Hyperbranched polymers are nanomaterials belonging to the class of dendritic architectures with increasing applications in many diverse fields. We studied the toxicity of two hyperbranched polymers to the freshwater crustacean Daphnia magna. A hyperbranched hydroxyl-terminated polyester and a commercial hyperbranched polyamidoamine, Helux-3316 were tested for the acute immobilization of daphnids, the overproduction of reactive oxygen species and the activity of the antioxidant enzymes catalase and glutathione S-transferase. The effect for D. magna immobilization was higher for the hyperbranched polyamidoamine Helux-3316, which was attributed to the presence of primary amino groups on its surface. Following exposure to both hyperbranched polymers, a clear overproduction of reactive oxygen species took place accompanied by concentration-dependent enzymatic antioxidant response. Our results showed that the overproduction of reactive oxygen species activated antioxidant defence mechanisms and was responsible for the immobilization of daphnids exposed to both hyperbranched polymers. We showed evidence of the uptake of fluorescently labelled Helux-3316 that accumulated into the gastrointestinal tract of D. magna, and its removal via excretion within fecal pellets. This is the first work reporting the internalization of hyperbranched polymers in aquatic organisms.

Perfluoroalkyl substances (PFASs) are known to be toxic, bioaccumulative, and persistent. However, exposure routes and toxic effects to humans are still widely unknown. Our objectives were to evaluate potential correlations between concentrations of PFASs in maternal plasma and infant cord blood with home characteristics and developmental effects, including wheezing. The concentrations of 17 PFASs were measured in plasma from prenatal women (n = 414), postnatal women (n = 247), and cord blood (n = 50) from a subset of participants in a population-based birth cohort in Winnipeg, Manitoba, Canada, using online solid phase extraction (SPE) with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Multiple linear regression and principal component analysis (PCA) were used to evaluate possible associations with PFAS concentrations. Surveys were used to collect information regarding maternal characteristics (e.g. age, parity, duration of breastfeeding), infant characteristics (e.g. birth weight, birth length, head circumference, gestational age, and incidence of recurrent wheezing), and home characteristics (e.g. home age,carpet coverage in the most used room, presence of new furniture, or recent home renovations). PFASs in plasma were associated with maternal characteristics but not home characteristics or early childhood wheezing. PFASs were not associated with developmental effects, with the exception that perfluoroundecanoic acid (PFUA) was negatively associated with birth weight. Further studies investigating the potential influences of PFUA on birth weight are warranted.

We investigated the profiles and levels of perfluoroalkyl carboxylic acid (PFCA) contamination in Pacific cod (Gadus macrocephalus) from the North Pacific Ocean. The mean concentrations of PFCAs containing 8 to 14 carbon atoms (C8–C14) in edible Pacific cod muscle ranged from 216 to 670 pg g⁻¹ wet weight in the Northeast Pacific Ocean (Seattle, Vancouver, Alaska, and Russia), from 819 to 1710 pg g⁻¹ wet weight in Japanese coastal waters (Hokkaido, Aomori, Iwate, Miyagi, Tottori, and Shimane), and from 288 to 892 pg g⁻¹ wet weight in Korean waters (Sokcho, Busan, and Yeosu). These results indicate there are geographical differences in the distribution of PFCAs. The long-chain PFCAs (C9–C14) contributed 96% of the total PFCA concentration across Japan, whereas they contributed only 33% of the total PFCA concentration in the USA and Canada. Long-chain PFCA concentrations in cod samples collected in Japanese and Korean waters were about three to four times those in samples from the USA, Canada, and Russia. Because seafood is considered an important dietary source of PFCAs, high concentrations of long-chain PFCAs in Pacific cod from Japanese and Korean waters may affect human dietary exposure and blood concentrations of long-chain PFCAs.

Tributyltin (TBT) is an organotin environmental pollutant widely used as an agricultural and wood biocide and in antifouling paints. Countries began restricting TBT use in the 2000s, but their use continues in some agroindustrial processes. We studied the acute effect of TBT on cardiac function by analyzing myocardial contractility and Ca²⁺ handling. Cardiac contractility was evaluated in isolated papillary muscle and whole heart upon TBT exposure. Isolated ventricular myocytes were used to measure calcium (Ca²⁺) transients, sarcoplasmic reticulum (SR) Ca²⁺ content and SR Ca²⁺ leak (as Ca²⁺ sparks). Reactive oxygen species (ROS), as superoxide anion (O2•⁻) was detected at intracellular and mitochondrial myocardium. TBT depressed cardiac contractility and relaxation in papillary muscle and intact whole heart. TBT increased cytosolic, mitochondrial ROS production and decreased mitochondrial membrane potential. In isolated cardiomyocytes TBT decreased both Ca²⁺ transients and SR Ca²⁺ content and increased diastolic SR Ca²⁺ leak. Decay of twitch and caffeine-induced Ca²⁺ transients were slowed by the presence of TBT. Dantrolene prevented and Tiron limited the reduction in SR Ca²⁺ content and transients. The environmental contaminant TBT causes cardiotoxicity within minutes, and may be considered hazardous to the mammalian heart. TBT acutely induced a negative inotropic effect in isolated papillary muscle and whole heart, increased arrhythmogenic SR Ca²⁺ leak leading to reduced SR Ca²⁺ content and reduced Ca²⁺ transients. TBT-induced myocardial ROS production, may destabilize the SR Ca²⁺ release channel RyR2 and reduce SR Ca²⁺ pump activity as key factors in the TBT-induced negative inotropic and lusitropic effects.

Crude oil and its constituents can have adverse effects on ecological and human health when released into the environment. The Canadian Council of Ministers of the Environment (CCME) has developed remedial guidelines and a risk assessment framework for both ecological and human exposure to PHC. One of the assumptions used in the derivation of these guidelines is that plants are unable to take up PHC from contaminated soil and therefore subsequent exposure at higher trophic levels is not a concern. However, various studies suggest that plants are indeed able to take up PHC into their tissues. Consumption of plants is a potential exposure pathway in both ecological (e.g., herbivorous and omnivorous birds, and mammals) and human health risk assessments. If plants can uptake PHC, then the current approach for risk assessment of PHC may underestimate exposures to ecological and human receptors. The present review aims to assess whether or not plants are capable of PHC uptake and accumulation. Twenty-one articles were deemed relevant to the study objective and form the basis of this review. Of the 21 primary research articles, 19 reported detectable PHC and/or its constituents in plant tissues. All but five of the 21 articles were published after the publication of the CCME Canada-Wide Standards. Overall, the present literature review provides some evidence of uptake of PHC and its constituents into plant tissues. Various plant species, including some edible plants, were shown to take up PHC from contaminated soil and aqueous media in both laboratory and field studies. Based on the findings of this review, it is recommended that the soil-plant-wildlife/human pathway should be considered in risk assessments to avoid underestimating exposure and subsequent toxicological risks to humans and wildlife.

Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7⁻/⁻ animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

Nitrogen (N) addition can change physicochemical properties and biogeochemical processes in soil, but whether or not these changes further affect the transport and transformation of heavy metal speciation is unknown. Here, a long-term (2004–2016) field experiment was conducted to assess the responses of different heavy metal speciation in three soil aggregate fractions to N additions in a temperate agroecosystem of North China. The organic matter turnover time was quantified based on changes in δ13C following the conversion from C3 (wheat) to C4 crop (corn). Averagely, N addition decreases and increases the heavy metal contents in bioavailable and organic bound fractions by 27.5% and 16.6%, respectively, suggesting N addition promotes the transformation of heavy metal speciation from bioavailable to organic bound, and such a promotion in a small aggregate fraction is more remarkable than that in a large aggregate fraction. The transformations of heavy metal speciation from bioavailable to organic bound in all soil aggregate fractions are largely dependent on the increments in the turnover time of organic matter. The increase in organic matter turnover time induced by N addition may inhibit the desorption of heavy metals from organic matter by prolonging the interaction time between heavy metals and organic matter and enhance the capacity of organic matter to adsorb heavy metals by increasing the humification degree and functional group. Our work can provide insights into the accumulation, migration, and transformation of heavy metals in soils in the context of increasing global soil N input from a microenvironmental perspective.

Groundwater pollution is a critical concern in karst areas. This study used the PLEIK (P: protective cover; L: land use; E: epikarst development; I: infiltration conditions; K: karst development) method to assess the vulnerability of groundwater pollution in Guangxi Province, which is the largest karst area in China. The pollution sources and attenuation consist of groundwater pollution hazards. The attributions for the vulnerability and hazard were measured using the geodetector method from geographical information system in Luzhai County in Guangxi. The results confirmed that the vulnerability of groundwater pollution was higher in karst areas than in non-karst areas. In Guangxi, 36.35% of the groundwater samples were polluted. A total of 49.73% of the areas in Luzhai County contained hazardous levels of pollution. The risk assessment map, which interacted with the vulnerability and hazards, was 58.2% similar to the groundwater pollution distribution. The influence of the hazard on groundwater pollution was 2.6 times that of the vulnerability. It is crucial to control pollution sources to prevent groundwater pollution.

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.

The aim of this study was to assess the effect of major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺, and H⁺) on cadmium toxicity to the springtail Folsomia candida. Survival of the animals was determined after seven days exposure to different cadmium concentrations in an inert sand-solution medium, in different experimental setups with modification of the cation concentrations. Among the cations tested, Ca²⁺ and Mg²⁺ had protective effects on the toxicity of cadmium to the springtails while Na⁺, K⁺, and H⁺ showed less competition with free cadmium ions for binding to the uptake sites of the collembolans. Toxicity predicted with a biotic ligand model agreed well with the observed values. Calculated conditional binding constants and the fraction of biotic ligands occupied by cadmium to show 50% effects were similar to values reported in the literature. The results emphasize the important role of solution chemistry in determining metal toxicity to soil invertebrates.