According to media reports, more than 23000 Chinese made vehicles in Australia may be recalled because their engine and exhaust pipe gaskets contain asbestos, and Australia has banned the import or use of asbestos since 2004.
What is asbestos? Asbestos is a generic term for natural fibrous siliceous mineral and the only natural mineral fiber. It is widely used because of its good tensile strength, good heat insulation and corrosion resistance, and is not easy to burn. Asbestos has a long history of application. Back in ancient Egypt, asbestos was used to make the wrappings of pharaohs. In the Zhou Dynasty, China was able to make fabrics from asbestos fibers. Because they were as white as new after being burned after being polluted, they were called Huohuan Cloth.
There are many kinds of asbestos, which can be divided into serpentine asbestos (chrysotile asbestos) and hornblende asbestos according to their mineral composition and chemical composition. Chrysotile asbestos is one of the most abundant asbestos with good spinnability. At present, chrysotile asbestos is the main asbestos produced in the world, accounting for about 95% of the world's asbestos production. Amphibole asbestos can also be divided into blue asbestos, tremolite asbestos, actinolite asbestos, etc.
At present, there are nearly 3000 kinds of asbestos products or products containing asbestos, which are mainly used in mechanical transmission, braking materials, heat preservation, fire prevention, heat insulation, anti-corrosion, sound insulation, insulation and other aspects, among which the more important ones are automobile, chemical industry, electrical equipment, construction and other industries.
Asbestos has been widely used since the 1970s due to its unique characteristics of high temperature resistance, corrosion resistance and insulation. But with the continuous expansion of the application scope, people realize that long-term contact with asbestos fibers will cause serious harm to human health, It can cause serious diseases such as asbestosis, lung cancer and pleural mesothelioma.
Asbestosis may be caused by long-term inhalation of asbestos dust by workers engaged in mining and transportation of asbestos ores, asbestos processing and asbestos products. The typical symptoms of asbestosis are cough, expectoration and dyspnea that appear slowly and gradually. The clinical manifestations of asbestosis are progressive, diffuse and irreversible pulmonary interstitial fibrosis, pleural plaque formation and pleural hypertrophy, which seriously damage the patient's respiratory function. Asbestosis is one of the incurable pneumoconiosis diseases. Operators who have been exposed to asbestos for a long time may still get sick 20-30 years after leaving the asbestos operation, which seriously endangers the health of workers.
Because of its hard physical properties, hornblende asbestos is not easy to be cleared by the respiratory tract, It is easy to pierce the lung tissue and reach the pleura, leading to lung and pleura diseases, The correlation with lung cancer has been unanimously recognized by experts at home and abroad. It was once thought that chrysotile was soft, It is easy to bend and can be blocked and cleared in the bronchus, It is not easy to penetrate the pleura, Therefore, the carcinogenicity of chrysotile asbestos once became the focus of debate. Domestic researchers have conducted longitudinal studies on workers exposed to chrysotile asbestos in asbestos factories for 25 years, The control study between the chrysotile asbestos exposed group and the non exposed group found that, The incidence of lung cancer in the chrysotile exposed group was 8.1 times higher than that in the non exposed group. The causal relationship between asbestos and pleural mesothelioma has also been confirmed by many studies.
Asbestos has been listed as a definite carcinogen by relevant international research institutions. Many reports agree that exposure to asbestos increases the risk of lung cancer; It is observed that mesothelioma occurs after occupational exposure to asbestos, and also occurs in people living near asbestos factories and mines and people living with asbestos workers.
It is reported that about 125 million people worldwide are exposed to asbestos at work, and a large number of people die each year from asbestos related lung cancer, mesothelioma and asbestosis caused by occupational exposure. The loss of life and property caused by asbestos related diseases is on the rise, even those countries that have banned asbestos since the 1990s. Because of the long incubation period of asbestos related diseases, even if the use of asbestos is stopped now, the number of deaths related to asbestos will not decrease until decades later.
Even if we stop using asbestos now, asbestos pollution may continue. The ceilings in some old residences, the insulation layers and sound insulation materials of buildings and pipelines mostly contain asbestos. When these asbestos containing materials are removed, repaired, cut and reshaped, a large number of small asbestos fibers will float in the air. One kilogram of asbestos contains about 1 million yuan fibers. The diameter of yuan fibers is generally 0.5 microns, and the length is less than 5 microns. It can be suspended in the atmosphere and water for weeks and months, causing continuous pollution.
At present, there is no threshold standard for the carcinogenic effect of asbestos, but some researchers believe that under the low level exposure of asbestos, there is still an increase in the risk of cancer in the population. Therefore, the most effective way to eliminate asbestos related diseases is to stop using all kinds of asbestos.
In 1995, Japan banned hornblende asbestos, and strictly stipulated that the banned content was 1%; In 2004, asbestos containing products of building and friction materials were banned; In 2005, Japan issued the asbestos hazard prevention decree, setting the asbestos content limit to a more stringent 0.1%. In 1990, South Korea stipulated that the production and use of chrysotile asbestos must be approved by the government; In 2009, South Korea banned the production, import and use of all kinds of asbestos; At the same time, in order to protect the health of workers in dismantling and other industries and prevent asbestos dust from escaping, Since 2003, South Korea has required that the demolition or removal of asbestos containing facilities or buildings must be approved by the government. Since 2009, it has required that the asbestos content of the demolition or removal of facilities or buildings exceed a certain range, The operation must be carried out by qualified personnel registered with the Ministry of Labor of South Korea.
40 Many countries prohibit the use of asbestos products, including chrysotile asbestos. To eliminate asbestos related diseases, WHO Commit to work with countries on the following strategic objectives:
1. Acknowledges that the most effective way to eliminate asbestos related diseases is to stop using all kinds of asbestos;
2. Provide relevant information, Including how to replace asbestos with safer alternatives and how to develop incentive mechanisms from the economic and technical aspects to promote such substitution;
3. Take measures to prevent asbestos exposure at the operation site and during the demolition of facilities and buildings;
4. Improve the early diagnosis, treatment and medical rehabilitation of asbestos related diseases, and establish a registration system for people who have been and/or are currently exposed to asbestos.
