Exposure to traffic-related PM₂.₅ mass and its components can affect human health. Meanwhile, indoor concentrations are better exposure predictors as compared to outdoor concentrations because individuals spend the majority of their time indoors. We estimated the impact of traffic emissions on indoor PM₂.₅ mass and its species as a function of road proximity in Massachusetts. A linear regression model was built using 662 indoor samples and 580 ambient samples. Analysis shows that indoor exposures to traffic-related particles increased dramatically with road proximity. We defined relative concentration decrease, R(α), as the ratio of the indoor concentration at perpendicular distance α in meters from the closest major road to the indoor concentration at 1800 m from the major road. R(13) values for PM₂.₅ mass and Black Carbon (BC) were 1.3 (95%CI: 1.4, 1.6) and 2.1 (95%CI: 1.3, 2.8) for A12 roads, and 1.3 (95%CI: 1.2, 1.4) and 1.2 (95%CI: 1.1, 1.3) for A3 roads. R(α) values were also estimated for Fe, Mn, Mo, Sr and Ti for A12 roads, and Ca, Cu, Fe, Mn, Mo, Ni, Si, Sr, V and Zn for A3 roads. R(α) values for species associated mainly with brakes, tires or road dust (e.g., Mn, Mo and Sr) were higher than others. For A12 roads, R(13) values for Mn and Mo were 10.9 (95%CI: 0.9, 20.9) and 6.5 (95%CI: 1.4, 11.5), and ranged from 1.3 to 2.1 for other species; for A3 roads, R(13) values for Mn, Mo and Sr were 1.9 (95%CI: 1.1, 2.9), 1.8 (95%CI: 1.1, 2.4), and 8.5 (95%CI: 5.9, 10.9), and ranged from 1.2 to 1.6 for others. Our results indicate a significant impact of local traffic emissions on indoor air, which depends on road proximity. Thus road proximity which has been used in many epidemiological studies is a reasonable exposure metric.

Heavy metal contamination of soil in the vicinity of mining sites is a serious environmental problem around the world when mining residue (slag) is dispersed as dust. We conducted an incubation experiment to investigate the effect of a slag containing high levels of Pb and Zn (62.2 and 33.6 g kg⁻¹ slag as PbO and ZnO, respectively, sampled from a site formerly used as a lead and zinc mine) on the nitrogen cycle when mixed with soil (0–0.048 g slag g⁻¹ soil). The nitrogen cycle provides many life supporting-functions. To assess the quality of the soil in terms of the nitrogen cycle we focused on the dynamics of nitrate and ammonium, and bacterial community structure and functions within the soil. After two weeks of pre-incubation, ¹⁵N-labeled urea (500 mg N kg⁻¹) was added to the soil. Changes in soil pH, the concentration and ¹⁵N ratio of nitrate (NO₃⁻-N) and ammonium, and bacterial relative abundance and community structure were measured. Results indicated that increasing the ratio of slag to soil had a stronger negative effect on nitrification than ammonification, as suggested by slower nitrate accumulation rates as the slag:soil ratio increased. In the treatment with the highest amount of slag, the concentration of NO₃⁻-N was 50% of that in the controls at the end of the incubation. Regarding the bacterial community, Firmicutes had a positive and Planctomycetes a negative correlation with increasing slag concentration. Bacterial community functional analysis showed the proportion of bacterial DNA sequences related to nitrogen metabolism was depressed with increasing slag, from 0.68 to 0.65. We concluded that the slag impacted the soil bacterial community structure, and consequently influenced nitrogen dynamics. This study could form the basis of further investigation into the resistance of the nitrogen cycle to contamination in relation to soil bacterial community.

In this study, the formation of nitrate aerosol from 16 to 24 December 2015 in the Guanzhong basin, China is simulated using the WRF-Chem model. The predicted near-surface O₃, NO₂, and fine particulate matters (PM₂.₅) in the basin and inorganic aerosols and nitrous acid (HONO) in Xi'an are generally in good agreement with the observations. Sensitivity studies show that the heterogeneous HONO sources play an appreciable role in the nitrate formation in the basin, contributing 9.2% of nitrate mass concentrations during heavy haze days. Nitrate formation is also affected by sulfate due to their competition for ammonia, particularly in urban areas. A 50% decrease in SO₂ emissions enhances the nitrate concentration by 6.2% during heavy haze days on average in the basin, and a 50% increase in SO₂ emission reduces the nitrate concentration by 9.7%. The roles of HONO and sulfate competition in nitrate formation are strongly modulated by ammonia. Agricultural emissions predominate the nitrate level in the basin (93.5%), but the non-agricultural sources cannot substantially influence nitrate formation (3.7%–14.6%). Reducing agricultural emission is an effective control strategy to mitigate nitrate pollution in the basin.

Biogas residue and organic manure are frequently used for crop planting. However, the evaluation of antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and bacterial community before their applications to fields is still lacking. This study monitored the variations of bacteria resistant to sulfadiazine, tetracycline and norfloxacin, 57 resistance genes for sulfonamides, tetracyclines and fluoroquinolones as well as the bacterial community during the 28-day aerobic storage of biogas residue and organic manure by using viable plate counts, high-throughput qPCR and Illumina MiSeq sequencing methods. Then two storage conditions, incubator (25 °C) and natural environment, were used to assess the responses of ARB and ARGs to the environmental factors. Results showed that a total of 35 and 21 ARGs were detected in biogas residue and organic manure, respectively. ARB and ARGs were enriched up to 8.01-fold in biogas residue after the 28-day storage, but varied in a narrow range during the storage of organic manure. Compared with the incubator condition, the proliferation of ARB and ARGs in biogas residue under the natural condition was relatively inhibited by the varied and complicated environmental factors. However, we found that there was no significant difference of ARB and ARGs in organic manure between the incubator and natural conditions. Bacterial community was also shifted during the storage of biogas residue, especially Bacteroidetes_VC2.1_Bac22, Aequorivita, Luteimonas and Arenimonas. Network analysis revealed that the relationship in biogas residue was much more complicated than that in organic manure, which ultimately resulted in large successions of ARB and ARGs during the short-term storage of biogas residue. Therefore, we suggest that further measures should be taken before the application of biogas residue to fields.

Drinking water safety is continuously threatened by the emergence of numerous toxic organic pollutants (TOPs) in environmental waters. In this study, an approach integrating in vitro bioassays and chemical analyses was performed to explore toxicological profiles of representative source and drinking water from waterworks of the Yangtze River (Yz), Taihu Lake (Th), and the Huaihe River (Hh) basins in eastern China. Overall, 34 of 96 TOPs were detected in all water samples, with higher concentrations in both source and drinking water samples of Hh, and pollutant profiles also differed across different river basins. Non-specific bioassays indicated that source water samples of Hh waterworks showed higher genotoxicity and mutagenicity than samples of Yz and Th. An EROD assay demonstrated dioxin-like toxicity which was detected in 5 of 7 source water samples, with toxin concentration levels ranging from 62.40 to 115.51 picograms TCDD equivalents per liter of water (eq./L). PAHs and PCBs were not the main contributors to observed dioxin-like toxicity in detected samples. All source water samples induced estrogenic activities of 8.00–129.00 nanograms 17β-estradiol eq./L, and estrogens, including 17α-ethinylestradiol and estriol, contributed 40.38–84.15% of the observed activities in examined samples. While drinking water treatments efficiently removed TOPs and their toxic effects, and estrogenic activity was still observed in drinking water samples of Hh. Altogether, this study indicated that the representative source water in eastern China, especially that found in Hh, may negatively affect human health, a finding that demonstrates an urgent requirement for advanced drinking water treatments.

Emissions from burning of biomass in the Amazon region have adverse effects on the environment and human health. Herein, particulate matter (PM) emitted from biomass burning in the Amazon region during two different periods, namely intense and moderate, was investigated. This study focused on: i) organic characterization of nitro- and oxy-polycyclic aromatic hydrocarbons (PAHs); ii) assessment of the excess lifetime cancer risk (LCR); and iii) assessment of the in vitro mutagenic effects of extractable organic matter (EOM). Further, we compared the sensitivity of two mutagenicity tests: Salmonella/microsome test and cytokinesis-block micronucleus (CBMN) with human lung cells. Among the nitro-PAHs, 2-nitrofluoranthene, 7-nitrobenz[a]anthracene, 1-nitropyrene, and 3-nitrofluoranthene showed the highest concentrations, while among oxy-PAHs, 2-metylanthraquinone, benz[a]anthracene-7,12-dione, and 9,10-anthraquinone were the most abundant. The LCR calculated for nitro-PAH exposure during intense biomass burning period showed a major contribution of 6-nitrochrysene to human carcinogenic risk. The EOM from intense period was more mutagenic than that from moderate period for both TA98 and YG1041 Salmonella strains. The number of revertants for YG1041 was 5–50% higher than that for TA98, and the most intense responses were obtained in the absence of metabolic activation, suggesting that nitroaromatic compounds with direct-acting frameshift mutagenic activity are contributing to the DNA damage. Treatment of cells with non-cytotoxic doses of EOM resulted in an increase in micronuclei frequencies. The minimal effective dose showed that Salmonella/microsome test was considerably more sensitive in comparison with CBMN mainly for the intense burning period samples. This was the first study to assess the mutagenicity of EOM associated with PM collected in the Amazon region using Salmonella/microsome test. The presence of compounds with mutagenic effects, particularly nitro- and oxy-PAHs, and LCR values in the range of 10⁻⁵ indicate that the population is potentially exposed to an increased risk of DNA damage, mutation, and cancer.

Heavy metal contamination of source water frequently occurred in developing countries as a result of accidents. To address the problems, most of the previous studies have focused on engineering countermeasures. In this study, we investigated the effects of heavy metals, particularly copper, on the development of antibiotic resistance by establishing a copper shock loading test. Results revealed that co-selection occurred rapidly within 6 h. Copper, at the levels of 10 and 100 mg/L, significantly increased bacterial resistance to the antibiotics tested, including rifampin, erythromycin, kanamycin, and a few others. A total of 117 antimicrobial-resistance genes were detected from 12 types of genes, and the relative abundance of most genes (particularly mobile genetic elements intⅠand transposons) was markedly enriched by at least one fold. Furthermore, the copper shock loading altered the bacterial community. Numerous heavy metal and antibiotic resistant strains were screened out and enriched. These strains are expected to enhance the overall level of resistance. More noticeably, the majority of the co-selected antibiotic resistance could sustain for at least 20 h in the absence of copper and antimicrobial drugs. Resistance to vancomycin, erythromycin and lincomycin even could remain for 7 days. The prominent selection pressure by the copper shock loading implies that a real accident most likely poses similar impacts on the water environment. An accidental release of heavy metals would not only cause harm to the ecological environment, but also contribute to the development of bacterial antibiotic resistance. Broader concerns should be raised about the biological risks caused by sudden releases of pollutants by accidents.

Numerous studies on microplastics (MPs; Ø < 5 mm) in the aquatic environment have been published, but knowledge about the occurrence and ecological risks of MPs is limited. This is in part because current data on the distribution of MPs are comparable only to a limited extent, due to the many different methods of investigation. In addition, sample preparation is often difficult such that standard procedures are lacking. The aim of this work was to simplify the preparation of different kinds of MP samples. Our method makes use of the electrostatic behavior of plastic particles to facilitate their separation from sample matter, with up to 99% of the original sample mass removed without any loss of MPs. To determine the efficacy of this approach, four different materials (quartz sand, freshwater suspended particulate matter, freshwater sediment, and beach sand) were spiked with MPs (size: 0.063–5 mm from the seven most common types of plastics, one bioplastic type, polyethylene fibers, and tire wear. A modified electrostatic metal/plastic separator was used to reduce the sample mass and concentrate the plastics based on their physical separation. The recovery achieved with this method was as high as nearly 100% for each type of material. The method was then tested on plastic particles of different shapes and types isolated from the Rhine River. These were successfully electroseparated from the four materials, which demonstrated the utility of this method. Its advantages include the simplified handling and preparation of different field samples as well as a much shorter processing time, because after the last separation step there is hardly any biological material remaining in the sample fraction.

Chemicals in consumer products have become the focus of recent regulatory developments including California's Safer Consumer Products Act. However, quantifying the amount of chemicals released during the use and post-use phases of consumer products is challenging, limiting the ability to understand their impacts. Here we present a comprehensive framework, OrganoRelease, for estimating the release of organic chemicals from the use and post-use of consumer products given limited information. First, a novel Chemical Functional Use Classifier estimates functional uses based on chemical structure. Second, the quantity of chemicals entering different product streams is estimated based on market share data of the chemical functional uses. Third, chemical releases are estimated based on either chemical product categories or functional uses by using the Specific Environmental Release Categories and EU Technological Guidance Documents. OrganoRelease connects 19 unique functional uses and 14 product categories across 4 data sources and provides multiple pathways for chemical release estimation. Available user information can be incorporated in the framework at various stages. The Chemical Functional Use Classifier achieved an average accuracy above 84% for nine functional uses, which enables the OrganoRelease to provide release estimates for the chemical, mostly using only the molecular structure. The results can be can be used as input for methods estimating environmental fate and exposure.

Organophosphate flame retardants (OPFRs) have been commonly observed in indoor dust, food, and drinking water in China, but little is known about their exposure levels or factors leading to exposure in Chinese children. In this study, we measured eight metabolites of OPFRs (mOPFRs) in 227 urine samples collected from 0- to 5-year-old children in China. The high detection rates of mOPFRs (60%–100%) in the collected urine samples demonstrated the widespread exposure of this population to OPFRs. The median concentrations indicated that bis(2-chloroethyl)phosphate (BCEP, 0.85 ng/mL) and diphenyl phosphate (DPHP, 0.27 ng/mL) were the dominant chlorinated mOPFRs and nonchlorinated mOPFRs, respectively. Interestingly, the median urinary levels of bis(1-chloro-2-propyl)phosphate (BCIPP, 6.48 ng/mL) and bis(2-butoxyethyl)phosphate (BBOEP, 0.31 ng/mL) in inpatient infants were one order of magnitude higher (p < 0.01) than those observed in outpatient infants. For home-stay participants, furthermore, infants (0–1 year) had the highest median levels of BCIPP (0.72 ng/mL) and dibutyl phosphate (DBP, 0.14 ng/mL) among the three age groups (i.e., 0–1, >1–3, and >3–5 years), and significantly (p < 0.05) negative age-related relationships were found for both urinary mOPFRs. Two set of data on estimated daily intakes (EDIs) were calculated based on the fraction of OPFR excreted as the corresponding mOPFR (FUE) in human liver microsomes (EDIHLM) and S9 fraction (EDIS₉) system, respectively. In general, children have relatively high EDIs of tris(2-chloroethyl)phosphate (TCEP: EDIHLM = 485 ng/kg bw/day, EDIS₉ = 261 ng/kg bw/day). Furthermore, 17% or 21% of inpatient infants had EDIs that exceeded the reference dose, whereas this value was reduced to 13% in outpatient infants; and this value decreased with age among all home-stay children (0–5 years). Our results indicated that inpatient and home-stay infants had a higher potential risk of OPFR exposure. To our knowledge, this is the first study to identify the elevated urinary levels of mOPFRs in inpatients.