A detailed introduction to asbestos detection methods and standards​

Views: 79     Author: Site Editor     Publish Time: 2022-12-12      Origin: Site

Since the discovery of asbestos in certain products imported from China, the Australian Border Enforcement Agency (ABF) has been strictly checking the asbestos content of goods arriving from China since September this year, stating that all Chinese products containing asbestos will be banned from import and use. Australia has had a total ban on the import and export of products containing asbestos since 2003, making it one of the few countries in the world to do so.

China is a big trading partner of Australia. From January to June this year, the total value of goods imported from China to Australia reached 20.35 billion US dollars, accounting for 22.5% of Australia's total imports, making China a major source of imports to Australia.

This time, ABF requires all Chinese products exported to Australia to provide a zero asbestos testing report, which will bring new challenges to Chinese products exported to Australia. The reason is, on the one hand, the wide range of exports involved. ABF's strict inspection targets all products exported to Australia, covering electromechanical, textile, furniture, toys, metal products, plastic and rubber, chemical products, light industrial products, transport equipment, mineral products, glass and ceramics, medical equipment, leather products, food, wood and products and other fields, with many categories, wide range and large coverage.

On the other hand, it increases the export cost of foreign trade enterprises. The ABF makes it mandatory for the applicant to provide a valid certificate from an NATA-approved or equivalent testing agency to prove that the requested commodity does not contain asbestos. But the high cost of testing in foreign laboratories, coupled with the time cost and personnel cost of sending samples back and forth, increased the burden of enterprises. The ABF also stipulates that if the applicant fails to provide a valid inspection certificate, Australia will not issue a customs clearance certificate on the grounds that the shipment may contain asbestos. This will bring huge economic losses to relevant foreign trade enterprises. So how do you test for asbestos? This article will give you a detailed introduction to asbestos detection methods and standards, I hope you have learned.

1. Asbestos control

Related Knowledge:

Asbestos, also known as "asbestos", is a commercial term for silicate mineral products with high tensile strength, high flexibility, resistance to chemical and thermal erosion, electrical insulation and spinnability. It is a general term for naturally fibrous silicate minerals. Under the jurisdiction of 2 categories of 6 kinds of minerals (serpentine asbestos, amphibole asbestos, actinite asbestos, rectoblite asbestos, iron asbestos, tremolite asbestos, etc.). Asbestos is made up of bundles of fibers, which in turn are made up of very long, thin fibers that can separate from each other. Asbestos has very good insulation, insulation, wear resistance, corrosion resistance, fire resistance, has been widely used in textile, building materials, transportation, mechanical and electrical, light industry and many other fields of products, such as fireproof cloth, brake belt, cement board, insulation board, insulation board, linoleum board, brake brake skin, gasket and so on, has played a very important role in improving product performance.

Commonly used chrysotile fibers can be split into tiny microfibers, smaller than the much-discussed PM2.5 particles. (The microfibers are generally 0.5 micrometers in diameter and less than 5 micrometers in length, and can stay suspended in the air and water for weeks or even months. We now refer to PM2.5 as airborne particles 2.5 microns or less in diameter). Because asbestos fibers are very small and stable, once they enter the human body for a long time, they may lead to asbestosis, lung cancer, laryngeal cancer, mesothelioma and other diseases. In recent years, more and more countries and regions have begun to ban or restrict the use of asbestos.

Another scary part is that health risks from asbestos often take 10 to 40 years to emerge. In Germany between 1980 and 2003, there were 12,000 deaths from asbestos-related occupational diseases. Asbestos kills 2,000 people a year in France. Nearly 20,000 cases of asbestosis were reported in the United States between 1990 and 1999. Due to such a wide range of hazards, many countries have chosen to completely ban the use of this dangerous substance. Take the United States for example, the United States has restricted the use of asbestos since 1971, and completely banned the production and use of asbestos and asbestos products in 1992, while neighboring Japan and South Korea also banned the use of asbestos products in 2008 and 2009 respectively.

China is the world's second largest producer of asbestos, with an annual output of more than 300,000 tons. As early as 2012, several brands of Chinese cars exported to Australia were found to contain asbestos in their gaskets, leading to massive vehicle recalls.

Banned fibrous asbestos:

1) Serpentine -- chrysotile (white asbestos);

2) Hornblende group -- actinite asbestos, iron asbestos (brown asbestos and gray asbestos), straight amphibole asbestos, blue asbestos, tremolite asbestos.

Asbestos is internationally recognized as a Class I carcinogen and has been banned in many countries. In 1998, the World Health Organization called for the use of asbestos substitutes, and many countries chose to completely ban the use of asbestos products. Therefore, only by doing a good job in the control of asbestos materials can we cope with trade barriers and national bans and avoid the occurrence of product investigation and recall.

The United States has restricted the use of asbestos since 1971 and completely banned the production and use of asbestos and asbestos products in 1992.

Ø Asbestos products have been banned in Germany since 1993.

øFrance has imposed a ban since 1997.

The UK banned the import of chrysotile asbestos in November 1999.

Ø Belgium has tightened the high exposure standard several times, and the import of asbestos dropped from 85,000 metric tons in 1975 to less than 1,000 metric tons in 1999.

China has banned brake pads containing asbestos since October 1, 2003, but has not completely banned the use of asbestos materials in auto parts.

The European Union has asked all member states to adopt a legislative ban on asbestos directive by the end of 2004.

Japan promulgated the "Asbestos Hazard Prevention Act" in 2005 and banned all asbestos-containing materials (except certain materials) in 2006.

Ø South Korea banned the production, import and use of all types of asbestos in 2009.

In August 2012, the Australian Competition and Consumer Commission (ACCC) issued a warning notice that some engines and exhaust gaskets sold by a Chinese carmaker in Australia contained a small amount of asbestos, a potentially carcinogenic substance, which attracted wide attention. In January 2014, the Australian Department of Customs and Border Protection launched an investigation into the suspected asbestos components of Chinese locomotives exported to Australia.

Ii. Asbestos detection methods

Asbestos is a natural fibrous mineral, so the methods of asbestos detection at home and abroad mainly refer to the research and identification methods of mineralogy. According to the detection methods: X-ray diffraction (XRD), polarizing microscopy (PLM), phase contrast microscopy (PCM), scanning electron microscopy (SEM), transmission electron microscopy (TSM), infrared spectroscopy (IR), differential thermal method (DTA), neutron activation method (NAA). For the environment where asbestos occurs, it is divided into air, dust (workplace, solid surface), soil, water, and asbestos detection in bulk materials (building materials, friction and sealing materials). According to the testing requirements, it can be divided into qualitative analysis and quantitative analysis (weight percentage or volume or quantity count).

There are many methods of testing for asbestos. Due to the different environments in which asbestos occurs, the different purposes of evaluation and the different methods chosen, no one test can solve the whole problem. Only by combining them can the validity and accuracy of detection be guaranteed. According to the practice of asbestos detection and referring to the relevant standards at home and abroad, XRD and PLM are mainly used as the technical method of asbestos detection in industrial products. The specific test methods for asbestos are as follows:

X-ray diffraction (XRD)

Test principle: Each mineral has its specific X-ray diffraction data and atlas, the intensity of its diffraction peak is directly proportional to its content, according to which to determine whether the sample contains some asbestos mineral and determine its content. The types of asbestos can be identified and quantitatively analyzed by this method. XRD is one of the most widely used methods for asbestos detection with small sample size, good reproducibility, rapid and effective. Of course, XRD is also controversial in the detection of asbestos, that is, some people think that XRD method has low sensitivity, low detection limit, can only meet the detection of asbestos content in more than 1%.

Test scope: chrysotile asbestos, iron asbestos, chrysotile asbestos, tremolite, argenite, straight amphibolite, manganese amphibolite, blue tremolite.

Polarizing microscopy (PLM)

Test principle: Each mineral has its specific mineral optical and morphological characteristics, through the polarizing microscope observation observation of mineral crystal morphology, refraction rate, interference color, 2V Angle, ductility, color, polychromatism, cleavage, contour, rough surface, gram line, protrusion and other characteristics to identify asbestos minerals; Under polarizing microscope, chrysotile is a slender fiber with light yellowy-green or low positive to low negative protrusion and refractive index of 1.540-1.550. In theory, PLM magnifies 1000 times and can identify and distinguish asbestos with a diameter greater than 0.25μm. Therefore, it is one of the methods widely used in various countries to identify asbestos types.

Test scope: chrysotile asbestos, iron asbestos, chrysotile asbestos, tremolite, argenite, straight amphibolite, manganese amphibolite, blue tremolite.