Pyrethroids are a class of widely-used insecticides that can be transported from terrestrial applications to aquatic systems via runoff and tend to sorb to organic carbon in sediments. Pyrethroid occurrence is detrimental to stream ecosystems due to toxicity to sediment-dwelling invertebrates which are particularly at risk of pyrethroid exposure in urban streams. In this work, 49 streams located in watersheds in the northeastern United States were surveyed for nine current-use pyrethroids using two extraction methods. Total sediment concentrations were determined by exhaustive chemical extraction, while bioaccessible concentrations were determined by single-point Tenax extraction. Total and bioaccessible pyrethroid concentrations were detected in 76% and 67% of the sites, and the average sum of pyrethroids was 232 ng/g organic carbon (OC) for total and 43.8 ng/g OC for bioaccessible pyrethroids. Bifenthrin was the most commonly detected pyrethroid in streambed sediments. Sediment toxicity was assessed using 10-d Hyalella azteca bioassays, and 28% and 15% of sediments caused a decrease in H. azteca biomass and survival, respectively. A temperature-based focused toxicity identification evaluation was used to assess pyrethroids as the causal factor for toxicity. The concentrations of pyrethroids was only weakly correlated with the degree of urban land use. Sediment toxicity was predicted by total and bioaccessible pyrethroid concentrations expressed as toxic units. This work suggests that bioaccessibility-based methods, such as Tenax extraction, can be a valuable tool in assessing sediment toxicity.

Heavy metal cadmium (Cd) is a widespread environmental contaminant with a potential toxicity that might adversely influence the health of experimental animals and humans. It has been known that Cd might accumulate in vertebrates for many years and thus leads to the hepatic and renal toxicity. Additionally, Cd concentration in the ovary increases with age and is highly related to the reproductive hazard. However, the underlying mechanisms regarding how Cd affects the female reproductive system especially the oocyte quality have not yet fully defined. Here, we reported that Cd exposure led to the defective nuclear maturation of oocytes via the impairment of cytoskeleton assembly, displaying the aberrant spindle organization, chromosome alignment and actin polymerization. In the meantime, Cd exposure caused the impaired cytoplasmic maturation by showing the disrupted dynamics of mitochondrial integrity and cortical granules, and thereby resulting in the compromised sperm binding ability and fertilization capacity of oocytes. More importantly, we found that glutathione (GSH) supplementation was able to recover the meiotic failure induced by Cd exposure through suppressing the excessive ROS level, DNA damage accumulation and apoptotic incidence. Taken together, our findings demonstrate that Cd exposure has the adverse effects on the oocyte meiotic maturation as well as subsequent fertilization, and provide a potential effective strategy to improve the quality of Cd-exposed oocytes.

The heavy metal concentration of soil samples often exhibits a skewed distribution, especially for soil samples from mining areas with an extremely high concentration of heavy metals. In this study, to model soil contamination in mining areas using reflectance spectroscopy, the skewed distribution was corrected and heavy metal concentration estimated. In total, 46 soil samples from a mining area, along with corresponding field soil spectra, were collected. Laboratory spectra of the soil samples and the field spectra were used to estimate copper (Cu) concentration in the mining area. A logarithmic transformation was used to correct the skewed distribution, and based on the sorption of Cu on spectrally active soil constituents, the spectral bands associated with iron oxides were extracted from the visible and near-infrared (VNIR) region and used in the estimation. A genetic algorithm was adopted for band selection, and partial least squares regression was used to calibrate the estimation model. After transforming the distribution of Cu concentration, the accuracies (R2) of the estimation of Cu concentration using laboratory and field spectra separately were 0.94 and 0.96. The results indicate that Cu concentration in the mining area can be estimated using reflectance spectroscopy following correction of skewed distribution.

Passive air sampling was conducted in Toronto and the Greater Toronto Area from 2016 to 2017 for 6 periods, in order to investigate ambient levels of polycyclic aromatic compounds (PACs) associated with different source types. The selected sampling sites (n = 8) cover geographical areas with varying source emissions including background, traffic, urban, industrial and residential sites. Passive air samples were analyzed for PACs which include PAHs, alkylated PAHs (alk-PAHs), dibenzothiophene and alkylated dibenzothiophenes (DBTs) and results for PAHs were used to calculate inhalation cancer risks using different approaches. The samples were also characterized for PAH derivatives including nitrated PAHs (NPAHs) and oxygenated PAHs (OPAHs). Concentrations of Σalk-PAHs and DBTs, which are known to be enriched in fossil fuels, as well as ΣNPAHs, were highest at a traffic site (MECP) located adjacent to the 18-lane Highway 401 that runs across Toronto. Except for an industrial site (HH/BU), PAC compositions were similar across the sampling sites with Σalk-PAHs being the most abundant class of PACs suggesting traffic emission was a major contributor to PACs in the atmosphere of Toronto. The industrial site exhibited a distinct chemical composition with ΣPAHs dominating over Σalk-PAHs and with elevated levels of fluoranthene, 9-nitroanthracene, and 9,10-anthraquinone, which likely reflects emissions from nearby industrial sources. MECP and HH/BU exhibited higher lifetime excess inhalation cancer risks indicating an association with traffic and industrial sources. The importance of the traffic sector as a source of PACs to ambient air is further supported by strong correlations of the ΣPAHs, Σalk-PAHs, DBTs, and ΣOPAHs with NOx. This study highlights the importance of traffic as an emission source of PACs to urban air and the relevance of PAC classes other than just unsubstituted PAHs that are important but currently not included in air quality guidelines or for assessing inhalation cancer risks.

Biodegradable plastics have been introduced and widely used as a promising alternative to traditional nondegradable plastics. However, the differences in sorption behavior of pesticides on nondegradable and biodegradable microplastics has been insufficiently studied. Here, four types of nondegradable [polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP)] and two types of biodegradable [polylactic acid (PLA), polybutylene succinate (PBS)] microplastics were selected to investigate the sorption mechanism of fipronil based on their sorption kinetics and isotherms. The results indicated that the sorption rates of PLA and PBS were much higher than those of PE, PP, PVC and PS and that the sorption capacities of fipronil on microplastics followed the order of PBS > PLA > PP > PE > PS > PVC. The sorption kinetics followed a pseudo-second-order kinetics model (R² = 0.953–0.998) for all tested microplastics. External mass transport and intraparticle diffusion were the main rate controlling steps of the sorption of fipronil on microplastics. Furthermore, isotherm results indicated that a Langmuir model provided the best fit for fipronil sorption on PE, PS, PVC and PP (R² = 0.997–0.999), while a Freundlich model was the most appropriate model for PLA and PBS (R² = 0.998–0.999). The presence of surface O-containing functional groups and the spatial arrangement of rubbery domains are likely to affect the sorption process. The results from this work suggest that microplastics, especially biodegradable ones, may play an important role in the fate and transport of pesticides, and their effects on soil organisms (e.g., earthworms) require further investigation.

In the present study, to assess the immunotoxicity of cypermethrin (CYP) in fish, Chinese rare minnows (Gobiocypris rarus) were exposed to environmentally relevant concentrations (0.15, 0.5, and 1.5 μg/L) of CYP for 28 d and subjected to pathogen challenge trials for 2 d. After 28 d of CYP exposure, the levels of Immunoglobulin M (IgM), Alkaline phosphatase (ALP), and C-reactive protein (CRP) were significantly decreased (p < 0.05) after treatment with 1.5 μg/L CYP. Moreover, an induction of inflammatory cytokine transcripts (tnfa, il-6, il-8, and il-12) was observed (p < 0.05) after treatment with 1.5 μg/L CYP. After challenge with Pseudomonas fluorescens (P. fluorescens), plasma lysozyme (LYS) activity at 24 and 48 hours post-injection (hpi) was significantly decreased in the 0.5 and 1.5 μg/L CYP treatment groups (p < 0.05). Moreover, liver Complement component 3 (C3) and CRP contents at 24 hpi were significantly decreased in the 1.5 μg/L CYP treatment group (p < 0.05), whereas significant decreases in liver C3 and IgM contents were observed at 48 hpi (p < 0.05). Inhibition of expression of Toll-like receptor-nuclear factor kappa B (TLR-NF-kB) signaling pathway-related genes was observed in the CYP treatment groups and resulted in significant down-regulation of inflammatory cytokines (il-1β and il-12) in the 1.5 μg/L CYP treatment group at 48 hpi (p < 0.05). Interestingly, the mortality in the 0.5 and 1.5 μg/L CYP treatments was significantly increased at 48 hpi (p < 0.05). These results indicated that environmentally relevant concentrations of CYP suppressed the Chinese rare minnow immune system and reduced immune defense against bacterial infection, thereby causing subsequent mortality. Meanwhile, our results demonstrated that a subsequent host resistance challenge is an effective method for determining the immunotoxicity of chemicals (e.g., CYP).

Polychlorinated biphenyls (PCBs) are a class of widespread environmental pollutants, commonly found in human blood, that have been suggested to be linked to the occurrence of sporadic Parkinson's disease (PD). It has been reported that some non-coplanar PCBs accumulate in the brains of female PD patients. To improve our understanding of the association between PCB exposure and PD risk we have applied whole transcriptome gene expression analysis in blood cells from 594 PCB-exposed subjects (369 female, 225 male).Interestingly, we observe that in females, blood levels of non-coplanar PCBs appear to be associated with expression levels of PD-specific genes. However, no such association was detected in males. Among the 131 PD-specific genes affected, 39 have been shown to display similar changes in expression levels in the substantia nigra of deceased PD patients. Especially among the down-regulated genes, transcripts of genes involved in neurotransmitter vesicle-related functions were predominant.

Beef cattle feedyards have been identified as sources of large amounts of particulate matter (PM) which may transport affiliated chemicals including steroids, beta agonists, and antibiotics from feedyards into the environment. This study is the first to examine persistence of PM-affiliated pharmaceuticals downwind of feedyards using multiple downwind samples collected at increasing distances from feedyard boundaries (n = 5). Concentrations of antibiotics and ractopamine per gram of PM remained consistent at all downwind locations (out to 4.8 km) whereas concentrations per m³ air decreased significantly at distances between 0.1 and 0.7 km downwind, corresponding to significant decreases in mass of PM. Monensin was present in the highest concentrations of any measured pharmaceutical, with concentrations of 37 μg/g PM (376 ng/m³) air in samples collected within 0.1 km downwind of feedyards. Total copy count of tetracycline resistance genes (tetW, tetQ, tetO, tetM, tetL, and tetB) were also significantly increased in samples collected within 0.1 km downwind of feedyards (10⁶ copies) as compared to samples collected upwind (10³ copies) and farther downwind (10⁴ copies) of feedyard boundaries. These results suggest that transport of pharmaceutical-laden PM into the terrestrial environment is occurring primarily via PM deposition within 0.7 km of the feedyard, while aerial transport persists over longer distances (>4.8 km).

Rice consumption is one of the primary sources of arsenic (As) exposure as the grains contain relatively higher concentration of inorganic As. Abundant studies on the ability of iron (Fe) plaque in hampering As uptake by plants has been reported earlier. However, little is known about its role in the mitigation of As mediated oxidative damage in rice plants. The present study highlights the effect of As and Fe co-supplementation on growth response, oxidative stress, Fe uptake related enzymes and nutrient status in rice varieties. Eight different Indica rice varieties were screened and finally four varieties (Varsha, Jaya, PB-1 and IR-64) were selected for detailed investigations. Improved germination and chlorophyll/protein levels during As+Fe co-exposure indicate healthier plants than As(III) treated ones. Interestingly Fe was found act both as an antagonist and also as a synergist of As treatments. It acted by reducing As translocation and improving the nutritional levels and enhancing the oxidative stress. Fe uptake related enzymes (nitrite reductase and ferric chelate reductase) and phytosiderophores analysis revealed that Fe supplementation can reduce its deficiency in rice plants. Morpho-biochemical, oxidative stress and nutrient analysis symbolizes higher tolerance of PB-1 towards As, while Varsha being most sensitive, efficiently combated the As(III) stress in the presence of Fe.