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1. Estimates of Occupational Inhalation Exposures to Six Oil-Related Compounds on the Four Rig Vessels Responding to the Deepwater Horizon Oil Spill

   https://doi.org/10.1093/annweh/wxaa072  

   Huynh, Tran B ; Groth, Caroline P ; Ramachandran, Gurumurthy ; Banerjee, Sudipto ; Stenzel, Mark ; Quick, Harrison ; Blair, Aaron ; Engel, Lawrence S ; Kwok, Richard K ; Sandler, Dale P ; et al ( October 2020 , Annals of Work Exposures and Health)

   null (Ed.)

   Abstract Background The 2010 Deepwater Horizon (DWH) oil spill involved thousands of workers and volunteers to mitigate the oil release and clean-up after the spill. Health concerns for these participants led to the initiation of a prospective epidemiological study (GuLF STUDY) to investigate potential adverse health outcomes associated with the oil spill response and clean-up (OSRC). Characterizing the chemical exposures of the OSRC workers was an essential component of the study. Workers on the four oil rig vessels mitigating the spill and located within a 1852 m (1 nautical mile) radius of the damaged wellhead [the Discoverer Enterprise (Enterprise), the Development Driller II (DDII), the Development Driller III (DDIII), and the Helix Q4000] had some of the greatest potential for chemical exposures. Objectives The aim of this paper is to characterize potential personal chemical exposures via the inhalation route for workers on those four rig vessels. Specifically, we presented our methodology and descriptive statistics of exposure estimates for total hydrocarbons (THCs), benzene, toluene, ethylbenzene, xylene, and n-hexane (BTEX-H) for various job groups to develop exposure groups for the GuLF STUDY cohort. Methods Using descriptive information associated with the measurements taken on various jobs on these rig vessels and with job titles from study participant responses to the study questionnaire, job groups [unique job/rig/time period (TP) combinations] were developed to describe groups of workers with the same or closely related job titles. A total of 500 job groups were considered for estimation using the available 8139 personal measurements. We used a univariate Bayesian model to analyze the THC measurements and a bivariate Bayesian regression framework to jointly model the measurements of THC and each of the BTEX-H chemicals separately, both models taking into account the many measurements that were below the analytic limit of detection. Results Highest THC exposures occurred in TP1a and TP1b, which was before the well was mechanically capped. The posterior medians of the arithmetic mean (AM) ranged from 0.11 ppm (‘Inside/Other’, TP1b, DDII; and ‘Driller’, TP3, DDII) to 14.67 ppm (‘Methanol Operations’, TP1b, Enterprise). There were statistical differences between the THC AMs by broad job groups, rigs, and time periods. The AMs for BTEX-H were generally about two to three orders of magnitude lower than the THC AMs, with benzene and ethylbenzene measurements being highly censored. Conclusions Our results add new insights to the limited literature on exposures associated with oil spill responses and support the current epidemiologic investigation of potential adverse health effects of the oil spill. 

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2. Exposure Assessment Techniques Applied to the Highly Censored Deepwater Horizon Gulf Oil Spill Personal Measurements

   https://doi.org/10.1093/annweh/wxab060  

   Stenzel, Mark R. ; Groth, Caroline P. ; Banerjee, Sudipto ; Ramachandran, Gurumurthy ; Kwok, Richard K. ; Engel, Lawrence S. ; Sandler, Dale P. ; Stewart, Patricia A. ( August 2021 , Annals of Work Exposures and Health)

   The GuLF Long-term Follow-up Study (GuLF STUDY) is investigating potential adverse health effects of workers involved in the Deepwater Horizon (DWH) oil spill response and cleanup (OSRC). Over 93% of the 160 000 personal air measurements taken on OSRC workers were below the limit of detection (LOD), as reported by the analytic labs. At this high level of censoring, our ability to develop exposure estimates was limited. The primary objective here was to reduce the number of measurements below the labs’ reported LODs to reflect the analytic methods’ true LODs, thereby facilitating the use of a relatively unbiased and precise Bayesian method to develop exposure estimates for study exposure groups (EGs). The estimates informed a job-exposure matrix to characterize exposure of study participants. A second objective was to develop descriptive statistics for relevant EGs that did not meet the Bayesian criteria of sample size ≥5 and censoring ≤80% to achieve the aforementioned level of bias and precision. One of the analytic labs recalculated the measurements using the analytic method’s LOD; the second lab provided raw analytical data, allowing us to recalculate the data values that fell between the originally reported LOD and the analytical method’s LOD. We developed rules for developing Bayesian estimates for EGs with >80% censoring. The remaining EGs were 100% censored. An order-based statistical method (OBSM) was developed to estimate exposures that considered the number of measurements, geometric standard deviation, and average LOD of the censored samples for N ≥ 20. For N < 20, substitution of ½ of the LOD was assigned. Recalculation of the measurements lowered overall censoring from 93.2 to 60.5% and of the THC measurements, from 83.1 to 11.2%. A total of 71% of the EGs met the ≤15% relative bias and <65% imprecision goal. Another 15% had censoring >80% but enough non-censored measurements to apply Bayesian methods. We used the OBSM for 3% of the estimates and the simple substitution method for 11%. The methods presented here substantially reduced the degree of censoring in the dataset and increased the number of EGs meeting our Bayesian method’s desired performance goal. The OBSM allowed for a systematic and consistent approach impacting only the lowest of the exposure estimates. This approach should be considered when dealing with highly censored datasets.

    

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3. Pathways linking caesarean delivery to early health in a dual burden context: Immune development and the gut microbiome in infants and children from Galápagos, Ecuador

   https://doi.org/10.1002/ajhb.23219  

   Thompson, Amanda L. ; Houck, Kelly M. ; Jahnke, Johanna R. ( January 2019 , American Journal of Human Biology)

   Global increases in caesarean deliveries are exposing more infants to perinatal environments that are evolutionarily novel and potentially increasing their risks for inflammatory conditions. Yet, the pathways linking caesareans to later health outcomes are not well understood, particularly in dual burden contexts. We test two of the hypothesized pathways, altered immune function and gut microbiota, which may link delivery mode to later health outcomes and test whether these associations persist when controlling for postnatal nutritional and pathogenic exposures.

   Data come from infants, aged 0 to 2 (n = 41), and young children, aged 2 to 11 (n = 135), from the Galápagos, Ecuador. Differences in morbidity, C‐reactive protein (CRP), and gut microbiota by delivery type were tested using linear and logistic regression models adjusted for nutritional and pathogenic exposures and infant age.

   Over half of infants and over 40% of children were delivered by caesarean. Morbidity and CRP did not differ between infants or children born by caesarean or vaginally. Microbial taxa abundance differed by delivery mode. Infants born by caesarean had a higher abundance of Firmicutes and a lower relative abundance of Bacteroidales. Children born by caesarean had a higher abundance of Proteobacteria and Enterobacteriales. These differences remained after adjustment for environmental exposure.

   Caesarean delivery is associated with differences in gut microbiota across childhood even in this dual burden context. Our results highlight the importance of examining caesarean delivery across diverse contexts to better understand the impact of perinatal interventions on short‐ and longer‐term health outcomes.

    

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4. Variation of Shear Wave Elastography With Preload in the Thyroid: Quantitative Validation

   https://doi.org/10.1002/jum.15456  

   Ozturk, Arinc ; Zubajlo, Rebecca E. ; Dhyani, Manish ; Grajo, Joseph R. ; Mercaldo, Nathaniel ; Anthony, Brian W. ; Samir, Anthony E. ( September 2020 , Journal of Ultrasound in Medicine)

   Thyroid shear wave elastography (SWE) has been shown to have advantages compared to biopsy or other imaging modalities in the evaluation of thyroid nodules. However, studies show variability in its assessment. The objective of this study was to evaluate whether stiffness measurements of the normal thyroid, as estimated by SWE, varied due to preload force or the pressure applied between the transducer and the patient.

   In this study, a measurement system was attached to the ultrasound transducer to measure the applied load. Shear wave elastographic measurements were obtained from the left lobe of the thyroid at applied transducer forces between 2 and 10 N. A linear mixed‐effects model was constructed to quantify the association between the preload force and stiffness while accounting for correlations between repeated measurements within each participant. The preload force effect on elasticity was modeled by both linear and quadratic terms to account for a possible nonlinear association between these variables.

   Nineteen healthy volunteers without known thyroid disease participated in the study. The participants had a mean age ± SD of 36 ± 8 years; 74% were female; 74% had a normal body mass index; and 95% were white non‐Hispanic/Latino. The estimated elastographic value at a 2‐N preload force was 16.7 kPa (95% confidence interval, 14.1–19.3 kPa), whereas the value at 10 N was 29.9 kPa (95% confidence interval, 24.9–34.9 kPa).

   The preload force was significantly and nonlinearly associated with SWE estimates of thyroid stiffness. Quantitative standardization of preload forces in the assessment of thyroid nodules using elastography is an integral factor for improving the accuracy of thyroid nodule evaluation.

    

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5. Relative tooth size, Bayesian inference, and Homo naledi

   https://doi.org/10.1002/ajpa.24353  

   Irish, Joel D. ; Grabowski, Mark ( June 2021 , American Journal of Physical Anthropology)

   Size‐corrected tooth crown measurements were used to estimate phenetic affinities amongHomo naledi(~335–236 ka) and 11 other Plio‐Pleistocene and recent species. To assess further their efficacy, and identify dental evolutionary trends, the data were then quantitatively coded for phylogenetic analyses. Results from both methods contribute additional characterization ofH. naledirelative to other hominins.

   After division by their geometric mean, scaled mesiodistal and buccolingual dimensions were used in tooth size apportionment analysis to compareH. nalediwithAustralopithecus africanus,A. afarensis,Paranthropus robustus,P. boisei,H. habilis,H. ergaster,H. erectus,H. heidelbergensis,H. neanderthalensis,H. sapiens, andPan troglodytes. These data produce equivalently scaled samples unaffected by interspecific size differences. The data were then gap‐weighted for Bayesian inference.

   Congruence in interspecific relationships is evident between methods, and with many inferred from earlier systematic studies. However, the present results placeH. naledias a sister taxon toH. habilis,based on a symplesiomorphic pattern of relative tooth size. In the preferred Bayesian phylogram,H. nalediis nested within a clade comprising allHomospecies, but it shares some characteristics with australopiths and, particularly, earlyHomo.

   Phylogenetic analyses of relative tooth size yield information about evolutionary dental trends not previously reported inH. nalediand the other hominins. Moreover, with an appropriate model these data recovered plausible evolutionary relationships. Together, the findings support recent study suggestingH. naledioriginated long before the geological date of the Dinaledi Chamber, from which the specimens under study were recovered.

    

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