Exposure to MMVF in residential and commercial buildings: A literature review and quantitative synthesis.

Man-made vitreous fibers (MMVF) are a class of inorganic fibrous materials that include glass and mineral wools, continuous glass filaments, and refractory ceramic fibers valued for their insulative properties in high temperature applications. Potential health effects from occupational exposure to MMVF have been investigated since the 1970s, with focus on incidence of respiratory tract cancer among MMVF-exposed production workers. The general population may experience exposure to MMVF in residential and/or commercial buildings due to deterioration, construction, or other disruption of materials containing these fibers. Numerous studies have characterized potential exposures that may occur during material disruption or installation; however, fewer have aimed to measure background MMVF concentrations in residential and commercial spaces (i.e., non-production settings) to which the general population may be exposed. In this study, we reviewed and synthesized peer-reviewed studies that evaluated respirable MMVF exposure levels in non-production, indoor environments. Among studies that analyzed airborne respirable MMVF concentrations, 110-fold and 1.5-fold differences in estimated concentrations were observed for those studies utilizing phase contrast optical microscopy (PCOM) versus transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. A positive correlation was observed between respirable air concentrations of MMVF and total surface concentrations of MMVF in seldom-cleaned areas. Ultimately, available evidence suggests that both ambient air and surface concentrations of MMVF in indoor environments are consistently lower than exposure limits developed to prevent negative health outcomes among sensitive populations.

Strategies for refinement of occupational inhalation exposure evaluation in the EPA TSCA risk evaluation process.

The focus on occupational exposures in the first published risk evaluations of existing chemicals by the Environmental Protection Agency (EPA) under the amended Toxic Substances Control Act (TSCA) puts a welcome spotlight on protecting the health of workers in the United States. Because new, fit-for-purpose occupational exposure assessment methodologies were developed by EPA, the objective of this analysis was to evaluate these methodologies in light of other existing occupational risk assessment frameworks. We focused our analysis on three chlorinated chemicals (methylene chloride, carbon tetrachloride, perchloroethylene). The EPA's methods were evaluated relative to peer-reviewed and professional organizations' guidelines for conducting site- and facility-based exposure assessment. Analyses of several key phases in the EPA approach were conducted to evaluate the effect of alternative approaches on exposure estimates. The revised exposure estimates using these alternative approaches yielded substantially different exposure estimates from those in the TSCA risk evaluations for these chemicals. The results also demonstrated the importance of utilizing a tiered approach to exposure estimation that includes collecting qualitative data, defining similar exposure groups, and integrating well-parameterized models with empirical data. These approaches aid in preventing mischaracterization of exposures and generating exposure estimates representative of current industrial practices. Collaboration among industry, EPA, and other government agencies to develop a harmonized approach to exposure assessment would improve the methodological rigor of, and increase stakeholder confidence in, the results of TSCA risk evaluations.

Analysis of dermal exposure assessment in the US Environmental Protection Agency Toxic Substances Control Act risk evaluations of chemical manufacturing.

The United States Environmental Protection Agency (EPA) regulates chemical manufacture, import, processing, distribution, use, and disposal under the 2016 amended Toxic Substances Control Act (TSCA) for the purposes of protecting the public and sensitive populations-including workers-from chemical exposure risk. The publication of several TSCA risk evaluations provided a unique opportunity to evaluate the evolving regulatory approach for assessing the dermal exposure pathway in occupational settings. In this analysis, the occupational dermal exposure assessment methods employed in several TSCA risk evaluations were assessed. Specifically, a methodology review was conducted for the occupational dermal scenarios of manufacturing and feedstock use in the risk evaluations of three chlorinated organic chemicals: trichloroethylene, carbon tetrachloride, and perchloroethylene. Additionally, alternative exposure estimates were generated using the exposure model IH SkinPermTM. The review and alternative exposure analyses indicate that the current TSCA modeling approach may generate total dermal absorbed doses for chlorinated chemical manufacturing and feedstock use scenarios that are 2- to 20-fold higher than those generated by IH SkinPerm. Best-practice recommendations developed in the methodology review support a tiered, integrated approach to dermal exposure assessment that emphasizes collecting qualitative data; employing validated, peer-reviewed models that align with current industrial practices; and gathering empirical sampling data where needed. Collaboration among industry, EPA, and other stakeholders to share information and develop a standard approach to exposure assessment under TSCA would improve the methodological rigor of, and increase confidence in, the risk evaluation results.

Assessment of formaldehyde exposures under contemporary embalming conditions in U.S. funeral homes.

The funeral service profession has used formaldehyde-containing embalming solutions for the preparation of decedents since the early 1900s. The available literature regarding funeral director exposure to formaldehyde largely consists of data collected prior to 2000, with most studies reporting task-length exposure concentrations rather than full-shift time-weighted average concentrations. As formaldehyde undergoes review in the U.S. Environmental Protection Agency Toxic Substances Control Act (TSCA) risk evaluation process, accurately characterizing long-term exposure potential in this profession is critical. This study presents passive badge sampling and air change rate measurement results conducted at 13 funeral home locations across the United States. Full-shift (approximately 8-hr) samples were collected on one embalmer per day in each funeral home and on one occupational non-user (ONU), e.g., a receptionist. Additionally, task-length samples were collected during each embalming that occurred during the shift, were one to occur. Full-shift concentrations ranged from 0.007 to 1.1 ppm and 0.007 to 0.042 ppm for embalmers and ONUs, respectively. Task-length formaldehyde concentrations ranged from 0.058 to 1.4 ppm, with the average embalming taking 72.8 min to complete. Air change rates in the preparation rooms ranged from 2.8 to 28.3 air changes per hour; however, no correlation between task-length formaldehyde concentrations and air change rate was observed. Following empirical data collection, a Monte Carlo analysis of estimated annual 8-hr time-weighted average (TWA) exposure was conducted to determine the potential exposure distribution for embalmers employed at private funeral homes. Inputs to the simulation were derived from responses to a National Funeral Directors Association survey and from empirical measurements collected during the study. With respect to the reconstructed 8-hr TWAs, the median 8-hr TWA was 0.037 ppm, with 93.6% of the predicted concentrations below 0.1 ppm. This study provides a robust characterization of contemporary formaldehyde exposures in the funeral service profession. Further, it provides a strategy for interpreting the results along with surveyed responses regarding embalming frequency to better inform risks associated with formaldehyde exposure in this profession.

Drainage of anorectal abscesses in the operating room is associated with a decreased risk of abscess recurrence and fistula formation.

BACKGROUND: Timely incision and drainage (I&D) is first line management for anorectal abscesses. We aimed to define current practices in anorectal abscess management and identify factors associated with abscess recurrence and fistula formation. METHODS: Index episodes of anorectal abscesses treated with I&D in 2014-2018 at a multi-hospital healthcare system were included. Association with one-year abscess recurrence or fistula formation was evaluated using Cox proportional hazard regression. Fistulae were captured only among patients without fistulae at the index operation. RESULTS: A total of 458 patients met study criteria. One-year rate of abscess recurrence or fistula formation was 20.3%. When compared to bedside procedures, drainage in the operating room was associated with a reduced risk of either recurrence or fistula formation (aHR 0.20 [95%CI 0.114-0.367]). CONCLUSIONS: Improved exposure and patient comfort in the operating room may allow more complete drainage contributing to decreased rates of abscess recurrence or fistula formation.