The IWGACP published its white paper on standardizing asbestos testing in cosmetic talc, and among many conclusions stated both optical and electron microscopy to catch as much of the contaminant as possible.
The working group was formed in 2018 following several cosmetic product recalls in the US, Canada, the Netherlands and Taiwan.
“The IWGACP was asked by FDA to develop a consensus document that would support the development of standardized testing methods to improve the sensitivity and consistency of analyses, and inter-laboratory concurrence when reporting asbestos and other mineral particles of health concern in talc that could potentially affect consumer’s health from cosmetic use,” the paper said.
The problem
Asbestos can appear as a contaminant in talc, which is a versatile and controversial powder cosmetic ingredient. The IWGACP said some talc deposits contain asbestos or other magnesium silicate minerals, particularly members of the amphibole group.
The contaminant also has many definitions, but are “generally silicate minerals belonging to the serpentine and amphibole groups that have an unusual fibrous crystal growth habit.” It is also a known carcinogen.
Those who inhale or ingest asbestos can see repercussions ranging from inflammation to pleural disease, lung, larynx, gastrointestinal tract, and ovarian cancer, and mesothelioma, and those issues often don’t crop up until months or years after the original exposure.
The working group said these issues are why it’s important for the development of a method to better determine asbestos contamination levels in talc, particularly because it’s so hard to remove contaminants from the material.
Today, talc suppliers generally use an XRD or infrared test to find amphiboles and, if they are detected, an optical microscopy test is conducted to determine if asbestiform amphibole or chrysotile is present, the paper said.
While these methods can be effective at finding some asbestos contamination, particles smaller than five micrometers in length or .02 micrometers in width may not be detected.
The analysis
The working group made eight recommendations in their analysis of talc testing methods, chief among them the use of both optical and electron microscopy, reporting all asbestos and other amphibole mineral particles meeting dimensional criteria, following sampling guidelines and that written protocols specify appropriate instruments, methods and reporting criteria.
“Such an approach for inclusive reporting will enhance transparency and help to provide a cumulative record of mineral particles, thereby facilitating more well-conceived health-based decisions about cosmetic product safety,” the paper said.
The full recommendations are as follows:
- Use both optical and electron methods to identify and report at minimum, the presence of amphibole minerals, other amphibole minerals, chrysotile, particles that contain talc and an amphibole and talc particles exhibiting non-platy morphology.
- Tabulating amphibole and chrysotiles .5 micrometers or larger in length by indicating the length, width and mineral type in the talc and avoiding categorizing those particles as non-asbestiform if the habit of growth is ambiguous.
- Use a combination of PLM with dispersion staining and TEM with EDS and SAED to achieve the sensitivity and specificity to detect and identify mineral particles.
- Electron microscopy should be reported as particles per mass of sample analyzed, not by weight percent.
- An adequate number of electron microscopy images, EDS spectra and SAED patterns for mineral identification and descriptions of each particle should be provided.
- Samples should be prepared to mitigate interference from the sample matrix using techniques similar to those used for the testing of bulk materials for asbestos.
- Reports should contain consistent and comprehensive reporting of particles, alongside documentation of findings.
- Training, quality assurance and quality control must have policies and procedures to maintain intra- and inter-laboratory consistency and lab qualifications should be reviewed regularly.
The future
Moving forward, IWGACP said further research must be done in several areas to “promote
reliability, sensitivity, and interlaboratory agreement of the analytical methods for asbestos and
other mineral particles of potential health concern in talc-containing cosmetic products and talc
intended for use in cosmetics.”
The areas of research are as follows:
- Developing cosmetic-talc-specific sampling methods to improve sample representativeness and minimize error and false positives and negatives.
- Methods for sample preparation and treatments to improve sensitivity without affecting the structure of the talc or asbestos.
- Studies of protocols of the two above issues for the development of interlaboratory agreements.
- “Development and qualification of reference materials that can be used to assess laboratory and analyst proficiency, increase inter-laboratory concurrence, minimize reporting errors, and potentially provide for improved reliability of quantitative analysis. Development of appropriate talc-specific reference standards containing known concentrations of characteristic amphibole and chrysotile mineral particles found in talc (of known size distributions) would be ideal for method development and quantitation.”