Perceived and Internalized Stigma Towards Suicide and Their Roles in Suicidal Thoughts and Behaviors Among Chinese College Students.

Although perceived and internalized suicide stigma are considered risk factors for suicidal thoughts and behaviors (STBs), their specific roles in STBs are not well understood. This study examined the relationships among perceived and internalized suicide stigma, hopelessness, unbearable pain, suicidal desire, and suicide attempts in college students. A total of 1,387 Chinese college students (mean age: 22.22 years) completed the relevant scales. Structural equation modeling was used to determine the relationships of interest. The results showed that perceived stigma primarily had indirect impacts on suicidal desire through internalized stigma, which subsequently affected unbearable pain and hopelessness. The findings of this study suggest that the internalization of suicide stigma is an important predictor of STBs. These findings advocate for stigma interventions aimed at reducing internalized stigma as a potentially effective strategy for suicide prevention, as it may alleviate unbearable pain and hopelessness, which are significant contributors to suicidal desire and attempts.

Sex differences in hemispheric lateralization of attentional networks.

Males and females differ in various abilities. However, sex differences in hemispheric lateralization of attentional processing are still not well-understood. Using a lateralized version of the attentional network test that combines the Posner cueing paradigm and visual field methodology, we aimed to examine sex differences in the lateralization of several attentional processes including alerting, executive control, orienting benefit, reorienting, and orienting cost. Fifty-six females and 59 males participated in this study. We found a left visual field (right hemisphere) advantage for alerting defined by the differences between no-cue and center-cue conditions in the male group, but it was mainly attributed to the left visual field advantage in the no-cue condition. In contrast, the female group exhibited a left visual field advantage in the center-cue condition. Both groups showed preferences to the left visual field for reorienting and orienting cost, but females exhibited larger effects. This indicates that the two sexes exhibit similarities in terms of the lateralization of these two attentional processes. Furthermore, the interactions between executive control and reorienting/orienting cost were more efficient in males than in females. The current study highlights sex differences in the hemispheric lateralization of attentional networks and possible underlying neural substrates.

Metabolic profile changes of zebrafish larvae in the single- and co-exposures of microplastics and phenanthrene.

Microplastics (MPs) are ubiquitous in the environment, and can adsorb organic contaminants (OCs) and be taken by various microorganisms and organisms, which could eventually lead to risk to humans. In this study, the phenotypic changes and metabolic profile alternations of zebrafish in the single- and co-exposure of MPs and phenanthrene (Phe) were investigated. The results showed that significantly higher tail malformation rate and edema rate in zebrafish induced by MPs can be enhanced due to the co-existence of Phe. The metabolomic analysis revealed that both synergistic and antagonistic effects of MPs and Phe on the metabolic alternation of zebrafish larvae exist, since unique perturbations of metabolites or pathways were found in all of the three exposure scenarios. Based on Partial least squares-discriminant analysis, porphine, ribose, and L-glutamic acid were the most important metabolites resulting in the difference between the treated and control groups in the MP exposure, Phe exposure and co-exposure, respectively. Two dysregulated pathways namely d-glutamine and D-glutamate metabolism, and alanine, aspartate and glutamate metabolism were significantly affected in the co-exposure while not in either of the single exposure. These findings provide new insights into the toxic effects of MPs on aquatic organisms, and further studies on combined effects of MPs and OCs are suggested to be conducted.

Occurrence and correlation of microplastics and dibutyl phthalate in rivers from Pearl River Delta, China.

Microplastics have been identified as the novel contaminants in various environments. Phthalates would be released from plasticized microplastics into a riverine environment while transporting to a marine region, but data on their relationship in rivers have been scarce. In this study, the occurrence, distribution and correlation of microplastics and dibutyl phthalate (DBP) in two rivers from the Pearl River Estuary were investigated. The elevated level of DBP in the Qianshan River (2.70 ± 0.20 µg/L) was in alignment with the presence of highest microplastic concentration at the same sampling site (15.8 ± 9.8 items/L). A positive correlation was observed between microplastics and DBP in all sampling sites (p < 0.05). The results showed that UV irradiation from sunlight was a majorly inducing factor of DBP leaching from polyethylene microplastics. The concentrations of chemical additives in some degrees reflect the microplastic pollution, but environmental factors and multidimensionality of microplastics such as residence times and types may cause spatial differences of chemical additives in aquatic systems.

Quantitative and qualitative determination of microplastics in oyster, seawater and sediment from the coastal areas in Zhuhai, China.

Microplastics as a new class of environmental contaminants have become the hot issue of global concern. We conducted quantitative and qualitative experiments to investigate microplastics in oyster, seawater and sediment along the Zhuhai coastline. The soft tissues of oysters were digested with potassium hydroxide (10%) and hydrogen peroxide (30%), seawaters and sediments with hydrogen peroxide (30%) to degrade organic matter, and analyzed using a digital camera, optical microscopy and micro-ATR-FTIR. The abundance of microplastics were in the range of 0.14-7.90 n/g in oysters (wet weight), 10.00-27.50 n/L in seawaters and 0.053-0.26 n/g in sediments. The fiber and fragment shape, black color, 101-500 µm of size and polyethylene composition were all classified as the major constituents of microplastics. The level of contaminants in oysters was correlated to those in their surrounding environments. Therefore, oysters may serve as a promising sentinel species for the indication of microplastic pollution in the coastal zone of Zhuhai.

Photo-oxidation of particle phase iron species dominates the generation of reactive oxygen species in secondary aerosol.

This study presents an experimental investigation on the photochemical transformation of iron species in aerosol including dissolution of insoluble iron species into soluble fraction, and soluble ferric oxidation to ferrous form. This process has significantly contributed to the aerosol oxidative potential in generation of reactive oxygen species (ROS). We conducted both laboratory experiment of UV irradiation and real world solar irradiation on large variation of aerosol samples for the characterization of iron speciation in insoluble and soluble fractions to investigate their transformation under photooxidation process. The results showed that the real world solar irradiation significantly increased the soluble Fe(II) fraction, and this is corroborated by laboratory simulation of UV irradiation showing increasing soluble Fe(II) fraction with elongating aging time. The results further exhibited that the dissolution of iron component into soluble fraction was a dominant process, followed by the conversion of soluble ferric to ferrous ions. Further, the study confirmed that the oxidative potential of particulate matter (PM) is attributed dominantly to the abundance of transition metals, i.e. Fe, and the incremental ROS generation after photochemical process is attributed largely to the transformation of solid phase iron species to soluble Fe(II). The results suggest that transition metals, for example by iron in this study, play an important role in secondary aerosol process.

Chemical characterization of size-segregated PM from different public transport modes and implications of source specific contribution to public exposure.

To investigate the chemical properties of particulate matter (PM) in different public transport microenvironments in Hong Kong, the coarse (2.5-10 µm) and fine (<2.5 µm) PM samples were collected in three different types of transport modes including Mass Transit Railway (MTR)-Aboveground (AG), MTR Underground (UG), and Bus routes from October 2013 to April 2014. Average PM2.5 concentrations through UG, AG, and Bus routes were 47.9, 86.8, and 43.8 µg m-3, respectively, whereas the coarse PM concentrations were 4-5 folds less. The PM2.5 total metal concentrations of AG route were 2.3 and 3.7 times of UG and BUS routes, respectively, compared to those in the other two routes. The most abundant metals at three stations in PM2.5 and coarse PM were quite similar and mainly generated by frictional processes of wheels, rails, and brakes of the system as well as by the mechanical wearing of these parts. The most abundant PAH in three routes in PM2.5 was ATRQN, followed by 2-MNA, and the sum of them contributed to 35 and 42% of total PAHs in coarse PM and PM2.5, respectively. Crude oils, lubricant oil, diesel emissions would be the major sources of PAHs from MTR aboveground stations. The relative abundance of the n-alkanes among different samples was similar to the PAHs and the carbon preference index (CPI) values of the whole n-alkanes range were consistently from 0.99 to 1.04 among all samples indicating the significant contribution from the vehicle exhaust and fossil fuel burning. The concentrations of hopanes and steranes were higher in PM2.5 than in coarse PM due to diesel and coal burning. These results may provide a unique opportunity to investigate source specific contribution of the PM pollutants to the commuter exposure in public transport.

Source apportionment and water solubility of metals in size segregated particles in urban environments.

Metals in atmospheric particulate matter (PM) have been associated with various adverse health effects. Different factors contributing to the characterization and distribution of atmospheric metals in urban environments lead to uncertainty of the understanding of their impact on public health. However, few studies have provided a comprehensive picture of the spatial and seasonal variability of metal concentration, solubility and size distribution, all of which have important roles in their contribution to health effects. This study presents an experimental investigation on the characteristics of metals in PM2.5 and coarse PM in two seasons from four urban sites in Hong Kong. The PM samples were extracted separately with aqua regia and water, and a total of sixteen elements were analyzed using ICP-MS and ICP-OES to determine the size segregated concentration and solubility of metals. The concentrations of major metals were distributed in similar patterns with the same order of magnitude among different urban sites. Source apportionment using Positive Matrix Factorization (PMF) indicated that three sources namely road dust, vehicular exhaust and ship emission are major contributors to the urban atmospheric metal concentrations in Hong Kong with distinctly different profiles between coarse PM and PM2.5 fractions. The individual metals were assigned to different sources, consistent with literature documentation, except potassium emerging with substantial contribution from vehicle exhaust emission. Literature data from past studies on both local and other cities were compared to the results from the present study to investigate the impact of different emission sources and control policies on metal distribution in urban atmosphere. A large variation of solubility among the metals reflected that the majority of metals in PM2.5 were more soluble than those in coarse PM indicating size dependent chemical states of metals. The data from this study provides a rich dataset of metals in urban atmosphere and can be useful for targeted emission control to mitigate the adverse impact of metallic pollution on public health.

Spatial and seasonal heterogeneity of atmospheric particles induced reactive oxygen species in urban areas and the role of water-soluble metals.

Adverse health effects are associated with exposure to atmospheric particulate matter (PM), which carry various chemical constituents and induce both exogenous and endogenous oxidative stress. This study investigated the spatial and seasonal variability of PM-induced ROS at four sites with different characteristics in Hong Kong. Cytotoxicity, exogenous and endogenous ROS was determined on a dose and time dependent analysis. Large spatial variation of ROS was observed with fine PM at urban site showing highest ROS levels while coarse PM at traffic site ranks the top. No consistent seasonal difference was observed for ROS levels among all sites. The highly heterogeneous distribution of PM-induced ROS demonstrates the differential capability of PM to produce oxidative stress, and the need to use appropriate metrics as surrogates of exposure instead of PM mass in epidemiologic studies. Several transition metals were found associated with ROS by different degree illustrating the complexity of mechanisms involved.