Methylsiloxanes (MSs) are a significant source of indoor environmental pollution due to their high production level and widespread application, and pose a potential health risk. Given the special vulnerability of children to environmental contaminants, assessment of indoor MSs exposure in children is quite essential. In this study, we assessed internal exposure doses and external exposure levels of MSs in children from industrial and residential areas in southwestern China. Indoor air, indoor dust, and personal care product (PCP) samples were collected to evaluate indoor non-dietary MSs exposure in children through various pathways. The concentrations of MSs in indoor environments of industrial areas were approximately one to four orders of magnitude higher than those of residential areas. Sun protection products contained the highest concentrations of MSs. Relatively high levels of cyclic methylsiloxanes (CMSs) were found in plasma of children from industrial areas, which were one to two orders of magnitude higher than those in children from residential areas. The highest MSs levels in plasma were detected in infants (0–1 year), with values of 1.4 × 102 ng/mL and 1.3 × 102 ng/mL for CMSs (D4–D6) and linear methylsiloxanes (LMSs) (L5–L16), respectively. The internal exposure dose of infants in residential areas is driven by major unknown sources of MSs. The average daily doses via inhalation and dust ingestion in children from industrial areas were one to three orders of magnitude higher than in those from residential areas, indicating that these children should be considered a highly exposed population. Inhalation and dust ingestion were both major exposure pathways to MSs for children of all age groups in industrial areas, whereas dermal absorption from PCPs was the predominant exposure pathway for children of all age groups in residential areas (except for infants). Although the exposure risk to D4 and D5 was at an acceptable level for all children studied, the total daily exposure doses of these two cyclic compounds via inhalation for infants in the industrial areas was near the chronic reference dose. Meanwhile, MSs may accumulate in infant plasma within a short period of time (<6 months). Therefore, infants should be the focus of greater attention in future research. As indoor environments may pose high risks for infants in industrial areas, they should be the focus of future research. © 2021

Neonicotinoid insecticides (NEOs) have attracted particular attention in recent years due to their wide occurrence and potential impacts on the ecosystem and human health. This study aimed to compare the composition and level of NEOs in soils of different land use types. Two rounds of sampling were performed in Tianjin, China, with 158 soil samples in fall and 61 soil samples in spring collected from five types of land, i.e., greenhouse, orchard, farm, park and residential area. The concentrations of eight NEOs, i.e., imidacloprid (IMI), acetamiprid (ACE), thiamethoxam (THX), clothianidin (CLO), thiacloprid (THA), dinotefuran (DIN), nitenpyram (NIT) and flonicamid (FLO), were analyzed in the soil samples using LC-MS/MS. Six NEOs were detected, with IMI, ACE and THX being the most frequently detected ones. Concentrations of NEOs (arithmetic means in fall and spring, respectively) in greenhouse were the highest (2.52×102 and 4.59×102 ng g−1), followed by in orchard (35.1 and 1.31×102 ng g−1), park (50.4 and 1.02×102 ng g−1), residential area (20.2 and 1.38×102 ng g−1) and farm (25.5 and 84.2 ng g−1). The contribution of individual NEO varied in soils of different land use types. Both IMI and THX were largely used in greenhouse, while IMI was the main NEO in the other four lands. The NEO levels in soils planted with different crops varied greatly. Extremely high levels of NEOs (>103 ng g−1) were observed in soils planted with watermelon, tomato and peach in greenhouse. The ubiquitous presence of NEOs in soils deserves more attention, particularly in greenhouse. © 2021 Elsevier B.V.

Peroxyacetyl nitrate (PAN) is the most important reservoir of nitrogen oxides, with effects on atmospheric oxidation capacity and regional nitrogen distribution. The first yearlong observational study of PAN was conducted from September 2018 to August 2019 at a suburban site and an urban site in Zhengzhou, Henan Province, central China. Compared with studies over the past two decades, summer PAN pollution at the suburban site and winter PAN pollution at both sites were more significant, with annual average concentrations of 1.96 ± 1.44 and 2.01 ± 1.59 ppbv, respectively. Seasonal PAN discrepancies between the urban and suburban areas were analyzed in detail. Active PAN formation, regional transport, photochemical precursors, and PAN lifetime played key roles during seasons with elevated PAN (winter and spring). According to the results of cluster analysis and potential source contribution function analysis, during the cold months, short-distance air mass transport from the east, south, and southeast of Henan Province and southern Hebei Province increased PAN pollution in urban Zhengzhou. PAN source areas were located in circumjacent industrial cities surrounding Zhengzhou except in the northeastern direction. Based on the relationships between pollutant concentrations, wind speed, and wind direction, a strong positive correlation between PAN and PM2.5 (and O3) existed in winter due to their joint transport. A slow-moving, low-height air mass passed through surrounding industrial cities before reaching the study area, carrying both pollutants and leading to strong consistency between PAN and O3 levels. The long-term PAN characteristics described in this study will help clarify the causes of regional air pollution in inland city agglomerations. Moreover, the PAN correlations and joint transport of PAN and PM2.5 (or O3) support the use of PAN as an indicator of air pollution introduced from surrounding industrial areas. © 2021 Elsevier B.V.

Neonicotinoid insecticide (NEO) concentrations in ambient fine particulate matter (PM2.5) and daily exposure via inhalation were investigated during spring and fall in an urban area in Beijing and in urban and rural areas of Zhengzhou, Henan Province, China. Four NEOs, including imidacloprid, acetamiprid, thiamethoxam and clothianidin, were assessed using a QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction procedure coupled to liquid chromatography–tandem mass spectrometry. Of 64 PM2.5 samples, 100% contained at least two NEOs (imidacloprid and acetamiprid). Imidacloprid was detected at the highest levels, ranging from 4.33 to 1.13 × 102 pg m−3. A relative potency factor method that considered different toxicities was used to integrate the four NEO concentrations. The total NEO concentrations in air in the Zhengzhou rural area (mean: 80.86 pg m−3) were higher than those in urban areas. Differences between seasons were not significant (p > 0.05). The highest value for the total average daily dose via inhalation of four NEOs (ADDinh,total), 91.0 pg kg−1 day−1, was found in rural children <6 years old. The ADDinh,total of rural residents was significantly higher than that of urban residents when there was no intensive pesticide application. Although the ADDinh,total values were below the current chronic reference dose, when possible joint toxicity and the increasing use of NEOs are considered, a potential health risk via inhalation is evident. We believe this study is the first to characterize NEO levels in fine particulate matter and to evaluate inhalation exposure in urban and rural residents under nonoccupational scenarios in China. It will enhance our understanding of exposure to NEOs and provide a basis for risk management decisions. © 2020 The Author(s)

Methylsiloxanes (MSs) are ubiquitous in indoor air and pose an important health risk. Thus, assessments of indoor inhalation exposure by measuring MSs levels in plasma are needed. In this study, we measured plasma MSs concentrations and evaluated daily indoor inhalation exposure in potentially exposed populations, including residents of industrial areas, university campus, and residential areas, all located in southwestern China. The concentrations of MSs in indoor air (gas-phase and PM2.5) collected from factory housing and from girls’ dormitories on university campus were approximately one to three orders of magnitude higher than in parallel samples from other areas. The consequences of MSs exposure were investigated by measuring MSs levels in the plasma samples of the exposed populations. Relatively high levels of cyclic MSs (CMSs: D4–D6) were found in the plasma of the co-resident family members of factory workers and in female college students living in campus dormitories. The highest levels of CMSs (D4–D6) and linear MSs (L5–L16), 2.3 × 102 and 2.0 × 102 ng/mL, respectively, were detected in the very young (0–3 years old) co-resident children of factory workers. The average daily dose via inhalation (ADDinh) in different groups showed that the ADDinh values of all MSs (D4–D6, L5–L16) were one to two orders of magnitude higher in the co-resident family members of factory workers and in female college students than in other groups, indicating that both populations should be considered as potentially highly exposed to MSs. A further assessment showed that inhalation exposure is the main source of CMSs (D4–D6) in plasma for people exposed to high indoor air levels of these compounds. Although the health risk assessment showed that the health risk from inhalation exposure to D4 and D5 was acceptable for all of the studied groups based on the current chronic reference dose (cRfD), the maximum ADDinh,CMSs value in 0- to 3-year-old children was only 7.9-fold below the cRfD. Because the toxicity of other MSs is unknown, the potential health risk of MSs to very young children via inhalation exposure should be further analysed. © 2020 The Author(s)

Volatile methylsiloxanes (VMSs) are widely used in various personal-care products and industrial additives and products. This study focused on VMSs exposure in the general population, workers, and the families of workers living in residential and industrial areas of southwestern China. VMSs concentrations in indoor environmental matrices from six industrial facilities were 3.4 × 10 2 to 9.0 × 10 2 μg m −3 in gas-phase samples, 4.7 × 10 2 to 1.5 × 10 4 μg g −1 in PM 2.5 samples, and 2.3 × 10 2 to 7.2 × 10 3 μg g −1 in dust samples, which were two to four orders of magnitude higher than the concentrations measured in residential areas. Exposure to VMSs was investigated by analysis of plasma samples from workers in residential and industrial areas for the presence of cyclic (D4–D6) and linear (L3–L16) VMSs. VMSs concentrations in plasma samples ranged from 84 to 2.3 × 10 2 ng ml −1 in workers, one to two orders of magnitude higher than those in the general population (2.2 ng ml −1 ). Daily VMSs indoor exposure via inhalation and ingestion in individuals from residential and industrial areas were estimated and assessed under working-time and leisure-time conditions. This study showed that exposure to VMSs in industrial areas is approximately two to four or one to two orders of magnitude higher than that in residential areas during the working- or leisure-time scenario, respectively. Furthermore, the families of workers (the non-occupational group) experienced higher levels of exposure to VMSs in their homes compared with the general population. The ratios of exposure to linear VMSs via PM 2.5 inhalation to that via the gas phase ranged from 7.8% to 43.1% in industrial areas. This study suggests that intake of linear VMSs via PM 2.5 inhalation should be considered when estimating human exposure to VMSs in areas with high levels of PM 2.5 air pollution. © 2019

Cyclic volatile methyl siloxanes (cVMS) used in personal care products are released to aquatic environments through wastewater effluent. cVMS are persistent, toxic, bioaccumulative, and have potential to cause ecological harm. In this study, the environmental behavior of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) were evaluated in the largest lake of southwest China, Dian Lake. Air, water and sediment samples were measured for three cVMS compounds in the winter (January) and summer (July) of 2017. In air, D5 exhibited the highest measured mean concentration among the three cVMS, which were 18.4 ± 8.0 ng·m−3 in winter and 5.78 ± 3.61 ng·m−3 in summer. In water and sediment, D6 was the cVMS with the highest measured mean concentration. The mean concentrations in water of D6 were 20.8 ± 5.8 ng·L−1 in winter and 20.4 ± 5.8 ng·L−1 in summer. The mean concentrations in sediment of D6 were 281 ± 45.8 ng·g−1 dw in winter and 270 ± 31.3 ng·g−1 dw in summer. A fugacity-based mass balance chemical fate model for lakes (QWASI) was used for Dian Lake to compare measurements and explore the behavior of cVMS. D6 was predicted to have the highest water column and sediment concentrations. Modeling results showed that most of the D5 and D6 partitioned into sediment and could persist for several years. Persistence was significantly influenced by the high rate of sediment burial. In an analysis of the impact of physicochemical properties and environmental parameters, KOC was identified as a key parameter for predicting cVMS behavior. This study illustrates the importance of cVMS in sediments and the potential aquatic risk that they may pose. © 2018

A method for simultaneous measure of nine neonicotinoid insecticide residues in soil was developed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with a quick pretreatment procedure. The soil was extracted with a mixture of acetonitrile and dichloromethane (1:2, v:v) and cleaned up with Primary Secondary Amine (PSA). Matrix-matched standards were prepared to eliminate the interference of the matrix. The LC–MS/MS conditions were optimized to separate the nine neonicotinoids within 6.7 min, and the obtained limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.01 to 0.84 ng g−1 and 0.05–2.79 ng g−1, respectively. Recoveries of the studied neonicotinoids (except for nitenpyram) ranged from 79.41 to 100.20% with relative standard deviations (RSDs) less than 10% at spiked levels of 5 ng mL−1, 100 ng mL−1 and 500 ng mL−1, and RSDs for the interday and intraday method repeatability were less than 9%. The method was applied to measure neonicotinoid residues in soil samples collected from parks (n = 35) and residential areas (n = 33) in Tianjin, China. Seven neonicotinoids were detected, with imidacloprid being the most frequently detected one, followed by acetamiprid and thiamethoxam. The total concentrations of neonicotinoids in soil ranged from 0.27 to 230.76 ng g−1 in parks and 0.23–132.66 ng g−1 in residential areas. © 2018 Elsevier B.V.

Fluorotelomer alcohol (6:2 FTOH) is a polyfluoalkyl substance that has been widely used in industry and consumer products in recent years, causing potential harm to the environment. However, currently the impact of 6:2 FTOH and its degradation products on microbial communities in sediment is unclear. The purpose of this study is to explore the impact of the biodegradation of 6:2 FTOH on bacterial community structures in surface sediment based on gene analysis. Surface sediment and river water were collected from Hai river, Tianjin, and a microcosm experiment was performed in the laboratory. The concentration of 6:2 FTOH and its degradation products were analyzed by liquid chromatograph-mass spectrometry/mass spectrometry (LC-MS/MS). The bacterial community structure was analyzed by denaturing gradient gel electrophoresis and high-throughput sequencing. The results showed that 6:2 FTOH could be degraded by microorganisms (half-life was less than 3 d), producing transient products such as 6:2 fluorotelomer carboxylic acid (FTCA) and 6:2 fluorotelomer unsaturated carboxylic acid (FTUCA) and stable products such as 5:2 fluorotelomer (FT) ketone, 5:2 fluorotelomer alcohol (sFTOH), perfluorohexanoic acid(PFHxA), perfluoro-n-pentanoic acid (PFPeA), perfluorobutanoic acid (PFBA) and 5:3 polyfluorinated acid. At different stages of 6:2 FTOH degradation, a change of bacteria and the predominant population became somewhat different. Based on the experimental results for 100 d, at the Phylum level, the biodegradation of 6:2 FTOH greatly increases the abundance of Chloroflexi (+24.8%) and decreases the abundance of Proteobacteria (-17.8%) and Firmicutes (-15.9%). At the Class level, due to the biodegradation of 6:2 FTOH, bacteria with notable increases included Anaerolineae (+19.6%) and δ-Proteobacteria (+4.3%), while bacteria with notable decreases included ε-Proteobacteria (-20.0%), Clostridia (-10.1%), Bacilli (-5.8%) and γ-Proteobacteria (-4.2%). At the Genus level, due to the biodegradation of 6:2 FTOH, bacteria with notable increases included Anaerolineaceae_(uncultured) (+19.1%) and Thioalkalispira (+13.3%), while bacteria with notable decreases included Vibrio (-14.1%), Sulfurimonas (-13.2%), Bacillus (-5.1%), Sulfurovum (-4.2%) and Fusibacter (-4.1%). These results are helpful for predicting the response of bacteria to the contamination of polyfluoalkyl substances and isolating the bacteria capable of the biodegradation of polyfluoalkyl substances. © 2017, Science Press. All right reserved.