Low Log Kow Research Articles

Trophic transfer of dechloranes in marine food webs in Dalian Bay, China

Dechloranes, including dechlorane 602 (Dec 602), dechlorane 603 (Dec 603), dechlorane 604 (Dec 604), dechlorane plus (DP, including syn- and anti-DP) and mirex, were determined in marine food web from Dalian Bay, Northeast China to investigate their occurrence andtrophic transfer. In all organisms, the detection rates were Dec 602 (99%) > mirex (95%) > Dec 603 (92%) > anti-DP (91%) > syn-DP (82%) > Dec 604 (9.6%). The concentrations were 0.92–16 ng/g lipid weight (lw) for mirex, 0.53–2.3 ng/g lw for syn-DP, 1.1–4.5 ng/g lw for anti-DP, 0.19–5.0 ng/g lw for Dec 602, 0.26–1.9 ng/g lw for Dec 603 and 0.020–0.33 ng/g lw for Dec 604. Significant positive relationships (p < 0.0001) were observed between lipid normalized concentrations and trophic levels for mirex (R2 = 0.80) and Dec602 (R2 = 0.82) in food webs, with the calculated TMFs values of 3.09 and 3.39, respectively, indicating the trophic magnification potential of these compounds. For syn-DP, anti-DP, Dec 603 and Dec 604, the similar significant relationships were not found, suggesting that these chemicals do not trophic magnification nor trophic dilution in the food web. With low log KOW values for mirex (7.01) and Dec 602 (8.05), these two compounds have the highest magnifications potentials, while the magnification potential of Dec 603, Dec 604 and DP dramatically decreased because of their extremely big log KOW values (higher than 10). The observed fractional abundance of anti-DP (fanti) ranged of 0.58–0.69, closing to the one in Chinese industrial products, indicating DP isomers had not undergone significant differences of physicochemical or biological process in the studied food web.

Tissue-Specific Accumulation of Orally Administered Short- and Medium-Chain Chlorinated Paraffins in Honeybees (Apis mellifera L.).

The prevalence and distribution of chlorinated paraffins (CPs) have been extensively studied in various matrices and organisms; however, there is a lack of information about insects, particularly in honeybees. To address this gap, we studied young honeybee workers exposed to short- and medium-chain CPs (SCCPs and MCCPs) at an environmentally relevant concentration of 10 mg/L for 7 days, followed by a 7-day elimination period. Results indicated that CPs could transfer into the head after oral consumption and SCCPs and MCCPs exhibited clear bioaccumulation trends: midgut > hindgut > head. An evaluation of congener group distribution patterns demonstrated that the dominant congener groups in all target tissues were C11-13Cl7-8 and C14Cl7-8 for SCCPs and MCCPs, respectively, consistent with the treated CP standards. In honeybees, a significant negative relationship was observed for the log concentration of MCCP congener groups and their log KOW, but not with their log KOA. Conversely, no such correlation was found for SCCPs. These findings suggest that honeybees have a high potential to bioaccumulate MCCPs, particularly those with a low log KOW, and exhibit weak selectivity for SCCPs.

Uptake, accumulation and translocation of traditional and novel organophosphate esters by rice seedlings in the presence of micro(nano)-polystyrene plastics: Effects of concentration and size of particles

Micro(nano)plastics (MNPs) and organophosphate esters (OPEs) are becoming ubiquitous as emerging pollutants. To data, the effects of MNPs on the uptake, accumulation and translocation of OPEs by rice plant are still unclear, especially for novel OPE species. In this study, the impacts of polystyrene MNPs of different sizes and concentrations on the uptake of eight OPEs (six traditional organophosphate triesters and two novel discovered aryl organophosphate triesters) by rice seedlings were investigated in hydroponic exposure experiments. The results showed that OPEs accumulated in a concentration-dependent manner in both the roots and shoots of rice seedlings. The impacts of MNPs on uptake by rice seedlings were concentration- and size-dependent by influencing the transpiration rate or activities of antioxidant enzymes. Especially, significant effects were usually found in exposure group of medium-size and high-concentration MNPs. MNPs had more obvious effects on OPE species with lower logKow in roots, whereas, more obvious effects on OPE species with higher logKow in shoots were observed. There was a significantly positive linear relationship between logTF and logKow (p < 0.001), and a significantly negative linear relationship between logRCF and logKow (p < 0.001), indicating that OPEs with higher hydrophobicity seemed to be more liable to be absorbed from solutions to roots, but difficult to further translocate to shoots. Without novel OPEs (bis-(2-ethylhexyl)-phenyl phosphate and tris(2,4-di-tert-butylphenyl)phosphate), better fits for a linear model for logKow and logRCF (or logTF) were exhibited, indicating differences between novel and traditional OPEs. This work highlights that the presence of MNPs could altered the characteristics of uptake, translocation and accumulation of OPEs in rice seedlings, and provides an important evidence for comprehensive control strategy of new pollutants.

Exploring sorption of pesticides and PAHs in microplastics derived from plastic mulch films used in modern agriculture

The sorption and vector effect of microplastics on the transfer of pesticides and polycyclic aromatic hydrocarbons (PAHs), as well as its impact on agriculture remain largely unexplored. This comparative study is first to investigate the sorption behavior of different pesticides and PAHs at environmentally realistic concentrations by model microplastics and microplastics derived from polyethylene mulch films. Sorption was found to be up to 90% higher in the case of microplastics derived from mulch films as opposed to pure polyethylene microspheres. For microplastics from mulch films, the sorption percentages for pesticides in media containing CaCl2 were reported to be: pyridate (75.68% and 52.44%), fenazaquin (48.54% and 32.02%), pyridaben (45.04% and 56.70%), bifenthrin (74.27% and 25.88%), etofenprox (82.16% and 54.16%) and pyridalyl (97.00% and 29.74%) at 5 μg/L and 200 μg/L pesticide concentration levels respectively. For PAHs, the sorption amounts were: naphthalene (22.03% and 48.00%), fluorene (38.99% and 39.00%), anthracene (64.62% and 68.02%) and pyrene (75.65% and 86.38%) at 5 μg/L and 200 μg/L PAH concentration levels respectively. Sorption was influenced by the octanol-water partition coefficient (log Kow) and ionic strength. Kinetics of the process in the case of sorption of pesticides were best explained by pseudo-first order kinetic model (R2 between 0.90 and 0.98) while the best fitting isotherm model was Dubinin-Radushkevich (R2 between 0.92 and 0.99). Results suggest the presence of surface level physi-sorption through a micropore volume filling mechanism and the role of hydrophobic and electrostatic forces. Pesticide desorption data in polyethylene mulch films indicate that pesticides with high log Kow were almost completely retained in mulch films, while those with lower log Kow were desorbed rapidly into the surrounding media. Our study highlights the role of microplastics from plastic mulch films as vectors for pesticide and PAH transport at environmentally realistic concentrations and the factors that influence it.

Occurrence and transport of N-nitrosamines in the urban water systems of the Pearl River Delta, southern China

The discharge of substantial amounts of N-nitrosamines-contained wastewater into receiving rivers can significantly deteriorate water quality, as these carcinogenic compounds can be easily transported into groundwater and drinking water systems. This study investigated the distribution of eight species of N-nitrosamines in river water, groundwater, and tap water located in the center of the Pearl River Delta (PRD), China. The results showed that three major N-nitrosamines, including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosodibutylamine (NDBA), with concentrations of up to 64 ng/L, were observed in river water, groundwater, and tap water, whereas the other compounds occurred sporadically. In river water and groundwater, high concentrations of NDMA, NDEA, N-nitrosomorpholine (NMOR), and NDBA were found in industrial and residential lands as compared to agricultural lands owing to the influence of various human activities. The primary sources of N-nitrosamines in river water were industrial and domestic wastewater, and the infiltration of river water was responsible for the high levels of N-nitrosamines in groundwater. Among the target N-nitrosamines, NDEA and NMOR with long biodegradation half-lives (>4 days) and low LogKow values (<1) displayed the highest potential for groundwater. N-nitrosamines in groundwater and tap water pose significant potential cancer risks to residents, especially children, and juveniles, with lifetime cancer risks of over 10−4, necessitating advanced water treatments for drinking water and critical controls on primary industrial discharge in urban areas.

Generic Model for Plant Uptake of Ionizable Pharmaceuticals and Personal Care Products.

Plant uptake of pharmaceuticals and personal care products (PPCPs) has been recognized as a potential path to human exposure. Most existing regressions and uptake models are limited to neutral organic compounds, but 80% of pharmaceuticals and an unknown number of personal care products ionize under environmentally relevant conditions. A widely used generic plant uptake model was expanded step-by-step with processes relevant for weak and strong acids and bases, such as ionization, membrane permeability, ion trap, phloem transport, and sorption to proteins. The differential equation system was solved analytically, and the equations were implemented in a spreadsheet version. The changes in predicted plant uptake of neutral substances, acids, and bases were found for a range of key input data (log KOW , pKa , pH, sorption to proteins). For neutral compounds, sorption to proteins and phloem transport are of relevance only for the more polar compounds (low log KOW , ≤2). Weak acids (pKa ≤6) are trapped in phloem due to pH-related effects, and in roots when pH in soil is low (pH 4-5). Cations sorb stronger and hence show less bioavailability and less translocation than anions. Sorption to proteins reduces translocation to leaves and fruits for all substances, but this is more evident for polar and ionic compounds that have negligible sorption to lipids. The new generic model considers additional processes that are of relevance for polar and ionizable substances. It might be used instead of existing standard approaches for chemical risk assessment and assessment of the environmental fate of PPCPs. Environ Toxicol Chem 2023;42:793-804. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Understanding impacts of organic contaminants from aquaculture on the marine environment using a chemical fate model.

As demand for sustainable marine aquaculture (mariculture) and marine food supply surges worldwide, there is a growing need for new tools to assess mariculture impacts on local ecosystems, including the cycling of toxic organic contaminants. With this in mind, we developed the Contaminant Fate in Aquaculture-Modified Ecosystems (CFAME) model. The current model was designed to explore the fate of mariculture-derived organic contaminants in the Marlborough Sounds, New Zealand, known for its Chinook salmon farming industry. Model evaluation indicated robust model design, with 80% of modeled concentrations falling within a factor of ten of measured ones for native biota. Model results showed that mariculture was a source of organic contaminants in the sediment even at the Marlborough Sounds regional level and in wild marine fishes with high trophic levels near the farm area. Future research attention should be directed toward measuring chemicals with low log KAW (<0) and high log KOW values (e.g., >3) in sediment, and chemicals with log KOW values of 3-9 in wild fish.

Analysis of highly polar pesticides in foods by LC-MS/MS.

Highly polar pesticides (HPP) are a group of pesticides that are characterize as low Log Kow. Many high-throughput multi-residue analysis methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of such polar pesticides have been proposed. In this article, we summarize the various sample preparation methods including quick polar pesticides (QuPPe), dispersive solid phase extraction (dSPE), solid phase extraction (SPE) and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), especially for QuPPe, which are mainly used for the determination of HPP in foods. In addition, we summarize LC-based separation methodologies that are currently used for the analysis of HPP in foods, including reversed-phase chromatography (RPC), hydrophilic interaction liquid chromatography (HILIC), ion chromatography (IC) and mixed-mode chromatography (MMC). Finally, the current mass spectrometry-based methodologies for the analysis of HPP are summarized with a specific focus on MS configurations and acquisition modes.

Metabolic Disorder Enhances Oxidative Stress after Exposure to Aromatic Components of Fine Particulate Matter

Metabolic disorder can exacerbate oxidative damage following exposure to fine particulate matter (PM2.5), but the role of chemical composition in this process remains unclear. This study comprehensively assessed the oxidative stress effect from the synergy of metabolic disorder and the organic components in PM2.5 as well as their molecular features. We high-throughput characterized 942 PM2.5 chemicals from an elderly urban population exposure and found the association between oxidative stress markers of exhaled nitric oxide (eNO) and urinary malondialdehyde (MDA) and 330 and 32 compounds, respectively, was enhanced by metabolic disorder. Most of these compounds were aromatics, including PAHs and their functionalized and oxidized products. The integrated explanatory random forest approach incorporating source tracers showed that primary aromatics arising from combustion with a high unsaturation degree, high logKOW, and low volatility were responsible for the increased eNO levels in participants with metabolic disorder, while compounds formed through atmospheric oxidation reactions with high numbers of carbonyl groups and oxygen atoms and relatively low logKOW were associated with elevated MDA in disordered individuals. This study provides the first evidence that metabolic disorder exacerbates oxidative stress after exposure to specific PM2.5 components, which could in turn exacerbate chronic diseases in the elderly population.

Pond mitigation in dissolved and particulate pesticide transfers: Influence of storm events and seasonality (Auradé agricultural catchment, SW-France)

In agricultural headwater catchments, wetlands such as ponds are numerous and well known to partly dissipate contamination. Most of the pesticides are transferred from soils to the aquatic environment during flood events. This study reports the annual/seasonal behaviour of 6 pesticides (metolachlor, boscalid, epoxiconazole, tebuconazole, aclonifen and pendimethalin) in such an environment. Because it is rarely considered, the study focussed on the high frequency of the distribution of pesticides between dissolved and particulate phases, as well as the main controlling factors of their upstream-downstream transfer. The pond removal rate was calculated to evaluate the wetland efficiency in pesticide mitigation. We conducted a one-year high frequency hydrochemical survey, with particular emphasis on flood events, in the upper Auradé catchment (SW-France), an area of long-term conventional agriculture on highly erosive carbonated soils. The inlet and outlet of the pond were instrumented for water level measurements and water sampling.The highest concentrations were observed for tebuconazole and, in general, the presence of the molecules during the year depended on the season. The pond showed satisfactory efficiency in pesticide attenuation for the six molecules considered, although the removal rate depended on the molecule and the bearing phase (from 28.4% for boscalid to 89.4% for aclonifen in the dissolved phase and from 22.1% for pendimethalin to 96.8% for metolachlor in the particulate fraction). Interestingly, the more hydrophilic the molecule (low LogKOW), the more efficient the pesticide removal rate was for its particulate fraction, and the opposite for hydrophobic molecules (high LogKOW).Flood events carried a large amount of Total Suspended Solid (TSS) bearing hydrophobic molecules from a major legacy of upper catchment soils, although 52% of the pesticides were transported by the dissolved fraction. Significant resuspension of TSS from the pond was evidenced by the annual mass balance with four tons of TSS released, while the positive rate of pesticide removal involved other effective mechanisms such as exchange and complexation. Although these constructed wetlands may be beneficial for pesticide mitigation, the results highlighted the need for improved land management in the upstream catchment during the different seasons to avoid bare soils that pose a risk of high surface water contamination, especially due to the presence of hydrophobic molecules in combination with a high erosive context.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion.

In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk. Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion. Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Octanol-water partition coefficient (logKow) dependent movement and time lagging of polycyclic aromatic hydrocarbons (PAHs) from emission sources to lake sediments: A case study of Taihu Lake, China

Understanding the movement of polycyclic aromatic hydrocarbons (PAHs) from emission sources to sediments is important for achieving long-term pollution control of PAHs in sediments. In this study, by exploring the correlation of individual PAHs concentrations (CPAHs) in Taihu Lake sediments reported in the past twenty years with their annual emissions (EPAHs) in the lake region, it was observed that mean concentrations of PAHs with low logKow (i.e., logKow≤4.00) in Taihu Lake sediments were correlated best with their emissions without lagging between the sediment sampling time and the PAHs emitting time. However, for PAHs with middle logKow (i.e., 4.00<logKow≤4.57) or high logKow (i.e., logKow>4.57), their mean concentrations in sediments were correlated best with the emissions of PAHs emitted 1 or 2 years before the sediment sampling time. The longer lagging time of PAHs with middle or high logKow from emission sources to lake sediments could be attributed to their retardation in soils and river sediments around the lake. Moreover, the retardation in soils and river sediments is dependent on PAHs logKow and degradation half-life, indicating the dependence of PAHs concentration in sediments on their environmental behaviors, including sorption and degradation. Kow dependent movement and the time lagging observed in Taihu Lake for PAHs from emission sources to sediments could be valuable for developing measures to control PAHs, especially for congeners with high logKow.

Microalgae-based removal of contaminants of emerging concern: Mechanisms in Chlorella vulgaris and mixed algal-bacterial cultures

Incomplete removal of contaminants of emerging concern (CECs) has been reported for conventional wastewater treatment technologies. Microalgae-based treatment has recently gained interest thanks to simultaneous removal capacity of organic and inorganic compounds and potentially CECs. In this study, a lab-scale monoculture of Chlorella vulgaris and mixed microalgal-bacterial culture were compared in terms of removal of 28 CECs (bisphenols, 2018 EU Watch List substances, including neonicotinoids, pharmaceuticals, selected transformation products). The removal pathways in light and dark abiotic controls were also studied. Batch photobioreactors were run at hydraulic retention times of 11–12 days and CECs spiked at environmentally relevant concentrations (1–20 μg L−1). The mixed culture was better at removing bisphenols, compared to C. vulgaris. Bisphenols’ log Kow was significant in removal pathways, where bisphenols with high log Kow were removed abiotically while bisphenols with low log Kow were mainly biodegraded. The removal degrees and the pathways of pharmaceuticals and EU Watch List substances were comparable between both cultures, showing no impact of log Kow for most compounds; however, the removal with C. vulgaris was faster for some. High log Kow was associated with high removal of estradiol in abiotic controls, showing the importance of adsorption onto biomass and suspended matter.

Bioaccumulation of legacy organic contaminants in pregnant Indo-Pacific humpback dolphins (Sousa chinensis): Unique features on the transplacental transfer

The placental transfer and congener composition of organic contaminants (OCs) in Indo-Pacific humpback dolphins have been little studied. In the present study, 16 polycyclic aromatic hydrocarbons (PAHs), 18 organochlorine pesticides (OCPs), and 28 polychlorinated biphenyl (PCB) congeners were analyzed in muscle, lung, liver, kidney, and blubber tissues from three mother–fetus pairs of this species stranded along the Pearl River Estuary, China. For PCBs, tetra-, penta-, hexa-, and hepta-chlorobenzene congeners were dominant in all the analyzed samples. Among them, hexachlorobenzene congeners showed the highest level in most dolphin mother-fetus tissue samples. The concentrations of PCBs and OCPs in adult females were higher in the detoxification organs (liver and kidneys) than in the muscles and lungs, whereas muscle tissues in fetuses generally exhibited higher PCBs and OCPs levels than the livers and kidneys. The most abundant PAHs in the four tissues were those with lower molecular weights, which were also the most water-soluble and bioavailable. Negative correlations between the octanol/water partition coefficients (log KOW) and the fetus/mother ratios for PCB congeners revealed that the transfer of PCBs may be determined by their lipid solubility. OCPs and PCBs with low molecular weights and low log KOW values would be more likely to accumulate in the dolphin liver, lung, kidney and muscle tissues. Furthermore, OCs with low molecular weights and low log KOW values were more concentrated in the fetal blubber, lung, and liver tissues than in their respective mothers. The ubiquitous existence of OCs in the mother–fetus pairs strongly suggested that these contaminants could pass through the placenta and partition in fetal tissue. The high transfer efficiency of PAHs and PCBs indicated that the placenta might not be an efficient barrier for these pollutants. PCBs levels in both mother and fetus dolphins could cause immunosuppression.

Uptake, Accumulation, and Biomarkers of PM2.5-Associated Organophosphate Flame Retardants in C57BL/6 Mice after Chronic Exposure at Real Environmental Concentrations.

Although the bioaccumulation of organophosphate flame retardants (OPFRs) in aquatic organisms has been investigated, little information is available about their bioaccumulation in mammals following chronic inhalation exposure. To address this knowledge gap, C57BL/6 mice were exposed to 7 PM2.5-associated OPFRs via the trachea to study their bioaccumulation, tissue distribution, and urinary metabolites. Low (corresponding to the real PM2.5 concentrations occurring during winter in Guangzhou), medium, and high dosages were examined. After 72 days' exposure, ∑OPFR concentrations in tissues from mice in the medium dosage group decreased in the order of intestine > heart > stomach > testis > kidney > spleen > brain > liver > lung > muscle. Of the OPFRs detected in all three exposure groups, chlorinated alkyl OPFRs were most heavily accumulated in mice. We found a significant positive correlation between the bioaccumulation ratio and octanol-air partition coefficient (KOA) in mice tissues for low log KOW OPFR congeners (log KOW ≤ 4, p < 0.05). Three urinary metabolites (di-p-cresyl phosphate: DCrP, diphenyl phosphate: DPhP, dibutyl phosphate: DnBP) were detected from the high dosage group. These results provide important insights into the bioaccumulation potential of OPFRs in mammals and emphasize the health risk of chlorinated alkyl OPFRs.

Effect of processing on herbicide residues and metabolite formation during traditional Chinese tofu production

The fates of clomazone, fomesafen, and quizalofop-p-ethyl and its metabolite quizalofop (acid) in soybean samples during tofu processing were systematically assessed. Residues were determined using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after each processing step, including washing, soaking, grinding and filtering, cooking, coagulating, and squeezing. The pesticide distribution at each step of the process was studied, and pesticide processing factors were calculated. Differences in the pesticide residue levels were found at each processing step. Changes in pesticide residues in the tofu products was closely related to their physicochemical properties such as octanol-water partition coefficient (Kow), water solubility, and vapor pressure. The results showed that soaking prominently decreased fomesafen residues by 72.0%, as indicated by its high water-solubility and low log Kow. Grinding and filtering reduced pesticide residues by 88.8%–94.8%, mainly due to dilution or okara separation. The processing factors were generally <1 for each step and for the entire process, except those for cooking, coagulating, and squeezing. These results demonstrated that the overall process could significantly reduce clomazone, fomesafen, quizalofop-p-ethyl, quizalofop (acid) residues during tofu processing.

Coastal biomonitoring survey on persistent organic pollutants using oysters (Saccostrea mordax) from Okinawa, Japan: Geographical distribution and polystyrene foam as a potential source of hexabromocyclododecanes

The present study determined contamination levels of POPs, such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs), in oysters (Saccostrea mordax) collected throughout the seacoast of Okinawa, Japan and their geographic distribution. PCBs, DDTs, CHLs, PBDEs and HBCDs were detected in almost all the oyster samples analyzed and higher concentrations of PCBs, DDTs and CHLs were found in oysters from southwestern populated areas. On the other hand, HBCDs in oysters showed similar levels throughout Okinawa and the highest concentration in a northern rural site with less human and industrial activities, although oyster concentrations of PBDEs were relatively lower. When POPs in expanded polystyrene (EPS) buoys and polystyrene foam debris floated and drifted on coastal seawater were analyzed, extremely high concentrations of HBCDs were detected in some of these EPS buoys and polystyrene foam debris but other POPs were below the limit of detection in all the samples. To evaluate the specific exposure route of HBCDs for oysters, we further analyzed HBCD diastereomers, and PCB congeners by way of comparison, in seawater and sediment samples collected at an urban site and a rural site and estimated their biota (oyster)-sediment accumulation factors (BSAF) and bioaccumulation factors (BAF). Interestingly, the highest log BAF values were found for α-HBCD despite its lower log Kow than those of γ-HBCD and PCB congeners, although log BSAF values for HBCDs were lower than those for PCBs. Considering that α-HBCD was detected in a few polystyrene foam samples as the predominant diastereomer, oysters inhabiting the coastal region of Okinawa might be frequently exposed to micronized polystyrene foam particles containing HBCDs.

Sex-Specific Bioamplification of Halogenated Organic Pollutants during Silkworm (Bombyx mori) Metamorphosis and Their Adverse Effects on Silkworm Development.

A partial life cycle test was performed with silkworms (Bombyx mori) exposed to different levels of halogenated organic pollutants (HOPs). The aims were to investigate the fate of HOPs during metamorphosis and the adverse effects of HOP exposures on silkworm development. Contaminant exposures resulted in decreased body weights, increased development times, and reductions of fecundity in silkworms. Assimilation efficiencies of HOPs decreased with an increasing octanol-water partition coefficient (log KOW). From the larvae to the pupae stage, bioamplification factors (BAmFs) exhibited concentration-dependent results, in which there was a positive correlation with the log KOW at the high concentrations but no correlation at the low concentrations. From the pupae to the moth stage, BAmFs were linearly negatively correlated with the log KOW for males, but a parabolic correlation with the log KOW was more suitable for females. Regarding reproductive activities, female moths selectively transferred low log KOW HOPs to eggs by the oviposition except for highly halogenated lipophilic pollutants. However, BAmFs of male moths during mating showed no correlation with the log KOW, although highly halogenated lipophilic pollutants had the highest BAmF values. The sex-specific bioamplification processes and special behaviors of highly halogenated lipophilic pollutants deserve further research.

Acute toxicity of organic pesticides to Daphnia magna is unchanged by co-exposure to polystyrene microplastics

Daphnia magna were exposed to two pesticides in the presence or absence of microplastics (300 000 particles ml−1 1 µm polystyrene spheres) and to microplastics alone. The pesticides were dimethoate, an organophosphate insecticide with a low log Kow, and deltamethrin, a pyrethroid insecticide with a high log Kow. Daphnia were exposed to a nominal concentration range of 0.15, 0.31, 0.63, 1.25, 2.5, 5 mg l−1 dimethoate and 0.016, 0.08, 0.4, 2, 5 and 10 µg l−1 deltamethrin. Exposure to polystyrene microplastics alone showed no effects on Daphnia magna survival and mobility over a 72 h exposure. In the dimethoate exposures, mobility and survival were both affected from a concentration of 1.25 mg l−1, with effects were seen on mobility from 28 h and survival from 48 h, with greater effects seen with increasing concentration and exposure time. In deltamethrin exposures, survival was affected from a concentration of 0.4 µg l−1 and mobility from a concentration of 0.08 µg l−1. Effects of deltamethrin on mobility were seen from 5 h and on survival from 28 h, with greater effects on survival and mobility seen with increasing concentration and exposure time. Contrary to expectations, pesticide toxicity to Daphnia magna was not affected by the presence of microplastics, regardless of chemical binding affinity (log Kow). This therefore suggests that polystyrene microplastics are unlikely to act as a significant sink, nor as a vector for increased uptake of pesticides by aquatic organisms. CapsulePolystyrene microplastics are unlikely to act as vector for increased uptake of pesticides by aquatic organisms

The effect of hydraulic retention time in onsite wastewater treatment and removal of pharmaceuticals, hormones and phenolic utility substances

Micropollutants such as pharmaceuticals, hormones and phenolic utility chemicals in sewage water are considered to be an emerging problem because of increased use and observed adverse effects in the environment. The study provides knowledge on the removal efficiency of micropollutants with a range of physical and chemical properties in three commercially available onsite wastewater treatment facilities (OWTFs), tested on influent wastewater collected from 2500 person equivalents in Bildchen, Germany. A longer hydraulic retention time would in theory be expected to have a positive effect, and this study presents results for three different OWTFs in full-scale comparable tests under natural conditions. A range of 24 different pharmaceuticals, five phenols and three hormones were analyzed. Flow-proportional consecutive sampling was performed in order to determine the removal efficiency. Twenty-eight substances were detected in the effluent wastewater out of 32 substances included. Average effluent concentrations of Simvastatin, Estrone, Estradiol and Ethinylestradiol were above the indicative critical-effect concentration of pharmacological effect on fish in all facilities. Average effluent concentrations of both Diclofenac and Estradiol were higher than the Environmental Quality Standards applied in Sweden (190–240 times and 9–35 times respectively). The removal efficiency of micropollutants was high for substances with high logKow, which enhance the adsorption and removal with sludge. Low removal was observed for substances with low logKow and acidic characteristics, and for substances with stabilizing elements of the chemical structure. Facilities that use activated sludge processes removed hormones more efficiently than facilities using trickling filter treatment technique. Moreover, longer hydraulic retention time increased the removal of pharmaceuticals, hormones, turbidity and total nitrogen. Removal of Caffeine, Ibuprofen, Estrone, Naproxen and Estradiol, was strongly correlated to the sludge and particles removal. Thus, the efficiency of the tested OWTFs could be improved by adjusting the technical methods and increasing the hydraulic retention time.