Viewed through an electron microscope, asbestos fibres look like thin glass straws, some no more than a fraction of a micrometre wide. If inhaled, they penetrate the soft alveoli of the lungs and the membranes that line the chest cavity. And there they stay. Over time, damaged cells can cause a malignant disease called mesothelioma, which often kills people, horribly, less than a year after diagnosis.
Before the widespread industrial use of asbestos began in the late nineteenth century, malignant mesothelioma was unheard of, yet it is now responsible for tens of thousands of deaths around the world every year. After the link between asbestos exposure and the disease was convincingly made in 1960, responsible nations eventually took strong measures to remove the mineral from commercial products and to halt mining and export. Less responsible nations did not; this is a scandal that deserves wider attention.
The United States has still not banned asbestos, despite the millions of dollars spent to clear it from homes and from communities near mines. And Canada has been criticized for plans to expand asbestos mining operations, which export the material to India, Indonesia and the Philippines. Although Canada enforces strict guidelines on asbestos use at home to protect its own people, those in countries to which it sends the mineral have little or no protection. Asbestos exported from Canada and other countries including Russia, Brazil and Kazakhstan is routinely mixed into building materials and consumer products, prized for the same durability that makes it troublesome for living tissue. Owing to the long time between exposure and the onset of disease, 30 years or more, the asbestos trade in North America and elsewhere is creating an epidemic that may take decades to peak and subside.
The minerals industry has long tried to convince regulators that white asbestos — or chrysotile — is safe when handled properly. It argues that only the already controlled forms — blue and brown asbestos, known collectively as amphibole — are of concern.
To support this, industry advocates point to scientific data and studies. Yet although the relevant literature is a mire of conflicting results, this should not be seen as an endorsement of their position. Rather, it reflects a string of industry-sponsored studies designed only to cast doubt on the clear links between chrysotile and lung disease. These are familiar tactics and several countries, including Britain, have seen through them and made the correct decision to ban all forms of asbestos, all of which have been proven to be carcinogenic in humans.
Meanwhile, researchers are finding new causes for concern with other natural fibrous minerals such as erionite (see page 884). Complacency is the problem. Much of the developed world has seen asbestos removed from public spaces, leaving in many minds a false sense of security. The public should once again be made aware of the risks associated with exposure to mineral fibres, as well as some man-made fibres. And governments must ban the extraction, processing and use of materials that can cause serious disease.