In recent years, "white pollution" has become increasingly serious, which has aroused great concern and strong response from the society. The "white pollution" along the railway, tourist attractions, rivers and lakes, and the urban-rural fringe of large and medium-sized cities has attracted the attention of governments and people at all levels, as well as the leadership of the Central the State Council, demanding that it be treated as soon as possible.
In this regard, China's plastic processing industry and packaging industry, as the main departments of polystyrene foamed tableware production, also attach great importance to it. They all take a positive attitude and scientific and technological progress as the starting point, and strengthen the research on recycling technology and degradable technology to reduce or alleviate the environmental pollution caused by their wastes.
In the past year, the seriousness of the problem of polystyrene foamed tableware has been escalating, from being initially accused of "white pollution" to being more serious than "nuclear accident or oil spill" (at the inaugural meeting of the national leading group for the replacement of convenient food packaging at the end of last year, Beijing XXX Company put forward in the preface of the green publicity materials distributed at the meeting: "The biggest man-made environmental disaster at the end of this century is not the explosion of Chernobyl nuclear power plant, nor the oil spill caused by the Gulf War, but only one." Later, when the environmental disaster was upgraded to above 65℃, dioxin, a strong carcinogen, was released and contained many harmful toxins. Recently, someone claimed that "people used to think that the purpose of banning disposable foamed plastic tableware was to protect the environment." According to the latest research by experts, foam plastics will also produce toxic substances at high temperature, and "banning white" is actually "drug control". There should be sufficient scientific basis for the characterization of toxic substances in polystyrene foamed tableware. I don't know who the latest research expert is, and whether his research results have been recognized by the World Health Organization and taken as a conclusion. If it really belongs to toxic substances, the problem will be much simpler. The national health department explicitly prohibits carcinogens or substances harmful to human health. In addition, polystyrene foamed tableware has been popular at home and abroad for more than 30 years, and the World Health Organization will not turn a deaf ear to such an important issue related to people's health. According to relevant data, the output of polystyrene tableware in the world is still increasing.
In recent years, some people have repeatedly incited this kind of wrong information in some conferences and news media. Small polystyrene foamed tableware has caused so many problems that it is worth pondering.
Regarding the problem of foamed polystyrene tableware and dioxin, a report "Farewell to foamed polystyrene tableware" was published in XX newspaper last year, which caused a great shock. For this reason, we have consulted a lot of information and made clarification and correct public opinion reports after consulting relevant experts, but some people still continue to spread this wrong news. At the first seminar on the prevention and control of "white pollution" held in Shanghai at the end of July this year, some people continued to spread the wrong message that polystyrene foamed tableware would release dioxins. After being refuted by the participants, I indignantly went online to find the so-called basis. These pages of photocopied materials are their foundation. In this data, the sources of dioxins in Germany, the United States, the Netherlands, Sweden and Japan were 0.9~5.8gTEQ/y, 4~6gTEQ/y and 3gTEQ/y, respectively, but polystyrene foamed tableware was not mentioned in the data. Recently, Professor Chen from Peking University and University of Chemical Technology made a detailed analysis of the formation conditions and mechanism of dioxins, and made it clear that polystyrene foamed tableware would not produce dioxins.
I mainly analyze whether the production process and use of polystyrene foamed tableware will produce or be contaminated by dioxin, and talk about my personal understanding of the problem of polystyrene containing harmful substances.
Possibility analysis of dioxin production or pollution in the production and use of polystyrene foamed tableware
1. Composition of raw materials
The main raw materials of polystyrene foamed tableware are polystyrene, talcum powder, calcium stearate, butane and so on.
Polystyrene: Its production process is that monomer styrene is polymerized in a sealed reaction kettle under the action of catalyst at high temperature and high pressure. Although styrene is an aromatic compound, its reaction is carried out under sealed oxygen-free conditions, and there is no condition to produce dioxins, which meets the food hygiene and requirements.
Talcum powder: it is an inorganic mineral (magnesium silicate containing crystal water), and its dosage is about 1%, which acts as a nucleating agent and is of medical grade.
Calcium stearate: saturated fatty acid salt, the dosage is about 1%, which acts as a lubricant and is medical grade.
Butane: saturated hydrocarbon, foaming agent. In the past, some production lines used freon as foaming agent. In order to protect the atmospheric ozone layer, with the assistance of the United Nations Multilateral Fund, butane foaming agent was completely used.
2. Process flow
The production process of polystyrene foamed tableware is a physical mixing process. Talcum powder is mainly used to absorb heat without chemical reaction: butane foaming agent is coated in molten polystyrene resin and expands into bubbles.
3. The process of transportation, storage and use of polystyrene foamed tableware
Styrofoam tableware is a container that comes into direct contact with food. Its hygiene conforms to the national standard GB131191,and there are strict requirements for its packaging, storage and transportation. After the tableware is formed, it will be packed in PE plastic film bags and then packed in cartons, which will not be in contact with the external environment, even if there is a trace of chlorine-containing gas in the air, it will not be polluted. The use process is to open the bag when using, and the temperature should not exceed 100℃ when filling hot rice.
According to Professor Chen and many materials, the possible sources of dioxins are: (1) formed as trace impurities in chlorinated aromatic products, such as PCBs and sodium chlorite; (2) It is generated during thermal reaction. When the banned substances contain petroleum products such as cellulose and coal, they contain inorganic chlorine at 300℃, which is easy to generate dioxins. Styrofoam tableware does not contain chlorine, nor does it have a high temperature of several hundred degrees, and it does not have the conditions for dioxin production.
According to the analysis of the above links, it can be concluded that polystyrene foamed tableware will not be polluted by substances that produce dioxins during production and use.
4. The problem that polystyrene foamed tableware contains toxic substances.
On this issue, four people, including Nozichikawa Village of Japan National Institute of Medical Devices and Food Hygiene, published a paper entitled "Styrene oligomer in food polystyrene products" at the Japan Health Association held on May 1998, saying that 25 kinds of polystyrene food packaging containers were widely collected in this study, including disposable water cups, vegetable trays, instant noodle bowls, soup bowls and so on. Taking the substances contained in food as solvent, the simulated dissolution test shows that these products contain dissolved oligomers: the average extraction amount of styrene dimer is 380μg/g, and the dimer is 9 1 20μ g/g. Mr. Kawamura did not mention the toxic amount of dimer and dimer in this article, but in1April, 1998. Although we don't know how seriously these substances damage hormone secretion, we must pay attention to the content of harmful substances in packaging containers that are in direct contact with imported food. " This shows that although harmful substances such as styrene dimer and trimer have been detected from Mr. Kawamura's experiment, their toxic content is still a problem to be determined.
However, after Tokyo News published a paper, 1998 once aroused the fear of polystyrene foamed tableware in Japan and South Korea. It is reported that the sales of instant noodles in Korea/KOOC-0/998 decreased by 30-40% in the second quarter, and that in Japan/KOOC-0/99 decreased by/KOOC-0/5% in the first quarter. After that, due to the foaming of polystyrene and the intensified publicity, explanation and continuous announcement of tableware manufacturers, the public's fear gradually disappeared. South Korea 1998' s sales of instant noodles rebounded by 20~30% in the third quarter, and now it has resumed normal production and sales. In addition, European organizations tested 23 brands of polystyrene containers, and the United States also studied and tested 7 samples, and found no problems.
My personal view on this issue is that, with the development of science and technology, it is right to trace some harmful substances that may lead to poisoning based on the responsibility for people's health. As we all know, many chemicals contain a certain amount, which will dissolve some harmful substances under certain conditions, which is not surprising. The question is how much of these substances constitute toxicity, or how much they accumulate will endanger human health. There should be a quantity standard, but there is no certain content standard. It is unscientific to judge all substances as containing some harmful components or substances that may affect people's health after excessive use. If so, we are exposed to too many toxic substances in our daily life. Long-term heavy drinking may cause fatty liver, liver cirrhosis, liver cancer and other physical diseases, and binge drinking may lead to alcoholism. As the saying goes, it is a three-point poison. Normal use can cure diseases, and excessive use can lead to poisoning and even death; So are alcohol and drugs also toxic substances? The knife cuts bread and fingers. Eating too much food can even kill people. So whether any substance contains poison or not should have a standard concept.
At present, the polystyrene detected in Japan will dissolve dimer and trimer under certain conditions, but how much toxicity it will have has not been determined, and the United Nations Health Organization has not stipulated it. Follow-up study is appropriate, but it is unreasonable to make a fuss or even attack it. In addition, measures have been taken at home and abroad to avoid direct contact with food through coating.