What is asbestos?
Asbestos is a general name for fibrous, double-chain silicate minerals that contain iron, magnesium, calcium or sodium. They can be divided into two main groups, known as serpentine (for example, chrysotile) and amphibole (for example, amosite, crocidolite and tremolite). Chrysotile is easily degraded by strong acids, while amphiboles are more resistant.
The various forms of asbestos are generally resistant to alkalis. The chemical nature and crystalline structure of asbestos gives it a number of characteristics, including high tensile strength, durability, flexibility, and resistance to heat and chemicals.
Asbestos refers to six unique minerals: chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite, which belong to the serpentine and amphibole families.
Asbestos, and specifically chrysotile, is used in a large number of applications, particularly in building materials. Examples include asbestos-cement (AC) sheets and pipes, electrical and thermal insulation, and friction products, such as brake linings and clutch discs.
Asbestos in drinking water
Asbestos reaches the water by dissolving the minerals already mentioned, as well as industrial effluents, also by air pollution, asbestos pipes in water distribution systems and tanks (reservoirs) made of this material. The detachment of asbestos fibers from asbestos pipes is related to the composition of the water that can be dissolved these minerals or simply the physical dragging.
Although asbestos pipes are still used in approximately 19% of water distribution systems today, the erosion of such pipes appears to contribute significantly to the asbestos content of drinking water supplies.
Health problems due to asbestos
The health risks associated with inhaling asbestos in the environment, especially at workplaces, have long been recognized, and include asbestosis, pulmonary carcinoma, malignant pleural mesothelioma and peritoneum, and possibly cancers of the gastrointestinal tract and larynx. In contrast, according to the WHO, little convincing evidence of the carcinogenicity of ingested asbestos has been found. This is done in epidemiological studies of populations supplied with drinking water containing high concentrations of asbestos. In addition, the ability of ingested asbestos fibers in drinking water to migrate through the walls of the gastrointestinal tract in sufficient quantities to cause local or systemic adverse effects has not been relevant.
In population studies, we found no consistent evidence of an association between mortality or cancer incidence and asbestos intake into drinking water.
What are the methods of analysis?
The method of choice for the quantitative determination of asbestos in ambient air and water is transmission electron microscopy (TEM) with energy dispersive X-ray identification and selected area electron diffraction (TEM / SAED).
Treatment methods for asbestos in water.
1) Flocculation / Filtration
2) Submicron filtration
3) Reverse Osmosis
Sorce: World Health Organization (WHO)