The goal of this article is to summarize new biological monitoring information on perfluorinated compounds (PFCs) in aquatic ecosystems (post-2005) as a followup to our critical review published in ...2006. A wider range of geographical locations (e.g., South America, Russia, Antarctica) and habitats (e.g., high-mountain lakes, deep-ocean, and offshore waters) have been investigated in recent years enabling a better understanding of the global distribution of PFCs in aquatic organisms. High concentrations of PFCs continue to be detected in invertebrates, fish, reptiles, and marine mammals worldwide. Perfluorooctane sulfonate (PFOS) is still the predominant PFC detected (mean concentrations up to 1900 ng/g ww) in addition to important concentrations of long-chain perfluoroalkyl carboxylates (PFCAs; sum PFCAs up to 400 ng/g ww). More studies have evaluated the bioaccumulation and biomagnification of these compounds in both freshwater and marine food webs. Several reports have indicated a decrease in PFOS levels over time in contrast to PFCA concentrations that have tended to increase in tissues of aquatic organisms at many locations. The detection of precursor metabolites and isomers has become more frequently reported in environmental assessments yielding important information on the sources and distribution of these contaminants. The integration of environmental/ecological characteristics (e.g., latitude/longitude, salinity, and/or trophic status at sampling locations) and biological variables (e.g., age, gender, life cycle, migration, diet composition, growth rate, food chain length, metabolism, and elimination) are essential elements in order to adequately study the environmental fate and distribution of PFCs and should be more frequently considered in study design.
Despite the growing ubiquity of organophosphate (OP) triesters as environmental contaminants, parameters affecting their aquatic chemical stabilities are currently unknown. The present study examined ...the pH-dependent (7, 9, 11, or 13) hydrolysis of 16 OP triesters in mixtures of 80 ng/mL for each OP triester over a period of 35 days at 20 °C. For the pH = 7, 9, and 11 solutions, 10 of the 16 OP triesters were stable and with no significant (p > 0.05) degradation. For the remaining 6 OP triesters, significant degradation occurred progressing from the pH = 7 to 11 solutions. At pH = 13, except for tributyl phosphate and tris(2-ethylhexyl) phosphate, 14 OP triesters were degraded with half-lives ranging from 0.0053 days (triphenyl phosphate) to 47 days (tripropyl phosphate). With increasingly basic pH the order of OP triester stability was group A (with alkyl moieties) > group B (chlorinated alkyl) > group C (aryl). Numerous OP diesters were identified depending on the pH level of the solution, whereas OP monoesters were not detectable. This is consistent with no significant (p > 0.05) depletion observed for 5 OP diesters in the same 4 solutions and over same 35 day period, suggesting OP diesters are end products of base-catalyzed hydrolysis of OP triesters. Our results demonstrated that pH-dependent hydrolysis of OP triesters does occur, and such instability would likely affect the fate of OP triesters in aqueous environments where the pH can be variable and basic.
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.
•We reviewed the OPE concentrations in foodstuffs in literature published up to 2018.•Twenty-two OPEs were detectable in at lease of analyzed foodstuff samples.•A tremendous difference exists on OPE levels among locations or food categories.•EHDPP was more prominently found in processed food rather than non-processed food.•Newly identified OPE derivatives/by-products could also be screened in future studies.
Organophosphate esters (OPEs) are synthetic phosphoric acid derivatives used in a wide variety of applications including as flame retardants and plasticizers. Their production and usage has increased ...in recent years, due to the phase-out of other flame retardant formulations (e.g., polybrominated diphenyl ethers). As such, there has been a recent push to understand the global distribution of OPEs and their behaviour in biota. Multiple studies have been published over the last few years pertaining to OPE concentrations in biotic and abiotic environmental compartments, as well as the metabolism of OPEs in biota. This paper aims to provide a brief review of the occurrence and levels of OPEs in the environment, as well as recent developments concerning the elucidation of OPE metabolism in biota.
Although recent usage of organophosphate (OP) flame retardants has increased substantially, very few studies have reported on OPs in biota including wildlife, and essentially there is no information ...on OP body compartment composition and in ovo or in utero transfer for any given wildlife species. Concentrations and patterns of 16 OP triesters were presently screened for and/or determined in six body compartments from female herring gulls (Larus argentatus; n = 8) and the separate egg yolk and albumen of their entire clutches of eggs (n = 16) (collected in 2010 from a Lake Huron colony site, Laurentian Great Lakes of North America). Fat (32.3 ± 9.8 ng/g wet weight; ww) contained the highest ΣOP concentration, followed by egg yolk (14.8 ± 2.4 ng/g ww) ≈ egg albumen (14.8 ± 5.9 ng/g ww) > muscle (10.9 ± 5.1 ng/g ww) ≫ red blood cells (1.00 ± 0.62 ng/g ww), whereas in liver, blood plasma, and brain all OPs were not detectable. Nine OPs accumulated in herring gulls, but the concentrations and proportions of OPs were dependent on the body and egg compartment. For example, tris(2-butoxyethyl) phosphate (TBOEP) accounted for 66% of the ΣOP concentration in albumen, but only for 13% in yolk. Tri-n-butyl phosphate (TNBP) accounted for 25% of the ΣOP concentration in yolk, but was not detected in albumen. Estimates showed that overall OP burdens in the body (3.5 μg) were greater than in the whole egg (1.2 μg), although depuration via in ovo transfer was substantial.
Display omitted
•At least 23 OP diesters have been reported as contaminants or as degradation products of OP triesters.•OP diesters containing halogen atoms and aryl groups could be more persistent ...in environmental matrices.•Multiple sources of OP diesters existed, i.e. industrial production and biotic or abiotic degradation from OP triesters.•Total annual output of OP diesters was estimated to be 17,050 metric tons (underestimated).•Various adverse effects following exposure to OP diesters in organisms have been reported.
Over the course of the continual phase-outs of toxic halogenated flame retardants (HFRs), there has been an increasing demand for organophosphate esters (OPEs) in global FR markets. OPE-FRs have largely been identified as OP triesters, which have a basic chemical structure of O = P(OR)3. In addition to OP triesters, OPEs can refer to another class of related substances, namely, OP diesters that have a typical chemical structure of O = P(OR)2(OH)). OP diesters are known as biotic or abiotic degradation products of OP triesters. In recent years, environmental scientists have proven that OP diesters widely exist in a variety of environmental matrices and biotic samples around the world, implying the potential risks from OP diester exposure to biota and humans in the environment. Here, we have reviewed the scientific literature for studies involving OP diesters and up to the end of 2020. The aim of the present review is to assess the present understanding of the physicochemical properties, sources (industrial production and degradation), environmental occurrence of OP diesters, and adverse effects to exposed organisms. Based on the literature in the Web of Science core collection, we found that at least 23 OP diesters have been reported as contaminants in various environments or as degradation products of OP triesters. The physicochemical properties of OP diesters vary depending on their specific chemical structures. OP diesters containing halogen atoms and aryl groups seem to be more persistent (with greater estimated half-life (t1/2) values) in environmental matrices. There were multiple sources of OP diesters, including industrial production and biotic or abiotic degradation from OP triesters. Specifically, we found that ten OP diesters are produced somewhere in the world, and the total annual output was estimated to be 17,050 metric tons (this number is underestimated due to the limitation of the available information). In addition, the wide application of OP triesters worldwide makes the degradation of OP triesters another critical source of OP diesters to the environment and to organisms. Current monitoring studies have demonstrated that some OP diesters were detectable in the human body (via both blood and urine samples), indoor dust, wastewater, or sewage sludge worldwide. The highest concentrations of diphenyl phosphate (DPHP) in human urine have been reported as high as 727 ng/mL (children (aged 0–5 years) urine samples from Australia). In addition, adverse effects following direct or indirect exposure to 11 OP diesters in organisms (including animals, bacteria, and algae) have been reported, and the recorded adverse outcomes following exposure to OP diesters included developmental toxicity, alteration of gene expression, and disturbance of nuclear receptor activity. Biomonitoring studies regarding human samples have frequently reported statistically significant associations between the concentrations of OP diesters and markers of human health (mainly related to reproductive toxicity). Finally, on the basis of current knowledge on OP diesters, we propose prospects for related research directions in future studies.
The organophosphate flame retardant, triphenyl phosphate (TPHP), has been detected with increasing frequency in environmental samples and its primary metabolite is considered to be diphenyl phosphate ...(DPHP). Information on the adverse effects of these compounds in avian species is limited. Here, we investigate the effects of TPHP and DPHP on cytotoxicity and mRNA expression, as well as in vitro metabolism of TPHP, by use of a chicken embryonic hepatocyte (CEH) screening assay. After 36 h of exposure, CEH cytotoxicity was observed following exposure to >10 μM TPHP (LC50 = 47 ± 8 μM), whereas no significant cytotoxic effects were observed for DPHP concentrations up to 1000 μM. Using a custom chicken ToxChip polymerase chain reaction (PCR) array, the number of genes altered by 10 μM DPHP (9 out of 27) was greater than that by 10 μM TPHP (4 out of 27). Importantly, 4 of 6 genes associated with lipid/cholesterol metabolism were significantly dysregulated by DPHP, suggesting a potential pathway of importance for DPHP toxicity. Rapid degradation of TPHP was observed in CEH exposed to 10 μM, but the resulting concentration of DPHP accounted for only 17% of the initial TPHP dosing concentration. Monohydroxylated-TPHP (OH-TPHP) and two (OH)2-TPHP isomers were identified in TPHP-exposed CEH, and concentrations of these metabolites increased over 0 to 36 h. Overall, this is the first reported evidence that across 27 toxicologically relevant genes, DPHP altered more transcripts than its precursor, and that TPHP is also metabolized via a hydroxylation pathway in CEH.
Despite of the ubiquity of organophosphate esters (OPEs) in various environmental matrices, information regarding the dietary intakes of OPEs is currently limited. To better understand dietary ...exposure and intake, the present study investigated 11 OPE flame retardants (FRs) in 105 composite food samples divided into 9 food categories, collected in 2018 and based on the contents of a typical Chinese food market basket. Nine OPEs, including triethyl phosphate (TEP), tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPHP), 2-ethylhexyl-diphenyl phosphate (EHDPP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-ethylhexyl) phosphate (TEHP) and tris(methyl-phenyl) phosphate (TMPP), were measurable above the method limits of quantifications (MLOQs) in at least one of the analyzed samples. Among the 9 food categories, sweets were contaminated most severely with a mean sum (Σ) OPE concentration of 10.34 ng/g wet weight (ww). Regardless the food categories, EHDPP and TEP were the predominant OPEs with mean concentrations of 1.12 and 0.95 ng/g ww, respectively. In addition, the levels of OPEs in “processed foods” were significantly (unpaired t-test, p < 0.01) higher than those in “non-processed foods”. Based on the measured OPE concentrations, we estimated daily per capita dietary intakes of ΣOPEs for Chinese adult population to be 44.3 ng/kg bw/day, that was mainly contributed by TCEP (14.3 ng/kg bw/day), TEP (12.7 ng/kg bw/day) and EHDPP (8.4 ng/kg bw/day). In addition to these 9 detected OPEs, further suspect screening in the combined extracts of foodstuffs by use of high-resolution spectrometry revealed a novel OP-FR, triphenyl phosphine oxide (TPPO). The highlight findings in this study were: 1) the amount of OPE via dietary intakes for the Chinese population is generally in the same order of magnitude as for other countries, i.e. the Swedish, Belgian and Australian adult population, and far less than the reference dosage value of each OPE (hazard index ≪ 1); 2) the total dietary intakes of OPEs were dominated by cereals, approximately accounting for 52.2%; and 3) the first reported detection of the novel OP-FR, TPPO, in foodstuff samples.
•Organophosphate esters (OPEs) were examined based on Chinese food market basket.•OPE concentrations were measured in n = 105 composite food samples.•Dietary intakes of OPE in China is comparable with those reported for other countries.•Total dietary intakes of OPEs were dominated (52.2%) by cereals.•First report on detection of the novel OP-FR, TPPO, in foodstuff samples
There is increasing scientific interest in environmental pollution and the effect on public health caused by organophosphate esters (OPEs). Using liquid chromatography coupled to a hybrid quadrupole ...Orbitrap high-resolution mass spectrometer, a novel, robust, and untargeted screening strategy for the identification of novel OPEs in indoor dust samples was presently developed based on the characteristic molecular fragmentation pathways, and 12 previously reported OPEs and six previously unrecognized OPEs were detected in the combined extracts of indoor dust samples, collected in Nanjing, eastern China. One of the six detected OPEs, bis-(2-ethylhexyl)-phenyl phosphate (BEHPP), was identified by comparison of unique LC and MS characteristics with a synthesized pure standard. Accurate concentrations of BEHPP were determined in n = 50 individual indoor dust samples with 100% detection frequency with a median concentration range of 50–1530 ng/g dry weight, which were generally greater or at least comparable to traditional OPEs, that is, triphenyl phosphate and 2-ethylhexyl diphenyl phosphate (EHDPP), in the same dust samples. Statistically significant, positive correlations were found for log-transformed concentrations of BEHPP versus EHDPP (r 2 = 0.7884, p < 0.0001), and BEHPP versus tris(2-ethylhexyl)phosphate (r 2 = 0.4054, p < 0.0001), suggesting their similar commercial applications and sources in the environment.
Side-chain fluorinated polymer surfactants are the main components of fabric protector sprays and used extensively on furniture and textiles. The composition of these commercial protector products ...has changed, but there is currently a total dearth of information on these novel fluorinated polymers in the environment. Using a developed analytical approach, two complementary studies examined the distribution of Scotchgard™ fabric protector components in aquatic sediment and in agricultural soils where wastewater treatment plant (WWTP) sourced biosolid application occurred, and in samples from sites in the Laurentian Great Lakes basin of North America. The main components in the pre- and post-2002 Scotchgard™ fabric protectors were identified by MS/MS and Q-TOF-MS to contain a perfluorooctane sulfonamide (S1) and perfluorobutane sulfonamide (S2) based side-chain, respectively, and bonded to a polymer backbone. In fifteen sediment samples collected in 2012–2013 from western Lake Erie and Saginaw Bay (Lake Huron), S1 was in all sediment samples (0.18 to 461.59ng/g dry weight (d.w.)); S2 was in 80% of the sediment samples (<0.03 to 24.08ng/g d.w.). Thirteen soil samples were collected (2015) from a biosolid applied and two non-biosolid applied farm field sites in southern Ontario (Canada). S1 was detected in 100% of the soil samples from biosolid-augmented agricultural sites (mean 236.36ng/g d.w.; range 41.87 to 622.46ng/g d.w.), and at concentrations much greater than in the aquatic sediment samples. The concentration of S1 and S2 in soil and sediment samples were also much greater than the total concentration of other per-and poly-fluoroalkyl substances (PFASs) that were measured.
The ratio of S1 concentration versus ∑22PFAS concentration was up to 1616 in sediment samples from Lake Erie. This results helps to explain why known PFASs account for low percentages of the total extractable organic fluorine (EOF) content in sediment.
Display omitted
•Major side-chain fluoroalkyl components found in pre- and post-2002 Scotchgard products•High concentrations of the pre-2002 product component found in biosolid-augmented agricultural soil samples•Both components were at greater concentrations in soil and sediment samples than all other perfluorinated compounds•These results help to explain the low PFAS portion accountability in extractable organic fluorine content in sediments
PDF
