research on the toxicity of plasticizers, carry out prospective epidemiological surveys related to human health, analyze and understand the toxicity of plasticizers from the aspects of cells, molecules and genes, develop better and safer alternative products in the polymer field, and study relevant intervention and preventive measures.