Asbestos exposures associated with the use and handling of drilling mud additives.

This paper summarizes historical asbestos exposure data collected during the handling of short-fiber chrysotile asbestos that was used as an additive to drilling fluid in oil and gas exploration. A total of 1171 industrial hygiene (IH) personal and area air samples were collected and analyzed from more than 20 drilling rigs between 1972 and 1985. The dataset consists of 1097 short-term samples (<240 min) with more than 80% having sample durations less than 30 min. Average airborne fiber concentrations measured during asbestos handling activities ranged from 0.62 f/cc to 3.39 f/cc using phase-contrast microscopy (PCM). An additional 14 samples were considered long-term samples (>240 min) and there were 60 samples with no reported sample duration. Eight-hour time-weighted average (8-h TWA) results, calculated using short-term samples, along with long-term samples greater than 240 min, did not exceed contemporaneous Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs). This analysis fills a data gap in the evaluation of asbestos exposures from the use of drilling mud additives (DMAs) that contained chrysotile asbestos.

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.

Characterization of asbestos exposures associated with the use of facial makeups.

There has been renewed interest in the safety of cosmetics that may contain asbestos or other elongate mineral particles at very low levels as a naturally occurring contaminant. The authors evaluated asbestos exposure during the application of facial makeups in a constructed chamber simulating a bathroom space. The facial makeups tested included products previously found to have very low or "trace" asbestos content by governmental and commercial laboratories using a variety of bulk analysis methods. Tremolite asbestos was detected in five of 54 personal air samples and three of 72 area air samples in 18 simulations. The calculated geometric mean and 95th percentile task-based asbestos concentration associated with personal facial makeup use in this study, incorporating censored data, is 0.0015 and 0.0018 fiber per cubic centimeter (f/cc), respectively, with a corresponding 95th percentile 24-h time-weighted average (TWA) asbestos concentration of 0.00008 f/cc for three applications per day in a simulated bathroom with no active ventilation. Based on these results, cumulative non-occupational asbestos exposures confer a less than one in 1,000,000 risk of asbestos-related disease based on many typical usage patterns and less than 1/100,000 risk with upper-end lifetime usage patterns, using the US Environmental Protection Agency asbestos risk model.

Relative Bioavailability of a Dolutegravir Dispersible Tablet and the Effects of Low- and High-Mineral-Content Water on the Tablet in Healthy Adults.

Dolutegravir (DTG) is approved in the United States to treat HIV-1-infected patients weighing ≥30 kg. A dispersible DTG tablet formulation was recently developed for pediatric patients. This study compares the pharmacokinetics (PK) of the dispersible tablet with that of a previously evaluated granule formulation. In this randomized, open-label, crossover study, 15 healthy adults received single oral doses of DTG 20 mg every 7 days across 5 treatment arms: granules consumed immediately after mixture with purified water, dispersible DTG consumed immediately after reconstitution in low-mineral-content (LMC) or high-mineral-content (HMC) water, and dispersible DTG consumed 30 minutes after dispersal in LMC or HMC water. Primary endpoints were bioavailability of immediately consumed dispersible tablet in LMC water relative to granule formulation reconstituted in purified water and PK of the dispersible tablet. Secondary endpoints included tolerability and palatability. The DTG dispersible tablet showed equivalent exposures to the granule formulation with geometric least-squares mean treatment ratios of 1.06 and 1.12 for AUC0-∞ and Cmax , respectively. DTG PK parameters were unaffected by mineral content or the 30-minute delay. Adverse events were mild; only nausea (n = 1) was considered drug related. DTG exposure observed with the dispersible tablet supports evaluation of this formulation for further development.