People's Daily: PX toxicity is lower than salt and lower than alcohol

This is not the first time the PX project has been boycotted. In June 2007, the Xiamen PX project, the August 2011 Dalian PX project, and the October 2012 Ningbo PX project were all suspended in public protests.

What exactly is the PX project? Why is this new material project that is booming in the world become a “crossing street mouse” in China? Let us uncover the mystery of PX.

What is PX?

According to international standards, PX is not a dangerous chemical, and it is a "possible carcinogen" with the coffee we drink.

People are opposed to the PX project, and even talk about the root cause of PX color change. It is believed that the PX project not only causes environmental pollution, but also PX itself has strong carcinogenicity and seriously endangers people's health.

In fact, PX is not so "devil"! Lv Dapeng, a current Sinopec spokesperson who has been engaged in PX production for a long time, explained that PX is an abbreviation for para-xylene. The Chinese literary name "p-xylene" is a liquid compound, colorless, transparent, odorous aromatic compound that tastes. Even a little sweet.

According to the Globally Harmonized System of Classification and Labelling of Chemicals and the List of Hazardous Chemicals, PX is not considered a hazardous chemical in many countries, such as the United States and Australia. The data show that PX is not a high-risk or high-toxic product, regardless of hazard markers, health hazards, toxicological data, or occupational disaster protection standards. In the EU, PX is also only classified as hazardous.

Why do we be so scared of a seemingly mild chemical? One of the main reasons is the "benzene" in PX. According to the International Agency for Research on Cancer (IARC), benzene is a class of carcinogenic chemicals. The meaning of a class of carcinogens is that there is sufficient evidence of carcinogenicity in humans.

However, IARC's assertion of PX is indeed the third of five gradient classifications - possibly carcinogenic. The institution may be carcinogenic because of limited evidence of carcinogenicity in humans, insufficient evidence of carcinogenicity in experimental animals, or insufficient evidence of carcinogenicity in humans, and evidence of carcinogenicity in experimental animals.

The IARC's assessment of the risk of human cancer caused by chemical substances is currently recognized as authoritative data. Interestingly, in the details of its five types of carcinogens, the name "coffee" appeared in 1991, and it belongs to the third category with our "deeply hated" PX.

Although there is no evidence of carcinogenicity in the human body, Gu Zongqin, president of the Petroleum and Chemical Planning Institute, admitted that this does not mean that PX is completely non-toxic. It is characterized by four words, low toxicity and flammability. Relevant medical data also show that the body absorbs excessive PX, which will cause irritation to the eyes and upper respiratory tract. Prolonged exposure to PX may also cause headaches, irritability, depression, insomnia, fatigue and other symptoms. In severe cases, it may cause short-term memory impairment. An experiment in the United States has shown that PX can have a certain impact on the fetus. Therefore, experts recommend that pregnant women or lactating women should minimize exposure to PX, just as they should minimize exposure to alcohol, tobacco and other drugs.

Speaking of low toxicity, experts on research toxicity tell us about such a profession, academically defining the toxicity of a substance, usually described by a half-lethal dose. Experiments have shown that the median lethal dose of oral salt in rats is 3000 mg/kg, PX is 3523 mg/kg, and alcohol is 7060 mg/kg. The simple expression of the half-lethal dose of the three is: salt <PX < alcohol.

The conclusions of rigorous scientific experiments and authoritative institutions that PX is a low-toxic chemical substance are clearly not accepted by more Chinese people. "Because of various misunderstandings, many people have regarded the PX project as a beast," said Li Runsheng, vice president of the China Petroleum and Chemical Industry Federation.

What can PX do?

PX solves the problem of natural fiber and food competition, and is also a necessity to improve the quality of gasoline.

However, the PX project is not only a savage beast, but, like modern society, it is inseparable from gasoline. We can't do without PX. It has become a part of our lives.

Li Runsheng said that as a basic chemical product, PX has become an indispensable element in people's lives, and it is integrated into the daily life of people. At present, most of the more than 30 million tons of PX produced worldwide are the raw materials for polyester fiber. A large number of polyester fibers are processed into garments, which not only meet the dressing problems of more than 6 billion people around the world, but also meet people's requirements for color, gloss, wrinkles, thickness and transparency.

In a sense, PX solves the problem of natural fiber and food disputes. China is a country with a large population and relatively scarce arable land resources. Each 10,000 tons of synthetic fiber is equivalent to the natural textile fiber produced by 70,000 mu of cultivated land. In 2012, China produced about 28 million tons of synthetic fiber. If you produce the same amount of natural fiber, you need nearly 200 million acres of cultivated land.

PX is not only related to people's clothing, it is also a direct entry, such as pharmaceutical capsules, PX is one of the raw materials. The main raw material for packaging materials such as mineral water bottles is also PX.

PX is also closely related to people's lives. It is the raw material for many building materials and can also be used to produce paint solvents. With the advancement of technology, PX's downstream product PET is increasingly replacing aluminum, glass, ceramics and paper for the electrical, electronics, automotive and machinery manufacturing industries.

China is entering the automotive society, and about 5% of gasoline is PX. PX is not only an important part of gasoline, but also a necessity for producing high quality gasoline.

Many cities in China are now suffering from PM2.5. One of the important ways to reduce urban haze is to speed up the upgrading of gasoline quality, reduce the sulfur content in gasoline, and increase the octane number in gasoline. From the current technology, the best and most environmentally friendly way to increase the octane number of gasoline is to add aromatics. Benzene is preferred if toxicity and carcinogenicity are not considered. Now, PX is the best choice. Some experts predict that the content of PX in gasoline will account for more in the future.

In view of the wide application of PX, China's demand for PX is gradually increasing in the rapid development of industrialization and urbanization.

Looking back at history, China's PX development has gone through three stages: before 2000, development was relatively slow, but the relationship between supply and demand was relatively balanced. In 2000, the domestic self-sufficiency rate was 88%. From 2000 to 2010, China's PX project developed rapidly and production capacity. It has become the world's number one; since 2010, domestic market demand has continued to rise, while PX construction has slowed down and capacity has not been able to meet demand.

According to statistics, in 2012, China's actual demand for PX was 13.85 million tons, which has become the world's largest consumer of PX, accounting for 32% of global consumption, but China's total PX production capacity is only 8.8 million tons, and the self-sufficiency rate is only 63%. .

Zhang Kehua, vice chairman of Sinopec Refining & Chemical Engineering Co., Ltd. pointed out that in recent years, domestic PX production capacity has expanded at a rate of about 10% per year. In 2011, it expanded by 1 million tons. In 2012, it expanded by 2.9 million tons, still unable to meet the current domestic demand.

Some experts predict that if the current PX project is suspended or slowed down, it is expected that the domestic PX self-sufficiency rate will fall below 50% by 2015.

The raw materials are subject to people, leading to the overall advancement of the profit of the chemical fiber industry chain, and more to the PX link. In other words, overseas raw material suppliers have gained more benefits, and the national manufacturing industry has been squeezed. Zhang Kehua pointed out that Japan, South Korea and other countries export PX products to China, which is much higher than domestic materials. All product prices related to PX will be passed to the terminal and eventually passed on to consumers.

Why are foreigners not afraid of PX?

In countries such as Japan, South Korea and Singapore, due to mature and strict environmental risk management, the PX project is close to residential areas.

Just as the domestic PX construction project slowed down and some were even permanently cancelled, the PX projects in Japan and South Korea were in full swing and became China's main importers.

South Korea is the largest PX producer in Asia with an annual production capacity of 5.84 million tons and an export volume of nearly 1.5 million tons. S-OIL is one of the three most important petrochemical companies in Korea, with an annual output of 1.7 million tons of PX and 700,000 tons exported to China. Last year, the company's largest single-unit PX unit built in Ulsan has been officially put into production, with a capacity equivalent to 3.2 billion sets of clothing per year.

As another major PX producer, Japan has an annual production capacity of more than 4 million tons, and half of it is exported abroad. In November last year, Japan JX Energy Co., Ltd. and South Korea SK cooperated to establish a large-scale PX production plant, which is expected to reach 1 million tons per year after it is put into production.

Singapore has made PX one of its pillar industries and has continued to increase its development. Singapore's Jurong Chemical Zone, which is built by reclamation, is Asia's largest petrochemical production and logistics base and the third largest petroleum refining base in the world. In 2012, a PX project with an annual output of 800,000 tons was introduced here.

Many Chinese PX opponents claim that the PX project is at least 100 kilometers away from the residential area and that it is an international standard or an international regulation. But in Singapore, the PX unit is only 900 meters away from the residential area. In Houston, USA, the PX unit is 1.2 km from the city. In many countries around the world, PX projects are not far from residential areas. Japan's Yokohama NPRC refinery 350,000 tons / year PX installation, separated from residential areas by only one expressway.

These foreign PX projects can coexist harmoniously with the public, mainly due to mature and strict environmental risk management.

Foreign chemical companies are willing to invest heavily to ensure the maximum elimination of the negative impact of PX production. For example, South Korea's Samsung Total has set a safety management standard that is six times higher than the government's regulations: double redundant settings on circuits and waterways; 10 times enhanced treatment for harmful gases; third-party companies to detect exhaust gases To make the data more credible; to conduct 8 safety trainings for new employees every year, the old employees have 1-2 safety drills each year; each factory has its own fire brigade; for natural disasters such as lightning strikes and tsunami.

At the same time, companies that produce PX are as transparent as possible and eliminate the insecurities of the people. In Korea, people can view safety production information at any time through the company's homepage. In Singapore, the government also plays an important role in communicating with the community and residents.

More importantly, the PX project is a basic chemical project. Controlling the environmental damage risk of the PX project is already a relatively mature technology in the global industry. “We didn’t think of the PX project as a very dangerous thing.” Shijing Junzhao, deputy director of the Social and Environmental Security Department of Japan’s JX Energy, said that PX’s safety management is not specific to other products in the petrochemical industry chain.

PX is an ordinary chemical product in foreign countries. It can also become an ordinary chemical product like gasoline and diesel in China. Wang Yubing, the current general manager of Sinopec Hainan Refining and Chemical Company, who has worked in the PX production workshop for many years, said that the existing PX installations in China, especially the PX projects developed in recent years, generally have a high level of technology and modern management of large installations. The level is also greatly improved. What's more gratifying is that in recent years, China has made breakthroughs in the core technology of PX production, and it has become the third country to master the core technology after the United States and France. Therefore, China can achieve foreign standards in PX production and achieve safety. Harm production.

The facts tell us that the PX project or other heavy chemical projects are not a problem of building or not, but how to build and how to operate. Relying on technology and management, heavy chemical projects can also be built into environmentally friendly enterprises. For example, in Maoming City, where the Sinopec Maoming Petrochemical Company is located, air quality has not been destroyed by huge petrochemical projects. Instead, it has remained at the first level and is one of the best air quality cities in the country. For example, the Chinese oil Guangxi Petrochemical in the Beibu Gulf, which has been in production for nearly three years, has not only reduced or increased the number of white dolphins in the vicinity of environmentalists who are most worried about water quality.

It is a fact that China needs PX. It is also true that residents do not fully understand PX and do not believe that PX projects can be managed and opposed to PX. These frequent "PX disputes" provide a new opportunity for the government, enterprises and the public to rationally explore the development of Chinese-style heavy chemical industry. The primary question is how the government and enterprises can invite people to participate in the construction and management of PX in a more open manner.

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