Determination of organophosphorus flame retardants in fish by pressurized liquid extraction using aqueous solutions and solid-phase microextraction coupled with gas chromatography-flame photometric detector

Occurrence and risk assessment of organophosphate esters in global aquatic products

Organophosphate esters (OPEs), as an important class of new pollutants, have been pervasively detected in global aquatic products, arousing widespread public concern due to their potential bioaccumulative behavior and consequent risks. With the continuous improvement of living standards of citizens, there have been constant increment of the proportion of aquatic products in diets of people. The levels of OPEs exposed to residents may also be rising due to the augmented consumption of aquatic products, posing potential hazards on human health, especially for people in coastal areas. The present study integrated the concentrations, profiles, bioaccumulation, and trophic transfer of OPEs in global aquatic products, including Mollusca, Crustacea, and fish, evaluated health risks of OPEs through aquatic products in daily diets by Mont Carol Simulation (MCS), and found Asia has been the most polluted area in terms of the concentration of OPEs in aquatic products, and would have been increasingly polluted. Among all studied OPEs, chlorinated OPEs generally showed accumulation predominance. It is worth noting that some OPEs were found bioaccumulated and/or biomagnified in aquatic ecosystems. Though MCS revealed relative low exposure risks of residents, sensitive and special groups such as children, adolescents, and fishermen may face more serious health risks than the average residents. Finally, knowledge gaps and recommendations for future research are discussed encouraging more long-term and systematic global monitoring, comprehensive studies of novel OPEs and OPEs metabolites, and more toxicological studies to completely evaluate the potential risks of OPEs.

Pressurized Liquid Extraction: A Powerful Tool to Implement Extraction and Purification of Food Contaminants

Pressurized liquid extraction (PLE) is considered an advanced extraction technique developed in the mid-1990s with the aim of saving time and reducing solvent with respect to traditional extraction processes. It is commonly used with solid and semi-solid samples and employs solvent extraction at elevated temperatures and pressures, always below the respective critical points, to maintain the solvent in a liquid state throughout the extraction procedure. The use of these particular pressure and temperature conditions changes the physicochemical properties of the extraction solvent, allowing easier and deeper penetration into the matrix to be extracted. Furthermore, the possibility to combine the extraction and clean-up steps by including a layer of an adsorbent retaining interfering compounds directly in the PLE extraction cells makes this technique extremely versatile and selective. After providing a background on the PLE technique and parameters to be optimized, the present review focuses on recent applications (published in the past 10 years) in the field of food contaminants. In particular, applications related to the extraction of environmental and processing contaminants, pesticides, residues of veterinary drugs, mycotoxins, parabens, ethyl carbamate, and fatty acid esters of 3-monochloro-1,2-propanediol and 2-monochloro-1,3-propanediol from different food matrices were considered.

Partitioning behavior-oriented health risk assessment on internal organophosphorus flame retardants exposure

Though the partitioning behavior of organophosphorus flame retardants (OPFRs) has been recognized in vitro incubation assay, health risk assessment on those internal exposure with or without partitioning indexes in human blood is still unclear. In this study, nine commonly used OPFRs were quantified in 96 pairs of plasma and blood cell samples from Chinese volunteers. Non-carcinogenic and carcinogenic risk (CR) assessment building upon two distinct scenarios were conducted and compared. The dominant OPFRs in both plasma and blood cells were TBEP, TBP and TPHP. TCEP was the most enriched compound in plasma with F_plasma nearly to 1.0 (0.92), followed by TCPP, TBEP, TPHP, TBP and TEHP (from 0.61 to 0.76). The partitioning behavior of TCP in plasma was equivalent to blood cells with F_plasma at 0.50. When fully considered the F_plasma, the estimated average daily intake (DI) of ∑OPFRs (638.44 ng/kg BW/day) reached nearly 1.48-fold higher than the conventional calculation (dividing the concentration of plasma (C_plasma) by a factor of 2.0). Accordingly, we found the average hazard quotation (index) of TBP, TPHP and ∑OPFRs was underrated 1.50-fold when neglected the partitioning behaviors. Notably, the average CR of TCEP exceeded 10^-6 at the highest concentration (1.19 × 10^-6 ng/mL in plasma) only when the F_plasma was introduced. These data conjointly demonstrated that most of the DI levels and the corresponding risk index of OPFRs would be underestimated without factoring F_plasma into calculation, especially for those of low plasma partitioning. To our best knowledge, this study initially uncovered the gap between introducing F_plasma and dividing C_plasma by 2.0 during health risk assessment on internal OPFRs exposure.

Computational Insight into Biotransformation Profiles of Organophosphorus Flame Retardants to Their Diester Metabolites by Cytochrome P450

Biotransformation of organophosphorus flame retardants (OPFRs) mediated by cytochrome P450 enzymes (CYPs) has a potential correlation with their toxicological effects on humans. In this work, we employed five typical OPFRs including tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tris(1-chloro-2-propyl) phosphate (TCIPP), tri(2-chloroethyl) phosphate (TCEP), triethyl phosphate (TEP), and 2-ethylhexyl diphenyl phosphate (EHDPHP), and performed density functional theory (DFT) calculations to clarify the CYP-catalyzed biotransformation of five OPFRs to their diester metabolites. The DFT results show that the reaction mechanism consists of Cα-hydroxylation and O-dealkylation steps, and the biotransformation activities of five OPFRs may follow the order of TCEP ≈ TEP ≈ EHDPHP > TCIPP > TDCIPP. We further performed molecular dynamics (MD) simulations to unravel the binding interactions of five OPFRs in the CYP3A4 isoform. Binding mode analyses demonstrate that CYP3A4-mediated metabolism of TDCIPP, TCIPP, TCEP, and TEP can produce the diester metabolites, while EHDPHP metabolism may generate para-hydroxyEHDPHP as the primary metabolite. Moreover, the EHDPHP and TDCIPP have higher binding potential to CYP3A4 than TCIPP, TCEP, and TEP. This work reports the biotransformation profiles and binding features of five OPFRs in CYP, which can provide meaningful clues for the further studies of the metabolic fates of OPFRs and toxicological effects associated with the relevant metabolites.

Maize plant (Zea mays) uptake of organophosphorus and novel brominated flame retardants from hydroponic cultures

The root uptake and root-shoot translocation of seven organophosphorus flame retardants (OPFRs) and four novel brominated flame retardants (NBFRs) were assessed in this investigation using hydroponic grown maize plants (Zea mays). Three initial liquid concentrations for each considered compound were examined (i.e., 0.3 μg L^-1, 3 μg L^-1, 30 μg L^-1). The results indicated that the 30 μg L^-1 treatments were phytotoxic, as they resulted in a significant decrease in shoot dry weight. Plant-driven removal of the tested FRs decreased with the increasing initial spiking level and were reportedly higher for the NBFRs (range 42%-10%) than OPFRs (range 19%-7%). All the considered FRs were measured in the roots (range 0.020-6.123 μg g^-1 dry weight -DW-) and shoots (range 0.012-1.364 μg g^-1 DW) of the tested plants, confirming that there was uptake. Linear relationships were identified between the chemical concentrations in the plant parts and the tested hydroponic concentrations. Root concentration factors were positively correlated with the specific lipophilicity (i.e., logK_ow) of the tested FRs and were determined to be higher for the NBFRs than the OPFRs. The NBFRs had a higher root uptake rate than the OPFRs, and this trend was more significant with the increasing treatment concentrations. Shoot/root concentration factors were found to be lower than the unity value for 10 of the 11 tested compounds. These results can be related to the specific molecular configurations and the occurrence of different functional groups in the tested compounds. The results will help to improve risk assessment procedures and fine tune our understanding of human receptor responses to the ingestion of maize crops grown on agricultural sites irrigated with water contaminated by FRs.

Bone developmental toxicity of organophosphorus flame retardants TDCIPP and TPhP in marine medaka Oryzias melastigma

The global phase-out has decreased the use of polybrominated diphenyl ethers (PBDEs), thereby, rapidly increasing the production and use of their important surrogates, organophosphorus flame retardants (OPFRs). Currently, OPFRs are often found at higher levels in the environments compared to PBDEs. Although the two typical OPFRs, tris (1,3-dichloroisopropyl) phosphate (TDCIPP) and triphenyl phosphate (TPhP), have been frequently detected in marine environments with significant concentrations, their toxicity to marine organisms remains unknown. We used Oryzias melastigma to investigate and compare their developmental toxicity in marine organisms through two-generational chronic exposure. The results showed that TDCIPP and TPhP exposure shortened the body length and length of the pectoral fin of O. melastigma. Both TDCIPP and TPhP deformed the pectoral fins in the 1st fry and caused spinal curvature in adult fish. Therefore, these two chemicals may pose potential risks to marine fish and marine ecosystems. Further studies suggested that although these two chemicals caused similar developmental bone toxicity, they had different modes of modulating the expression of bone developmental genes such as, bmp4, bmp2 and runx2.

A review of environmental occurrence, analysis, bioaccumulation, and toxicity of organophosphate esters

The ban and restriction of polychlorinated biphenyls (PCBs) and major brominated flame retardants (BFRs), including hexabromocyclododecane (HBCD) and polybrominated diphenyl ethers (PBDEs), due to their confirmed detrimental effects on wildlife and humans have paved the way for the wide application of organophosphate esters (OPEs). OPEs have been extensively used as alternative flame retardants, plasticizer, and antifoaming agents in various industrial and consumer products, which leads to an increase in production, usage, and discharge in the environment. We compile recent information on the production/usage and physicochemical properties of OPEs and discussed and compared the available sample treatment and analysis techniques of OPEs, including extraction, clean-up, and instrumental analysis. The occurrence of OPEs in sediment, aquatic biota, surface, and drinking water is documented. Toxicity, human exposure, and ecological risks of OPEs were summarized; toxicological data of several OPEs shows different adverse health effects on aquatic organisms and humans. Much attention was given to document evidence regarding the bioaccumulation and biomagnification potential of OPEs in aquatic organisms. Finally, identified research gaps and avenues for future studies are forwarded.

A critical review of human exposure to organophosphate esters with a focus on dietary intake

Organophosphate esters (OPEs) are common additives in a wide range of commercial and industrial products. Elevated and prolonged exposure to OPEs may induce several adverse effects. This is concerning as they are ubiquitous in air, indoor dust, drinking water, and other environmental matrices. However, information on the presence of OPEs in foodstuffs and consequent health risks remains scant. This review critically evaluates available information on levels and sources of OPEs in food, discusses the relative significance of diet as a pathway of human exposure, identifies knowledge gaps, and suggests directions for future research. For toddlers, dermal uptake from dust ingestion appears the predominant pathway of exposure to chlorinated OPEs, as well as ethylhexyl diphenyl phosphate (EHDPP) and triphenyl phosphate (TPHP). In contrast, diet appears the main pathway of exposure to all eight OPEs considered for adults, and for tri n-butyl phosphate (TnBP), tris 2-ethylhexyl phosphate (TEHP), and tris (2-butoxyethyl) phosphate (TBOEP) for toddlers. While summed exposures via all pathways are within reference dose (RfD) values, they do not include high-end exposure estimates, and for highly-exposed individuals, the margin between exposure and RfD values is smaller. Moreover, our exposure estimates are based on a meta-analysis of multiple exposure assessments conducted over a range of points in space and time. There is an urgent need for assessments of human exposure to OPEs that examine all relevant pathways in a spatially and temporally-consistent fashion. Given food is an important exposure pathway to OPEs, regular monitoring of their presence as well as their metabolites (that may have toxicological significance) in foodstuffs is recommended. While dermal uptake from indoor dust appears an important human exposure pathway, no evaluations exist of exposure via dermal uptake from OPE-containing products such as foam-filled furniture. This review also highlights very few data exist on OPEs in drinking water.

Modeling the relationship between emerging and persistent organic contaminants in water, sediment and oysters from a temperate lagoon

The concentrations of emerging and persistent organic contaminants (EPOC) in oysters (C_O) from Aveiro Lagoon are represented as a function of their concentrations in water (C_W) and sediment (C_S) using linear and generalized additive models (LM, GAM). Additionally, four sampling seasons, octanol/water partition coefficients (K) and type of EPOC (pyrethroids, flame-retardants, musks, UV filters, polycyclic aromatic hydrocarbons, others) are included in the models. The probabilities of detection of EPOC in water, sediment and oysters are analyzed by GAM. The behavior of contaminants in water is determined by K with a clear seasonal trend. Sediments are reservoirs for hydrophobic compounds with less seasonal variation. Seasonal changes are found for C_O, the last being determined additively both by C_W and hydrophobicity from one side and by C_S and type of contaminants from the other side. The seasonal change of EPOC concentration in water, sediment and oysters is specific for each contaminant type.

Occurrence, analysis and risk assessment of organophosphate esters (OPEs) in biota: A review

Due to their widespread use, organophosphate esters (OPEs) are commonly detected in various environmental matrices and have been identified as emerging contaminants. In this review article, the occurrence and analytical techniques of OPEs in the biotic environment have been compiled and reviewed. Data from studies published the last decade all over the world covering a variety of species in trophic chain have been synthesized and evaluated. OPEs are among the most frequent detected flame retardants and high concentrations are detected in biota to date. Knowledge gaps and recommendations for future research are discussed emphasizing on further monitoring, advanced analytical methodologies, and risk assessment studies to completely understand the science of OPEs in biota.

Determination of organophosphate ester flame retardants and plasticisers in fish samples by QuEChERs followed by gas chromatography-tandem mass spectrometry. Exposure and risk assessment through fish consumption

The presence of organophosphate esters (OPEs) in everyday commodities such as furniture, household appliances and baby toys have rendered these contaminants ubiquitous in environmental fates such as air, water, soils and biota. Their presence in food-related species suggests that an additional route of exposure to these esters for the general population is fish intake through diet. Their incipient toxicity and carcinogenetic behaviour make it essential to develop methods for determining OPEs in fish samples. In this paper we have developed a new method for determining 9 OPEs based on the QuEChERS extraction method followed by a simple clean-up using a novel device for selective lipid removal (LipiFiltr) and GC-MS/MS to extract these compounds from fish samples regardless of lipid content. QuEChERS salt packet optimisation and clean-up strategies such as liquid-liquid extraction, dispersive-solid phase extraction and LipiFiltr were tested. Our results showed that EN 15662 method salts and Lipifiltr were the best combination to produce efficient analyte apparent recovery (67-116%) and negligible matrix effects (<10%). Limits of detection ranged from 0.05 ng g^-1 (dry weight) for TiBP and TBP to 2.00 ng g^-1 (dry weight) for TCEP. Fish samples from four fish species were determined with a median concentration of ΣOPEs 5.31 ng g^-1 on a wet weight basis, with TBP, TiBP and TCPP as the main contenders. Estimates of exposure and risk associated with consuming these compounds via dietary intake showed low levels of concern for the population of Tarragona.

Comparison of the Toxicity Effects of Tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) with Tributyl Phosphate (TNBP) Reveals the Mechanism of the Apoptosis Pathway in Asian Freshwater Clams (Corbicula fluminea)

To compare the toxicities of a chlorinated and a nonchlorinated organophosphorus flame retardant (OPFR) in this study, adult calms (Corbicula fluminea) were exposed to tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) and tributyl phosphate (TNBP) at 20, 200, and 2000 μg/L for 30 days. Toxicity screening using transcriptomics indicated that the apoptosis pathway was significantly affected in the groups exposed to 2000 μg/L TDCIPP and TNBP (p ≤ 0.05), and this finding was further confirmed by the protein interaction network. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay suggested that TDCIPP and TNBP can cause apoptosis. The significant (p ≤ 0.05) increases in the activities of caspases 3 and 8 obtained with all treatments and in that of caspase 9 obtained with 2000 μg/L exposure treatments indicated the presence of mitochondria-dependent and mitochondria-independent apoptosis. Interestingly, a noticeable dose-dependent increase in DNA damage was observed in all treatments, resulting in apoptosis. Therefore, our results demonstrate that TDCIPP and TNBP induce DNA damage and apoptosis in C. fluminea, which indicates that these chemicals pose an ecological risk to benthic organisms. Moreover, through a similar mechanism of action in apoptosis, TDCIPP induced more serious toxicity than TNBP, which indicated that chlorination or differences in structure-specific metabolism could be key factors influencing toxicity.

Tissue-specific bioaccumulation, metabolism and excretion of tris (2-ethylhexyl) phosphate (TEHP) in rare minnow (Gobiocyprisrarus)

Tris (2-ethylhexyl) phosphate (TEHP) is one of the most commonly used organophosphorus flame retardant (OPFR) analogues and is commonly detected in surface water and sediments. Limited information is available about the metabolic pathway or metabolite formation related to TEHP in fish. In this study, rare minnows (Gobiocyprisrarus) were exposed to TEHP in static water for 30 d to investigate the bioaccumulation and metabolite distribution in the fish muscle, liver, kidney, gill, GI-tract, ovary and testis. Based on the estimated k_up,_parent and k_d,parent values, the bioconcentration factors (BCF_parent) of TEHP in fish tissues were calculated in the order of kidney > ovary ≈ liver ≈ testis > gill ≈ GI-tract > muscle; this finding was consistent with the results of our previous study on other alkyl-substituted OPFRs. In addition, this study identified the metabolic profiles of TEHP in the liver. TEHP was oxidatively metabolized by the fish to a dealkylated metabolite (di 2-ethylhexyl phosphate; DEHP) and hydroxylated TEHP (OH-TEHP). OH-TEHP further underwent extensive phase II metabolism to yield glucuronic acid conjugates. DEHP was mainly distributed in rare minnow in the following order: liver > GI-tract > kidney ≫ other tissues. However, the metabolite showed lower accumulation potential in fish tissues than TEHP, with metabolite parent concentration factors (MPCFs) for DEHP of less than 0.1 in all the investigated tissues. The BCF_parent values of TEHP in various fish tissues were only 9.0 × 10^-3-7.2 × 10^-4 times its estimated tissue-water partition coefficient (K_tissue-water) values based on tissue lipid, protein and water contents, which indicated the significance of biotransformation in reducing the bioaccumulation potential of TEHP in fish. The toxicokinetic data in the present study help in understanding the tissue-specific bioaccumulation and metabolism pathways of TEHP in fish and highlight the importance of toxicology research on TEHP metabolites in aquatic organisms.

Organophosphate esters in human serum in Bohai Bay, North China

Organophosphate esters (OPEs), as a class of emerging flame retardant and plasticizers, have attracted particular attention due to their ubiquitous existence in the environment and potential effects on human health. Here, we investigated the levels of OPEs in human serum and examined the role of demographic variables on the body burden of such compounds. Of 11 OPEs screened, 8 were detected in human serum samples collected from a population (n = 89) in Bohai Bay, North China. The ∑OPE concentrations ranged from 4.7 to 948 ng/g lipid weight (lw), with a median concentration of 243 ng/g lw. Tris(2-chloroethyl)phosphate (TCEP) was identified as the most abundant OPEs with a median concentration of 214 ng/g lw. The concentrations of the triphenyl phosphate (TPhP) in older adults were higher than those in young adults (p < 0.05), and lower concentrations of tri-iso-butyl phosphate (TIBP) were observed in female samples compared to males. Furthermore, significant differences were observed in tri-n-propyl phosphate (TPrP) concentrations between urban and rural residence groups (p < 0.05). This study provides important information on the accumulation potential of OPEs in human bodies and suggests the need for further investigation to understand the potential human health risk.

Halogenated and organophosphorus flame retardants in cetaceans from the southwestern Indian Ocean

PBDEs, HBCD, DBDPE, PBEB and HBB, dechloranes and OPFRs, as well as natural MeO-PBDEs were monitored in muscle tissue of three dolphin species from the southwestern Indian Ocean (Delphinus delphis, Sousa plumbea and Tursiops aduncus) collected between 2012 and 2015. The mean PBDE concentration was 416 ± 333 ng g^-1 lw. BDE-47 was found in all samples and was almost half the total PBDE contamination. BDE-209, BDE-100 and BDE-99 were present in ≥85% of the samples. HBCD was detected in just two samples at 20 and 330 ng g^-1 lw. PBEB and HBB were not detected, while DBDPE was in all samples but always below its limit of quantification. Dec 602 was the only quantifiable dechlorane at 232 ± 549 ng g^-1 lw. Mean OPFR concentration was 10452 ± 11301 ng g^-1 lw. TBOEP was found in all samples making up most of the total OPFR contamination. MeO-PBDEs were detected in all samples at 114 ± 137 ng g^-1 lw. Data on flame retardants in biota and environmental samples from the southwestern Indian Ocean are scarce and, as a result, comparisons are difficult. However, data from other marine predators in the region, such as penguins, suggest that further studies are needed to determine if these concentrations are the consequence of a high local contamination or widespread thoughout the Indian Ocean.

A Review of a Class of Emerging Contaminants: The Classification, Distribution, Intensity of Consumption, Synthesis Routes, Environmental Effects and Expectation of Pollution Abatement to Organophosphate Flame Retardants (OPFRs)

Organophosphate flame retardants (OPFRs) have been detected in various environmental matrices and have been identified as emerging contaminants (EC). Given the adverse influence of OPFRs, many researchers have focused on the absorption, bioaccumulation, metabolism, and internal exposure processes of OPFRs in animals and humans. This paper first reviews the evolution of various types of flame retardants (FRs) and the environmental pollution of OPFRs, the different absorption pathways of OPFRs by animals and humans (such as inhalation, ingestion, skin absorption and absorption), and then summarizes the environmental impacts of OPFRs, including their biological toxicity, bioaccumulation, persistence, migration, endocrine disruption and carcinogenicity. Based on limited available data and results, this study also summarizes the bioaccumulation and biomagnification potential of OPFRs in different types of biological and food nets. In addition, a new governance idea for the replacement of existing OPFRs from the source is proposed, seeking environmentally friendly alternatives to OPFRs in order to provide new ideas and theoretical guidance for the removal of OPFRs.

A review on organophosphate Ester (OPE) flame retardants and plasticizers in foodstuffs: Levels, distribution, human dietary exposure, and future directions

Given the ongoing studies on the adverse effects of organophosphate ester (OPE) flame retardants and plasticizers on human health, there is an increasing scientific interest in the risk of exposure to OPEs via dietary intake. Using peer-reviewed literature published up to 2018, this review surveyed and compiled the available and reported data on the concentrations and distributions of 30 OPEs based on their occurrence in various food samples from around the world. Regardless of sampling locations or food categories, 22 OPEs were detectable in at least one of analyzed sample, and there were clear variations in OPE levels among samples from different locations or food categories. For instance, cereals and fats/oils were the most contaminated by OPEs in China and Belgium, whereas fats/oils and desserts were the main polluted products in Sweden. In contrast, vegetables, fruits, fluid dairy products, and cereals were reported as the primary categories of food polluted by OPEs in Australia. Animal-based food categories such as eggs, fish and meat were the least contaminated, whereas the highest median OPE concentrations were found in meat and fish from the United State. The levels and distribution patterns of OPEs in foodstuffs demonstrated a tremendous difference even when collected from the same country and the same food item. Rice from China had the highest tris(2‑chloroethyl) phosphate (TCEP, mean: 29.8 ng/g dw) levels, whereas 2‑ethylhexyl‑diphenyl phosphate (EHDPP, mean: 4.17 ng/g ww), triphenyl phosphate (TPHP, mean: 26.14 ng/g ww), tris(2-chloroisopropyl) phosphate (TCIPP, mean: 0.87 ng/g ww) and tributyl phosphate (TNBP, median: 0.55 ng/g ww) concentrations were the highest in the same food category from Sweden, Belgium, Australia, and the United States, respectively. These discrepancies may be due to a variety of reasons such as differences in OPE physico-chemical properties, extent of usage, uptake, metabolic pathways, industrial food manufacturing processes, OPE level differences as a function of habitat, and accumulation and degradability of OPEs in different species. It is worth noting that, due to its worldwide usage in food packaging materials, EHDPP was more prominently found in processed food compared to non-processed food. Based on reported OPE levels in various foods, this review conducted a preliminary assessment of human exposure to OPEs through dietary intake, which suggested that the OPE estimated daily intake (EDI) for humans was around 880 ng/kg bw/day (95th percentile). This value was well below the corresponding OPE health reference dose given by the U.S. EPA (≥15,000 ng/kg bw/day). Even so, dietary exposure to OPEs via food intake may be not negligible based on some important factors such as dilution effects, cooking processes, and the contribution of as yet unknown means of OPE exposure. Overall, this review highlights several gaps in our understanding of OPEs in foodstuffs: 1) the investigation of contamination levels of OPEs in foodstuffs should be extended to other regions, especially North America and European countries, where OPEs are widely used and frequently detected in environmental samples, and 2) newly identified OPE derivatives/by-products, e.g., OP diesters and hydroxylated metabolites, which have been reported as end-products of OPE enzymatic metabolism or degradation through aqueous hydrolysis, and which may co-exist with parent OPEs, could also be screened with precursor OPEs in foodstuffs in future studies.

Persistent and emerging pollutants assessment on aquaculture oysters (Crassostrea gigas) from NW Portuguese coast (Ria De Aveiro)

The study aim was to determine a range of relevant persistent and emerging pollutants in oysters produced in an aquaculture facility located in an important production area, to assure their safety for human consumption. Pollutants, including 16 PAHs, 3 butyltins (BTs), 29 flame retardants (FRs, including organophosphate and halogenated FRs), 35 pesticides (including 9 pyrethroid insecticides) and 13 personal care products (PCPs, including musks and UV filters), were determined in oysters' tissues collected during one year in four seasonal sampling surveys. The seasonal environmental pollution on the production site was evaluated by water and sediment analysis. Furthermore, oysters' nutritional quality was also assessed and related with the consumption of healthy seafood, showing that oysters are a rich source of protein with low fat content and with a high quality index all year around. Results showed that most analysed pollutants were not detected either in oyster tissues or in environmental matrixes (water and sediments). The few pollutants detected in oyster tissues, including both regulated and non-legislated pollutants, such as a few PAHs (fluorene, phenanthrene, anthracene, fluoranthene, pyrene and indenopyrene), FRs (TPPO, TDCPP, DCP, BDE-47, BDE-209 and Dec 602) and PCPs (galaxolide, galaxolidone, homosalate and octocrylene), were present at low levels (in the ng/g dw range) and did not represent a significant health risk to humans. The observed seasonal variations related to human activities (e.g. tourism in summer) highlights the need for environmental protection and sustainable resource exploration for safe seafood production.

Monitoring and exposure assessment of organophosphorus flame retardants in source and drinking water, Nanjing, China

This study developed a new method to determine the residues of 13 organophosphorus flame retardants (OPFRs) in drinking water by gas chromatography-tandem mass spectrometry (GC-MS/MS) technique and investigated the chemical distribution in water samples from municipal plants along the Yangtze River in Nanjing. The linear calibration correlation coefficients R² for all 13 OPFRs were at least 0.998 0. Three levels of spiked test were performed. Most of the recoveries were in the range of 80~120%, and the relative standard deviations (RSDs) for the 13 OPFRs were 2.1~17% (n = 6). Five OPFRs were 100% positively detected in the samples, and 3 OPFRs were positively detected in some samples. The concentrations of detected OPFR in the water ranged from 0.7 to 5780.0 ng L^-1. The average concentrations of OPFRs in wet season were higher than those in dry season, and the contaminants mainly originated from the source water in the Yangtze River. The exposure assessments of individual and total OPFRs were investigated. The estimated daily intakes of total OPFRs via ingestion of drinking water reached up to 64.8 and 45.2 ng/kg bw/day in dry and wet season, respectively. This study demonstrates a profile of OPFR distribution in Nanjing municipal water and provides information on human exposure assessment via drinking water in the Nanjing District, China.

Accelerated solvent extraction coupled to high-performance liquid chromatography-tandem mass spectrometry for simultaneous determination of 11 organophosphorus flame retardants in aquatic products

BACKGROUND

A new method based on accelerated solvent extraction was developed for the extraction and determination of 11 organophosphorus flame retardants by using a high-performance liquid chromatography-tandem mass spectrometry technique.

RESULTS

After optimization of the extraction temperature (80 °C), the extraction solvent (n-hexane), the flush volume (40%) and the static extraction time (4 min), all 11 organophosphorus flame retardants illustrated good linearities (R > 0.999). The limits of detection of the method ranged from 0.016 to 26.58 µg kg^-1 in the different matrices. The recoveries were 90.4-111.2% with relative standard deviations 0.21-5.3% for the various aquatic products.

CONCLUSION

The proposed method was applied successfully to detect 11 organophosphorus flame retardants in aquatic products, including grass carp, ribbon fish, mud fish, common eel, shrimp and frog. © 2018 Society of Chemical Industry.

Residuals of organophosphate esters in foodstuffs and implication for human exposure

Foodstuffs may be contaminated by organophosphate esters (OPEs) and become an important source of human exposure since OPEs are ubiquitous in the environment. In the present study, 10 OPEs were analyzed in various food matrices collected from a city in Eastern China including chicken, pork, fishes, vegetables, tofu, eggs, milk and cereals. The concentrations of Σ₁₀OPEs ranged from 1.1 to 9.6 ng g^-1 fresh weight (fw) in the foodstuffs. Cereals had the highest residual level of total OPEs with a mean value of 5.7 ng g^-1 fw. Tris(2-ethylhexyl) phosphate was detected in all foodstuff samples and showed the highest median residual concentration of 1.3 ng g^-1 fw among the OPE analogs. The daily dietary intake of OPEs was calculated as 3.6 and 2.4 μg d^-1 for adults and children. Cereals were identified as the major contributor to the total OPEs among different types of foodstuffs. Preliminary exposure assessment revealed that the current non-cancer health risks of OPEs via dietary intake were in the range of 10^-5-10^-3, indicating low risk levels. Moreover, the hazard index of OPEs indicated that the risk for children (3 × 10^-3) was higher than adults (2 × 10^-3).

Halogenated and organophosphorus flame retardants in European aquaculture samples

This work monitors flame retardants in sediment, mussel and water samples from European fish farms. Polybrominated diphenyl ethers (PBDEs) were detected in 95% of the sediment and mussel samples with mean levels of 8.60±22.6ngg^-1 dw in sediments and 0.07±0.18ngg^-1 dw in mussels. BDE-209 was the main contributor for the sediments and BDE-47 was found in about 60% of the samples of both matrices. Pentabromoethylbenzene (PBEB) and hexabromobenzene (HBB) were detected in 42% of the sediments, but not in mussels. Decabromodiphenyl ethane (DBDPE) was found in about 55% of the samples of both matrices. The same happened for dechloranes in mussels, but they were detected in 92% of the sediments. Syn-DP and anti-DP were always the main contributors. Methoxylated PBDEs (MeO-PBDEs) were detected in all mussels and some sediments, mainly 6-MeO-BDE-47 and 2'-MeO-BDE-68. Organophosphorus flame retardants (OPFRs) were found in all matrices with concentrations of 0.04-92.8ngg^-1 dw in sediment, 0.50-102ngg^-1 dw in mussel and 0.43-867ngl^-1 in water. Only OPFRs were analysed in water samples as halogenated flame retardants and MeO-PBDEs are highly unlikely to be detected in water due to their physicochemical properties. Flame retardants have no application in fish farming so results should reflect the impact of human activity on the farm locations. A large majority of the most contaminated samples were collected from sampling spots that were at urban shores or in enclosed water bodies not completely open to the sea.

Isomers of tris(chloropropyl) phosphate (TCPP) in technical mixtures and environmental samples

Tris(chloropropyl) phosphate (TCPP) is an environmentally abundant organophosphate ester (OPE). TCPP is comprised of four isomers with seven possible structures, eight CAS numbers, and even more common names. A review of 54 studies reporting one or more TCPP isomers confirmed that the most abundant and most often reported TCPP isomer was tris(2-chloro-1-methylethyl) phosphate, also known as tris(chloroisopropyl) phosphate (TCiPP, referred to hereafter as TCPP1). Full-scan gas chromatography-mass spectrometry (GC-MS) was used to identify the other three isomers numbered here according to their elution order on a non-polar GC column (DB-5): bis(2-chloro-1-methylethyl) (2-chloropropyl) phosphate (TCPP2), bis(2-chloropropyl)(2-chloro-1-methylethyl) phosphate (TCPP3), and tris(2-chloropropyl) phosphate (TCPP4). GC with a flame ionization detector (FID) was used to identify the relative abundances of the isomers in commercially available standards with unknown isomer composition. In technical TCPP, TCPP1-4 isomers averaged 71 ± 1, 26 ± 0.4, 3 ± 0.5, and 0.1 ± 0.02%, respectively. When these percent masses are incorporated into GC-MS quantification, response factors (RFs) for TCPP1 and TCPP2 are significantly different from TCPP3 and TCPP4, indicating that the multiple RF approach is more accurate than the commonly employed single RF method. Samples from urban streams and wastewater treatment plant (WWTP) effluent from Toronto, Canada, had isomeric ratios of TCPP1/2 that were not significantly different from a technical mixture whereas rain had a significantly different ratio indicating enrichment in the more volatile TCPP1 isomer. Reporting TCPP isomers can provide insight into sources, transport, and fate of TCPP in the environment. Graphical Abstract ᅟ.

Review of OPFRs in animals and humans: Absorption, bioaccumulation, metabolism, and internal exposure research

Due to their widespread use, organophosphate flame retardants (OPFRs) are commonly detected in various environmental matrices and have been identified as emerging contaminants. Considering the adverse effects of OPFRs, many researchers have paid their attention on the absorption, bioaccumulation, metabolism and internal exposure processes of OPFRs in animals and humans. In this article, we first review the diverse absorption routes of OPFRs by animals and humans (e.g., inhalation, ingestion, dermal absorption and gill absorption). Bioaccumulation and biomagnification potentials of OPFRs in different types of organisms and food webs are also summarized, based on quite limited available data and results. For metabolism, we review the Phase-I and Phase-II metabolic processes for each type of OPFRs (chlorinated OPFRs, alkyl-OPFRs and aryl-OPFRs) in the animals and humans, as well as toxicokinetic information and putative exposure biomarkers on OPFRs. Finally, we highlight gaps in our knowledge and critical directions for future internal exposure studies of OPFRs in animals and humans.

Pressurized liquid extraction of chlorinated polycyclic aromatic hydrocarbons from soil samples using aqueous solutions

Pressurized liquid extraction of chlorinated polycyclic aromatic hydrocarbons from soil samples using aqueous solutions.

Acute and developmental behavioral effects of flame retardants and related chemicals in zebrafish

As polybrominated diphenyl ethers are phased out, numerous compounds are emerging as potential replacement flame retardants for use in consumer and electronic products. Little is known, however, about the neurobehavioral toxicity of these replacements. This study evaluated the neurobehavioral effects of acute or developmental exposure to t-butylphenyl diphenyl phosphate (BPDP), 2-ethylhexyl diphenyl phosphate (EHDP), isodecyl diphenyl phosphate (IDDP), isopropylated phenyl phosphate (IPP), tricresyl phosphate (TMPP; also abbreviated TCP), triphenyl phosphate (TPHP; also abbreviated TPP), tetrabromobisphenol A (TBBPA), tris (2-chloroethyl) phosphate (TCEP), tris (1,3-dichloroisopropyl) phosphate (TDCIPP; also abbreviated TDCPP), tri-o-cresyl phosphate (TOCP), and 2,2-,4,4'-tetrabromodiphenyl ether (BDE-47) in zebrafish (Danio rerio) larvae. Larvae (n≈24 per dose per compound) were exposed to test compounds (0.4-120 μM) at sub-teratogenic concentrations either developmentally or acutely, and locomotor activity was assessed at 6 days post fertilization. When given developmentally, all chemicals except BPDP, IDDP and TBBPA produced behavioral effects. When given acutely, all chemicals produced behavioral effects, with TPHP, TBBPA, EHDP, IPP, and BPDP eliciting the most effects at the most concentrations. The results indicate that these replacement flame retardants may have developmental or pharmacological effects on the vertebrate nervous system.

Disposable ionic liquid-coated etched stainless steel fiber for headspace solid-phase microextraction of organophosphorus flame retardants from water samples

An ionic liquid-coated etched stainless steel fiber was prepared for solid-phase microextraction of organophosphorus flame retardants from water.