Organophosphate esters (OPEs)in Chinese foodstuffs: Dietary intake estimation via a market basket method, and suspect screening using high-resolution mass spectrometry

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 co

Industrial production of organophosphate flame retardants (OPFRs): big knowledge gaps need to be filled?

Since the phase-out of traditional halogenated flame retardants (HFRs), interests of research are gradually being shifted to organophosphate flame retardants (OPFRs), and this can be reflected by the increasing number of publications on OPFRs year by year. Here, an extensive survey is conducted in an attempt to generate a list of OPFRs that are being produced in factories, and to investigate the annual production volume (APV). This survey suggests that at least n = 56 OPFR monomers and n = 62 OPFR mixtures are being currently produced in 367 factories around the world, and 201 out of them are in Mainland China. APV of OPFRs was estimated as 598,422 metric tons, and this number could be underestimated due to the limitation of available information. We also notice that current researches are confined to a limited number of OPFRs, especially for OP esters (OPEs), and other OPFRs with different structures from OPEs has been rarely studied. Based on all the collected datasets, we provide five recommendations for how to proceed with future research to more comprehensively understand the currently-produced OPFRs in the environment.This research was supported by the National Natural Science Foundation of China (Grant 21976088), and the Fundamental Research Funds for the Central Universities (Grant No. 30919011101)

Metabolic transformation of environmentally-relevant brominated flame retardants in Fauna : A review

Over the past few decades, production trends of the flame retardant (FR) industry, and specifically for brominated FRs (BFRs), is for the replacement of banned and regulated compounds with more highly brominated, higher molecular weight compounds including oligomeric and polymeric compounds. Chemical, biological, and environmental stability of BFRs has received some attention over the years but knowledge is currently lacking in the transformation potential and metabolism of replacement emerging or novel BFRs (E/NBFRs). For articles published since 2015, a systematic search strategy reviewed the existing literature on the direct (e.g., in vitro or in vivo) non-human BFR metabolism in fauna (animals). Of the 51 papers reviewed, and of the 75 known environmental BFRs, PBDEs were by far the most widely studied, followed by HBCDDs and TBBPA. Experimental protocols between studies showed large disparities in exposure or incubation times, age, sex, depuration periods, and of the absence of active controls used in in vitro experiments. Species selection emphasized non-standard test animals and/or field-collected animals making comparisons difficult. For in vitro studies, confounding variables were generally not taken into consideration (e.g., season and time of day of collection, pollution point-sources or human settlements). As of 2021 there remains essentially no information on the fate and metabolic pathways or kinetics for 30 of the 75 environmentally relevant E/BFRs. Regardless, there are clear species-specific and BFRspecific differences in metabolism and metabolite formation (e.g. BDE congeners and HBCDD isomers). Future in vitro and in vivo metabolism/biotransformation research on E/NBFRs is required to better understand their bioaccumulation and fate in exposed organisms. Also, studies should be conducted on well characterized lab (e. g., laboratory rodents, zebrafish) and commonly collected wildlife species used as captive models (crucian carp, Japanese quail, zebra finches and polar bears).Funding agencies:Natural Sciences and Engineering Research Council of Canada (NSERC)ECCC's Chemicals Management Plan</p

Organophosphate Flame Retardants and Plasticizers in Aqueous Solution: pH-Dependent Hydrolysis, Kinetics, and Pathways

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 (<i>p</i> > 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 (<i>p</i> > 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

Photolysis of highly brominated flame retardants leads to time-dependent dioxin-responsive mRNA expression in chicken embryonic hepatocytes

Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) and 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) are flame retardant chemicals that can undergo photolytic degradation. The present study compared the time-dependent photolyic degradation of TeDB-DiPhOBz and BDE-209, and dioxin-like product formation as a result of (UV) irradiation (I; irradiation time periods of 0, 1, 4, 15 and 40 days). Photo-degraded product fractions of UV-I-TeDB-DiPhOBz (nominal concentration: 1.9 μM) were administered to chicken embryonic hepatocytes (CEH), and significant induction of CYP1A4/5 mRNA expression was observed for fractions collected at the day 15 and 40 time points (fold change of 7.3/3.6 and 9.1/4.7, respectively). For the UV-I-BDE-209 fractions (nominal concentration: 10 μM), significant CYP1A4/5 up-regulation occurred at all time points, and the fraction collected on day 1 induced the greatest fold change of 510/86, followed by 410/68 (day 4) and 110/26 (day 15), respectively. For the UV-I-BDE-209 fraction collected at day 40, significant CEH cytotoxicity was observed. As a result, CYP1A4/5 expression was determined at a nominal concentration of 1 μM instead of 10 μM and CYP1A4/5 fold changes of 11/8.2 (day 40) were observed. Fractions eliciting the greatest CYP1A4/5 mRNA upregulation were further screened for transcriptomic effects using a PCR array comprising 27 dioxin-responsive genes. A total of 6 and 16 of the 27 target genes were up or down-regulated following UV-I-TeDB-DiPhOBz and UV-I-BDE-209 exposure, respectively. Overall, and regardless of the formation rate, these results raise concerns regarding the potential formation of dioxin-like compounds from flame retardant

Halogenated Flame Retardants in Predator and Prey Fish from the Laurentian Great Lakes: Age-Dependent Accumulation and Trophic Transfer

The identification, persistence, accumulation and trophic transfer of 25 polybrominated diphenyl ether (PBDE) congeners, 23 non-PBDE halogenated flame retardants (NPHFRs), 4 polybrominated-diphenoxybenzenes (PB-DiPhOBzs) and 6 methoxylated (MeO-) PB-DiPhOBzs were investigated in predator and prey fish collected in 2010 from sites in the North American Great Lakes of Ontario (n = 26) and Erie (n = 39). Regardless of locations or species, 20 PBDEs and 12 NPHFRs were quantifiable in at least one of the 65 analyzed samples, and polybrominated-1,4-diphenoxybenzenes (PB-DiPhOBzs) and MeO-PB-DiPhOBzs were not detectable in any of analyzed samples. Among the FRs, the greatest concentrations were the -PBDE, ranging from 1.06 (Rainbow Smelt, Lake Erie) to 162 (Lake Trout, Lake Ontario) ng/g wet weight (ww), which was followed by mean HBCDD concentrations ranging ND to 17.3 (Lake Trout, Lake Ontario) ng/g ww. The remaining FRs were generally not detectable or at sub-ppb levels. In most of cases, FR concentrations in samples from Lake Ontario were greater than those from Lake Erie. Strong and significant positive linear relationships occurred between log-normalized FR concentrations (ww or lipid weight (lw)) and ages of the top predator Lake Trout (n = 16, from Lake Ontario), and the estimated FR doubling ages (T2) were 2.9-6.4 years. For Walleye from Lake Erie, significantly positive linear relationships were also observed for some FRs, but the linear relationships generally became negative after FR concentrations were normalized with lipid weight. This study provides novel information on FR accumulation in aquatic organisms, and for the first time, significant positive linear relationships are reported between log-normalized FR concentrations (lw or ww) and ages of Lake Trout from the Great Lakes