Evolution of groundwater system in the Pearl River Delta and its adjacent shelf since the late Pleistocene.

Our extensive field studies demonstrate that saline groundwater inland and freshened groundwater offshore coexist in the same aquifer system in the Pearl River delta and its adjacent shelf. This counterintuitive phenomenon challenges the commonly held assumption that onshore groundwater is typically fresh, while offshore groundwater is saline. To address this knowledge gap, we conduct a series of sophisticated paleo-hydrogeological models to explore the formation mechanism and evolution process of the groundwater system in the inland-shelf systems. Our findings indicate that shelf freshened groundwater has formed during the lowstands since late Pleistocene, while onshore saline groundwater is generated by paleo-seawater intrusion during the Holocene transgression. This reveals that terrestrial and offshore groundwater systems have undergone alternating changes on a geological timescale. The groundwater system exhibits hysteresis responding to paleoclimate changes, with a lag of 7 to 8 thousand years, suggesting that paleoclimatic forcings exert a significantly residual influence on the present-day groundwater system.

Exploring role of green financing in blockchain markets for climate change mitigation in China.

This study explores the potential of green finance as a strategic method to addressing climate change mitigation in China's blockchain industry. This research methodically analyzes a large dataset collected from many sources across the period between 1999 and 2020. Using a mixed approach of quantitative research and qualitative case studies, this study delves into the tangled web of relationships between alternative finance sources for green initiatives and the use of blockchain technology to promote more environmentally friendly business practices. The results provide light on how green finance and blockchain technologies might work together to boost China's climate change mitigation efforts, revealing fresh insights into the possible synergies and obstacles that erupt from this intersection. In response to the worsening climate problem, there is a pressing need for unconventional methods of financing that can lead holistic sustainable growth. Concurrently, blockchain technology's disruptive potential reverberates across numerous sectors. However, research on blockchain's potential for combating climate change, especially in conjunction with green funding systems, is still in its infancy. Intrinsic interest has motivated this study, which provides a new viewpoint on paths that might transform climate change mitigation in China by mapping the unexplored territory at the intersection of the green finance and blockchain sectors. This research hopes that by examining this interface, it will shed light on the hidden opportunities presented by the combination of green financing and blockchain innovation, allowing for more well-informed and effective decisions to be made in support of environmentally sustainable futures.

Storm accelerated subsurface Escherichia coli growth and exports to coastal waters.

Storm significantly deteriorates coastal water fecal pollution now and beyond. Questions relating to storm exerting on coastal water safety are often intertwined with both surface water and subsurface processes. Stormwater runoff is a vital metric for coastal water fecal pollution under current cognition, while the controls of subsurface system remain unclear. Here, this study leveraged two time-series field data collected in a sandy beach during storm and non-storm periods to probe subsurface Escherichia coli (E. coli) growth and exports to coastal waters under storm events. Results demonstrated that storm events can not only stimulate subsurface E. coli growth, but also accelerate subsurface E. coli exports into the receiving water. Storm-intensified rainfall injected more oxygenous rainwater in the shallow groundwater, subsequently stimulating subsurface E. coli growth. Storm-strengthened wave energy was responsible for accelerating subsurface E. coli exports through enhanced wave-induced recirculated seawater. This study proposes a new insight for the stress of storm events on microbial pollution in coastal waters. The findings are constructive to the prevention of beach ecosystem pollution and can pave the way for coastal safety management to future extreme weather.

Effective coastal Escherichia coli monitoring by unmanned aerial vehicles (UAV) thermal infrared images.

Coastal Escherichia coli (E. coli) significantly influence ocean safety and public health, thus requiring an effective E. coli pollution monitoring. However conventional detection relying on manual field sampling is time-consuming. Here, this study established an E. coli estimation model based on thermal remote sensing of unmanned aerial vehicles (UAV). This model was developed against one-year comprehensive field work in a representative sandy beach and further validated against 50 beaches in Hong Kong to evaluate its applicability. The estimated E. coli concentrations were in a reliable agreement with direct measurements. For this model, this study deployed the radon-222 (222Rn) as a bridging tracer to couple UAV thermal images and coastal E. coli concentrations. Coastal 222Rn can be reflected on the UAV thermal images, and there was a good positive correlation between the 222Rn activity and coastal E. coli concentration via one-year field data. Hence, coupling the 222Rn activity estimated from UAV thermal images and the relationship between 222Rn and E. coli, this study can readily monitor coastal E. coli by UAV. These findings highlighted that UAV technology is an effective approach to measure the E. coli concentrations and can further pave the way for an efficient coastal E. coli monitoring and public health risk warning.

Microbial community assembly and co-occurrence relationship in sediments of the river-dominated estuary and the adjacent shelf in the wet season.

In the estuarine ecosystem, microbial community plays a vital role in controlling biogeochemical processes. However, there is currently limited comprehensive study on the deterministic and stochastic processes that drive the microbial community assembly in the estuaries and adjacent shelves. In this study, we systematically investigated the co-occurrence relationship and microbial community assembly in the sediments along a large river-dominated estuary to shelf in the northern South China Sea during the wet season. The sampling sites were divided into estuary, transection, and shelf sections based on their salinity values. The microbial co-occurrence networks, hierarchical partitioning-based canonical analysis, null model, neutral community model, and the Mantel test were used to investigate the community assembly. Results suggested that microbial community in the estuary section exhibited more interactions and a higher positive interaction ratio than those in the transition and shelf sections. Stochastic processes dominated community assembly in the study, with homogenizing dispersal contributing the most. The estuary exhibited a higher degree of heterogeneous selection than the transition and shelf sections, whereas homogeneous selection showed an opposite trend. Only the estuary section showed dispersal limitation and undominated processes. The river inflow and the resulting environmental heterogeneity were believed to be the key regulators of the community assembly in the studied area. Our study improved the understanding of how microbial community assembly in estuaries and adjacent shelves.

Delineating E. coli occurrence and transport in the sandy beach groundwater system by radon-222.

Fecal pollution poses a global threat to environmental safety and ecosystem, but the mechanism of microbial transport and occurrence in the beach groundwater system is still poorly explored. Here, we leveraged one-year field data of Escherichia coli (E. coli) and radon-222 (222Rn) and found that E. coli occurrence and transport in the sandy beach groundwater system can be delineated by 222Rn. The underlying mechanism behind this phenomenon is due to similar half-lives of 222Rn and E. coli in the sandy beach groundwater system. Thus, the unique relationship between 222Rn and E. coli can provide additional critical context to the microbial water quality assessments and ecosystem resilience. Also, the beach aquifer in this study is found to be a vital compartment for E. coli removal. The net E. coli removal/production capacity is identified to be highly impacted by submarine groundwater discharge. Finally, a conceptual model is constructed for a better understanding of the occurrences and characteristics of E. coli and 222Rn at multiple spatial scales. These findings are constructive to mitigate the hazardous influences of microbe on water quality, especially in recreational sandy beaches and mariculture zones.

Pollution assessment and sources of dissolved heavy metals in coastal water of a highly urbanized coastal area: The role of groundwater discharge.

Heavy metal concentrations and physicochemical parameters in coastal waters were measured to analyze the spatial distribution characteristics, pollution degrees, and sources of heavy metals in the heavily urbanized Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China. Heavy metal concentrations in the eastern GBA were higher than those in the west, and the levels of Pb and Zn in seawater were higher than those in groundwater and river water. Both the pollution factors and comprehensive water quality index demonstrated that seawater was not contaminated with As, Cd, Cr, and Ni, whereas low to considerable levels of contamination of Pb and Zn were observed in the central and eastern sections of the GBA. Multiple statistical analyses suggested that the Pb and Zn contaminations in seawater were probably derived from atmospheric deposition and human activities, and the excess amounts of As, Cd, Cu, Ni, and Zn in groundwater were attributed to anthropogenic activities. The heavy metal fluxes from submarine groundwater discharge (SGD) were comparable to, or even greater than, those from local rivers. Therefore, SGD is a significant invisible contributor of heavy metals into the coastal ocean that has often been overlooked in comparison to other visible pollution sources. This study suggests that SGD should be considered in the assessment of heavy metal pollution and future water quality management protocols in marine ecosystems.

Stroke hospitalizations, posttraumatic stress disorder, and 9/11-related dust exposure: Results from the World Trade Center Health Registry.

BACKGROUND: Few studies have examined the association between disaster-related factors and stroke by subtype or number. We investigated the association between 9/11-related posttraumatic stress disorder (PTSD), dust exposure, and stroke subtype as well as recurrent strokes. METHODS: The study included 29,012 individuals enrolled in the World Trade Center Health Registry. Stroke cases were obtained by matching Registry enrollees to the New York State Department of Health's discharge records for inpatient visits between 2000 and 2016. Cox proportional hazards regression models were performed to examine the association between 9/11-related risk factors and stroke by subtype. Multinomial logistic regression models were conducted to assess the associations between the same risk factors and the number of stroke hospitalizations. RESULTS: Having PTSD significantly increased the risk of developing ischemic and hemorrhagic stroke, with adjusted hazards ratios (AHRs) of 1.64 (95% confidence interval [CI]: 1.28-2.10) and 1.73 (95% CI: 1.10-2.71), respectively. The point estimate for dust cloud exposure, although not significant statistically, suggested an increased risk of ischemic stroke (AHR = 1.20, 95% CI: 0.96-1.50). PTSD was significantly associated with recurrent strokes with an adjusted odds ratio of 1.79 (95% CI: 1.09-2.95). CONCLUSIONS: PTSD is a risk factor for both ischemic and hemorrhagic stroke and is associated with recurrent strokes. Dust exposure on 9/11 is a possible risk factor for ischemic stroke but not for hemorrhagic stroke, and was not associated with recurrent strokes. Our findings warrant additional research on stroke-morbidity and mortality associated with 9/11-related PTSD and dust exposure.

Effects of 9/11-related injury on retirement patterns among World Trade Center Health Registry enrollees.

BACKGROUND: Many survivors of the 9/11/2001 terrorist attacks in New York City sustained injuries. The aim of this study was to understand how 9/11-related injuries affected retirement patterns of World Trade Center Health Registry enrollees. METHODS: The study included enrollees who participated in the 2017 Health & Quality of Life Survey, focused on 9/11-related injuries and quality of life, and the 2017-2018 Health & Employment Survey, focused on retirement and employment (N = 3535). Using Cox proportional hazards and logistic regression modeling, we calculated the risk of retiring at earlier ages and the odds of retirees working again, controlling for relevant covariates. RESULTS: Results showed that 9/11-related injuries did affect retirement patterns. Injured enrollees were at greater risk of retiring at younger age compared to non-injured enrollees. Compared to more severely injured retirees, non-injured and less severely injured retirees were significantly more likely to work again postretirement. Our results suggested that being injured on 9/11 was associated with retirement, meaning that if the injury had not occurred, the individual may have continued working longer. CONCLUSIONS: The need to retire earlier than planned could be addressed with employer and societal changes. Employers should consider making accommodations for those impacted by 9/11 a priority, as it is imperative for those who were injured on 9/11 to have the ability to work to support their physical, mental, and financial well-being.

Proteogenomic Analysis Provides Novel Insight into Genome Annotation and Nitrogen Metabolism in Nostoc sp. PCC 7120.

Cyanobacteria, capable of oxygenic photosynthesis, play a vital role in nitrogen and carbon cycles. Nostoc sp. PCC 7120 (Nostoc 7120) is a model cyanobacterium commonly used to study cell differentiation and nitrogen metabolism. Although its genome was released in 2002, a high-quality genome annotation remains unavailable for this model cyanobacterium. Therefore, in this study, we performed an in-depth proteogenomic analysis based on high-resolution mass spectrometry (MS) data to refine the genome annotation of Nostoc 7120. We unambiguously identified 5,519 predicted protein-coding genes and revealed 26 novel genes, 75 revised genes, and 27 different kinds of posttranslational modifications in Nostoc 7120. A subset of these novel proteins were further validated at both the mRNA and peptide levels. Functional analysis suggested that many newly annotated proteins may participate in nitrogen or cadmium/mercury metabolism in Nostoc 7120. Moreover, we constructed an updated Nostoc 7120 database based on our proteogenomic results and presented examples of how the updated database could be used to improve the annotation of proteomic data. Our study provides the most comprehensive annotation of the Nostoc 7120 genome thus far and will serve as a valuable resource for the study of nitrogen metabolism in Nostoc 7120. IMPORTANCE Cyanobacteria are a large group of prokaryotes capable of oxygenic photosynthesis and play a vital role in nitrogen and carbon cycles on Earth. Nostoc 7120 is a commonly used model cyanobacterium for studying cell differentiation and nitrogen metabolism. In this study, we presented the first comprehensive draft map of the Nostoc 7120 proteome and a wide range of posttranslational modifications. In addition, we constructed an updated database of Nostoc 7120 based on our proteogenomic results and presented examples of how the updated database could be used for system-level studies of Nostoc 7120. Our study provides the most comprehensive annotation of Nostoc 7120 genome and a valuable resource for the study of nitrogen metabolism in this model cyanobacterium.

Quantitative Proteomics Reveals the Protein Regulatory Network of Anabaena sp. PCC 7120 under Nitrogen Deficiency.

Anabaena sp. PCC 7120 (Anabaena 7120) is a photoautotrophic filamentous cyanobacterium capable of fixing atmospheric nitrogen. It is a model organism used for studying cell differentiation and nitrogen fixation. Under nitrogen deficiency, Anabaena 7120 forms specialized heterocysts capable of nitrogen fixation. However, the molecular mechanisms involved in the cyanobacterial adaptation to nitrogen deficiency are not well understood. Here, we employed a label-free quantitative proteomic strategy to systematically investigate the nitrogen deficiency response of Anabaena 7120 at different time points. In total, 363, 603, and 669 proteins showed significant changes in protein abundance under nitrogen deficiency for 3, 12, and 24 h, respectively. With mapping onto metabolic pathways, we revealed proteomic perturbation and regulation of carbon and nitrogen metabolism in response to nitrogen deficiency. Functional analysis confirmed the involvement of nitrogen stress-responsive proteins in biological processes, including nitrogen fixation, photosynthesis, energy and carbon metabolism, and heterocyst development. The expression of 10 proteins at different time points was further validated by using multiple reaction monitoring assays. In particular, many dysregulated proteins were found to be time-specific and involved in heterocyst development, providing new candidates for future functional studies in this model cyanobacterium. These results provide novel insights into the molecular mechanisms of nitrogen stress responses and heterocyst development in Anabaena 7120.

Impact of Health on Early Retirement and Post-Retirement Income Loss among Survivors of the 11 September 2001 World Trade Center Disaster.

The health consequences of the 9/11 World Trade Center (WTC) terrorist attacks are well documented, but few studies have assessed the disaster's impact on employment among individuals exposed to the disaster. We examined the association between 9/11-related health conditions and early retirement among residents and workers who resided and/or worked near the WTC site on 9/11, and the association between such conditions and post-retirement income loss. The study included 6377 residents and/or area workers who completed the WTC Health Registry longitudinal health surveys in 2003-2004 and 2006-2007, and the 2017-2018 Health and Employment Survey. Logistic regression models were used to examine the associations. We found that 9/11-related health conditions were significantly associated with the likelihood of early retirement. Residents and/or area workers with more physical health conditions, especially when comorbid with posttraumatic stress disorder (PTSD), were more likely to retire before age 60 than those with no conditions. For retirees, having PTSD or PTSD comorbid with any number of physical conditions increased the odds of reporting substantial post-retirement income loss. Disaster-related outcomes can negatively impact aging individuals in the form of early retirement and income loss. Long-term effects of major disasters must continue to be studied.

A Cognitive Reserve and Social Support-Focused Latent Class Analysis to Predict Self-Reported Confusion or Memory Loss among Middle-Aged World Trade Center Health Registry Enrollees.

The World Trade Center Health Registry includes 9/11 survivors who have been surveyed about their health conditions over time. The prevalence of posttraumatic stress disorder (PTSD) remains high among the cohort and is a risk factor for cognitive impairment or dementia. We thus sought to examine the degree to which confusion or memory loss (CML)-potential symptoms of cognitive decline-are occurring among enrollees aged 35-64 years. Cognitive reserve theory suggests that higher levels of education and engaging in cognitively challenging activities can create stronger neural connections, offering protection against cognitive decline. We hypothesized that enrollees with less cognitive reserve would be more likely to report CML. In this study, we: (1) estimated the incidence of CML in our study sample; (2) identified indicators of cognitive reserve (e.g., indicators of educational attainment, social support); and (3) determined whether CML is associated with cognitive reserve level, stratified by PSTD status. First, we described demographics of the study sample (n = 14,574) and probable PTSD status, also stratifying by CML. Next, we conducted a latent class analysis on two groups: those with probable PTSD and those without probable PTSD, creating classes with varying cognitive reserve levels. Finally, using adjusted log binomial models, we predicted risk of CML based on cognitive reserve level. The probable PTSD group (n = 1213) and not probable PTSD group (n = 13,252) each had four latent classes: low, medium-low, medium-high, and high cognitive reserve. In the probable PTSD model, compared to the high cognitive reserve class, those with medium-low cognitive reserve were 35% more likely to report CML (relative risk (RR) = 1.4, 95% confidence interval (CI): 1.1, 1.7). Among the not probable PTSD group, those with low and medium levels of cognitive reserve were significantly more likely to report CML (RR = 1.8 and 1.4, respectively). Overall, those with less cognitive reserve were more likely to report CML regardless of PTSD status.

Risk of Stroke Among Survivors of the September 11, 2001, World Trade Center Disaster.

OBJECTIVE: The aim of this study was to investigate the association between 9/11-related posttraumatic stress disorder (PTSD), dust cloud exposure, and subsequent development of stroke among 42,527 enrollees in the World Trade Center (WTC) Health Registry. METHODS: Using four waves of longitudinal data from the WTC Health Registry surveys, we employed Cox proportional hazards regression models to assess the associations. RESULTS: Incidence of stroke was higher among those with PTSD or intense dust cloud exposure than those without, and it was even higher for those who had experienced both. In fully adjusted models, participants with PTSD had an increased risk of developing stroke [adjusted hazards ratio (AHR) 1.69, 95% confidence interval (95% CI) 1.42 to 2.02], as did those with intense dust exposure (AHR 1.29, 95% CI 1.09 to 1.53). CONCLUSION: We found that individuals with 9/11-related PTSD and/or intense dust exposure may have an increased risk of developing stroke.

Characterization of the Catalytic Subunits of the RNA Exosome-like Complex in Plasmodium falciparum.

The eukaryotic ribonucleic acid (RNA) exosome is a versatile multiribonuclease complex that mediates the processing, surveillance, and degradation of virtually all classes of RNA in both the nucleus and cytoplasm. The complex, composed of 10 to 11 subunits, has been widely described in many organisms. Bioinformatic analyses revealed that there may be also an exosome-like complex in Plasmodium falciparum, a parasite of great importance in public health, with eight predicted subunits having high sequence similarity to their counterparts in yeast and human. In this work, the putative RNA catalytic components, designated as PfRrp4, PfRrp41, PfDis3, and PfRrp6, were identified and systematically analyzed. Quantitative polymerase chain reaction (QPCR) analyses suggested that all of them were transcribed steadily throughout the asexual stage. The expression of these proteins was determined by Western blot, and their localization narrowed to the cytoplasm of the parasite by indirect immunofluorescence. The recombinant proteins of PfRrp41, PfDis3, and PfRrp6 exhibited catalytic activity for single-stranded RNA (ssRNA), whereas PfRrp4 showed no processing activity of both ssRNA and dsRNA. The identification of these putative components of the RNA exosome complex opens up new perspectives for a deep understanding of RNA metabolism in the malarial parasite P. falciparum.

Review of Non-Respiratory, Non-Cancer Physical Health Conditions from Exposure to the World Trade Center Disaster.

After the World Trade Center attacks on 11 September 2001 (9/11), multiple cohorts were developed to monitor the health outcomes of exposure. Respiratory and cancer effects have been covered at length. This current study sought to review the literature on other physical conditions associated with 9/11-exposure. Researchers searched seven databases for literature published in English from 2002 to October 2017, coded, and included articles for health condition outcome, population, 9/11-exposures, and comorbidity. Of the 322 titles and abstracts screened, 30 studies met inclusion criteria, and of these, 28 were from three cohorts: the World Trade Center Health Registry, Fire Department of New York, and World Trade Center Health Consortium. Most studies focused on rescue and recovery workers. While many of the findings were consistent across different populations and supported by objective measures, some of the less studied conditions need additional research to substantiate current findings. In the 16 years after 9/11, longitudinal cohorts have been essential in investigating the health consequences of 9/11-exposure. Longitudinal studies will be vital in furthering our understanding of these emerging conditions, as well as treatment effectiveness.

Injury, intense dust exposure, and chronic disease among survivors of the World Trade Center terrorist attacks of September 11, 2001.

BACKGROUND: The World Trade Center attack of September 11, 2001 in New York City (9/11) exposed thousands of people to intense concentrations of hazardous materials that have resulted in reports of increased levels of asthma, heart disease, diabetes, and other chronic diseases along with psychological illnesses such as post-traumatic stress disorder (PTSD). Few studies have discriminated between health consequences of immediate (short-term or acute) intense exposures versus chronic residential or workplace exposures. METHODS: We used proportional hazards methods to determine adjusted hazard ratios (AHRs) for associations between several components of acute exposures (e.g., injury, immersion in the dust cloud) and four chronic disease outcomes: asthma, other non-neoplastic lung diseases, cardiovascular disease, and diabetes, in 8701 persons free of those conditions prior to exposure and who were physically present during or immediately after the World Trade Center attacks. Participants were followed prospectively up to 11 years post-9/11. RESULTS: Heart disease exhibited a dose-response association with sustaining injury (1 injury type: AHR =2.0, 95% CI (Confidence Interval) 1.1-3.6; 2 injury types: AHR = 3.1, 95% CI 1.2-7.9; 3 or more injury types: AHR = 6.8, 95% CI 2.0-22.6), while asthma and other lung diseases were both significantly associated with dust cloud exposure (AHR = 1.3, 95% CI 1.0-1.6). Diabetes was not associated with any of the predictors assessed in this study. CONCLUSION: In this study we demonstrated that the acute exposures of injury and dust cloud that were sustained on 9/11/2001 had significant associations with later heart and respiratory diseases. Continued monitoring of 9/11 exposed persons' health by medical providers is warranted for the foreseeable future.

The effectiveness of a monetary incentive offer on survey response rates and response completeness in a longitudinal study.

BACKGROUND: Achieving adequate response rates is an ongoing challenge for longitudinal studies. The World Trade Center Health Registry is a longitudinal health study that periodically surveys a cohort of ~71,000 people exposed to the 9/11 terrorist attacks in New York City. Since Wave 1, the Registry has conducted three follow-up surveys (Waves 2-4) every 3-4 years and utilized various strategies to increase survey participation. A promised monetary incentive was offered for the first time to survey non-respondents in the recent Wave 4 survey, conducted 13-14 years after 9/11. METHODS: We evaluated the effectiveness of a monetary incentive in improving the response rate five months after survey launch, and assessed whether or not response completeness was compromised due to incentive use. The study compared the likelihood of returning a survey for those who received an incentive offer to those who did not, using logistic regression models. Among those who returned surveys, we also examined whether those receiving an incentive notification had higher rate of response completeness than those who did not, using negative binomial regression models and logistic regression models. RESULTS: We found that a $10 monetary incentive offer was effective in increasing Wave 4 response rates. Specifically, the $10 incentive offer was useful in encouraging initially reluctant participants to respond to the survey. The likelihood of returning a survey increased by 30% for those who received an incentive offer (AOR = 1.3, 95% CI: 1.1, 1.4), and the incentive increased the number of returned surveys by 18%. Moreover, our results did not reveal any significant differences on response completeness between those who received an incentive offer and those who did not. CONCLUSIONS: In the face of the growing challenge of maintaining a high response rate for the World Trade Center Health Registry follow-up surveys, this study showed the value of offering a monetary incentive as an additional refusal conversion strategy. Our findings also suggest that an incentive offer could be particularly useful near the end of data collection period when an immediate boost in response rate is needed.

Impact of 9/11-related chronic conditions and PTSD comorbidity on early retirement and job loss among World Trade Center disaster rescue and recovery workers.

BACKGROUND: The economic impact of the 9/11 terrorist attacks has rarely been studied. We examined the association between 9/11-related chronic health conditions with or without post-traumatic stress disorder (PTSD) and one important aspect of the economic impact, retirement, and job loss before age 60. METHODS: A total of 7,662 workers who participated in the World Trade Center Health Registry surveys were studied. Logistic regression models examined the association of 9/11-related health and labor force exit. RESULTS: Workers with chronic conditions were more likely to experience early retirement and job loss, and the association was stronger in the presence of PTSD comorbidity: the odds ratios for reporting early retirement or job loss were increased considerably when chronic conditions were comorbid with PTSD. CONCLUSIONS: Disaster-related health burden directly impacts premature labor force exit and income. Future evaluation of disaster outcome should include its long-term impact on labor force. Am. J. Ind. Med. 59:731-741, 2016. © 2016 Wiley Periodicals, Inc.

Evaluation of non-response bias in a cohort study of World Trade Center terrorist attack survivors.

BACKGROUND: Few longitudinal studies of disaster cohorts have assessed both non-response bias in prevalence estimates of health outcomes and in the estimates of associations between health outcomes and disaster exposures. We examined the factors associated with non-response and the possible non-response bias in prevalence estimates and association estimates in a longitudinal study of World Trade Center (WTC) terrorist attack survivors. METHODS: In 2003-04, 71,434 enrollees completed the WTC Health Registry wave 1 health survey. This study is limited to 67,670 adults who were eligible for both wave 2 and wave 3 surveys in 2006-07 and 2011-12. We first compared the characteristics between wave 3 participants (wave 3 drop-ins and three-wave participants) and non-participants (wave 3 drop-outs and wave 1 only participants). We then examined potential non-response bias in prevalence estimates and in exposure-outcome association estimates by comparing one-time non-participants (wave 3 drop-ins and drop-outs) at the two follow-up surveys with three-wave participants. RESULTS: Compared to wave 3 participants, non-participants were younger, more likely to be male, non-White, non-self enrolled, non-rescue or recovery worker, have lower household income, and less than post-graduate education. Enrollees' wave 1 health status had little association with their wave 3 participation. None of the disaster exposure measures measured at wave 1 was associated with wave 3 non-participation. Wave 3 drop-outs and drop-ins (those who participated in only one of the two follow-up surveys) reported somewhat poorer health outcomes than the three-wave participants. For example, compared to three-wave participants, wave 3 drop-outs had a 1.4 times higher odds of reporting poor or fair health at wave 2 (95% CI 1.3-1.4). However, the associations between disaster exposures and health outcomes were not different significantly among wave 3 drop-outs/drop-ins as compared to three-wave participants. CONCLUSION: Our results show that, despite a downward bias in prevalence estimates of health outcomes, attrition from the WTC Health Registry follow-up studies does not lead to serious bias in associations between 9/11 disaster exposures and key health outcomes. These findings provide insight into the impact of non-response on associations between disaster exposures and health outcomes reported in longitudinal studies.