Urban street canyons formed by high-rise buildings restrict the dispersion of vehicle emissions, which pose severe health risks to the public by aggravating roadside air quality. However, this issue is often overlooked in city planning. This paper reviews the mechanisms controlling vehicle emission dispersion in urban street canyons and the strategies for managing roadside air pollution. Studies have shown that air pollution hotspots are not all attributed to heavy traffic and proper urban design can mitigate air pollution. The key factors include traffic conditions, canyon geometry, weather conditions and chemical reactions. Two categories of mitigation strategies are identified, namely traffic interventions and city planning. Popular traffic interventions for street canyons include low emission zones and congestion charges which can moderately improve roadside air quality. In comparison, city planning in terms of building geometry can significantly promote pollutant dispersion in street canyons. General design guidelines, such as lower canyon aspect ratio, alignment between streets and prevailing winds, non-uniform building heights and ground-level building porosity, may be encompassed in new development. Concurrently, in-street barriers are widely applicable to rectify the poor roadside air quality in existing street canyons. They are broadly classified into porous (e.g. trees and hedges) and solid (e.g. kerbside parked cars, noise fences and viaducts) barriers that utilize their aerodynamic advantages to ease roadside air pollution. Post-evaluations are needed to review these strategies by real-world field experiments and more detailed modelling in the practical perspective.

Soil contamination in urban environment by trace metals is of public concerns. For better risk assessment, it is important to determine their background concentrations in urban soils. For this study, we determined the background concentrations of 9 trace metals including As, Ba, Cd, Co, Cu, Ni, Pb, Se, and Zn in 214 urban soils in Florida from two large cities (Orlando and Tampa) and 4 small cities (Clay County, Ocala, Pensacola and West Palm Beach). The objectives were to determine: 1) total concentrations of trace metals in urban soils in cities of different size; 2) compare background concentrations to Florida Soil Cleanup Target Levels (FSCTLs); and 3) determine their distribution and variability in urban soils via multivariate statistical analysis. Elemental concentrations in urban soils were variable, with Pb being the highest in 5 cities (165–552 mg kg⁻¹) and Zn being the highest concentration in Tampa (1,000 mg kg⁻¹). Besides, the As and Pb concentrations in some soils exceeded the FSCTL for residential sites at 2.1 mg kg⁻¹ As and 400 mg kg⁻¹ Pb. Among the cities, Clay County and Orlando had the lowest concentrations for most elements, with Cd, Co, and As being the lowest while Ba, Pb and Zn being the highest. Among all values, geometric means were the lowest while 95th percentile was the highest for all metals. Most 95th percentile values were 2–3 folds higher than the GM data, with Pb presenting the greatest difference, being 4 times greater than GM value (58.9 vs. 13.6 mg kg⁻¹). Still they were lower than FSCTL, with As exceeding FSCTL for residential sites at 2.1 mg kg⁻¹. In addition, the linear discriminate analysis showed distinct separation among the cities: Ocala (Ba & Ni) and Pensacola (As & Pb) were distinctly different from each other and from other cities with higher metal concentrations. The large variations among elemental concentrations showed the importance to establish proper background concentrations of trace metals in urban soils.

F–53B and PFOS are two per- and polyfluoroalkyl substances (PFASs) widely utilized in the metal plating industry as mist suppressants. Recent epidemiological studies have linked PFASs to cardiovascular diseases and alterations in heart geometry. However, we still have limited understanding of the effects of F–53B and PFOS on the developing heart. In this study, we employed a human embryonic stem cell (hESC)-based cardiac differentiation system and whole transcriptomics analyses to evaluate the potential developmental cardiac toxicity of F–53B and PFOS. We utilized F–53B and PFOS concentrations of 0.1–60 μM, covering the levels detected in human blood samples. We demonstrated that both F–53B and PFOS inhibited cardiac differentiation and promoted epicardial specification via upregulation of the WNT signaling pathway. Most importantly, the effects of F–53B were more robust than those of PFOS. This was because F–53B treatment disrupted the expression of more genes and led to lower cardiac differentiation efficiency. These findings imply that F–53B may not be a safe replacement for PFOS.

Data (N = 10644) for US adults aged ≥20 years for 2003–2016 from National Health and Nutrition Examination Survey were analyzed to evaluate the impact of co-occurrence of obesity with diabetes, anemia, albuminuria, and hypertension on concentrations of five perfluoroalkyl acids (PFAA), namely, perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid (PFDA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA). For the total population, males, and females, co-occurrence of obesity with hypertension, albuminuria, anemia, and diabetes was found to be associated with lower adjusted geometric means (AGM) than nonobese for every PFAA. For example for females, for PFOS, AGMs for obese with no diseases, hypertension, albuminuria, anemia, and diabetes were 8.2, 10.8, 5.8, 4.6, and 7.7 ng/mL respectively. In comparison, for PFOS, for nonobese females, AGMs for those with no diseases, hypertension, albuminuria, anemia, and diabetes were found to be 8.9, 13.4, 7.7, 6.0, and 10.2 ng/mL respectively. This implies obesity is associated with higher excretion rates. Females, in general, had lower AGMs than males for both obese and nonobese for every PFAA for every disease group. For example, percent ratios of obese females to males AGMs for PFOA were 66.7%, 87.1%, 88.2%, 70.6%, and 90% for those with no diseases, hypertension, albuminuria, anemia, and diabetes respectively. The ratios of obese to nonobese AGMs for females were lower than males for every PFAA for those with no diseases and hypertension only. For example, for PFOA for those with no diseases, obese to nonobese AGM ratios were 87% for females and 100% for males. Thus, additional excretion of certain PFAAs due to obesity is higher in females than males for those with no diseases and hypertension only.

Incineration has overtaken landfilling as the most important option for disposal of the increasing volumes of municipal solid waste (MSW) generated in China. Accordingly, disposal of the incineration fly ash, which is enriched with a range of heavy metals, has become a key challenge for the industry. This review analyzes the temporal and spatial trends in the distributions of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg in MSW incineration fly ash between 2003 and 2017, and estimates the inventories of heavy metals associated with the fly ash and the average levels of heavy metals in Chinese MSW based on their mass flow during MSW incineration. It was estimated that MSW incinerators in China released approximately 1.12 × 10², 2.96 × 10³, 1.82 × 10², 3.64 × 10⁴, 1.00 × 10², 7.32 × 10³, 2.42 × 10², and 1.47 × 10¹ tonnes of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg, respectively, with the fly ash in 2016. Due to the much greater fly ash generation rate, the incinerators based on circulating fluidized bed combustor (CFBC) technology released more heavy metals during incineration of MSW compared to those based on grate furnace combustor (GFC) technology. Results of mass-flow modeling indicate that the geometric mean contents of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg in Chinese MSW were 3.0, 109, 101, 877, 34, 241, 21, and 1.7 mg/kg, respectively, which are comparable to those in the MSW from other countries. To protect the environment from the significant potential ecological risk posed by heavy metals in the mismanaged fly ash, strict regulation enforcement and compliance monitoring are necessary to reduce the heavy metal pollution brought by improper disposal of MSW incineration fly ash, and more research and development efforts on advanced technologies for stabilization of heavy metals in fly ash and its environmentally sound reuse can help mitigate its environmental risk.

While several mechanisms may explain metal-related health effects, the exact cellular processes are not fully understood. We evaluated the association between leukocyte telomere length (LTL) and urine arsenic (ΣAs), cadmium (Cd) and tungsten (W) exposure in the Strong Heart Study (SHS, N = 1702) and in the Strong Heart Family Study (SHFS, N = 1793).Urine metal concentrations were measured using ICP-MS. Arsenic exposure was assessed as the sum of inorganic arsenic, monomethylarsonate and dimethylarsinate levels (ΣAs). LTL was measured by quantitative polymerase chain reaction.In the SHS, median levels were 1.09 for LTL, and 8.8, 1.01 and 0.11 μg/g creatinine for ΣAs, Cd, and W, respectively. In the SHFS, median levels were 1.01 for LTL, and 4.3, 0.44, and 0.10 μg/g creatinine. Among SHS participants, increased urine ΣAs, Cd, and W was associated with shorter LTL. The adjusted geometric mean ratio (95% confidence interval) of LTL per an increase equal to the difference between the percentiles 90th and 10th in metal distributions was 0.85 (0.79, 0.92) for ΣAs, 0.91 (0.84, 1.00) for Cd and 0.93 (0.88, 0.98) for W. We observed no significant associations among SHFS participants. The findings also suggest that the association between arsenic and LTL might be differential depending on the exposure levels or age.Additional research is needed to confirm the association between metal exposures and telomere length.

Tin is a naturally occurring heavy metal that occurs in the environment in both inorganic and organic forms. Human exposure to tin is almost ubiquitous; however, surprisingly little is known about factors affecting environmental tin exposure in humans. This study analyzed demographic, socioeconomic and lifestyle factors associated with total urinary tin levels in adults (N = 3522) and children (N = 1641) participating in the National Health and Nutrition Examination Survey (NHANES) 2011–2014, a nationally representative health survey in the United States. Urinary tin levels, a commonly used biomarker of environmental tin exposure, were determined by inductively coupled plasma mass spectrometry (ICP-MS). Detection frequencies of tin were 87.05% in adults and 91.29% in children. Median and geometric mean levels of urinary tin in the adult population were 0.42 μg/L and 0.49 μg/L, respectively. For children, median and geometric mean levels of urinary tin were 0.60 μg/L and 0.66 μg/L, respectively. Age was identified as an important factor associated with urinary tin levels. Median tin levels in the ≥60 year age group were almost 2-fold higher than the 20–39 year age group. Tin levels in children were 2-fold higher than in adolescents. Race/ethnicity and household income were associated with tin levels in both adults and children. In addition, physical activity was inversely associated with urinary tin levels in adults. These results demonstrate that total tin exposures vary across different segments of the general U.S. population. Because the present study does not distinguish between organic and inorganic forms of tin, further studies are needed to better characterize modifiable factors associated with exposures to specific tin compounds, with the goal of reducing the overall exposure of the U.S. population.

An investigation of ambient levels and sources of volatile organic compounds (VOCs) and associated public health risks was carried out at two northern Alberta oil sands communities (Fort McKay and Fort McMurray located < 25 km and >30 km from oil sands development, respectively) for the period January 2010–March 2015. Levels of total detected VOCs were comparatively similar at both communities (Fort McKay: geometric mean = 22.8 μg/m³, interquartile range, IQR = 13.8–41 μg/m³); (Fort McMurray: geometric mean = 23.3 μg/m³, IQR = 12.0–41 μg/m³). In general, methanol (24%–50%), alkanes (26%–32%) and acetaldehyde (23%–30%) were the predominant VOCs followed by acetone (20%–24%) and aromatics (∼9%). Mean and maximum ambient concentrations of selected hazardous VOCs were compared to health risk screening criteria used by United States regulatory agencies. The Positive matrix factorization (PMF) model was used to identify and apportion VOC sources at Fort McKay and Fort McMurray. Five sources were identified at Fort McKay, where four sources (oil sands fugitives, liquid/unburned fuel, ethylbenzene/xylene-rich and petroleum processing) were oil sands related emissions and contributed to 70% of total VOCs. At Fort McMurray six sources were identified, where local sources other than oil sands development were also observed. Contribution of aged air mass/regional transport including biomass burning emissions was ∼30% of total VOCs at both communities. Source-specific carcinogenic and non-carcinogenic risk values were also calculated and were below acceptable and safe levels of risk, except for aged air mass/regional transport (at both communities), and ethylbenzene/xylene-rich (only at Fort McMurray).

In this study, we measured the concentrations of 58 flame retardants (and related compounds) in bald eagle (Haliaeetus leucocephalus) egg and plasma samples from the Michigan. These analytes include polybrominated diphenyl ethers (PBDEs), novel flame retardants (nFRs), Dechlorane-related compounds (Decs), and organophosphate esters (OPEs). A total of 24 paired eaglet plasma and egg samples were collected from inland (IN, N = 13) and the Great Lakes (GL, N = 11) breeding areas from 2000 to 2012. PBDEs were the most abundant chemical group with a geometric mean of 181 ng/g wet weight (ww) in egg and 5.31 ng/g ww in plasma. Decs were barely found in plasma samples, but they were frequently found in eggs (geometric mean 23.5 ng/g ww). OPE levels were comparable to those of PBDEs in the plasma but lower than those of PBDEs in eggs. Dec and PBDE concentrations were significantly higher in GL than in IN (p < 0.05). The ratio of egg to plasma concentrations (lipid normalized) varied with chemicals and correlated with the chemical's octanol-water partition coefficient. The lipid normalized bald eagle egg and plasma concentrations from Lake Superior and Huron were one to three orders of magnitude higher than concentrations measured in composite lake trout (Salvelinus namaycush) from the same lake, implying that they biomagnify in the environment.

Bisphenol S (BPS) has been progressively used due to the potential safety problems of bisphenol A (BPA). Thus Human studies are needed to investigate the developmental effects of BPS. In this study, the impact of maternal BPS exposure on birth outcomes was evaluated with linear and logistic regression models. BPS was analyzed in spot urine samples collected from 985 pregnant women at admission to labor. It was found in 93.7% of the urine samples with the specific gravity adjusted geometric mean concentration of 0.17 μg/L. One ln-unit increase in urinary BPS was associated with a 0.72-day increase in pregnancy duration (95% CI: 0.34, 1.09). When stratified by fetal sex, each ln-unit increase in maternal urinary BPS was significantly correlated with increased gestational age [adjusted β = 1.02, 95% confidence intervals (CI): 0.47, 1.57] and increased odds of late term birth [adjusted odds ratio = 1.29, 95% CI: 1.00, 1.67] for girls, but not significantly for boys. Including maternal urinary BPA and BPS in one model did not change the results. Associations of BPS with birth weight or length were not observed. This is the first report about BPS exposure for pregnant women from China. Higher maternal urinary BPS concentrations were associated with increased gestational age, suggesting maternal BPS exposure may interfere with pregnancy duration. The findings require replication but reveal the probable risks posed by the developmental BPS exposure.