Authors' response to the letter to the editor on "characterization of asbestos exposures associated with the use of facial makeups".

We appreciate the opportunity to respond to the comments of the letter writer. The writer states in his Letter to the Editor that the findings in our publication are not interpretable and/or cannot be generalized due to the lack of understanding of the source mine and bulk content of the cosmetic talc used in the facial makeups. In brief, we performed an exposure simulation study using established industrial hygiene methods, planned and conducted by Certified Industrial Hygienists (CIHs), to assess asbestos exposures during the use of facial makeups that were found to contain very low levels of asbestos below the conventional detection limits of X-ray diffraction and polarized light microscopy. In total, 54 personal air samples and 72 area samples were collected from six different products. Out of the 126 samples collected and analyzed, asbestos was only found in eight samples (five personal samples and three area samples). A 95th percentile 24-h time-weighted average (TWA) result of 0.00008 fibers/cubic centimeter was calculated based on censored data and an assumed three applications per day. We believe these results may be of utility to understand the risk of low-level asbestos content in facial makeups regardless of source or bulk content, as described in our study, and do not find the writer's assertion of generalizability or interpretability to be compelling reasons not to apply our results, as is, for prospective purposes.