Reduced physical performance is an important feature of aging, and walking speed is a valid measure of physical performance and mobility in older adults. Previous epidemiological studies suggest that cadmium exposure, even at low environmental levels, may contribute to vascular, musculoskeletal, and cognitive dysfunction, which may all be associated with reductions in physical performance. To this end, we investigated the associations of blood and urine cadmium concentrations with walking speed in middle-aged and older adults in the U.S. general population. We studied U.S. adults from the National Health and Nutrition Examination Survey 1999 to 2002 who were ≥50 years of age, who had determinations of cadmium in blood or in urine, and who had measurements of the time taken to walk 20 feet. Walking speed (ft/sec) was computed as walked distance (20 ft) divided by measured time to walk (in seconds). The weighted geometric means of blood and urine cadmium were 0.49 [95% confidence interval (CI): 0.47, 0.52] μg/L and 0.37 (95% CI: 0.34, 0.42) ng/mL, respectively. After adjusting for sociodemographic, anthropometric, health-related behavioral, and clinical risk factors and inflammation markers, the highest (vs. lowest) quintile of blood cadmium was associated with a 0.18 (95% CI: 0.10, 0.25) ft/sec reduction in walking speed (p-Trend <0.001). No association was observed for urine cadmium levels with walking speed. Cadmium concentrations in blood, but not in urine, were associated with slower gait speed. Our findings add to the growing volume of evidence supporting cadmium's toxicity even at low levels of exposure.

A green alga, Chlamydomonas reinhardtii, was used to verify whether a simple Biotic Ligand Model (BLM) could be used to predict carefully controlled short-term biouptake for the lanthanide, Nd. In the absence of ligands or competitors, Nd biouptake was well described by a Michaelis-Menten equation with an affinity constant, KNd, of 10⁶.⁸ M⁻¹ and a maximum internalization flux of Jₘₐₓ = 1.70 × 10⁻¹⁴ mol cm⁻² s⁻¹. For bi-metal mixtures containing Nd and Ca, Mg, Sm or Eu, Nd uptake could also be well modelled by assigning experimentally determined affinity constants of KCₐ = 10².⁶ M⁻¹, KMg = 10³.⁴ M⁻¹, KSₘ = 10⁶.⁵ M⁻¹ and KEᵤ = 10⁶.⁵ M⁻¹. The similar values of Kₘ and Jₘₐₓ for the three rare earth elements (REEs): Sm, Eu and Nd is consistent with them sharing a common metal uptake site. On the other hand, in the presence of the small organic ligands (citric or malic acid), neither, free or total Nd concentrations could be used to quantitatively predict Nd internalization fluxes. In other words, in order to predict biouptake by simple BLM determinations, it was necessary to consider that the Nd complexes were bioavailable. The data strongly suggest that risk evaluations of the REE will require a new paradigm and new tools for evaluating bioavailability.

Novel 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and legacy PFASs, such as perfluorohexane sulfonate (PFHxS), have been used to replace perfluorooctane sulfonate (PFOS), a known persistent organic pollutant. Thus, it is critical to understand these PFOS alternatives regarding their sources and concentrations in the natural environment. In this study, 41 surface water samples as well as edible aquatic organisms were collected from Baiyangdian Lake, the largest freshwater lake in Hebei Province, China. Perfluorooctanoate acid (PFOA) and PFHxS were the predominant PFASs detected in the surface water, reaching concentrations of 8 397.23 ng/L and 1 478.03 ng/L, respectively, with PFHxS accounting for the greatest proportion (∼80.00%) in most water samples. PFHxS (mean: 87.53 ng/g) and PFOS (mean: 35.94 ng/g) were also the most prevalent compounds detected in aquatic organisms. Estimated daily intake (EDI) values of PFOS (16.56 ng/kg bw/d) and PFHxS (16.11 ng/kg bw/d) via aquatic food and drinking water were the highest among PFASs, indicating potential exposure risks to residents. In addition, fish product consumption was the important exposure pathway for residents to PFOA, PFHxS, PFOS, and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA). This study reports on the highest PFHxS levels ever recorded in surface water, suggesting that further quantification of PFHxS in human serum and assessment of its health risks to local residents are warranted and critical.

The prevalence of allergic diseases has increased in the past few decades. Bio-aerosol proteins and their chemical modifications, such as 3-nitrotyrosine (3-NT), in the atmosphere have been attracting attention due to their promotive effects on allergies. 3-NT is generated from the amino acid, tyrosine, through a reaction with ozone (O3) and nitrogen dioxide (NO2). However, the underlying mechanisms have not yet been elucidated in detail. Therefore, we measured 3-NT and evaluated the relationships among 3-NT and various pollutants such as sulfur dioxide (SO2), NOx (NO + NO2), ozone (O3), PM7, total suspended particulate matter (TSP) containing proteins, humidity, and temperature. 3-NT positively correlated with O3, SO2, humidity, and temperature, and negatively correlated with NOx. A multiple regression analysis showed that 3-NT positively associated with O3, humidity, and PM7. O3 positively associated with 3-NT and PM7, and negatively associated with NOx and humidity. These results suggest that 3-NT is generated from PM proteins through a reaction with O3 under high humidity conditions, and that the measurement of 3-NT is important and useful for the research of O3.

Crude oil and its derivatives are considered as one group of the most pervasive environmental pollutants in marine environments. Bioremediation using oil-degrading bacteria has emerged as a promising green cleanup alternative in more recent years. The employment of biosurfactant-producing and hydrocarbon-utilizing indigenous bacteria enhances the effectiveness of bioremediation by making hydrocarbons bioavailable for degradation. In this study, the best candidates of biosurfactant-producing indigenous bacteria were selected by screening of biochemical tests. The selected bacteria include Bacillus algicola (003-Phe1), Rhodococcus soli (102-Na5), Isoptericola chiayiensis (103-Na4), and Pseudoalteromonas agarivorans (SDRB-Py1). In general, these isolated species caused low surface tension values (33.9–41.3 mN m−1), high oil spreading (1.2–2.4 cm), and hydrocarbon emulsification (up to 65%) warranting active degradation of hydrocarbons. FT-IR and LC-MS analyses indicated that the monorhamnolipid (Rha-C16:1) and dirhamnolipid (Rha-Rha-C6-C6:1) were commonly produced by the bacteria as potent biosurfactants. The residual crude oil after the biodegradation test was quantitated using GC-MS analysis. The bacteria utilized crude oil as their sole carbon source while the amount of residual crude oil significantly decreased. In addition the cell-free broth containing biosurfactants produced by bacterial strains significantly desorbed crude oil in oil-polluted marine sediment. The selected bacteria might hold additional capacity in crude oil degradation. Biosurfactant-producing indigenous bacteria therefore degrade crude oil hydrocarbon compounds, produce biosurfactants that can increase the emulsification of crude oil and are thus more conducive to the degradation of crude oil.

Permeable reactive barriers (PRBs) remove nitrogen from groundwater by enhancing microbial denitrification. The PRBs consist of woodchips that provide carbon for denitrifiers, but these woodchips also support other anaerobic microbes, including sulfate-reducing bacteria. Some of these anaerobes have the ability to methylate inorganic mercury present in groundwater. Methylmercury is hazardous to human health, so it is essential to understand whether PRBs promote mercury methylation. We examined microbial communities and geochemistry in fresh water and sulfate-enriched PRB flow-through columns by spiking replicates of both treatments with mercuric chloride. We hypothesized that mercury addition could alter bacterial community composition to favor higher abundances of genera containing known methylating taxa and that the sulfate-rich columns would produce more methylmercury after mercury addition, due mainly to an increase in abundance of sulfate reducing bacteria (SRB). However, methylmercury output at the end of the experiment was not different from output at the beginning, due in part to coupled Hg methylation and demethylation. There was a transient reduction in nitrate removal after mercury addition in the sulfate enriched columns, but nitrate removal returned to initial rates after two weeks, demonstrating resilience of the denitrifying community. Since methylmercury output did not increase and nitrate removal was not permanently affected, PRBs could be a low cost approach to combat eutrophication.

Methylparaben, which is known to be an endocrine-disrupting chemical, is added to various personal care products, including cosmetics, and is also used as a food preservative and in pharmaceuticals. However, information on the toxicity of methylparaben in soil ecosystems is limited. Furthermore, unlike other substances such as metals and pesticides, there is no regulation of levels or safe concentrations of methylparaben in soil ecosystems. Therefore, the aims of this study were to evaluate the toxicity of methylparaben on soil species and to derive hazardous concentration (HC) values with respect soil ecosystem protection. We conducted acute bioassays on eight species within six taxonomic groups and chronic bioassays on five species within four taxonomic groups. On the basis of the results obtained, we derived an acute HC₅ value of 44 mg/kg soil and a corresponding chronic value of 27 mg/kg soil for methylparaben using species sensitivity distribution methodology following Australian and New Zealand guidelines. Given that there has been no proposed standard value for methylparaben in soil in any country, it was not possible to compare the HC values calculated in this study with regulation standard levels. Nevertheless, to our knowledge, this study is first to assess the toxicity of methylparaben against soil-inhabiting species and to estimate acute and chronic HCs for soil fauna and flora. The results of this study will provide valuable fundamental data for the establishment of acceptable levels of methylparaben in soil.

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) receive increasing attention as hazardous pollutants in terms of the high environmental persistence and toxicities. Ambient concentrations of 24 ClPAHs and 24 PAHs were investigated at 14 sites in the Tokyo Bay area of Japan. Twelve of 18 ClPAH species were detected in air samples, in spite of small sampling volumes. Mean concentrations of total PAHs in gas and particle phases were 5400 and 1400 pg/m³, and mean concentrations of total ClPAHs in gas and particle phases were 40 and 14 pg/m³, respectively. The spatial distributions of both total ClPAH and PAH concentrations indicated heavy pollution at sites in industrial activity areas. Principal component analysis suggested that the dominant sources of gaseous and particulate ClPAHs differed substantially from each other. In particular, gaseous ClPAHs could be produced by specific sources different from those of particulate ClPAHs. However, the dominant sources of particulate ClPAHs could be the same as those of particulate PAHs, including industrial activities such as steel and gas-production plants and natural gas-fired power plants. The influences of spatial relationships among sampling sites were represented using a network analysis. The constructed network showed that ambient ClPAHs and PAHs were dominated by local rather than regional pollution, because there were weaker relationships among nearby sites. Finally, exposure risks for ClPAHs were dominated by 7-chlorobenz[a]anthracene, followed by 9-chlorophenanthrene and 6-chlorobenzo[a]pyrene, and total risk was ∼1/200 that of PAHs.

Although weekly consumption of fish is recommended, the presence of contaminants in seafood has raised many concerns regarding the benefits of fish intake. In the present study microplastics (MPs) and metals’ concentration in muscles of both benthic and pelagic fish species from northeast of Persian Gulf were investigated and the risk/benefit of their consumption was assessed. The results demonstrated that MPs and Hg in all species and Se in benthic species increase with size, while relationship between other metals, and fish size is not consistent. Consumption of a meal ration of 300 and < 100 g/week for adults and children, respectively, is recommended since it would provide the required essential elements with no human health risk. On the other hand, the estimated intake of MPs from fish muscles revealed that the mean intake of MPs for P. indicus, E. coioides, A. djedaba, and S. jello consumption is 555, 240, 233, and 169 items/300 g-week, respectively. Moreover, the relationship between MPs and metals in fish muscles were positive for A. djedaba, and negative for E. coioides. Considering the chemical toxicity of MPs and metals, and their good linear relationships in some species, consumption of high doses of the studied fish may pose a health threat to the consumers.

Although the roles of earthworms and soil collembolans in the transport of microplastics have been studied previously, the effects of the soil biota at different trophic levels and interspecific relationships remain poorly understood. Here, we examine three soil microarthropod species to explore their effects on the transport of microplastics. The selected Folsomia candida and Hypoaspis aculeifer are extensively used model organisms, and Damaeus exspinosus is a common and abundant indigenous species in China. A model food chain (prey-collembolan and predator-mite) was structured to test the role of the predator-prey relationship in the transport of microplastics. Commercial Polyvinyl chloride (PVC) particles (Diameter: 80–250 μm) were selected as the test microplastics, because large amounts of PVC have persisted and accumulated in the environment. Synchronized soil microarthropods were held in plates for seven days to determine the movement of microplastics. The 5000 microplastic particles were carefully placed in the center of each plate prior to the introduction of the animals. Our results clearly show that all three microarthropod species moved and dispersed the microplastics in the plates. The 0.54%, 1.8% and 4.6% of the added microplastic particles were moved by collembolan, predatory mite and oribatid mite, respectively. Soil microarthropods (<0.2 cm) transported microplastic particles up to 9 cm. The avoidance behavior was observed in the collembolans in respect of the microplastics. The predatory -prey relationship did promote the transport of microplastics in the plates, increasing transport by 40% compared with the effects of adding single species (P < .05). Soil microarthropods commonly occur in surface soils (0–5 cm) and, due to their small body size, they can enter soil pores. Our results therefore suggest that the movement of microplastics by soil microarthropods may influence the exposure of other soil biota to microplastics and change the physical properties of soils.