Organophosphate esters and their diester metabolites in infant formulas and baby supplementary foods collected in Beijing, China: Occurrence and the implications for infant exposure

Exposure to the main Organic Plastic Additives through food contamination

The use of organic plastic additives (OPAs) in food packaging has led to their widespread presence in various foodstuffs. These additives, including mainly flame-retardants, bisphenols, UV-stabilizers and plasticizers, are known for their potential hazards and environmental impact. This review aims to comprehensively assess the contamination of food products by OPAs and evaluate their role as vectors of exposure to hazardous chemicals. A review of recent literature was conducted, focusing on studies that report on the presence and concentrations of OPAs in different food categories, including aquatic products, beverages, cereals, dairy products, eggs, oils, fats, meat, poultry, vegetables, fruits and other food categories. The review also examines regional variations in contamination levels and identifies the pollutants. Significant contamination of foodstuffs by OPAs are highlighted, with varying concentrations reported across different regions and food types. Potential sources of contamination include food-packaging materials and environmental pollution. This review also identifies research gaps and proposes future directions to improve the study of OPAs in food, aiming to enhance the reliability and comparability of findings while supporting efforts to mitigate contamination risks.

Plastic additives in the diet: Occurrence and dietary exposure in different population groups

A total diet study focused on exposure to plastic additives has been performed on 109 food samples. Plasticizers were detected in 85 % of analyzed samples with total concentrations ranging between not detected (nd) and 22.0 µg/g wet weight (ww). Non-phthalate plasticizers (NPPs), such as acetyl tributyl citrate (ATBC) or di(2-ethylhexyl) adipate (DEHA), were detected predominantly in baby foods (nd-3.38 µg/g ww) and meat (nd-15.0 µg/g ww), respectively. Significant differences (p ≤ 0.001) were observed across foods with different packaging types regarding the presence of ATBC and DEHA. ATBC was primarily detected in foods packaged in glass containers, meanwhile DEHA is mainly related to fresh food wrapped in plastic materials. Additionally, transference assays in selected ready to cook meals and fresh vegetables were performed, with NPPs exhibiting a higher transference from packaging to food than other compounds. The data obtained have been used for an assessment of estimated daily intake (EDI) of plastic additives in infants (6-12 months), toddlers (1-3 years), and adults (>18 years), resulting in values ranging 0.29-516 µg/kg body weight (bw)/day. Human risk related to baby food consumption, expressed as hazard quotients (HQs), was found with di(2-ethylhexyl) phthalate (DEHP) in the infant population sub-group.

Detection and screening of organophosphate esters in infant formula from Shanghai, China: distribution characteristics and risk evaluation

Organophosphate esters (OPEs) have raised great concerns in recent years. However, information regarding their occurrence in infant formula remains limited. Thus, thirty-two OPEs were measured in infant formula sold in Shanghai, China in 2023. The results showed that OPE occurrence in infant formula was widespread. The median concentrations of organophosphate diesters, organophosphate triesters, and total OPEs were 2.28, 5.20, and 8.63 ng/g, respectively. Tris(2-chloroisopropyl) phosphate (TCPP) showed the highest median concentration (1.95 ng/g), followed by triethyl phosphate, bis(1-chloro-2-propyl) phosphate (BCPP), tri-isobutyl phosphate, and triphenyl phosphate (0.532-0.581 ng/g). The dominant chloro-OPEs (TCPP and BCPP) were regional-specific. Compared to corresponding triesters, the diester concentrations were often lower, except for bis(2-butoxyethyl) phosphate and tributoxyethyl phosphate. Additionally, five novel OPEs with phenyl groups were identified, showing high detection frequencies and comparable concentrations to TCPP. Raw materials and food processing methods might affect individual OPEs. The estimated daily intakes (EDIs) ranged from 62.3 to 355 ng/kg bw/day. The highest EDI occurred in infants of 0-6 months of age but posed no obvious health risk for infants and toddlers. Further studies are still needed to evaluate the possible health implications arising from the novel OPEs and their metabolites, as well as the potentially synergistic effects.

Organophosphate esters and their metabolites in Beijing total diets: Occurrence, time trend, and dietary exposure assessment

Organophosphate esters (OPEs) and their metabolites (mOPEs) are emerging pollutants. In this study, 18 OPEs and 10 mOPEs were measured in the 6th and 7th Beijing total diet studies (TDSs), and the dietary intakes of these pollutants by Beijing adults were estimated to assess related health concerns. Most OPEs and mOPEs had high detecting frequencies in both TDSs, which indicated that various foods in Beijing have been universally contaminated with OPEs and mOPEs. Statistical analysis further confirmed that the levels of both ∑OPEs and ∑mOPEs in the 7th Beijing TDS were significantly higher than those in the 6th study, indicating heavier contamination of both OPEs and their metabolites with time. Along with increasing OPE/mOPE contamination level and food consumption values, significant increases of EDIs were observed during the two studies, with the average EDIs of ∑OPEs increasing from 5.07 to 24.1 ng/kg bw/day, and that of ∑mOPEs increasing from 2.07 to 7.23 ng/kg bw/day. Although a comparison between EDIs and reference of doses (RfDs) indicated that current intakes of OPEs could still not cause significant health risks, the sharply increasing contamination levels and EDIs suggested the necessity to continuously monitor these emerging food contaminants.

Organophosphorus flame retardants in infant's diets from Beijing, China: Detection and risk assessment

As a group of widely used flame retardants, organophosphate esters (OPEs) and their metabolites, organophosphate diesters (di-OPEs), have been widely detected in various environmental media and human samples. However, the information on dietary exposure to OPEs for lactating infants is still limited. Here, 38 OPEs and 10 di-OPEs were monitored in 110 infant formula samples and 122 breast milk samples collected in Beijing, China. 20 OPEs (median: 49.9 ng/g, 16.5-160 ng/g) and 6 di-OPEs (median: 20.6 ng/g, 12.4-30.5 ng/g) were detected with frequency above 50% in infant formula, while 5 OPEs (median: 6.66 ng/g, 0.0566-221 ng/g) and 3 di-OPEs (median: 18.8 ng/g, 1.39-591 ng/g) had detection frequency above 50% in breast milk samples. For lactating infants, the total estimated daily intake (EDI) of ∑20OPEs (850 ng/kg bw/day) from infant formula was comparable with that of ∑5OPEs (836 ng/kg bw/day) from breast feeding, while the EDI of ∑6di-OPEs (333 ng/kg bw/day) from infant formula was significantly lower than that of ∑3di-OPEs (2456 ng/kg bw/day) from breast feeding. In summary, the results highlighted the risks of OPEs exposure from breast feeding. Further studies are warranted to evaluate the developmental toxicity of direct exposure to di-OPEs.

Fluorinated liquid-crystal monomers in infant formulas and implication for health risk

Fluorinated liquid-crystal monomers (FLCMs), a new class of potential persistent, bioaccumulative and toxic (PBT) emerging pollutants, are extensively utilized in the display panel of various electronic devices. These compounds have been found in various environmental matrixes and dietary. Our previous studies have documented their ubiquitous occurrence in high fat foodstuffs. Infants, a vulnerable group, are more susceptible to the impacts of these pollutants compared to adults. Herein, we provided an assessment of the health risks posed by FLCMs to infants, focusing on their exposure through infant formula. The presence of FLCMs was detected in all infant formulas, with median concentration of 16.5 ng/g dry weight (dw) and the 95th percentile concentration of 65.7 ng/g dw. The most prevalent pollutant in these formulas was 2-fluoro-4-[4'-propyl-1,1'-bi(cyclohexyl)-4-yl] phenyl trifluoromethyl ether (FPrBP), with median and a 95th percentile concentration of 12.2 ng/g dw and 23.8 ng/g dw, accounting for 55.2% to the total FLCMs. Infants aged 0-6 months had the highest estimated daily intakes (EDIs) of FLCMs, with the EDImedian of 267 ng/kg bw/day. FPrBP and 4-[trans-4-(trans-4-Propylcyclohexyl) cyclohexyl]-1-trifluoromethoxybenzene (PCTB) together made up 83.3% of the total EDIs in median exposure scenario of 0-6 months infant. The highest EDI value was 1.30 × 103 ng/kg bw/day, 77.1% of which was attributed to a combination of FPrBP, 4″-ethyl-2'-fluoro-4-propyl-1,1':4',1″-terphenyl (EFPT), 2-[4'-[difluoro(3,4,5-trifluoro-2-methyl-phenoxy)methyl]-3',5'-difluoro-[1,1'-biphenyl]-4-yl]-5-ethyl-tetrahydro-pyran (DTMPMDP), 4-[Difluoro-(3,4,5-trifluoro-2-methyl-phenoxy)-methyl]-3,5-difluoro-4'-propyl-1,1-biphenyl (DTMPMDB), 2,3-difluoro-1-methyl-4-[(trans, trans)-4'-pentyl[1,1'-bicyclohexyl]-4-yl]benzene (DMPBB) and PCTB. It's worth noting that FLCMs have higher exposure risk. Based on the threshold of toxicological concern (TTC) method, the EDImedian of FPrBP (183 ng/kg bw/day) and FPCB (3.27 ng/kg bw/day) were beyond their TTC values (2.5 ng/kg bw/day) in 0-6 months infant, implying their prospective health risk.

Comprehensive dietary exposure assessment of the Chinese population to organophosphate esters (OPEs): Results of the sixth China total diet study

Organophosphate esters (OPEs) are emerging pollutants, while data on their occurrence in foods and human dietary intake are limited. Based on the 6th China total diet study conducted in 2016-2019, this study implemented a comprehensive survey of OPEs in plant-derived foods of cereals, potatoes, legumes, fruits, vegetables, and further assessed dietary exposure from both plant- and animal-derived food. The sum concentrations of 15 OPEs in the plant-derived samples ranged from 0.567 to 106 ng/g ww. 2-Ethylhexyl diphenyl phosphate (EHDPP) (median: 1.14 ng/g ww) had the highest level in plant-derived foods, with a proportion of 35.6% in the total median OPEs. Regional distribution analysis showed a higher contamination of OPEs in plant-derived food from northern area of China. Estimated dietary intakes (EDIs) of ∑OPEs for Chinese population were from 109 ng/kg bw/day in Beijing to 1164 ng/kg bw/day in Gansu province, with mean and median of 296 and 222 ng/kg bw/day, respectively. Although animal-derived foods had higher levels of OPEs, plant-derived foods, specifically cereals, was the major source of dietary OPE intake. The EDIs were much lower than reference doses, which suggested the intakes of OPEs via food consumption could not cause significant health risks to the Chinese population at present.

Single injection by LC-ESI-MS/MS for simultaneous determination of organophosphate tri- and di-esters in plant tissue based on ultrasonic-assisted sequential extraction and single-step purification

A novel methodology based on ultrasonic-assisted sequential extraction, dispersive-SPE purification, and single-injection on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is proposed, for the first time, to simultaneously measure 14 tri-OPEs and 9 di-OPEs in plant tissues. The samples were successively ultrasonicated with a mixture of hexane:dichloromethane (1:1, v/v) and 8% acetic acid in acetonitrile for extracting tri- and di-OPEs purified with graphitized carbon black and quantitated on LC-MS/MS at the same time. The recoveries of targeted tri- and di-OPEs in the matrix spike ranged from 66% to 120% and 71% to 110% respectively. The proposed method was validated by processing eight types of common vegetables including spinach (Spinacia oleracea L.), lettuce (Lactuca sativa), carrot (Daucus carota var. sativa Hoffm.), sweet potato (Solanum tuberosum L.), cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), green beans (Phaseolus vulgaris), and cowpeas (Vigna unguiculata), with the recoveries of surrogates ranging from 84% to 98%.

Critical review on organophosphate esters in water environment: Occurrence, health hazards and removal technologies

Organophosphate esters (OPEs), which are phosphoric acid ester derivatives, are anthropogenic substances that are widely used in commerce. Nevertheless, there is growing public concern about these ubiquitous contaminants, which are frequently detected in contaminated water sources. OPEs are mostly emitted by industrial operations, and the primary routes of human exposure to OPEs include food intake and dermal absorption. Because of their negative effects on both human health and the environment, it is clear that innovative methods are needed to facilitate their eradication. In this study, we present a comprehensive overview of the existing characteristics and origins of OPEs, their possible impacts on human health, and the merits, drawbacks, and future possibilities of contemporary sophisticated remediation methods. Current advanced remediation approaches for OPEs include adsorption, degradation (advanced oxidation, advanced reduction, and redox technology), membrane filtration, and municipal wastewater treatment plants, degradation and adsorption are the most promising removal technologies. Meanwhile, we proposed potential areas for future research (appropriate management approaches, exploring the combination treatment process, economic factors, and potential for secondary pollution). Collectively, this work gives a comprehensive understanding of OPEs, providing useful insights for future research on OPEs pollution.

Spatial and temporal variability and risk assessment of organophosphate esters in seawater and sediments of the Yangtze River estuary

Organophosphate esters (OPEs) as substitutes for PBDEs have been widely detected in the marine environment, while little is known about the pollution characteristics and variation of OPEs in estuarine environments with complex hydrodynamic conditions and land-based input. Yangtze River Estuary (YRE) is a typical highly urbanized and industrialized estuary, with a complex hydrological environment and geochemical behavior. This study found that the concentrations of OPEs in both seawater and sediments in the YRE were higher in spring than in summer. Alkyl OPEs were the first contributor, with TnBP and TiBP as the main components, where the contribution of alkyl OPEs had exceeded 75 % in both seawater and sediments in spring, and 60 % in summer seawater, and even 80 % in sediments. In spring, OPEs peaked in the central to southern region near the YRE. In summer, OPEs were mainly concentrated in the southern branch waterway and southern nearshore area of the YRE and showed a decreasing trend to the northeast. The OPEs in the sediments were mainly concentrated in the Yangtze River Mud Area (YREMA) and the Zhe-Min Coastal Mud Area (ZMCMA). Based on the fugacity model and principal component analysis, sediments could be released into the aquatic environment as an endogenous source, and exogenous sources were mainly municipal and industrial sewage discharge sources, urban and marine traffic discharge sources, and atmospheric deposition sources. The ecological risk analysis showed that the Σ14OPEs had exhibited a low to moderate ecological risk in the southern branch waterway and the south-central region offshore.

Establishment of an Integrated Nontarget and Suspect Screening Workflow for Organophosphate Diesters (Di-OPEs) and Identification of Seven Previously Unknown Di-OPEs in Food Contact Plastics

In this study, an innovative, integrated nontarget and suspect screening workflow was developed for identifying organophosphate diesters (di-OPEs) using high-resolution mass spectrometry. The workflow featured the utilization of 0.02% acetic acid as a mobile-phase additive, differentiated screening methods for alkyl and aryl di-OPEs, and a combination of electrospray negative ionization and positive ionization. Using this workflow, 18 di-OPEs were identified in the extracts of 75 food contact plastic (FCP) samples sourced from South China. Among these, six alkyl and one aryl di-OPEs were previously unknown (one unequivocal identification and six probable structures based on diagnostic evidence). (Semi)quantification revealed that bis(2,4-di-tert-butylphenyl) phosphate was the major di-OPE in FCPs, with a median concentration of 1079 ng/g (range: 23.4-158,414 ng/g). The migration efficiencies of di-OPEs from an FCP sample to four kinds of food simulants were between 2.58 and 54.3%. This study offered a useful workflow for the comprehensive profiling of di-OPEs in FCPs.

A modified QuEChERS method for determination of organophosphate esters in milk by GC-MS

Organophosphate esters (OPEs) are substances that have been detected in several matrices due to their use as flame retardants and plasticizers. Human exposure to OPEs can cause endocrine disruption, hormonal problems, and reproductive disturbance. Ingestion of contaminated food can be a significant route of exposure to OPEs. Food can be contaminated by OPEs in the food chain, during cultivation, and by contact with plasticizers during the production chain of processed foods. In this study, a method for the determination of 10 OPEs in commercial bovine milk was developed. The procedure was based on QuEChERS extraction and gas chromatography coupled to mass spectrometry (GC-MS) analysis. QuEChERS modification included a freezing-out step after the extraction followed by the concentration of the entire acetonitrile phase before the clean-up step. Calibration linearity, matrix effects, recovery, and precision were evaluated. Significant matrix effects were observed, which could be compensated by the isotopically labeled internal standard quantification and matrix-matched calibration curves. Recoveries ranged from 77 to 105%, with a relative standard deviation ranging from 3 to 38%. The method detection limits (MDLs) were in the range of 0.031-6.7 ng mL^-1, while the method quantification limits (MQLs) were within the range from 0.27 to 20 ng mL^-1. The proposed method was successfully validated and applied to determine the concentrations of OPEs in bovine milk. The 2-ethylhexyl diphenyl phosphate (EHDPHP) was detected in the analyzed milk samples but at levels below the MQL.

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.

Organophosphate esters in Chinese rice: Occurrence, distribution, and human exposure risks

Dietary intake is a crucial pathway of organophosphate esters (OPEs) exposure for human. However, information about the exposure risk of OPEs via rice consumption is still largely unknown. In the present study, a total of 234 rice samples from 25 provinces or city of China were collected and the concentrations of 24 OPEs were determined. Sixteen OPEs were detected in these rice samples and each rice sample was contaminated with at least 5 OPEs, indicating a ubiquitous occurrence of OPEs in Chinese rice. Moreover, the concentrations of Σ16 OPEs ranged from 1.46 to 552.65 μg/kg dry weight (dw), with a mean value of 64.74 μg/kg dw. For the composition profile of OPEs, three Cl-OPEs, including tris(2-chloroethyl) phosphate (TCEP), tri(2-chloroisopropyl) phosphate (TCIPP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), accounted for the highest proportion of Σ16 OPEs. For the spatial distribution of OPEs, although obvious spatial variations were observed among the 25 provinces or city, no obvious variations were found among the six rice-cultivating regions of China. Additionally, estimated dietary intakes (EDI) values of the 16 OPEs for adults and children were 1105.24 and 1399.13 ng/kg bw/day, respectively, under the high intake scenario. The hazard indexes of the 10 OPEs were 0.108 and 0.137 for adults and children, respectively. The risk assessment results indicated that Chinese adults and children did not suffer significant adverse effects from OPEs via rice intake.

A global survey of organophosphate esters and their metabolites in milk: Occurrence and dietary intake via milk consumption

The first global survey of organophosphate esters (OPEs) and their metabolites (mOPEs) in milk was carried out in this study. Concentrations of 21 OPEs and 9 mOPEs were measured in 178 milk samples collected from 30 countries located on 5 continents, and the ubiquity of both OPEs and mOPEs was observed in milk. Concentrations of ∑₂₁OPEs ranged from 53.3 pg/mL to 4270 pg/mL, with a median level of 367 pg/mL. The median level of ∑₉mOPEs was 153 pg/mL, with a range of 15-7440 pg/mL. No difference was observed among the levels of both ∑₂₁OPEs and ∑₉mOPEs in milk from the five continents. For the relationship between mOPEs and their parent OPEs, some pairs presented significant and positive correlations, which indicated that they shared similar sources. Estimated daily intakes (EDIs) of OPEs/mOPEs via milk consumption were calculated. Asian countries presented relatively low EDIs, and European and American countries, especially Denmark, the Netherlands, Finland and Argentina, presented high EDIs. Current daily OPE intake via milk consumption for global adult populations was far lower than the corresponding reference dose; however, considering that human intake of OPEs occurs via multiple sources, it is too early to conclude that the intake of OPEs were unable to cause health concerns.