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Technical advisory note

Asbestos is a naturally occurring group of fibrous minerals that occurs in different mineral forms and fibre types. These fibres can vary significantly in their physical characteristics, including length, thickness, and shape. Some asbestos fibres are relatively coarse and more easily detected, while others are extremely thin making them more difficult to identify. All asbestos fibre types, regardless of size, have the potential to pose a health risk if fibres become airborne and are inhaled.

UK regulations prohibit the placing on the market of products containing asbestos fibres due to their classification as carcinogens. This document sets out OPSS鈥� position on the most appropriate testing methodologies for detecting asbestos in consumer products containing sand such as toys, hobby and decorative products.

X-Ray Diffraction (XRD)

XRD works by directing an X-ray beam at the sample measuring how it diffracts the X-rays and comparing the resulting diffraction pattern to known reference patterns. Generally, XRD is very good as a screening tool which is relatively quick and inexpensive, and suitable for materials with relatively high asbestos levels. It is generally not reliable when asbestos is present at lower levels, less than ~1%.

Polarized Light Microscopy (PLM)

Polarized Light Microscopy (PLM) is an optical microscopy technique that uses polarised light to identify and characterise materials based on their optical properties. PLM can be suitable for materials with relatively high asbestos levels and larger fibres, such as bulk construction materials. However, it is generally not reliable when asbestos is present at low levels, less than ~0.1%, and may miss very fine or thin fibres.

Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)

Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are electron-based laboratory techniques used to detect very small fibres that cannot be reliably identified using standard based optical methods. By using electrons rather than light, these techniques provide a much higher sensitivity and are able to detect asbestos at levels below 0.1% and very fine or thin asbestos fibres.

Energy Dispersive X-ray Spectroscopy (EDX)

Energy Dispersive X-ray Spectroscopy (EDX) is an analytical technique used to determine the elemental composition of materials. In this method, a sample is bombarded with an electron beam, causing its atoms to emit characteristic X鈥憆ays. By detecting and analysing these X鈥憆ays, the elements present in the sample can be identified. EDX is most commonly integrated with scanning electron microscopy (SEM).

Recommendation

SEM coupled with EDX (SEM-EDX) or TEM are the recommended techniques for detecting asbestos in consumer products containing sand such as toys, hobby and decorative products because they can more reliably identify low asbestos concentrations, below 0.1%, and fine or thin asbestos fibres likely to be present in contaminated products.

When employing SEM-EDX or TEM, representative characterisation of the product requires both, using appropriate sampling methods and analysing a sufficient number of images to ensure that the analysed sub鈥憇ample is truly representative of the overall product.

As an alternative, a tiered testing approach may be used where it is suspected that significant levels of asbestos may be present. XRD can serve as an initial screening method, where a positive result would confirm the presence of asbestos. If the XRD result is negative, the sample can then be examined using PLM as a second step. A positive PLM result would also confirm asbestos. If PLM results are negative, SEM-EDX or TEM, as the currently most sensitive available tests, should be used as a final step.