Long term temporal and spatial changes in the distribution of polychlorinated biphenyls and polybrominated diphenyl ethers in Scottish soils

Selected legacy and emerging organic contaminants in sediments of China's Yangtze - the world's third longest river: Response to anthropogenic activities

To explore contaminant concerns as a result of anthropogenic disturbance of the river system, this study provided the first extensive investigation of the contamination profiles, possible driving factors, and ecological risks of 40 target compounds including pharmaceuticals and personal care products (PPCPs), neonicotinoid pesticides (NNIs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) in sediments of the whole Yangtze River (the world's third longest river). Among these target compounds, PPCPs were the dominant contaminants with a total concentration (∑15PPCPs) of 2.13-14.99 ng/g, followed by ∑7PCBs ( Collapse

Key Words

• NNIs
• PBDEs
• PCBs
• PPCPs
• Sediment
• Yangtze River

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MESH Headings

• Polychlorinated Biphenyls/analysis
• Halogenated Diphenyl Ethers/analysis
• Anthropogenic Effects
• Water Pollutants, Chemical/analysis
• Rivers/chemistry
• Plastics
• Environmental Monitoring/methods
• Geologic Sediments/chemistry
• China

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Sexually dimorphic impact of preconceptional and gestational exposure to a real-life environmental chemical mixture (biosolids) on offspring growth dynamics and puberty in sheep

Humans are ubiquitously exposed to complex mixtures of environmental chemicals (ECs). This study characterised changes in post-natal and peripubertal growth, and the activation of the reproductive axis, in male and female offspring of sheep exposed to a translationally relevant EC mixture (in biosolids), during pregnancy. Birthweight in both sexes was unaffected by gestational biosolids exposure. In contrast to females (unaffected), bodyweight in biosolids males was significantly lower than controls across the peripubertal period, however, they exhibited catch-up growth eventually surpassing controls. Despite weighing less, testosterone concentrations were elevated earlier, indicative of early puberty in the biosolids males. This contrasted with females in which the mean date of puberty (first progesterone cycle) was delayed. These results demonstrate that developmental EC-mixture exposure has sexually dimorphic effects on growth, puberty and the relationship between body size and puberty. Such programmed metabolic/reproductive effects could have significant impacts on human health and wellbeing.

Polybrominated diphenyl ethers (PBDEs) in household dust: A systematic review on spatio-temporal distribution, sources, and health risk assessment

Much attention has been paid on polybrominated diphenyl ethers (PBDEs) in household dust due to their ubiquitous occurrences in the environment. Based on the data from 59 articles sampled from 2005 to 2020, we investigated the spatio-temporal distribution, sources, and health risk of 8 PBDE homologues in household dusts worldwide. BDE-209 is the predominant PBDE in household dusts, followed by BDE-99 and BDE-47. The total concentrations of PBDEs (∑₈PBDEs) are found to be high in household dusts sampled from 2005 to 2008 and show a significant decline trend from 2009 to 2016 (p < 0.05) and a little upward tendency from 2017 to 2020. The concentrations of PBDEs in household dusts vary greatly in different countries of the world. The use of penta-BDE is the main source of three to five bromo-biphenyl ether monomers contributing 17.4% of ∑₈PBDEs, while BDE-209 and BDE-183 are derived from the use of household appliances contributing 82.6% of ∑₈PBDEs. Ingestion is the main exposure route for adults and toddlers, followed by dermal contact. The values of hazard index (HI) exposed to PBDEs in household dusts are all less than 1 for both adults and toddlers, indicating a low non-cancer risk. The incremental lifetime cancer risks (ILCRs) of BDE-209 are less than 10^-6 for both adults and toddlers, suggesting a negligible risk. However, the total carcinogenic risk of toddlers is higher than that of adults, indicating that much attention should be paid to toddlers exposed to BDE-209 in household dust.

Polybrominated diphenyl ethers in the environment: a wake-up call for concerted action in India

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants (POPs) used as flame retardants in the products utilized in day-to-day life. Their bioaccumulation, low volatility, and high persistence in the environment have led to their global spread even to remote and distant regions. The present study identifies gaps in the investigation of the neurotoxic potential of PBDEs, their effects on brain development, toxicokinetic, and their potential as a carcinogen. In India, to date, only human breast milk was assessed for levels of PBDEs, and it is suggested that other human tissues can also be explored. No data on the reproductive toxicity of PBDEs are reported from Indian cohorts. Long-range transport and deposition of PBDEs in colder regions necessitates monitoring of Himalayan regions in India. An inventory of PBDEs is required to be made for addressing the worrisome situation of the unregulated import of E-waste from the developed countries in India. The study also emphasizes providing guidelines for the articulation of policies regarding sound surveillance and management of PBDE production, consumption, and release in the Indian context. It is recommended that a separate cell for monitoring and follow-up of PBDEs should be established in India. Also, the development of better alternatives and environment-friendly remediation technologies for PBDEs is the need of the hour.

Toward a better understanding of the effects of endocrine disrupting compounds on health: Human-relevant case studies from sheep models

There are many challenges to overcome in order to properly understand both the exposure to, and effects of, endocrine disruptors (EDs). This is particularly true with respect to fetal life where ED exposures are a major issue requiring toxicokinetic studies of materno-fetal exchange and identification of pathophysiological consequences. The sheep, a large, monotocous, species, is very suitable for in utero fetal catheterization allowing a modelling approach predictive of human fetal exposure. Predicting adverse effects of EDs on human health is frequently impeded by the wide interspecies differences in the regulation of endocrine functions and their effects on biological processes. Because of its similarity to humans as regards gestational and thyroid physiologies and brain ontogeny, the sheep constitutes a highly appropriate model to move one step further on thyroid disruptor hazard assessment. As a grazing animal, the sheep has also proven to be useful in the evaluation of the consequences of chronic environmental exposure to "real-life" complex mixtures at different stages of the reproductive life cycle.

Levels of Polychlorinated Biphenyls Are Still Associated with Toxic Effects in Harbor Porpoises (Phocoena phocoena) Despite Having Fallen below Proposed Toxicity Thresholds

Polychlorinated biphenyls (PCBs) are toxic, persistent, and lipophilic chemical compounds that accumulate to high levels in harbor porpoises (Phocoena phocoena) and other cetaceans. It is important to monitor PCBs in wildlife, particularly in highly exposed populations to understand if concentrations are declining and how levels relate to toxicological thresholds and indices of health like infectious disease mortality. Here we show, using generalized additive models and tissue samples of 814 U.K.-stranded harbor porpoises collected between 1990 and 2017, that mean blubber PCB concentrations have fallen below the proposed thresholds for toxic effects. However, we found they are still associated with increased rates of infectious disease mortality such that an increase in PCB blubber concentrations of 1 mg kg^-1 lipid corresponds with a 5% increase in risk of infectious disease mortality. Moreover, rates of decline and levels varied geographically, and the overall rate of decline is slow in comparison to other pollutants. We believe this is evidence of long-term preservation in the population and continued environmental contamination from diffuse sources. Our findings have serious implications for the management of PCB contamination in the U.K. and reinforce the need to prevent PCBs entering the marine environment to ensure that levels continue to decline.

Polybrominated Diphenyl Ethers in Surface Soils from the Yellow River Delta Natural Reserve, China: Occurrence, Sources, and Potential Risk

A total of 39 lower brominated PBDE congeners in surface soils from the Yellow River Delta Natural Reserve (YRDNR) were analyzed in the present study. The total concentrations of PBDEs (ΣPBDEs) ranged from "not detected" to 0.732 ng g^-1, with a mean concentration of 0.142 ng g^-1. The concentrations of the ΣPBDEs displayed no correlation with the content of the total organic carbon in the YRDNR. The ΣPBDEs concentrations in the Experimental Area were significantly higher than that of the Buffer Area and Core Area, and ΣPBDEs in soils in the North were lower than that of the South. PentaBDEs and HexaBDEs were the most abundant homologues, and the occurrence of PBDEs in the YRDNR may be attributed to the debromination and long range transport of DecaBDEs. Even though the cancer risk and mass inventory of PBDEs in the present study area were estimated to be very low, due to the widespread presence of PBDEs and the particularity of the natural reserve, vigilance should not be let up on the issue of environmental contamination caused by these compounds despite the gradual phase out of their commercial products in the world.

Concentrations and uptake pathways of polychlorinated biphenyls from soil to grass

Field coupled samples in soil and grass were collected to determine the concentrations and identify the uptake pathways of PCBs into the grass at a pasture from Scotland, UK. Concentrations of indicator PCBs (∑₇PCBs) in soils ranged from 0.20 to 0.88 ng g^-1 dw (dry weight), with a mean of 0.33 ng g^-1 dw, and in grass ranged from 0.20 to 2.14 ng g^-1 dw, with a mean of 0.48 ng g^-1 dw. The comprehensive factors of low concentrations and detection rate (PCB28: 18.8%; PCB52: 37.5%) of PCBs in soil, as well as continuously declined air concentrations of PCBs in the UK since the 1990s suggested that the secondary emission from the soil is becoming the supplied source of PCBs to air and grass. The significant correlations between bioconcentration factor (BCF) values and the log K_OW (R = -0.850, p < 0.05) and log K_OA (R = -0.860, p < 0.05) of indicator PCB congeners were found in the present study, indicating that these two parameters are likely to affect the bioaccumulation and uptake of grass. A generic one-compartment model was employed to identify uptake pathways of grass and evaluate the uptake amounts for PCBs. This suggested that the most important pathway for uptake of PCBs by grass was at the aerial part, and the difference of PCBs concentrations between leaves and roots was about four orders of magnitude. Removing and risk transfer of PCBs or other organic pollutants by grass need to be investigated and assessed further.

The occurrence of polybrominated diphenyl ether (PBDE) contamination in soil, water/sediment, and air

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.

Photocatalytic debromination of polybrominated diphenyl ethers (PBDEs) on metal doped TiO2 nanocomposites: Mechanisms and pathways

Nanoparticles of four noble metal doped titanium dioxide (i.e., Pd/TiO₂, Ag/TiO₂, Pt/TiO₂ and Cu/TiO₂) were synthesized and investigated for their effectiveness to degrade polybrominated diphenyl ethers (PBDEs) under UV light. All the investigated noble metal additives can greatly enhance the performance of TiO₂ to degrade 2,2',4',4'-tetrabromodiphenyl ether (BDE-47). However, the debromination pathways of BDE-47 in Ag/TiO₂ and Cu/TiO₂ systems are just contrary to those in Pd/TiO₂ and Pt/TiO₂ systems, and there was an induction period in the former systems but not in the latter systems. The hydrogenation experiment suggests a direct H-atom transfer mechanism in Pd/TiO₂ and Pt/TiO₂ systems, while in Ag/TiO₂ and Cu/TiO₂ systems, electron transfer is still the dominant mechanism. Electronic method was applied to explain why BDE-47 exhibit different debromination pathways based on different degradation mechanism. In addition, oxygen was proved to be able to capture both electrons and H atoms, and thus can greatly inhibit the degradation of PBDEs in all investigated systems. Finally, the merit and demerit of each metal doped TiO₂ were discussed in detail, including the reactivity, stability and the generation of byproducts. We proposed our study greatly enhance our understanding on the mechanisms of PBDE degradation in various metal doped TiO₂ systems.

Rapid debromination of polybrominated diphenyl ethers (PBDEs) by zero valent metal and bimetals: Mechanisms and pathways assisted by density function theory calculation

Polybrominated diphenyl ethers (PBDEs) undergo debromination when they were exposed in zerovalent metal or bimetallic systems. Yet their debromination pathways and mechanisms in these systems were not well understood. Here we reported the debromination pathways of three BDE congeners (BDE-21, 25 and 29) by nano-zerovalent iron (n-ZVI). All these BDE congeners have three bromine substituents that were located in ortho-, meta- and para-positions. Results demonstrated that BDE-21, 25 and 29 preferentially debrominate meta-, ortho- and para-bromines, respectively, suggesting that bromine substituent at each position (i.e. ortho-, meta- or para-) of PBDEs can be preferentially removed. Singly occupied molecular orbitals of BDE anions are well correlated with their actual debromination pathways, which successfully explain why these BDE congeners exhibit certain debromination pathways in n-ZVI system. In addition, microscale zerovalent zinc (m-ZVZ), iron-based bimetals (Fe/Ag and Fe/Pd) were also used to debrominate PBDEs, with BDE-21 as target pollutant. We found that the debromination pathways of BDE-21 in m-ZVZ and Fe/Ag systems are the same to those in n-ZVI system, but were partially different from those in Fe/Pd systems. The debromination of BDE-21 in Pd-H₂ system as well as the solvent kinetic isotope effect in single metal and bimetallic systems suggests that H atom transfer is the dominant mechanism in Fe/Pd system, while e-transfer is still the dominant mechanism in Fe/Ag system.

Critical review of soil contamination by polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs); concentrations, sources and congener profiles

Polybrominated diphenyl ethers (PBDEs) have been used in a broad array of polymeric materials such as plastics, foams, resins and adhesives to inhibit the spread of fires since the 1970s. The widespread environmental contamination and well documented toxic effects of PBDEs have led to bans and voluntary withdrawals in many jurisdictions. Replacement novel brominated flame retardants (NBFRs) have, however, exhibited many of the same toxic characteristics as PBDEs and appear to share similar environmental fate. This paper presents a critical review of the scientific literature regarding PBDE and NBFR contamination of surface soils internationally, with the secondary objective of identifying probable pollution sources. An evaluation of NBFR distribution in soil was also conducted to assess the suitability of the newer compounds as replacements for PBDEs, with respect to their land contamination potential. Principle production of PBDEs and NBFRs and their consequent use in secondary polymer manufacture appear to be processes with strong potential to contaminate surrounding soils. Evidence suggests that PBDEs and NBFRs are also released from flame retarded products during disposal via landfill, dumping, incineration and recycling. While the land application of sewage sludge represents another major pathway of soil contamination it is not considered in this review as it is extensively covered elsewhere. Both PBDEs and NBFRs were commonly detected at background locations including Antarctica and northern polar regions. PBDE congener profiles in soil were broadly representative of the major constituents in Penta-, Octa- and Deca-BDE commercial mixtures and related to predicted market place demand. BDE-209 dominated soil profiles, followed by BDE-99 and BDE-47. Although further research is required to gain baseline data on NBFRs in soil, the current state of scientific literature suggests that NBFRs pose a similar risk to land contamination as PBDEs.

Seasonal variation and health risk assessment of organochlorine compounds in urban soils of Novi Sad, Serbia

The aim of this paper was to determine spatial and seasonal variation of 6 indicator polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides (OCPs) in urban soils of Novi Sad, Serbia. Sixty surface soil samples were collected during both winter and summer season, from different types of locations: schools, recreational areas, residential and industrial zones. Samples were treated using the method of accelerated solvent extraction, which allows simultaneous extraction and clean up of PCBs and OCPs. Targeted compounds were analyzed by GC-μECD and confirmed by GC-MS. The total concentrations of studied PCBs varied from <LOD to 18.9 ng g^-1 (mean 2.84 ng g^-1 and median value of 1.21 ng g^-1) in winter and from <LOD to 24.6 ng g^-1 (mean 3.27 ng g^-1 and median value of 1.60 ng g^-1) in summer. Regarding the OCPs analyzed, dichlorodiphenyltrichloroethanes (DDTs) were only detected in both seasons. The total concentration of DDTs ranging from <LOD to 86.3 ng g^-1 (mean 7.57 ng g^-1 and median value of 1.87 ng g^-1) in summer and from <LOD to 182 ng g^-1 (mean 15.6 ng g^-1 and median value of 3.15 ng g^-1) in winter. There were no significant difference between seasons for studied PCBs and DDTs. Spatial distribution of PCBs and DDTs were also evaluated using Arc GIS. Additional, principle component analysis was performed to evaluate relationships between PCBs, DDTs and soil characteristics. Positive correlation was observed among p,p'-DDE, p,p'-DDD and organic matter. The total lifetime carcinogenic risk indicated that the lifetime cancer risk was acceptable.

The flame retardant DE-71 (a mixture of polybrominated diphenyl ethers) inhibits human differentiated thyroid cell function in vitro

BACKGROUND

Normal thyroid function is essential for general growth and metabolism, but can be affected by endocrine disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs) have been used worldwide to reduce flammability in different materials and are suspected to be EDCs. The production of the commercial Penta- and OctaBDE mixtures is banned, but DecaBDEs and existing products may leak PBDEs into the environment. Our aim was to investigate the effect of the PentaBDE mixture DE-71 on human thyroid cells in vitro.

MATERIALS AND METHODS

Primary human thyroid cells were obtained as paraadenomatous tissue and cultured in monolayers. The influence of DE-71 on cyclic adenosine monophosphate (cAMP) and thyroglobulin (Tg) production was examined in the culture medium by competitive radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Real-time quantitative PCR analysis of thyroid-specific genes was performed on the exposed cell cultures. PBDE concentrations were determined in cellular and supernatant fractions of the cultures.

RESULTS

DE-71 inhibited Tg-release from TSH-stimulated thyrocytes. At 50 mg/L DE-71, mean Tg production was reduced by 71.9% (range: 8.5-98.7%), and cAMP by 95.1% (range: 91.5-98.8%) compared to controls). Expression of mRNA encoding Tg, TPO and TSHr were significantly inhibited (p<0.0001, p = 0.0079, and p = 0.0002, respectively). The majority of DE-71 added was found in the cell fraction. No cytotoxicity was found.

CONCLUSIONS

DE-71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of Tg and cAMP production, respectively, as well as expression of mRNA encoding Tg, TPO and TSHr. Our findings suggest an inhibiting effect of PBDEs on thyroid cells.

Review of contamination of sewage sludge and amended soils by polybrominated diphenyl ethers based on meta-analysis

Polybrominated diphenyl ethers (PBDEs) are still present in sewage sludge and sludge-amended soil, even though commercial PBDEs were prohibited or voluntarily phased out several years ago. In this study, levels and compositional profiles of seven major PBDE congeners in sludge are assessed in relation to their usage patterns in commercial products, and years of being banned and phased out in North America, Europe, and Asia. Annual accumulations and future long-term changes of PBDE in sludge-amended soil are estimated. BDE-209 has the highest concentration, followed by BDE-99 and BDE-47. The highest concentrations, up to 23,500 ng g^-1, of PBDEs in sludge were found in North America until 2004-2007, whereas since then sludge PBDE concentrations, up to 6600 ng g^-1 have been higher in Asia than on the other two continents. The amount of sludge applied and the soil organic matter content play important roles in determining PBDE concentrations in sludge-amended soil. The estimated concentrations of BDE-47, -99, and -209 in soils receiving sludge applications during the past 15 years are 40-300 times higher than in soils after the initial sludge application. The accumulated concentrations of BDE-47 and BDE-99 are expected to decrease by 99% between 2016 and 2100, whereas the decrease in the BDE-209 concentration is predicted to be approximately 87%.

Effects of the Commercial Flame Retardant Mixture DE-71 on Cytokine Production by Human Immune Cells

INTRODUCTION

Although production of polybrominated diphenyl ethers (PBDEs) is now banned, release from existing products will continue for many years. The PBDEs are assumed to be neurotoxic and toxic to endocrine organs at low concentrations. Their effect on the immune system has not been investigated thoroughly. We aimed to investigate the influence of DE-71 on cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated with Escherichia Coli lipopolysaccharide (LPS) or phytohaemagglutinin-L (PHA-L).

MATERIAL AND METHODS

PBMCs isolated from healthy donors were pre-incubated with DE-71 at various concentrations and subsequently incubated with the monocyte stimulator LPS, or the T-cell activator PHA-L. Interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, IL-17A, and IL-17F were quantified in the supernatants by Luminex kits.

RESULTS

At non-cytotoxic concentrations (0.01-10 μg/mL), DE-71 significantly enhanced secretion of IL-1β, IL-6, CXCL8, IL-10, and TNF-α (p<0.001-0.019; n = 6) from LPS-stimulated PBMCs. IFN-γ, TNF-α, IL-17A, and IL-17F (p = <0.001-0.043; n = 6) secretion were enhanced from PHA-L-stimulated PBMCs as well. Secretion of IL-1β, IL-2, IL-10, IL-8 and IL-6 was not significantly affected by DE-71.

CONCLUSIONS

We demonstrate an enhancing effect of DE-71 on cytokine production by normal human PBMCs stimulated with LPS or PHA-L ex vivo.

Persistent Organic Pollutants and Heavy Metal Concentrations in Soil from the Metropolitan Area of Monterrey, Nuevo Leon, Mexico

The purpose of this study was to assess the levels of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDE), and four heavy metals (arsenic, cadmium, and lead) in outdoor surface soils (50 samples) collected from the metropolitan area of Monterrey in Mexico. Total PBDEs levels ranged from 1.80 to 127 µg/kg, with mean total PBDEs level of 14.2 ± 21.5 µg/kg (geometric mean ± standard deviation). For PCBs, the mean total level in the studied soils was 23.5 ± 20.2 µg/kg (range 4.0-65.5 µg/kg). An important finding in our study was that all soil samples (100%) had detectable levels of the metabolite p,p'-DDE. Moreover, the mean total DDT level (∑p'p-DDT and p'p-DDE) was approximately 132 ± 175 µg/kg. The mean levels for arsenic, cadmium, and lead in soil were 5.30 ± 1.35 (range 1.55-7.85) mg/kg, 2.20 ± 1.20 (range 0.65-6.40) mg/kg, and 455 ± 204 (range 224-1230) mg/kg, respectively. Our study has several limitations, the most notable of which is the small sample of soils evaluated. However, this screening study provided concentration data for the occurrence of POPs and four heavy metals in soil from the metropolitan area of Monterrey, Nuevo Leon, Mexico, and taking into consideration that soil is an important pathway of exposure for people, a biomonitoring program for the surveillance of the general population in the metropolitan area of Monterrey, Nuevo Leon is deemed necessary.

Concentrations of legacy and emerging flame retardants in air and soil on a transect in the UK West Midlands

Passive air samples were collected monthly for 6 months from 8 sites along a transect of Birmingham, United Kingdom between June 2012 and January 2013. Soil samples were collected once at each site. Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in ambient air were 150, 49, and 180 pg m(-3), respectively. Atmospheric concentrations of PBDEs were negatively correlated with distance from the city centre, exhibiting an "urban pulse". The average ΣHBCDD air concentration was 100 pg m(-3), however concentrations were not correlated with distance from the city centre. Several emerging flame retardants (EFRs) were identified in air and/or soil samples: 2,3,4,5-tetrabromo-bis(2-ethylhexyl) phthalate (BEH-TEBP), 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane (TBECH or DBE-DBCH), allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DP or DDC-CO). Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in soil were 11, 3.6, and 15 ng g(-1) soil organic matter. PBDE concentrations in soil were higher at sites closest to the city centre, however correlations with distance from the city centre were not significant. BDEs-47 and -99 contributed more to ΣPBDEs in soil samples than air samples, but in both, the predominant congener was BDE-209. BATE was more abundant in air than soil but ATE was abundant in soil but not air.

Polybrominated diphenyl ethers (PBDEs) concentration in soil from San Luis Potosi, Mexico: levels and ecological and human health risk characterization

The aim of this study was to assess the levels of polybrominated diphenyl ethers (PBDEs) in soils from the city of San Luis Potosi in Mexico and perform an ecological and human health risk characterization. In order to confirm the presence of PBDEs, outdoor surface soil samples were collected and the concentrations of PBDEs in urban, industrial, agricultural, and brick kiln industry areas were determined. The mean total PBDEs levels obtained in the study sites were 25.0 ± 39.5 μg/kg (geometric mean ± standard deviation) in the brick kiln industry zone; 34.5 ± 36.0 μg/kg in the urban zone; 8.00 ± 7.10 μg/kg in the industrial zone and 16.6 ± 15.3 μg/kg in the agricultural zone. The ecological and human health risk characterization showed relatively low-hazard quotient values. However, the moderately high PBDEs levels found in soils highlight the necessity to establish a systematic monitoring process for PBDEs in environmental and biological samples.

Polychlorinated biphenyls and organochlorine pesticides in atmospheric particulate matter of Northern China: distribution, sources, and risk assessment

The objectives of this work are to track the contamination levels, distribution characteristics, and sources of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in atmospheric particulate matter (APM) of Northern China and to provide more comprehensive and fundamental data for risk assessment of organochlorine contaminants (OCs) in environments. Samples were extracted and purified by the microwave-assisted extraction and solid-phase extraction system, respectively. PCBs and OCPs were analyzed by gas chromatograph-mass spectrometer. The concentrations of ΣPCBs and ΣOCPs ranged from 0.73 to 112.65 ng/g and 0.14 to 34.73 ng/g, respectively. PCBs in atmospheric particulates collected from Shijiazhuang City had the highest concentration, whereas OCP congeners were at the relatively low levels. However, the highest concentration of OCPs occurred in Yongning City. The principal component analysis indicated that the predominant compositions of PCBs in most of samples were tetrachlorobiphenyl (Tetra-CB), pentachlorobiphenyl (Penta-CB), hexachlorobiphenyl (Hexa-CB), and heptachlorbiphenyl (Hepta-CB), while hexachlorocyclohexanes (HCHs), DDTs, chlordanes, and endosulfans were the dominant components of OCPs, which was attributed to their application characteristics. OCs in those particles were further used to assess a potential cancer risk to humans via ingestion, dermal contact, and inhalation. Cancer risk was evaluated in airborne particles caused by PCBs and OCPs. TEQPCBs values suggested that the representative areas were subject to different pollution degrees. However, the pollution of OCPs in certain areas should be a concern due to 41.6% of the high risk, which could pose a potential risk to organisms.

PCB1254 exposure contributes to the abnormalities of optomotor responses and influence of the photoreceptor cell development in zebrafish larvae

Polychlorinated biphenyls (PCBs), a group of highly toxic environmental pollutants, have been report to influence the visual system development in children. However, the underlying mechanism is unclear. The study was aim to investigate the effects of continuous PCBs exposure on optomotor response (OMR) and retinal photoreceptor cell development-related gene expression in zebrafish larvae. The fertilized zebrafish embryos were exposed to PCBs at concentrations of 0.125, 0.25, 0.5, and 1mg/L until 7 days post-fertilization. Control groups with blank and 0.01% methanol were also prepared. OMR test was used to detect the visual behavior. The mRNA expression of the CRX, RHO, SWS1, and SWS2 was assessed by the Quantitative Real-Time PCR. The OMR test showed that the visual behavior of the larvae was most sensitive when the grating spatial frequency was 0.20LP/mm and the moving speed was 25cm/s. Moreover, the proportion of positively swimming fish was significantly reduced in the 0.5 and 1mg/L PCB1254 treatment group (P<0.05) compared with the controls. In addition, the expression of SWS2 was significantly down-regulated in all PCB1254 treatment groups (P<0.05), whereas the decreased expression of the CRX, RHO and SWS1 was found in the 0.5 and 1mg/L PCB1254 groups (P<0.05). This is the first report to demonstrate that continue exposure of zebrafish larvae to PCBs causes photoreceptor cell development-related gene expression changes that lead to OMR behavioral alterations. Analysis of these visual behavioral paradigms may be useful in predicting the adverse effects of toxicants on visual function in fish.

Reproduction Symposium: does grazing on biosolids-treated pasture pose a pathophysiological risk associated with increased exposure to endocrine disrupting compounds?

Biosolids (processed human sewage sludge), which contain low individual concentrations of an array of contaminants including heavy metals and organic pollutants such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and polychlorinated dibenzodioxins/polychlorinated dibenzofurans known to cause physiological disturbances, are increasingly being used as an agricultural fertilizer. This could pose a health threat to both humans and domestic and wild animal species. This review summarizes results of a unique model, used to determine the effects of exposure to mixtures of environmentally relevant concentrations of pollutants, in sheep grazed on biosolids-treated pastures. Pasture treatment results in nonsignificant increases in environmental chemical (EC) concentrations in soil. Whereas EC concentrations were increased in some tissues of both ewes and their fetuses, concentrations were low and variable and deemed to pose little risk to consumer health. Investigation of the effects of gestational EC exposure on fetal development has highlighted a number of issues. The results indicate that gestational EC exposure can adversely affect gonadal development (males and females) and that these effects can impact testicular morphology, ovarian follicle numbers and health, and the transcriptome and proteome in adult animals. In addition, EC exposure can be associated with altered expression of GnRH, GnRH receptors, galanin receptors, and kisspeptin mRNA within the hypothalamus and pituitary gland, gonadotroph populations within the pituitary gland, and regional aberrations in thyroid morphology. In most cases, these anatomical and functional differences do not result in altered peripheral hormone concentrations or reproductive function (e.g., lambing rate), indicating physiological compensation under the conditions tested. Physiological compensation is also suggested from studies that indicate that EC effects may be greater when exposure occurs either before or during gestation compared with EC exposure throughout life. With regard to human and animal health, this body of work questions the concept of safe individual concentration of EC when EC exposure typically occurs as complex mixtures. It suggests that developmental EC exposure may affect many different physiological systems, with some sex-specific differences in EC sensitivity, and that EC effects may be masked under favorable physiological conditions.