Updated Italian cohort data continues to confirm lack of mesothelioma risk in pooled cohort of international cosmetic talc miners and millers.

OBJECTIVES: To assess potential mesothelioma risk following inhalation of cosmetic talc, we updated previous iterations of a pooled cohort analysis, post-study statistical power analysis, and confidence interval function analysis for a pooled cohort of international cosmetic talc miners/millers given new Italian cohort data. METHODS: Five cohorts of cosmetic talc miners/millers were pooled. Expected numbers of mesotheliomas for each cohort were reported by the original authors. We based our post-study statistical power analysis on an a priori one-sided significance level of 0.05, and exact Poisson and approximate distribution probabilities. To evaluate the confidence interval function for the observed pooled mesothelioma standardized mortality ratios (SMRs), we calculated the probability for the upper 100(1-2α)% confidence limit that equals various SMRs of interest. RESULTS: The pooled cohorts generated a total observation time of 135,524.38 person-years. Overall, 4.14 mesotheliomas were expected (mid-value estimate), though only one case of mesothelioma has been confirmed in the pooled cohort to date. We calculated 71% and 87% post-study power to detect a 2.5-fold or greater and a 3.0-fold or greater increase in mesothelioma, respectively. Our complimentary confidence interval function analysis demonstrated that the probability that the true mesothelioma SMR for the pooled cohort was at or above 2.0 or at or above 3.0 was 0.00235 and 0.00005, respectively. CONCLUSIONS: Based on the updated results of our various analyses, the current epidemiological evidence from cosmetic talc miner/miller cohort studies continues to not support the hypothesis that the inhalation of cosmetic talc is associated with an increased risk of mesothelioma.

A quantitative weight of evidence assessment of Hill's guidelines for causal inference for cosmetic talc as a cause of mesothelioma.

Cosmetic talc has been suggested to cause mesothelioma. To assess a potential causal relationship between cosmetic talc and mesothelioma, a quantitative weight of evidence analysis was performed in accordance with Hill's nine original guidelines for causal inference using a published empirical model to weight each respective guideline. Various epidemiological, toxicological, and exposure studies related to cosmetic talc and risk of mesothelioma were included in an evaluation of each of Hill's guidelines. Probabilities that the guidelines were true were assigned based on expert judgment. We applied a sensitivity analysis to evaluate the variability of our probability estimates. The overall probability of causality for cosmetic talc and mesothelioma was approximately 1.29% (range: 0.73%-3.96%). This low probability of causality supports the conclusion that cosmetic talc is not related to the development of mesothelioma.

Potential airborne asbestos exposures in dentistry: a comprehensive review and risk assessment.

Chrysotile was formerly used in the manufacture of casting ring liner (CRL) and periodontal dressing powder (PDP). The purpose of this study was to describe the potential for airborne asbestos exposure among dental professionals who may have used these products and to assess their risk of asbestos-related disease (ARD). Task-specific exposure data associated with CRL and PDP were identified and compared to regulatory standards for asbestos and health-based benchmarks. Personal airborne fiber concentrations ranged from 0.008-3.5 f/cc by PCM (duration: 3-420 minutes) for CRL (tearing, placement), and from <0.0044-<0.297 f/cc by PCM (duration: 5-28 minutes) for PDP (mixing). Eight-hour time-weighted average (TWA) exposures were calculated using the reported task-based airborne fiber concentrations and associated sampling durations. For CRL tasks, the upper-bound calculated 8-hour TWA of 0.022 f/cc (tearing, placement) did not exceed regulatory standards for asbestos (≥0.1 f/cc). All samples collected during the mixing of PDP resulted in non-measurable fiber concentrations. The greatest estimated cumulative asbestos exposure for dental professionals using CRL (tearing, placement) of 0.33 f/cc-years is well below "best estimate", published chrysotile no-observed-adverse-effect-levels (NOAEL) for ARD (lung cancer = 89-168 f/cc-years; pleural mesothelioma = 208-415 f/cc-years). As such, the use of asbestos-containing CRL and/or PDP is not expected to pose an increased risk of ARD among dental professionals. This conclusion is consistent with the lack of an increased risk of ARD reported in epidemiological studies of these occupations.

Estimating aerosol transmission risk of SARS-CoV-2 in New York City public schools during reopening.

The objective of this study was to estimate the risk of SARS-CoV-2 transmission among students and teachers in New York City public schools, the largest school system in the US. Classroom measurements conducted from December 2017 to September 2018 were used to estimate risk of SARS-CoV-2 transmission using a modified Wells-Riley equation under a steady-state conditions and varying exposure scenarios (infectious student versus teacher, susceptible student versus teacher, with and without masks). We then used multivariable linear regression with GEE to identify school and classroom factors that impact transmission risk. Overall, 101 classrooms in 19 schools were assessed, 86 during the heating season, 69 during cooling season, and 54 during both. The mean probability of transmission was generally low but varied by scenario (range: 0.0015-0.81). Transmission rates were higher during the heating season (beta=0.108, p=0.010), in schools in higher income neighborhoods (>80K versus 20K-40K beta=0.196, p<0.001) and newer buildings (<50 years beta=0.237, p=<0.001; 50-99 years beta=0.230, p=0.013 versus 100+ years) and lower in schools with mechanical ventilation (beta=0.141, p=0.057). Surprisingly, schools located in older buildings and lower-income neighborhoods had lower transmission probabilities, likely due to the greater outdoor airflow associated with an older, non-renovated buildings that allow air to leak in (i.e. drafty buildings). Despite the generally low risk of school-based transmission found in this study, with SARS-CoV-2 prevalence rising in New York City this risk will increase and additional mitigation steps should be implemented in schools now.

Absence of mesothelioma risk maintained in an expanded international cohort of cosmetic talc miners and millers.

Objectives: Based on novel information for the Vermont cosmetic talc miner/miller cohort, including a reported case of mesothelioma, we sought to update our prior pooled statistical power analyses of mesothelioma incidence among European cosmetic talc miners/millers. With the inclusion of the Vermont cohort, we expanded our pooled analysis by 17,170 person-years of observation.Methods: Cosmetic talc miner/miller cohort studies conducted in Italy, Norway, France, Austria, and Vermont were pooled. The expected numbers of mesothelioma cases for each cohort as reported in these studies were used. Our statistical power analysis was based on an a priori one-sided significance level of 0.05 and Poisson distribution probabilities.Results: A total of 130,514 person-years of observation was generated across the five cohorts. One case of mesothelioma was observed (in the Vermont cohort), while approximately 3.34 cases (a mid-value estimate) were expected overall. Thus, we found that the pooled cohorts had 59% and 78% power to detect a 2.5-fold or greater and a 3.0-fold or greater increase in mesothelioma, respectively. The work history characteristics of the one mesothelioma case, which included mention of prior asbestos exposure on the case's death certificate, do not support a causal link with cosmetic talc exposure.Conclusions: Despite the recent finding of one case of mesothelioma in the Vermont cohort (a case unlikely related to talc exposure), we continue to conclude that the epidemiological evidence from the cosmetic talc miner/miller cohort studies does not support the hypothesis that cosmetic talc exposures are associated with an increased risk of pleural mesothelioma.

Confidence interval function analysis to evaluate the risk of mesothelioma among an expanded international cohort of cosmetic talc miners and millers.

We used pooled data from international cosmetic talc miner/miller cohorts to determine whether hypothesized increased mesothelioma risks are consistent with the observed data. We evaluated the confidence interval function for the observed pooled mesothelioma SMRs (observed = 1; expected = 3.17, 3.34, or 3.60), and calculated the value of α for the upper 100(1 - 2α)% confidence limit that equals various SMRs of interest (1.5, 2.0, 2.5, 3.0). Using the mid-value estimate of expected number of cases (3.34), the probability (α) that the true mesothelioma SMR is at or above 2.0, or at or above 3.0 is 0.0096 and 0.0005, respectively. Thus, a mesothelioma SMR ≥2.0 is not compatible with the observed pooled data, providing further support for our conclusion that cosmetic talc exposure is not associated with an elevated risk of mesothelioma.

An estimation of airborne SARS-CoV-2 infection transmission risk in New York City nail salons.

Although airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from person-to-person over long distances is currently thought to be unlikely, the current epidemiological evidence suggests that airborne SARS-CoV-2 infection transmission in confined, indoor spaces is plausible, particularly when outdoor airflow rates are low and when face masks are not utilized. We sought to model airborne infection transmission risk assuming five realistic exposure scenarios using previously estimated outdoor airflow rates for 12 New York City nail salons, a published quanta generation rate specific to SARS-CoV-2, as well as the Wells-Riley equation to assess risk under both steady-state and non-steady-state conditions. Additionally, the impact of face mask-wearing by occupants on airborne infection transmission risk was also evaluated. The risk of airborne infection transmission across all salons and all exposure scenarios when not wearing face masks ranged from <0.015% to 99.25%, with an average airborne infection transmission risk of 24.77%. Wearing face masks reduced airborne infection transmission risk to between <0.01% and 51.96%, depending on the salon, with an average airborne infection transmission risk of 7.30% across all salons. Increased outdoor airflow rates in nail salons were generally strongly correlated with decreased average airborne infection transmission risk. The results of this study indicate that increased outdoor airflow rates and the use of face masks by both employees and customers could substantially reduce SARS-CoV-2 transmission in New York City nail salons. Businesses should utilize multiple layers of infection control measures (e.g. social distancing, face masks, and outdoor airflow) to reduce airborne infection transmission risk for both employees and customers.

Heat stress risk among New York City public school kitchen workers: a quantitative exposure assessment.

Despite the known human health risks associated with excessive heat exposure, particularly in occupational settings, data describing potential heat exposures in school kitchens is scarce, and no published studies to date have performed a quantitative heat exposure assessment for workers employed in this setting. The purpose of this study was to quantify the extent of heat stress in New York City public school kitchens and to assess potential risk of heat-related illness and/or acute injury. Full-shift indoor Wet Bulb Globe Temperature (WBGT) indices, as well as indoor CO2 and CO concentrations were measured for ten school kitchens. A quantitative exposure assessment for three metabolic work-rate scenarios (light, moderate, heavy) was performed in accordance with the Occupational Safety and Health Administration's (OSHA) Heat Hazard Assessment methodology. The overall mean indoor WBGT index for all ten sites was approximately 25.0 °C (77.0 °F; Standard Deviation [SD] = 2.0 °C). Regarding the estimated Action Limit, 10% of school kitchens sampled exceeded this recommended limit for the light work-rate scenario; 60% of schools exceeded this limit for the moderate work-rate scenario; and 80% of schools exceeded this limit for the heavy work-rate scenario. For the Threshold Limit Value (TLV), none of the kitchens exceeded this limit for the light or moderate work-rate scenarios; 30% of kitchens were in excess of this limit for the heavy work-rate scenario. Mean full-shift CO2 and CO air concentrations ranged from 435-911 ppm (mean = 648; SD = 158) and 0.0-3.2 ppm (mean = 0.9; SD = 0.9), respectively. The data collected in the current study suggest that kitchen staff employed in New York City public schools may be exposed to excessive indoor heat levels. Adequate work-rest schedules should be implemented for kitchen workers, in addition to other feasible engineering and administrative controls to mitigate potential risk of heat-related illness and/or acute injury.

Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period.

Objectives: We previously published a pooled statistical power analysis of mesothelioma incidence in the Italian, Norwegian, Austrian, and French cosmetic talc miner and miller cohorts. Soon thereafter, updates to the Italian and Norwegian cohorts were published, providing an additional 14,322 person-years of observation. In this study, we provide an updated power analysis using the newly available information. Methods: We pooled the current results regarding pleural cancer/mesothelioma mortality or incidence in four cosmetic talc miner and miller cohorts in Italy, Norway, Austria, and France. We used the expected numbers of cases as reported by the authors and the power analysis was based on an a priori one-sided significance level of 0.05 and Poisson distribution probabilities. Results: There was a pooled total of 113,344 person-years in the cohorts. Although 3.0 pleural cancers/mesotheliomas were expected, there were no reported pleural cancer or mesothelioma cases in any cohort. Our pooled analysis was associated with 79 and 62% power to detect a 3.0-fold and 2.5-fold or greater increase in pleural cancer/mesothelioma, respectively. These favorable power characteristics were effectively maintained when restricting the pooled cohort to workers with a latency period of 30 or more years (observation time from first employment). Conclusions: The epidemiological evidence from the cosmetic talc miner/miller cohort studies does not support the hypothesis that exposure to cosmetic talc is associated with the development of pleural cancer/mesothelioma.

Systematic review of the association between talc and female reproductive tract cancers.

Talc is a hydrous magnesium sheet silicate used in cosmetic powders, ceramics, paints, rubber, and many other products. We conducted a systematic review of the potential carcinogenicity of genitally applied talc in humans. Our systematic review methods adhere to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and incorporated aspects from the US Institute of Medicine (IOM, now the National Academy of Medicine) and several US EPA frameworks for systematic reviews, evaluating and integrating the epidemiological, animal, and mechanistic literature on talc and cancer. We conducted a comprehensive literature search. Detailed data abstraction and study quality evaluation, adapting the Toxic Substances Control Act (TSCA) framework, were central to our analysis. The literature search and selection process identified 40 primary studies that assessed exposure to talc and female reproductive cancer risks in humans (n = 36) and animals (n = 4). The results of our evaluation emphasize the importance of considering biological plausibility and study quality in systematic review. Integrating all streams of evidence according to the IOM framework yielded classifications of suggestive evidence of no association between perineal application of talcum powders and risk of ovarian cancer at human-relevant exposure levels. We also concluded that there is suggestive evidence of no association between genital talc application and endometrial cancer, and insufficient evidence to determine whether a causal association exists between genital talc application and cervical cancer based on a smaller but largely null body of literature.

Systematic review of the scientific evidence of the pulmonary carcinogenicity of talc.

We conducted a systematic review to assess the potential pulmonary carcinogenicity of inhaled talc in humans. Our systematic review methods adhere to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and incorporated aspects from the US Institute of Medicine (IOM) and several United States (US) Environmental Protection Agency (EPA) frameworks for systematic reviews. A comprehensive literature search was conducted. Detailed data abstraction and study quality evaluation, adapting the US Toxic Substances Control Act (TSCA) framework, were central to our analysis. The literature search and selection process identified 23 primary studies that assessed exposure to talc and pulmonary cancer risks in humans (n = 19) and animals (n = 3). Integrating all streams of evidence according to the IOM framework yielded classifications of suggestive evidence of no association between inhaled talc and lung cancer and pleural mesothelioma at human-relevant exposure levels.