Occurrence of novel organophosphate esters derived from organophosphite antioxidants in an e-waste dismantling area: Associations between hand wipes and dust

Seasonal variations of organophosphate esters (OPEs) in atmospheric deposition, and their contribution to soil loading

Organophosphate esters (OPEs) are ubiquitous in surface soil, and atmospheric deposition is considered to be the major pollution source. However, the research on the environmental transport behaviors of OPEs between atmospheric deposition and soil is very limited. In this study, we investigated the contamination levels and seasonal variations of OPEs in atmospheric deposition samples (n = 33) collected from an area of South China every month between February 2021 and January 2022, and evaluated the contribution of OPEs in atmospheric deposition to soil. The concentrations of ∑21target-OPEs ranged from 3670 to 18,600 ng/g dry weight (dw), with a mean of 8200 ng/g dw (median: 7600 ng/g dw). ∑21target-OPEs concentrations in all atmospheric deposition samples exhibited significant seasonal differences (p < 0.05) with higher concentrations observed in winter and lower concentrations in summer. Tris(2,4-di-tert-butylphenyl) phosphate (TDTBPP) was the most dominant target OPE in atmospheric deposition (4870 ng/g dw), and its seasonal variation trend was consistent with ∑21OPEs (p < 0.05). Simultaneously, in order to further explore the effect of atmospheric deposition on the levels of OPEs in soil of the study region, input fluxes and accumulation increments were estimated. Ten OPEs (including seven target OPEs and three suspect OPEs) exhibited high input flux means and accumulation increments, indicating that these compounds are prone to accumulate in soil via atmospheric deposition. It is noteworthy that the non-target phosphonate analyte bis(2,4-di-tert-butylphenyl) dibutyl ethane-1,2-diylbis(phosphonate) (BDTBPDEDBP) was detected at highest median concentration (8960 ng/g dw) in atmospheric deposition. Correspondingly, the average input flux and accumulation increment of BDTBPDEDBP were higher than those of all target and suspect OPEs. Collectively, this study quantifies the environmental transport behavior of OPEs between atmospheric deposition and soil, and provides new evidences for the fact that atmospheric deposition is the important pollution source of OPEs in soil.

Traditional and Novel Organophosphate Esters in Plastic Greenhouse: Occurrence, Multimedia Migration, and Exposure Risk via Vegetable Consumption

The migration and risk of organophosphate esters (OPEs) in agricultural air-soil-plant multimedia systems due to plastic film application remain unclear. This study investigates the multimedia distribution of traditional OPEs (TOPEs), novel OPEs (NOPEs), and their transformation products (POPEs) in plastic and solar greenhouses. The total concentration of OPE-associated contaminants in air and airborne particles ranged from 594 to 1560 pg/m3 and 443 to 15600 ng/g, respectively. Significant correlations between air OPE concentrations and those in polyolefin film (P < 0.01) indicate plastic film as the primary source. Contaminants were also found in soils (96.8-9630 ng/g) and vegetables (197-7540 ng/g). The primary migration pathway for NOPEs was particle dry deposition onto the soil and leaf, followed by plant accumulation. Leaf absorption was the main uptake pathway for TOPEs and POPEs, influenced by vegetable specific leaf surface area. Moreover, total exposure to OPE-associated contaminants via vegetable intake was assessed at 2250 ng/kg bw/day for adults and 2900 ng/kg bw/day for children, with an acceptable hazard index. However, a high ecological risk was identified for NOPE compounds (median risk quotient, 975). This study provides the first evidence of the multimedia distribution and potential threat posed by OPE-associated contaminants in agricultural greenhouses.

Contamination of dairy products with tris(2,4-di-tert-butylphenyl) phosphite and implications for human exposure

Tris(2,4-di-tert-butylphenyl) phosphite (AO168), an organophosphite antioxidant, can be oxidized to tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) during the production, processing, and application of plastics. AO168 = O can be further transformed to bis(2,4-di-tert-butylphenyl) phosphate and 2,4-di-tert-butylphenol. Here, we discovered the contamination of AO168 and its transformation products in dairy products for the first time. More samples contained AO168 (mean concentration: 8.78 ng/g wet weight [ww]), bis(2,4-di-tert-butylphenyl) phosphate (mean:11.1 ng/g ww) and 2,4-di-tert-butylphenol (mean: 46.8 ng/g ww) than AO168 = O (mean: 40.2 ng/g ww). The concentrations of AO168 and its transformation products were significantly correlated, and differed with the packaging material and storage conditions of the product. Estimated daily intakes (EDIs) of AO168 and its transformation products were calculated. Although the overall dietary risks were below one, transformation products accounted for 96.7% of the total hazard quotients. The high-exposure EDIs of total AO168 were above the threshold of toxicological concern (300 ng/kg bw/day), and deserve continual monitoring.

Contamination Status of Novel Organophosphate Esters Derived from Organophosphite Antioxidants in Soil and the Effects on Soil Bacterial Communities

The contamination status of novel organophosphate esters (NOPEs) and their precursors organophosphite antioxidants (OPAs) and hydroxylated/diester transformation products (OH-OPEs/di-OPEs) in soils across a large-scale area in China were investigated. The total concentrations of the three test NOPEs in soil were 82.4-716 ng g-1, which were considerably higher than those of traditional OPEs (4.50-430 ng g-1), OPAs (n.d.-30.8 ng g-1), OH-OPEs (n.d.-0.49 ng g-1), and di-OPEs (0.57-21.1 ng g-1). One NOPE compound, i.e., tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) contributed over 65% of the concentrations of the studied OPE-associated contaminants. A 30-day soil incubation experiment was performed to confirm the influence of AO168 = O on soil bacterial communities. Specific genera belonging to Proteobacteria, such as Lysobacter and Ensifer, were enriched in AO168 = O-contaminated soils. Moreover, the ecological function of methylotrophy was observed to be significantly enhanced (t-test, p < 0.01) in soil treated with AO168 = O, while nitrogen fixation was significantly inhibited (t-test, p < 0.01). These findings comprehensively revealed the contamination status of OPE-associated contaminants in the soil environment and provided the first evidence of the effects of NOPEs on soil microbial communities.

Acute exposure to tris(2,4-di-tert-butylphenyl)phosphate elicits cardiotoxicity in zebrafish (Danio rerio) larvae via inducing ferroptosis

Tris(2,4-di-tert-butylphenyl)phosphate (AO168 =O), a novel organophosphate ester, is prevalent and abundant in the environment, posing great exposure risks to ecological and public health. Nevertheless, the toxicological effects of AO168 =O remain entirely unknown to date. The results in this study indicated that acute exposure to AO168 =O at 10 and 100 μg/L for 5 days obviously impaired cardiac morphology and function of zebrafish larvae, as proofed by decreased heartbeat, stroke volume, and cardiac output and the occurrence of pericardial edema and ventricular hypertrophy. Transcriptomics, polymerase chain reaction, and molecular docking revealed that the strong interaction of AO168 =O and transferrin receptor 1 activated the transportation of ferric iron into intracellular environment. The release of free ferrous ion to cytoplasmic iron pool also contributed to the iron overload in heart region, thus inducing ferroptosis in larvae via generation of excessive reactive oxygen species, glutathione peroxidase 4 inhibition, glutathione depletion and lipid peroxidation. Ferroptosis inhibitor (Fer-1) co-exposure effectively relieved the cardiac dysfunctions of zebrafish, verifying the dominant role of ferroptosis in the cardiotoxicity caused by AO168 =O. This research firstly reported the adverse impact and associated mechanisms of AO168 =O in cardiomyogenesis of vertebrates, underlining the urgency of concerning the health risks of AO168 =O.

Occurrence, potential sources, and ecological risks of traditional and novel organophosphate esters in facility agriculture soils: A case study in Beijing, China

Although traditional organophosphate esters (OPEs) in soils have attracted widespread interest, there is little information on novel OPEs (NOPEs), especially in facility agriculture soils. In this work, we surveyed 11 traditional OPEs, four NOPEs, and four corresponding organophosphite antioxidant precursors (OPAs) for the NOPEs in soil samples collected from facility greenhouses and open fields. The median summed concentrations of traditional OPEs and NOPEs were 14.1 μg/kg (range: 5.38-115 μg/kg) and 702 μg/kg (range: 348-1952 μg/kg), respectively, in film-mulched soils from greenhouses. These concentrations were much higher than those in soils without mulch films, which suggests that OPEs in soils are associated with plastic mulch films. Tris(2,4-di-tert-butylphenyl) phosphate, which is a NOPE produced by oxidation of (2,4-di-tert-butylphenyl) phosphite, was the predominant congener in farmland soils, with concentrations several orders of magnitude greater than those of traditional OPEs. Comparisons of OPEs in different mulch films and the corresponding mulched soils revealed that degradable and black films caused more severe pollution than polyethylene and white films. Traditional OPEs, including tris(2-ethylhexyl) phosphate and tricresyl phosphate, exhibited moderate risks in farmland soils, especially in film-mulched soils. NOPEs, including trisnonylphenol phosphate, posed high ecological risks to the terrestrial ecosystem. Risk evaluations should be conducted for a broad range of NOPEs in the environment.

Emerging organophosphite and organophosphate esters in takeaway food and the implications for human exposure

Takeaway food has become a prominent component of the diet in urban areas of China, especially for young people. Although dietary intake is a major pathway to contaminants for human exposure, studies on emerging organophosphite antioxidants (OPAs) and organophosphate esters (OPEs) in food are scarce. Here, we investigated four OPAs and 19 OPEs in takeaway foods (n = 99) and paired takeaway food packaging (n = 50) in China. AO168=O (mean: 14.9 ng/g ww), TPPO (mean: 1.05 ng/g ww), and TCIPP (mean: 0.579 ng/g ww) were dominant in the takeaway food. Some OPEs had significant correlations in takeaway food. Emerging OPAs and OPEs in takeaway food varied significantly depending on the packaging materials and food types. AO168 and AO168=O were widespread in the paired takeaway food packaging. The migration efficiencies of emerging OPAs and OPEs were low in takeaway food packaged in aluminum foil. Although the actual contamination of emerging OPAs and OPEs in takeaway food significantly differed from those of in food simulants migrated from paired takeaway food packaging, the results imply that food itself and takeaway food packaging are potential contamination sources of emerging OPAs and OPEs in takeaway food. The average estimated dietary intakes of emerging OPAs and OPEs were 465 ng/kg body weight (bw)/day and 91.9 ng/kg bw/day, respectively. The exposure risk of emerging OPAs and OPEs through takeaway food intake is low in China.

Aromatic amine antioxidants (AAs) and p-phenylenediamines-quinones (PPD-Qs) in e-waste recycling industry park: Occupational exposure and liver X receptors (LXRs) disruption potential

Recently, evidence of aromatic amine antioxidants (AAs) existence in the dust of the electronic waste (e-waste) dismantling area has been exposed. However, there are limited studies investigating occupational exposure and toxicity associated with AAs and their transformation products (p-phenylenediamines-quinones, i.e., PPD-Qs). In this study, 115 dust and 42 hand wipe samples collected from an e-waste recycling industrial park in central China were analyzed for 19 AAs and 6 PPD-Qs. Notably, the median concentration of ∑6PPD-Qs (1,110 ng/g and 1,970 ng/m2) was significantly higher (p < 0.05, Mann-Whitney U test) than that of ∑6PPDs (147 ng/g and 34.0 ng/m2) in dust and hand wipes. Among the detected analytes, 4-phenylaminodiphenylamine quinone (DPPD-Q) (median: 781 ng/g) and 1,4-Bis(2-naphthylamino) benzene quinone (DNPD-Q) (median: 156 ng/g), were particularly prominent, which were first detected in the e-waste dismantling area. Occupational exposure assessments and nuclear receptor interference ability, conducted through estimated daily intake (EDI) and molecular docking analysis, respectively, indicated significant occupational exposure to PPD-Qs and suggested prioritized Liver X receptors (LXRs) disruption potential of PPDs and PPD-Qs. The study provides the first evidence of considerable levels of AAs and PPD-Qs in the e-waste-related hand wipe samples and underscores the importance of assessing occupational exposure and associated toxicity effects.

The hidden diet: Synthetic antioxidants in packaged food and their impact on human exposure and health

Synthetic antioxidants (AOs) are commonly used in everyday items and industrial products to inhibit oxidative deterioration. However, the presence of AOs in food packaging and packaged foods has not been thoroughly documented. Moreover, studies on human exposure to AOs through skin contact with packaging or ingesting packaged foods are limited. In this study, we analyzed twenty-three AOs-including synthetic phenolic antioxidants (SPAs) and organophosphite antioxidants (OPAs)-along with six transformation products in various food samples and their packaging materials. We found AOs in food products at concentrations ranging from 1.30 × 103 to 1.77 × 105 ng/g, which exceeded the levels in both outer packaging (6.05 × 102-3.07 × 104 ng/g) and inner packaging (2.27 × 102-1.09 × 105 ng/g). The most common AOs detected in foodstuffs were tris(2,4-di-tert-butylphenyl) phosphate (AO168O), butylated hydroxytoluene (BHT), and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (AO1076), together constituting 95.7 % of the total AOs found. Our preliminary exposure assessment revealed that dietary exposure-estimated at a median of 2.55 × 104 ng/kg body weight/day for children and 1.24 × 104 ng/kg body weight/day for adults-is a more significant exposure route than dermal contact with packaging. Notably, four AOs were identified in food for the first time, with BHT making up 76.8 % and 67.6 % of the total BHT intake for children and adults, respectively. These findings suggest that food consumption is a significant source of BHT exposure. The estimated daily intakes of AOs via consumption of foodstuffs were compared with the recommended acceptable daily intake to assess the risks. This systematic investigation into AOs contributes to understanding potential exposure and health risks associated with AOs in packaged foods. It emphasizes the need for further evaluation of human exposure to these substances.

Occurrence of liquid crystal monomers in indoor and outdoor air particle matters (PM10): Implications for human exposure indoors

Liquid crystal monomers (LCMs) are potentially persistent, bioaccumulating, and toxic substances. However, limited data are available on the occurrence of LCMs in indoor and outdoor air particle matter (PM10) in residential areas. Herein, residential areas near an e-waste dismantling center (Guiyu Town, Shantou City), as well as areas away from the e-waste site (Jiedong District, Jieyang City) were selected as the sampling areas. PM10 was collected from the indoor environments of Guiyu (IGY) and Jieyang (IJY), as well as those from the outdoor environments (OGY and OJY) using the high-volume air samplers (TH-10000C). The levels of 57 LCMs in PM10 were analyzed, and the highest concentrations of LCMs were found in IGY (0.970-1080 pg/m3), followed by IJY (2.853-455 pg/m3), OGY (0.544-116 pg/m3) and OJY (0.258-35.8 pg/m3). No significant difference was observed for LCM levels in indoor PM10 between the two areas (p > 0.05), which were significantly higher than those in outdoors (p < 0.05), indicating that the release of electronic products in general indoor environments is a source of LCMs that cannot be ignored. The compositions of LCMs in outdoors were not consistent with those of indoors. The correlation analysis of individual LCMs suggested potential different sources to the LCMs in indoor and outdoor environments. The median daily intake values of Σ46LCMs via inhalation were estimated as 0.440, 1.46 × 10-2, 0.170 and 1.19 × 10-2 ng/kg BW/day for adults, and as 2.27, 2.60 × 10-2, 0.880 and 2.10 × 10-2 ng/kg BW/day for toddlers, respectively, indicating much higher exposure doses of LCMs indoors compared with the outdoors, and much higher doses for toddlers compared with adults (p < 0.05). These results reveal the potentially adverse effects of LCMs on vulnerable populations, such as toddlers, in indoor environments.

Indirect Emissions from Organophosphite Antioxidants Result in Significant Organophosphate Ester Contamination in China

Organophosphite antioxidants (OPAs) have been seriously neglected as potential sources of organophosphate esters (OPEs) in environments. This study utilizes a modeling approach to quantify for the first time national emissions and multimedia distributions of triphenyl phosphate (TPHP)─a well-known flame retardant─and three novel OPEs: tris(2,4-ditert-butylphenyl) phosphate (AO168═O), bis(2,4-ditert-butylphenyl) pentaerythritol diphosphate (AO626═O2), and trisnonylphenol phosphate (TNPP). Emphasis is on the quantitative assessment of OPA source in China. TPHP has 1.1-9.7 times higher emission (300 Mg/year in 2019 with half from OPA sources) than AO168═O (278 Mg/year), AO626═O2 (53 Mg/year), and TNPP (32 Mg/year), but AO168═O is predominant in environments (63-79%) except freshwaters. About 72-99% of the studied OPEs are emitted via air, with 88-99% ultimately distributed into soils as the major sink. OPA-source emissions contribute 9.5-57% and 4.7-56% of TPHP masses and concentrations (except in sediments) in different media, respectively. Both AO168═O and AO626═O2 exhibit high overall persistence ranging between 2 and 11 years. Source emissions and environmental concentrations are elevated in economically developed areas, while persistence is higher in northern areas, where precipitation and temperature are lower. This study shows the significance of the sources of OPA to OPE contamination, which supports chemical management of these substances.

Eight novel brominated flame retardants in indoor and outdoor dust samples from the E-waste recycling industrial park: Implications for human exposure

As alternatives for legacy brominated flame retardants, novel brominated flame retardants (NBFRs) have a wide array of applications in the electronic and electrical fields. The shift of recycling modes of electronic and electrical waste (e-waste) from informal recycling family workshop to formal recycling facilities might come with the change the chemical landscape emitted including NBFRs, however, little information is known about this topic. This study investigated the occurrence characteristics, distribution, and exposure profiles of eight common NBFRs and their derivatives in an e-waste recycling industrial park in central China and illustrated the differences in various functional zones in the recycling park. The highest level of ΣNBFRs in dust samples was found in e-waste storage area at median concentration of 27,400 ng/g, followed by e-waste dismantling workshops (23,300 ng/g), workshop outdoor area (7770 ng/g), and residential area outdoor (536 ng/g). In the e-waste dismantling associated dust samples, tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), tetrabromobisphenol A (TBBPA) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) were the predominant components. This paper presented the first evidence regarding the occurrence characteristic and distribution of tetrabromobisphenol S (TBBPS), tetrabromobisphenol A bismethyl ether (TBBPA-BME) and tetrabromobisphenol S bis(2,3-dibromopropyl ether) (TBBPS-BDBPE) in the e-waste associated dust samples. By comparing with previous studies performed in China, this paper also noticed the significant decrease of TBBPA concentrations in the dust probably due to the shift of e-wastes sources and recycling modes. We further assessed the risk of occupational workers exposure to NBFRs. The median EDI (estimated daily intake) value of ΣNBFRs among e-waste dismantling workers was 9.71 ng/kg BW/d with the maximum EDI value being 19.6 ng/kg BW/d, hundreds of times higher than those exposed by general population. The study raises great concern for the health risk of occupational exposure to NBFRs in the e-waste recycling industrial park.

Established and emerging organophosphate esters (OPEs) and the expansion of an environmental contamination issue: A review and future directions

The list of organophosphate esters (OPEs) reported in the environment continues to expand as evidenced by the increasing number of OPE studies in the literature. However, there remains a general dearth of information on more recently produced and used OPEs that are proving to be emerging environmental contaminants. The present review summarizes the available studies in a systematic framework of the current state of knowledge on the analysis, environmental fate, and behavior of emerging OPEs. This review also details future directions to better understand emerging OPEs in the environment. Firstly, we make recommendations that the current structural/practical abbreviations and naming of OPEs be revised and updated. A chemical database (CDB) containing 114 OPEs is presently established based on the suspect list from the current scientific literature. There are 12 established OPEs and a total of 83 emerging OPEs that have been reported in human and/or biota samples. Of the emerging OPEs more than 80% have nearly 100% detection frequencies in samples of certain environmental media including indoor air, wastewater treatment plants, sediment, and fish. In contrast to OPEs considered established contaminants, most emerging OPEs have been identified more recently due to the more pervasive use of high-resolution mass spectrometry (HRMS) based approaches and especially gas or liquid chromatography coupled with HRMS-based non-target analysis (NTA) of environmental sample fractions. Intentional/unintentional industrial use and non-industrial formation are sources of emerging OPEs in the environment. Predicted physical-chemical properties in silico of newer, molecularly larger and more oligomeric OPEs strongly suggest that some compounds such as bisphenol A diphenyl phosphate (BPA-DPP) are highly persistent, bioaccumulative and/or toxic. Limited information on laboratory-based toxicity data has shown that some emerging OPEs elicit harmful effects such as cytotoxicity, development toxicity, hepatotoxicity, and endocrine disruption in exposed humans and mammals. Established, and to a much lesser degree emerging OPEs, have also been shown to transform and degrade in biota and possibly alter their toxicological effects. Research on emerging OPE contaminants is presently limited and more study is warranted on sample analysis methods, source apportionment, transformation processes, environmental behavior, biomarkers of exposure and toxicity.

Does mask wearing affect skin health? An untargeted skin metabolomics study

Wearing masks is used as an effective way to prevent the spread of viruses. However, the effect of wearing masks on skin health requires further assessment. In this study, a non-invasive D-squame sampling method coupled with an untargeted metabolomics analysis by liquid chromatography high-resolution mass spectrometry was developed to identify the changes in the skin metabolome caused by wearing masks. D-squame method was found to have advantages over the commonly used sterile gauze method, especially for the lipids and lipid-like molecules. A total of 356 skin metabolites were putatively identified from the stratum corneum of 10 volunteers, and 17 differential metabolites were significantly downregulated after wearing surgical masks or N95 respirators. The downregulation of metabolites such as phosphatidylethanolamine and sphingomyelin might be related to hypoxia or increased skin moisture caused by wearing masks. Changes in skin metabolomics indicated a potential risk of skin barrier disruption and skin inflammation. Intermittent removal of the masks can effectively alleviate changes in the skin metabolome.

Co-occurrence and distribution of organophosphate tri- and di-esters in dust and hand wipes from an e-waste dismantling plant in central China

Electronic waste (e-waste) dismantling facilities are a well-known source of emerging contaminants including organophosphate esters (OPEs). However, little information is available regarding the release characteristics and co-contaminations of tri- and di-esters. This study, therefore, investigated a broad range of tri- and di-OPEs in dust and hand wipe samples collected from an e-waste dismantling plant and homes as comparison. The median ∑tri-OPE and ∑di-OPE levels in dust and hand wipe samples were approximately 7- and 2-fold higher than those in the comparison group, respectively (p < 0.01). Triphenyl phosphate (median: 11,700 ng/g and 4640 ng/m²) and bis(2-ethylhexyl) phosphate (median: 5130 ng/g and 940 ng/m²) were the dominant components of tri- and di-OPEs, respectively. The combination of Spearman rank correlations and the determinations of molar concentration ratios of di-OPEs to tri- OPEs revealed that apart from the degradation of tri-OPEs, di-OPEs could originate from direct commercial application, or as impurities in tri-OPE formulas. Significant positive correlations (p < 0.05) were found for most tri- and di-OPE levels between the dust and hand wipes from dismantling workers, whereas this was not observed in those from the ordinary microenvironment. Our results provide robust evidence that e-waste dismantling activities contribute to OPEs contamination in the surroundings and further human exposure pathways and toxicokinetics are needed to be elucidated.

Electronic-waste-associated pollution of per- and polyfluoroalkyl substances: Environmental occurrence and human exposure

Occupational exposure to per- and polyfluoroalkyl substances (PFASs) is of serious concern because their adverse health effects. Nevertheless, knowledge regarding contamination in e-waste dismantling regions is rather scarce. We therefore analysed seven neutral PFASs (n-PFASs) and forty ionized PFASs (i-PFASs) in dust and hand wipes collected from an e-waste dismantling plant and homes. Both dust (1370 ng/g) and workers' hand wipe (1100 ng/m²) in e-waste dismantling workshops contained significantly higher median levels of ∑PFASs than those from homes (684 ng/g and 444 ng/m²) (p < 0.01). ∑PFAS concentrations in dust and on workers' hand wipes from workshops were significantly higher than those from storage area. 8:2 fluorotelomer alcohol was the dominant n-PFAS in workshop dust (70.7%) and on worker's hand wipes (46.6%). Perfluoroalkyl carboxylic acids (C2 -C3) were the significant components (based on concentration) of i-PFASs in dust (57.9%) and on hand wipes (89.6%). A significant positive correlation (p < 0.001) of ∑PFAS concentrations between workshop dust and workers' hand wipes was observed, indicating that they come from common sources. Compared to dust ingestion, hand-to-mouth contact was highlighted as a vital exposure route, accounting for 68.8% for workers and 72.2% for residential population, respectively, of the sum of two exposure doses.

Occurrences and migration of organophosphite and organophosphate esters into food simulants from single-use food packaging in China

Organophosphite antioxidants (OPAs) and organophosphate esters (OPEs) are used as additives in food packaging. Because these chemicals have been found in various foods, they have caused increasing concern about potential health risks through food intake. Little information is available about the migration behaviors of OPAs and OPEs from single-use food packaging into food. In the present study, four OPAs and 23 OPEs were analyzed in paper and plastic single-use food packaging (n = 312), which are widely used for take-out food in China. The total concentrations of OPAs and OPEs in the packaging samples were 1966 and 189 ng/g, respectively. Tris (2,4-di-tert-butylphenyl) phosphite (AO168) was the dominant compound. OPAs and OPEs were present at higher concentrations in the plastic packaging than in the paper packaging. In a migration test, four OPAs and 15 OPEs were found in food simulants (4% acetic acid, 10% ethanol, and hexane). Higher levels of individual and total OPAs were found in hexane than the other food simulants, especially for AO168 migration from plastic packaging. The amounts of OPEs in the food simulants increased from the aqueous simulants (4% acetic acid and 10% ethanol) to the fatty food simulant (hexane). The migration efficiencies of the OPAs were higher than those of the OPEs. Preliminary calculations suggest that dietary exposure to OPAs and OPEs because of migration will be low for the population in China.

Organophosphate Flame Retardants in Pregnant Women: Sources, Occurrence, and Potential Risks to Pregnancy Outcomes

Organophosphate flame retardants (OPFRs) are found in various environmental matrixes and human samples. Exposure to OPFRs during gestation may interfere with pregnancy, for example, inducing maternal oxidative stress and maternal hypertension during pregnancy, interfering maternal and fetal thyroid hormone secretion and fetal neurodevelopment, and causing fetal metabolic abnormalities. However, the consequences of OPFR exposure on pregnant women, impact on mother-to-child transmission of OPFRs, and harmful effects on fetal and pregnancy outcomes have not been evaluated. This review describes the exposure to OPFRs in pregnant women worldwide, based on metabolites of OPFRs (mOPs) in urine for prenatal exposure and OPFRs in breast milk for postnatal exposure. Predictors of maternal exposure to OPFRs and variability of mOPs in urine have been discussed. Mother-to-child transmission pathways of OPFRs have been scrutinized, considering the levels of OPFRs and their metabolites in amniotic fluid, placenta, deciduae, chorionic villi, and cord blood. The results showed that bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP) were the two predominant mOPs in urine, with detection frequencies of >90%. The estimated daily intake (EDI_M) indicates low risk when infants are exposed to OPFRs from breast milk. Furthermore, higher exposure levels of OPFRs in pregnant women may increase the risk of adverse pregnancy outcomes and influence the developmental behavior of infants. This review summarizes the knowledge gaps of OPFRs in pregnant women and highlights the crucial steps for assessing health risks in susceptible populations, such as pregnant women and fetuses.

Organophosphite Antioxidants and Novel Organophosphate Esters in Dust from China: Large-Scale Distribution and Heterogeneous Phototransformation

A large-scale survey was conducted by measuring five organophosphite antioxidants (OPAs) and three novel organophosphate esters (NOPEs) in 139 dust samples across China. The median summed concentrations of OPAs and NOPEs in outdoor dust were 33.8 ng/g (range: 0.12-53,400 ng/g) and 7990 ng/g (2390-27,600 ng/g), respectively. The dust concentrations of OPAs associated with the increasing economic development and population density from western to eastern China, whereas the NOPE concentration in Northeast China (median, 11,900 ng/g; range, 4360-16,400 ng/g) was the highest. Geographically, the distribution of NOPEs was significantly associated with annual sunshine duration and precipitation at each sampling site. Results of laboratory experiments further revealed that the simulated sunlight irradiation promoted the heterogeneous phototransformation of OPAs in dust, and this process was accelerated with the existence of reactive oxygen species and enhanced relative humidity. Importantly, during this phototransformation, the hydroxylated, hydrolyzed, dealkylated, and methylated products, e.g., bis(2,4-di-tert-butylphenyl) methyl phosphate, were identified by nontargeted analysis, part of which were estimated to be more toxic than their parent compounds. The heterogeneous phototransformation pathway of OPAs was suggested accordingly. For the first time, the large-scale distribution of OPAs and NOPEs and the phototransformation of these "new chemicals" in dust were revealed.

Novel Brominated Flame Retardants in Dust from E-Waste-Dismantling Workplace in Central China: Contamination Status and Human Exposure Assessment

Novel brominated flame retardants (NBFRs) have been widely used as alternatives to legacy BFRs. However, information on the contamination status and human exposure risks of electronic waste (e-waste)-derived NBFRs in the e-waste workplace is limited. In this study, six NBFRs and the legacy BFRs, hexabromocyclododecanes (HBCDs), were analyzed in 50 dust samples from an e-waste-dismantling workplace in Central China. The dust concentration of NBFRs in e-waste-dismantling workshops (median, 157−169 ng/g) was found to be significantly higher than those in an outdoor environment (17.3 ng/g) (p < 0.01). Differently, the highest median concentration of HBCDs was found in dust from the dismantling workshop for cellphones and computers (367 ng/g) among studied areas. The bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEHTBP) was the predominant compound, which contributed 66.0−88.0% of measured NBFR concentrations. NBFRs might originate from plastic and rubber materials in wastes based on the correlation and principal component analysis. Moreover, the total estimated daily intakes (average scenario) of NBFRs were calculated at 2.64 × 10−2 ng/kg bw/d and 2.91× 10−2 ng/kg bw/d for the male and female dismantling workers, respectively, via dust ingestion, inhalation, and dermal contact pathways, which were lower than the reference dose values, and thus indicated a limited human exposure risk for NBFRs at the current level. Although the dust concentrations and daily intakes of NBFRs were still lower than those of other emerging pollutants (e.g., organophosphate and nitrogenous flame retardants) measured in the same sampling set, the elevated levels of NBFRs suggested the progressive BFR replacement process in China, which deserves more attention regarding their adverse effects on both the environment and human health.

Wide occurrence of seven phthalate plasticizers and two typical microplastics in pig feed

Plastics are widely used as packaging and engineering materials in feed processing, which leads to the potential contamination of plasticizers and microplastics (MPs) in animal feeds. In this study, the concentrations of two typical MPs, i.e., polyethylene terephthalate (PET) and polycarbonate (PC), and seven phthalates (PAEs) as well as their corresponding monoester metabolites (mPAEs) in 45 pig feed samples in China were analyzed by mass spectrometers. Among PAEs, dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) were detected in all samples, and DEHP showed the highest concentrations of 8.26-2464 μg/kg, which accounted for 65.6% of the total detected PAEs. PET MPs (<MDL-302 μg/kg) were detected in 97.8% of samples. Meanwhile, mPAEs were also detected in feed samples with high detection rates but of much lower concentrations. A significantly positive correlation was observed between DEHP and PET MPs. This indicates that the sources of DEHP and MPs in feeds are homologous, mainly from processing and packaging. Besides, the significantly positive correlations between DBP/DEHP and mBP/mEHP indicated the degradation of PAEs to mPAEs during feed production and transportation. The estimated daily intake (EDI) of PAEs and PET MPs were 2.40-70.3 and 0.800-7.79 μg/kg-bw-day, respectively. The results of this study provided new insight into the first evidence of the co-occurrence and risk of MPs, PAE, and mPAEs in pig feed.

Accumulation and translocation of traditional and novel organophosphate esters and phthalic acid esters in plants during the whole life cycle

Organophosphate esters (OPEs) and phthalic acid esters (PAEs) are widespread contaminants in the environment. The variations of these chemicals in plants throughout their life cycle is little known. In this study, OPEs, OPE metabolites, and PAEs in peanut and corn grown under field conditions, soil, and air were measured to understand the uptake and translocation, distributions in the plant compartments, and metabolism in the plants. The soil concentrations showed an enrichment effect of OPEs onto the rhizosphere soil but a depletion effect of PAEs on rhizosphere soils. The PAE concentrations between peanut (with a mean of 1295 ng/g dw) and corn (3339 ng/g dw) were significantly different, but the OPE concentrations were not significantly different (with means of 15.6 and 19.2 ng/g dw, respectively). OPE metabolites were also detected in the plants, with lower concentrations and detection rates. Similarities and differences in the temporal variations of the concentrations of traditional OPEs, novel OPEs, and PAEs in plants during their growth were observed. The variations were dependent on both plant species and particular tissues. The leaf compartment is the most important reservoir of OPEs and PAEs (but not OPE metabolites) for both species, highlighting the importance of an aerial uptake pathway. The chemicals have a low potential to be translocated into peanut and corn kernels, reducing their risks via food consumption. Less hydrophobic compounds have higher root concentration factors in this study. These observations differ from those of previous hydroponic experiments.

The respiratory cytotoxicity of typical organophosphorus flame retardants on five different respiratory tract cells: Which are the most sensitive one?

Triphenyl phosphate (TPHP) is a frequently used flame retardant and indoor semi-volatile pollutant exposing humans with endocrinal disrupting effects. However, its respiratory tract toxicity remains unclear. Herein, we mainly focused on exploring the cytotoxicity of TPHP to the cells from five different parts of the human respiratory tract (from top to bottom): human nasal epithelial (HNEpC) cells, human bronchial epithelial (16HBE) cells, normal nasopharyngeal epithelial (NP69) cells, human lung epithelial cells (Beas-2B) cells, and human lung fibrocells (HFL1 cells) cells. The cell viability, micronucleus induction, endoplasmic reticulum stress gene, intracellular Ca²⁺ concentration, mitochondrial membrane potential (MMP) were investigated in short-term as well as extended exposure of TPHP. HFL1 and HNEpC cells were found to be irreversible damage, while other three type cells achieved homeostasis through self-rescue. Moreover, expression of downstream genes of Nrf2 signaling pathway were upregulated for 1.3-7.0 times and glutathione detoxification enzyme activity changed for 2-10 (U/mg protein) in HNEpC cells. Furthermore, the vascular endothelial growth factor (VEGF), a disease-related factor, increased 1.0-3.5-fold in HNEpC cells. RNA-sequencing results suggested that protein linkage recombination, molecular function regulation and metabolic processes signal pathway were all affected by TPHP exposure in HNEpC. This is a first report to compare respiratory cytotoxicity in whole human respiratory tract under OPFR exposure and found HNEpC cells were the most sensitive target of TPHP. Molecular biological mechanisms uncovered that TPHP exposure in HNEpC can induce the activation of MAPK signal pathway and demonstrate potential respiratory growth differentiation and stress disorder in human nasal cells upon TPHP exposure.

E-waste dismantling-related occupational and routine exposure to melamine and its derivatives: Estimating exposure via dust ingestion and hand-to-mouth contact

Melamine (MEL) and its derivatives are increasingly applied as nitrogenous flame retardants in consumer products. Nevertheless, limited information is available on their environmental occurrence and subsequent human exposure via multiple exposure pathways. In this study, we analysed MEL and its derivatives in dust (indication of the dust ingestion route) and hand wipe samples (indication of the hand-to-mouth route) collected in various microenvironments. The levels of ∑MELs in both dust (median: 24,100 ng/g) and participant hand samples (803 ng/m²) collected in e-waste dismantling workshops were significantly higher than those in samples collected in homes (15,600 ng/g and 196 ng/m², respectively), dormitories (13,100 ng/g and 227 ng/m², respectively) and hotel rooms (11,800 ng/g and 154 ng/m², respectively). Generally, MEL dominated in dust samples collected in e-waste dismantling workshops, whereas cyanuric acid dominated in hand wipe samples. This may occur partly because the latter is an ingredient in disinfection products, which are more frequently employed in daily lives during the COVID-19 pandemic. Exposure assessment suggests that dust ingestion is an important exposure pathway among dismantling workers and the general population, whereas hand-to-mouth contact could not be overlooked in certain populations, such as children and dismantling workers not wear gloves at work.

Electronic-Waste-Driven Pollution of Liquid Crystal Monomers: Environmental Occurrence and Human Exposure in Recycling Industrial Parks

Liquid crystal monomers (LCMs) in liquid crystal displays (LCDs) may be released into the environment, especially in electronic waste (e-waste) recycling industrial parks with a high pollution risk. However, little has been known about the environmental release and human exposure to LCMs until now. Herein, a total of 45 LCMs were detected in LCDs of commonly used smartphones and computers by high-resolution mass spectrometry with suspect screening analysis. Fluorinated biphenyls and their analogs were the dominant LCMs. Based on available standards of the screening results and previous studies, 55 LCMs were quantified in samples from an e-waste recycling industrial park in Central China. The LCMs were frequently detected in outdoor dust (n = 43), workshop #1 indoor dust (n = 53), and hand (n = 43) and forehead wipes (n = 43), with median concentrations of 6950 ng/g, 67,400 ng/g, 46,100 ng/m², and 62,100 ng/m², respectively. The median estimated daily intake values of the LCMs via dust ingestion and dermal absorption were 48.3 and 16.5 ng/kg body weight/day, respectively, indicating a high occupational exposure risk of these compounds. In addition, 16 LCMs were detected in the serum of eight elderly people (≥60 years old) with over 5 years of experience in e-waste dismantling operations, resulting in a total concentration range of 3.9-26.3 ng/mL.

Organophosphate Esters in China: Fate, Occurrence, and Human Exposure

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers. OPEs have been released into various environments (e.g., water, sediments, dust and air, and soil). To investigate the occurrence and distribution of OPEs in various environments in China, this review collects and discusses the published scientific studies in this field. Chlorinated OPEs, as flame retardants, are the predominant OPEs found in the environment. The analysis of data revealed large concentration variations among microenvironments, including inflowing river water (range: 0.69-10.62 µgL^-1), sediments (range: 0.0197-0.234 µg/g), dust (range: 8.706-34.872 µg/g), and open recycling sites' soil (range: 0.122-2.1 µg/g). Moreover, OPEs can be detected in the air and biota. We highlight the overall view regarding environmental levels of OPEs in different matrices as a starting point to monitor trends for China. The levels of OPEs in the water, sediment, dust, and air of China are still low. However, dust samples from electronic waste workshop sites were more contaminated. Human activities, pesticides, electronics, furniture, paint, plastics and textiles, and wastewater plants are the dominant sources of OPEs. Human exposure routes to OPEs mainly include dermal contact, dust ingestion, inhalation, and dietary intake. The low level of ecological risk and risk to human health indicated a limited threat from OPEs. Furthermore, current challenges and perspectives for future studies are prospected. A criteria inventory of OPEs reflecting the levels of OPEs contamination association among different microenvironments, emerging OPEs, and potential impact of OPEs on human health, particularly for children are needed in China for better investigation.