High-Throughput Computational Screening of All-MXene Metal-Semiconductor Junctions for Schottky-Barrier-Free Contacts with Weak Fermi-Level Pinning.

Van der Waals (vdW) metal-semiconductor junctions (MSJs) exhibit huge potential to reduce the contact resistance and suppress the Fermi-level pinning (FLP) for improving the device performance, but they are limited by optional (2D) metals with a wide range of work functions. Here a new class of vdW MSJs entirely composed of atomically thin MXenes is reported. Using high-throughput first-principles calculations, highly stable 80 metals and 13 semiconductors are screened from 2256 MXene structures. The selected MXenes cover a broad range of work functions (1.8-7.4 eV) and bandgaps (0.8-3 eV), providing a versatile material platform for constructing all-MXene vdW MSJs. The contact type of 1040 all-MXene vdW MSJs based on Schottky barrier heights (SBHs) is identified. Unlike conventional 2D vdW MSJs, the formation of all-MXene vdW MSJs leads to interfacial polarization, which is responsible for the FLP and deviation of SBHs from the prediction of Schottky-Mott rule. Based on a set of screening criteria, six Schottky-barrier-free MSJs with weak FLP and high carrier tunneling probability (>50%) are identified. This work offers a new way to realize vdW contacts for the development of high-performance electronic and optoelectronic devices.

The relationship of residential formaldehyde pollution in 11 Chinese cities to schoolchildren pneumonia prevalence in actual living condition.

Residential formaldehyde pollution is one of the leading residential harmful pollutants with a large production and consumption globally and remains much uncertainty in Chinese families with huge health burden for children worldwide. A multi-center observation study from 11 cities was conducted to investigate residential formaldehyde pollution levels measured by phenol reagent spectrophotometry. Data on household characteristics and schoolchildren's health were collected by questionnaire. The median concentration of residential formaldehyde was 0.025 (0.002-0.281) mg/m3 among 11 cities with the total exceeding standard rate of 7.40% according to the reference value of 0.10 mg/m3 (1-h average). Residential formaldehyde pollution in warm season, bedrooms and northern cities was more serious than that in cold season, living rooms and southern cities, respectively. The potential influencing factors of residential formaldehyde included household characteristics (distance from a traffic road, building history, residence duration, window glass layers, decoration and furniture) and use of air conditioner. The positive regulation effect of temperature on residential formaldehyde was explored with the approximately turning-point temperature of 28.9 °C for peak concentration. Long-term exposure to residential formaldehyde of low concentrations (0.010-0.090 mg/m3) would increase the prevalence of childhood pneumonia and a more stringent criteria value for residential formaldehyde should be discussed cautiously.

Levels, distributions and influential factors of residential airborne culturable bacteria in 12 Chinese cities: Multicenter on-site survey among dwellings.

Residential airborne culturable bacteria (RAB) are commonly used to assess indoor microbial loads, which is a very effective and recognized indicator of public concern about residential air quality. Many countries and organizations have set exposure limits for residential bacteria. Nevertheless, few studies have been conducted in multicenter cities about the distribution and influencing factors of RAB. It is a challenge to investigate the distribution of RAB and identify the association between indoor influencing variables and RAB in China. The current finding implied the comparative results from a one-year on-site survey of 12 cities in China. The concentration of RAB ranged from 0 CFU/m3 to 18,078 CFU/m3, with an arithmetic median of 350 CFU/m3. RAB concentrations were more in the warm season than those in the cold season, and were more in the bedrooms than those in the living rooms. Indoor environmental indicators (including PM2.5 and PM10) showed the mediating role in the process of temperature and relative humidity effects on RAB. . Influential factors including family-related information (income), architectural characteristics (house type, building history, living floor, the layers of window glass, and decoration) and lifestyle behaviors (heating, new furniture, incense-burned, insecticides-used, air condition-used, and plants-growed) were related with the concentration of RAB. This study presents essential data on the distribution of RAB in some Chinese cities, and reveals the residential influential factors that might minimize health risk from RAB.

Association of indoor noise level with depression in hotel workers: A multicenter study from 111 China's cities.

Several studies have elucidated the link between outdoor noise and depression, but the relationship between indoor noise levels and depression symptoms in residential and public places remains unclear. This study was a multicenter observational study with a cross-sectional design. In 2019, a total of 10 545 indoor noise levels on-site and 26 018 health data from practitioners were collected from 2402 hotels in 111 cities. Indoor daily noise data levels were detected, and PHQ-9 questionnaires were used to collect health data. Logistic analysis was used to determine the association between depression score and noise level, negative binomial regression was used to determine potential risks. The geometric mean indoor noise level was 38.9 dB (A), with approximately 40.9% of hotels exceeding the 45 dB value (A). Approximately 19.1% of hotel workers exhibited mild and above depressive symptoms. In addition to functional zoning, geographic location, central air conditioner, decoration status, and other factors had an impact on noise levels (p < 0.05). Results of logistic and negative binomial regression showed the following: (1) there was significantly positive association between indoor noise and high depression scores above 2 (OR = 1.007, 95% CI: 1.002, 1.012) and (2) some sub-groups were more susceptible to this effect, especially for the younger female workers working in the first-tier cities, having higher education level, lower level of income, smoking, and longer working hours. This study confirms an early potential effect of indoor noise on depression. It is recommended to implement evidence-based measures to control noise sources in hotels.

Characteristics, distribution, and children exposure assessment of 13 metals in household dust in China: A big data pilot study.

To explore the pollution characteristics of metals in household dust in China and their exposure to children, this study searched peer-reviewed papers published during 1980-2020 and analyzed 30 eligible papers screened under the per-decided strategy. We evaluated the sample-weighted concentration (SWC) of each metal, explored the sources of metals, and presented the quantitative description of spatial-temporary characteristics and children exposure to 13 metals with multi-route under a general living scenario. The results showed the concentrations of 13 metals with a range of 0.89-29 090.19 mg/kg. The SWC of Cd in household dust from rural areas was 3.29 times of that from urban areas, while the SWC of Ni from urban areas was 3.71 times of that from rural areas. The results showed that four principal components were extracted, and the cumulative contribution rate reached 79.127%. The exposure dose of 13 metals to children aged 2-3 years was presented with the highest by ingestion. Metals such as Fe, Zn, and Mn posed inevitable health risk to children with high exposure. Countermeasures should be carried out to minimize the children exposure to metals in household dust urgently, such as the establishment of environmental health standard for household dust.

Effect of the phthalates exposure on sex steroid hormones in the US population.

BACKGROUND: New alternative phthalates have been increasingly substituted for certain phthalates in some consumer products due to safety concerns. However, research on the steroidal effect of exposure to the newer replacement phthalates in the general adult population is lacking. OBJECTIVES: This study aimed to examine the associations of exposure to the older generation and newer replacement phthalates with sex hormone levels in the U.S. general population. METHODS: The current cross-sectional study was based on the National Health and Nutrition Examination Survey (NHANES) 2015-2016. Sixteen urinary phthalates metabolites and three serum sex hormones were measured in 1768 adults. Gender-specific associations between urinary phthalate concentrations and sex hormones were estimated by using adjusted multiple linear regression. Logistic regression was performed to calculate the risk of phthalates exposure on hormones dysfunction. RESULTS: Most phthalates metabolites concentrations were lower than 50 ng/mL. MEP, MBP, MiBP, MECPP, MCOP, MEHHP, MEOHP were higher than others, suggesting that new alternative DEP, DBP, and DiNP were exposed at high levels in daily life while DINCH was at a low level. Phthalates exposure was associated with decreased testosterone levels and increased estradiol and SHBG in total samples. Testosterone level was negatively associated with MnBP (ß: -0.05, 95% CI: -0.09, 0), MEOHP (ß:-0.05, 95% CI:-0.09,-0.01), MEHHP (ß:-0.04, 95% CI:-0.08,0), MECPP (ß:-0.07, 95% CI:-0.11,-0.03), MEP (ß: -0.03, 95% CI: -0.06, 0), MiBP (ß: -0.05, 95% CI: -0.10, -0.01) in males; ln-transformed estradiol were increased by 0.18 pg/mL (95% CI: 0.05,0.31), 0.15 pg/mL (95% CI: 0.01,0.29) with each 1 ln-concentration increase in MEHP and MNP, respectively, in females. CONCLUSIONS: Our results suggest that phthalates exposure may disturb the hormone homeostasis in adults. The safe alternative should be used with caution in industrial production in the future and the need for further research into the safety of the new alternative replacements is necessary.

Surface-enhanced Raman scattering of monolayer transition metal dichalcogenides on Ag nanorod arrays.

In this work, we studied surface-enhanced Raman scattering (SERS) of MS2 (M=Mo, W) monolayers that were transferred onto Ag nanorod arrays. Compared to the suspended monolayers, the Raman intensity of monolayers on an Ag nanorod substrate was strongly enhanced for both in-plane and out-of-plane vibration modes: up to 8 (5) for E2g and 20 (23) for A1g in MoS2 (WS2). This finding reveals a promising SERS substrate for achieving uniform and strong enhancement for two-dimensional materials in the applications of optical detecting and sensing.

Equally efficient interlayer exciton relaxation and improved absorption in epitaxial and nonepitaxial MoS2/WS2 heterostructures.

Semiconductor heterostructures provide a powerful platform to engineer the dynamics of excitons for fundamental and applied interests. However, the functionality of conventional semiconductor heterostructures is often limited by inefficient charge transfer across interfaces due to the interfacial imperfection caused by lattice mismatch. Here we demonstrate that MoS(2)/WS(2) heterostructures consisting of monolayer MoS(2) and WS(2) stacked in the vertical direction can enable equally efficient interlayer exciton relaxation regardless the epitaxy and orientation of the stacking. This is manifested by a similar 2 orders of magnitude decrease of photoluminescence intensity in both epitaxial and nonepitaxial MoS(2)/WS(2) heterostructures. Both heterostructures also show similarly improved absorption beyond the simple superimposition of the absorptions of monolayer MoS(2) and WS(2). Our result indicates that 2D heterostructures bear significant implications for the development of photonic devices, in particular those requesting efficient exciton separation and strong light absorption, such as solar cells, photodetectors, modulators, and photocatalysts. It also suggests that the simple stacking of dissimilar 2D materials with random orientations is a viable strategy to fabricate complex functional 2D heterostructures, which would show similar optical functionality as the counterpart with perfect epitaxy.

Cadmium Exposure was Associated with Sex-Specific Thyroid Dysfunction: Consistent Evidence from Two Independent Cross-Sectional Studies Based on Urinary and Blood Cadmium Measurements.

Population-based studies on the association between cadmium (Cd) exposure and thyroid function are limited and have shown conflicting results. Two independent cross-sectional studies using different Cd biomarkers were carried out in six rural areas with different soil Cd levels in China. Thyroid dysfunction was defined based on levels of thyroid stimulating hormone (TSH) and free thyroxine (FT4). Multivariable linear regression, multiple logistic regression, and restrictive cubic splines models were used to estimate the association between Cd and thyroid dysfunction. For both of the two independent studies, higher Cd levels were observed to be associated with lower TSH levels and higher risk of thyroid dysfunction. The negative relationship between urinary Cd and TSH was found in both total participants (ß = - 0.072, p = 0.008) and males (ß = - 0.119, p = 0.020) but not in females; however, the negative relationship between blood Cd and TSH was only found in females (ß = - 0.104, p = 0.024). Higher urinary Cd was associated with higher risk of thyroid dysfunction (OR = 1.77, p = 0.031), while higher blood Cd was associated with higher risk of thyroid dysfunction (OR = 1.95, p = 0.011). Results from the two independent cross-sectional studies consistently suggested that higher Cd levels were associated with sex-specific thyroid dysfunction.

Multi-element Exposure and Cognitive Function in Rural Elderly Chinese.

To investigate the relationship between selenium (Se) based multi-element combined exposure and cognitive function in rural elderly individuals, a cross-sectional study was conducted. The study involved 416 older adults aged 60 and above, residing in four different areas of Enshi county, China, with varying soil Se levels. Inductively coupled plasma mass spectrometry (ICP-MS) was employed to measure the concentrations of Se, copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), magnesium (Mg), cadmium (Cd), arsenic (As), and lead (Pb) in whole blood. Nine standard cognitive tests were applied to assess cognitive function. Analysis of the least absolute shrinkage and selection operator regression (LASSO), covariance (ANCOVA), and generalized linear model (GLM) were utilized to investigate the relationship between element exposure and cognitive function. The results of LASSO revealed that Se, Cu, Fe, Zn, Ca, and Pb were independently identified to be associated with cognition. Both ANCOVA and GLM demonstrated that Se and Ca were correlated with cognitive function. The multi-element model showed higher composite Z scores of 0.32 (95% CI: 0.09 to 0.55) for log-transformed Se (P = 0.007), 0.75 (95% CI: 0.01 to 1.49) for log-transformed Cu (P = 0.048), and a lower score of - 0.67 (95% CI: - 1.26 to - 0.08) for log-transformed Ca (P = 0.025). Furthermore, there was evidence that Se could counteract the negative impact of Ca on cognitive function (P for interaction = 0.031). Our findings suggested that higher levels of Se and Cu were associated with better cognitive function in the elderly and Se can counteract the cognitive damage caused by Ca.

Selenium Status Associates with Thyroid Hormone and Thyroid Dysfunction in Older Chinese Adults.

Selenium (Se) is physiologically essential for thyroid function. However, epidemiological studies on the association between Se status and thyroid function are limited and the results are inconsistent. Therefore, we explored this association in an elderly Chinese population sample. Participants in the cross-sectional study were people aged 65 years or older who provided fingernail and whole blood samples. Hyperthyroidism and hypothyroidism were defined by serum thyroid hormones concentrations, including thyroid stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free thyroxine (FT3), and free thyrotropin (FT4). Significant positive association was observed between whole blood and fingernail Se concentrations (r = 0.672, P < 0.001). Compared with the lowest Se quartile (Q1), the other fingernail Se quartile groups had lower TSH, higher FT3 and FT4 levels, and Q2 had higher TT3 levels after adjusting for covariates; the other whole blood Se quartile groups had lower TSH levels, Q2 had higher FT3, FT4 and TT3 levels, Q3 had higher FT3 levels, and Q4 had higher FT4 levels after adjusting for covariates. Compared with Q1, the adjusted odds ratios (OR) and 95% confidence intervals (95%CIs) of hypothyroidism for Q4 of whole blood Se was 0.141 (0.029,0.675), and the adjusted OR (95%CIs) of hyperthyroidism for Q2 and Q3 of fingernail Se were 4.121 (1.233,13.733) and 3.614 (1.095,11.926). Higher Se levels were significantly associated with lower TSH levels and higher levels of TT3, FT3 and FT4. Meanwhile, higher Se levels were associated with lower risk of hypothyroidism and higher risk of hyperthyroidism.

The association between per-/polyfluoroalkyl substances in serum and thyroid function parameters: A cross-sectional study on teenagers living near a Chinese fluorochemical industrial plant.

Thyroid hormones (THs) play an important role in a wide range of crucial biological functions related to growth and development, and thyroid antibodies (TAs) can influence the biosynthesis of THs. Epidemiological studies have indicated that per- and polyfluoroalkyl substances (PFAS) could induce thyroid disruption, but studies on teenagers living in areas with high PFAS exposure are limited. This cross-sectional study focused on 836 teenagers (11- 15 years) living near a Chinese fluorochemical industrial plant. Decreased levels of free thyroxine (FT4, ﹤9.6 pmol/L, abnormal rate = 19.0 %) and elevated levels of free triiodothyronine (FT3, ï¹¥6.15 pmol/L, abnormal rate = 29.8 %) were observed. Correlations of serum PFAS concentrations and TAs/THs were analyzed. Increased PFOA was identified as a risk factor of decreased FT4 by using unadjusted (OR: 11.346; 95 % CI: 6.029, 21.352, p < 0.001) and adjusted (OR: 12.566; 95 % CI: 6.549, 24.115, p < 0.001) logistic regression models. In addition, significantly negative correlations were found between log10 transformed PFOA and FT4 levels using linear (unadjusted: ß = -1.543, 95 % CI: -1.937, -1.148, p < 0.001; adjusted: ß = -1.534, 95 % CI: -1.930, -1.137, p < 0.001) and BKMR models. For abnormal FT3, a significantly positive association between PFHxS and FT3 levels was observed in a regression model (unadjusted: ß = -0.903, 95 % CI: -1.212, -0.595, p < 0.001; adjusted: ß = -0.894, 95 % CI: -1.204, -0.583, p < 0.001), and PFHxS was identified as a risk factor (unadjusted: OR: 4.387; 95 % CI: 2.619, 7.346, p < 0.001; adjusted: OR: 4.527; 95 % CI: 2.665, 7.688, p < 0.001). Sensitivity analyses confirmed the robustness of the above results. This study reported the elevated PFAS exposure and thyroid function of teenagers living near a fluorochemical industrial plant from China.

Phase-Controllable Growth of Air-Stable SnS Nanostructures for High-Performance Photodetectors with Ultralow Dark Current.

The epitaxial growth of low-dimensional tin chalcogenides SnX (X = S, Se) with a controlled crystal phase is of particular interest since it can be utilized to tune optoelectronic properties and exploit potential applications. However, it still remains a great challenge to synthesize SnX nanostructures with the same composition but different crystal phases and morphologies. Herein, we report a phase-controlled growth of SnS nanostructures via physical vapor deposition on mica substrates. The phase transition from α-SnS (Pbnm) nanosheets to ß-SnS (Cmcm) nanowires can be tailored by the reduction of growth temperature and precursor concentration, which originates from a delicate competition between SnS-mica interfacial coupling and phase cohesive energy. The phase transition from the α to ß phase not only greatly improves the ambient stability of SnS nanostructures but also leads to the band gap reduction from 1.03 to 0.93 eV, which is responsible for fabricated ß-SnS devices with an ultralow dark current of 21 pA at 1 V, an ultrafast response speed of ≤14 µs, and broadband spectra response from the visible to near-infrared range under ambient condition. A maximum detectivity of the ß-SnS photodetector arrives at 2.01 × 108 Jones, which is about 1 or 2 orders of magnitude larger than that of α-SnS devices. This work provides a new strategy for the phase-controlled growth of SnX nanomaterials for the development of highly stable and high-performance optoelectronic devices.

Higher cadmium exposure was associated with sex-specific thyroid dysfunction: Consistent evidence from two independent cross-sectional studies based on urinary and blood cadmium measurements.

Population-based studies on the association between cadmium (Cd) exposure and thyroid function are limited and have shown conflicting results. Two independent cross-sectional studies using different Cd biomarkers were carried out in six rural areas with different soil Cd levels in China. Thyroid dysfunction was defined based on levels of thyroid stimulating hormone (TSH) and free thyroxine (FT4). Both multivariable linear regression, multiple logistic regression and restrictive cubic splines models were used to estimate the association between Cd and thyroid dysfunction. For both of the two independent studies, higher Cd levels were observed to be associated with lower TSH levels and higher risk of thyroid dysfunction. The negative relationship between urinary Cd and TSH was found in both total participants (ß = -0.072, p = 0.008) and males (ß = -0.119, p = 0.020) but not in females, however, the negative relationship between blood Cd and TSH was only found in females (ß = -0.104, p = 0.024). Higher urinary Cd (> 2.52 µg/g creatinine) was associated with higher risk of thyroid dysfunction, while higher blood Cd was associated with higher risk of hyperthyroidism status. The adjusted Odds Ratio (OR) for the risk of hyperthyroidism status was 3.48 (95%CI:1.36-8.92) and 6.94 (95%CI:1.23-39.31) times higher with every natural log unit higher in blood Cd in total participants and males, respectively. Results from the two independent cross-sectional studies consistently suggested that higher Cd levels were associated with sex-specific thyroid dysfunction.

Domain nucleation kinetics and polarization-texture-dependent electronic properties in two-dimensional α-In2Se3 ferroelectrics.

Two-dimensional (2D) ferroelectric semiconductors, such as α-In2Se3 with switchable spontaneous polarization and superior optoelectronic properties, exhibit large potential for functional device applications. The electric transport properties and device performance of 2D α-In2Se3 are strongly sensitive to the ferroelectric domain structures and polarization textures, but they are rarely explored at the atomic scale. Herein, by a combination of first-principles calculations and a developed domain switching theory, we report the domain nucleation kinetics and polarization-texture dependent electronic properties in α-In2Se3 ferroelectrics. Our calculated results reveal that the reversed domains characterized by armchair boundaries tend to form triangular or stripped shape. The energy barrier for propagating domain boundaries is ∼1.42 eV and can be reduced by loading external electric field, which is responsible for driving the evolution of domain structures. Moreover, the domain switching leads to notable changes in the band gap and carrier spatial distribution of α-In2Se3 monolayer, resulting in higher electric resistance of multi-polarization domain structures than that of single-polarization state. The domain structures of multilayer α-In2Se3 follow a layer-by-layer switching mechanism, which causes the transition of electronic structures from self-doped p-n junctions to type-II semiconductor homojunctions. This study not only provides an in-depth insight into the domain switching mechanisms of α-In2Se3 but also opens up the possibility to tailor their electronic and transport properties.

Higher blood selenium level is associated with lower risk of hyperhomocysteinemia in the elderly.

BACKGROUND AND AIMS: Earlier studies have reported inconsistent association between selenium (Se) and homocysteine (Hcy) levels, while no evidence could be found from Chinese population. To fill this gap, we investigated the association between blood Se and hyperhomocysteinemia (HHcy) of rural elderly population in China. METHODS: A cross-sectional study on 1823 participants aged 65 and older from four Chinese rural counties was carried out in this study. Whole blood Se and serum Hcy concentrations were measured in fasting blood samples. Analysis of covariance and restricted cubic spline models were used to examine the association between Se and Hcy levels. Logistic regression models were used to evaluate the risk of prevalent HHcy among four Se quartile groups after adjusting for covariates. RESULTS: For this sample, the mean blood Se concentration was 156.34 (74.65) µg/L and the mean serum Hcy concentration was 17.25 (8.42) µmol/L. A significant non-linear relationship was found between blood Se and serum Hcy, the association was inverse when blood Se was less than 97.404 µg/L and greater than 156.919 µg/L. Participants in the top three blood Se quartile groups had significantly lower risk of prevalent HHcy compared with the lowest quartile group. When defined as Hcy> 10 µmol/L, the odds ratios and 95% confidence interval of HHcy were 0.600 (0.390, 0.924), 0.616 (0.398, 0.951) and 0.479 (0.314, 0.732) for Q2, Q3, and Q4 Se quartile groups compared with the Q1 group, respectively. When defined as Hcy≥ 15 µmol/L, the odds ratios and 95% confidence interval of HHcy were 0.833 (0.633, 1.098) and 0.827 (0.626, 1.092), 0.647 (0.489, 0.857) for Q2, Q3, and Q4 Se quartile groups compared with Q1 group. CONCLUSIONS: Our findings suggest that higher blood Se level could be a protective factor for HHcy in the elderly.

Blood Selenium and Serum Glutathione Peroxidase Levels Were Associated with Serum ß-Amyloid in Older Adults.

BACKGROUND: Studies have established the association between blood ß-amyloid (Aß) levels and Alzheimer's disease, but population-based studies concerning the association between selenium (Se) and Aß levels in blood samples are very limited. Therefore, we explored the association in an elderly population with Se status and serum Aß measures. METHODS: A cross-sectional study on 469 elderly individuals from four rural counties with diverse soil Se levels was carried out. Fasting blood Se, serum selenoprotein P (SELENOP), and glutathione peroxidase (GPX), serum Aß42, and Aß40 were measured. Quantile regression models were used to determine the associations of blood Se, serum GPX, and SELENOP with Aß levels. RESULTS: Significant negative associations were observed between blood Se and serum Aß42 and Aß40 levels at all percentiles (P < 0.05). The associations were generally stronger at higher Aß42 and Aß40 percentiles than lower Aß42 and Aß40 percentiles. Blood Se was positively associated with serum Aß42/Aß40 ratio at 25th, 50th, and 75th percentiles. Significant positive associations were observed between serum GPX and Aß42 and Aß40 levels at all percentiles (P < 0.05). The positive associations were generally stronger at higher Aß42 and Aß40 percentiles than at lower percentiles. Serum GPX was negatively associated with Aß42/Aß40 ratio at 25th, 50th, 75th, and 95th percentiles. No associations with serum SELENOP and Aß levels were observed. CONCLUSIONS: Our results suggest that higher Se levels are associated with lower serum Aß42 and Aß40 levels and with higher Aß42/Aß40 ratio, and the results are specific for different selenoproteins.

Levels, distribution, childhood exposure assessment, and influencing factors of polybrominated diphenyl ethers (PBDEs) in household dust from nine cities in China.

Household dust is an important source of premature exposure to polybrominated diphenyl ethers (PBDEs), especially for children. In this onsite study, 246 dust samples were collected from 224 households in nine Chinese cities during 2018-2019. Questionnaires were administered to explore the association between household-related information and PBDEs in household dust. The median concentration of Σ12PBDEs in household dust from 9 cities was 138 ng/g (94-227 ng/g), with the arithmetic mean of 240 ± 401 ng/g. Among the nine cities, the highest median concentration of Σ12PBDEs in household dust was found in Mianyang (295.57 ng/g), while the lowest was found in Wuxi (23.15 ng/g). BDE-71 was the most dominant congener, ranging from 42.08 % to 98.15 % of the 12 PBDE congeners among 9 cities. Three potential sources for the indoor environment were Penta-BDE, Octa-BDE commercial products, and photolytic bromine from Deca-BDEs based on the largest contribution (81.24 %). Under the moderate exposure scenario, the exposure levels through ingestion and dermal absorption for children were 7.30 × 10-1 ng/kg BW/day and 3.26 × 10-2 ng/kg BW/day, respectively. Temperature, CO2, years of residence, income, family size, household size, use of computers, heating, use of insecticide, and use of humidifiers were influential factors for PBDE concentrations in household dust. Based on the evidence of the correlation between PBDEs and these household parameters, it can be applied to reduce PBDE concentrations in household dust, which is a basis for controlling PBDEs pollution in Chinese households and protecting population health.

Levels, distribution, sources and children health risk of PAHs in residential dust: A multi-city study in China.

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are typical residential pollutants mainly from biofuel combustion that impose inevitable risk to children. The PAHs in residential dust is universal in most Chinese households with an obvious public health concern. METHODS: In this observational study, a total of 235 residential dust samples from 8 Chinese cities (Panjin, Shijiazhuang, Lanzhou, Luoyang, Xi'an, Wuxi, Mianyang, and Shenzhen) were collected from April 2018 to March 2019, which were extracted and analyzed for 16 priority PAHs by HPLC/FD-UV. Diagnostic ratios, hierarchical clustering analysis and principal component analysis were applied simultaneously for source apportionments. Incremental lifetime cancer risk was employed to estimate children's health risks based on the assumed exposure scenarios. Spearman correlation, Mann-Whitney U test, Kruskal-Wallis H test and Partial Least Squares were used to screen the factors affecting the concentration of PAHs in residential dust. RESULTS: The median concentration of ∑16PAHs in residential dust from 8 cities was 44.11 µg/g (0.04 - 355.79 µg/g). ∑16PAHs were found both higher in dust samples in heating season and from downwind households only in Mianyang (p < 0.05). The leading two sources of PAHs were combustion processes and automobile exhaust emissions based on four principal components that accounted for 74.29 % of the total variance. Indoor air environmental factors, household characteristics, and residents' behavioral lifestyles may be the influencing factors of residential dust PAHs. The carcinogenic risk of children aged 0 - 5 years, under the moderate exposure level of PAHs in residential dust, exceeded the acceptable level (10-5 - 10-4 for dermal contact and 10-6 - 10-5 for ingestion). CONCLUSIONS: There was serious PAHs pollution in residential dust under actual living conditions in eight cities across China. More evidence-based measures were needed to control PAHs pollution to safeguard children's health according to appointed sources and influencing factors in residential dust.

Higher selenium was associated with higher risk of diabetes: Consistent evidence from longitudinal and cross-sectional studies based on nail and serum selenium measures.

Although the association between selenium (Se) and diabetes has been well-discussed in recent years, few studies have focused on the effects of long-term natural Se exposure and rarely concerned the effects of different Se biomarkers. To address this question, we carried out a 7-year longitudinal study on older adults aged over 65 and another cross-sectional study on middle-aged and older adults aged 40 and above from Chinese soil Se-deplete and Se-optimum areas. Cox proportional hazard models were used to evaluate the associations between nail Se levels and incidence risk of diabetes. Unconditional logistic regression models and analysis of variance models were used to examine the associations between serum Se levels and the prevalence risk of diabetes. The nail and serum Se levels were 0.47 ± 0.20 µg/g and 111.09 ± 55.01 µg/L for the two study populations, respectively. For both of the independent studies, higher Se levels were observed to be associated with a higher risk of diabetes and prediabetes. Compared with the Second nail Se quartile (Q2), the adjusted hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) of diabetes for Q1, Q3 and Q4 were 1.24(0.70, 2.21), 1.53(0.98, 2.39) and 1.31(0.76, 2.26), respectively, and the adjusted HRs (95 % CIs) of prediabetes were 1.47(0.77, 2.81), 1.38(0.83, 2.30), and 1.97(1.13, 3.44), respectively. Compared with the first serum Se quintile (Q1), the adjusted odds ratios (ORs) and 95 % CIs of diabetes for higher quintiles were 1.12(0.75, 1.66), 1.05(0.71, 1.57), 1.09(0.73, 1.62) and 1.51(1.02, 2.19), and the adjusted ORs (95 % CIs) of prediabetes were 1.27(0.77, 2.09), 1.70(1.05, 2.74), 1.94(1.21, 3.11) and 1.67(1.03, 2.71). Our findings consistently suggest that higher Se status is associated with a higher risk of diabetes in adults.