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General Chapter Prospectus: <901> Detection of Asbestos in Pharmaceutical Talc

Posting Date: 30-Apr-2021; updated 09–Aug–2021*
Expert Committee: Excipients Test Methods 
Input Deadline: 30-May-2021 

Proposed New Title:  <901> Detection of Asbestos in Pharmaceutical Talc

Suggested audience: Pharmaceutical industry and excipient manufacturers, users and distributors, academia, QA/QC specialists, formulators, regulatory affairs and governmental agencies.

Estimated proposal PF:  Pharmacopeial Forum 48(1) [Jan.–Feb. 2022] 

Background and objective:  In response to a request from FDA’s Monograph Modernization Task Group in 2010 to revise the asbestos test in the USP Talc monograph, USP intends to develop a new general chapter which can be cross-referenced by the Talc monograph revision for detection of asbestos in pharmaceutical Talc.

Description of scope and application: As part of the USP Talc monograph Phase 1 revision (refer to Stimuli article Modernization of Asbestos Testing in USP Talc—Part 2, found in PF 46(5)), the new chapter will provide detailed testing procedures and instructions for users to perform analysis and data interpretation of x-ray powder diffraction (XRD) and polarized light microscopy (PLM). Electron microscopy tests including transmission electron microscopy (TEM) and scanning electron microscopy (SEM) will be investigated as part of the Phase 2 revision, and the information regarding TEM and SEM will be updated in the new chapter at a future time.

Due to the safety concern and special handling requirements, USP proposes to establish virtual reference standards to facilitate the implementation of proposed asbestos test methods in pharmaceutical Talc. The virtual reference standards may include representative XRD diffractograms and PLM images and/or mounted slides using different types of asbestos in Talc. More virtual reference standards may be included for TEM and SEM when the chapter is revised in the future.

Although the asbestos testing methodologies described in this new general chapter will provide instructions for asbestos detection in the pharmaceutical grades of Talc, given the universal application of Talc across many products in industries, this chapter has a potential to be used by industry and regulators as a reference for asbestos testing, wherever appropriate.

Preliminary outline:  The following represents the sections for the proposed General Chapter: 

  • X-RAY DIFFRACTION (XRD) – also termed X-Ray Powder Diffraction (XRPD). It can be used for determining overall purity of a talc product with respect to accessory minerals and can be important in determining general suitability for pharmaceutical use. This test method is used to identify and determine a relative level (presence or absence) of total amphibole and total serpentine in a talc powder matrix. It is intended to be used in combination with the PLM microscopy technique. Detailed testing procedure and acceptance criteria for XRD are described in this section.
  • POLARIZED LIGHT MICROSCOPY (PLM) - PLM is used to identify asbestos particles in a talc powder matrix. It is intended to be used with XRD as a complimentary microscopy technique. It can detect asbestos at a lower level than XRD and it can differentiate different types of asbestos. Detailed testing procedure and acceptance criteria for PLM are described in this section.

Anticipated implementation timing: To be determined based on stakeholder feedback.  

Additional Information:  USP published a Stimuli article in PF 46(5). The Talc monograph revision proposal will be published in the same PF as the <901> proposal because the Test for Asbestos in the USP Talc monograph will cross-reference this new chapter.

Additionally, a new informational general chapter <1901> Theory and Practice of Asbestos Detection in Pharmaceutical Talc will also be published in the same PF to provide additional information of the aforementioned methodologies and the recommended practice for utilizing these analytical methodologies.

A separate prospectus regarding the new informational general chapter <1901> Theory and Practice of Asbestos Detection in Pharmaceutical Talc can be found here.

Furthermore, USP is planning to hold an open forum to further engage stakeholders and solicit their feedback when the proposals of the new general chapters and the revision proposal of the Talc monograph are published in PF.

Contact: Tong (Jenny) Liu, Ph.D., Principal Scientist, at (240)221-2072,


*This Notice was updated on August 9, 2021 to update the PF in which the proposal is expected to appear.