Concentrations and Dietary Exposure to Organophosphate Esters in

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Concentrations and Dietary Exposure to Organophosphate Esters in Foodstuffs from Albany, New York, United States Yu Wang, and Kurunthachalam Kannan J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b06114 • Publication Date (Web): 10 Dec 2018 Downloaded from http://pubs.acs.org on December 13, 2018

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Journal of Agricultural and Food Chemistry

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Concentrations and Dietary Exposure to Organophosphate Esters in

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Foodstuffs from Albany, New York, United States

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Yu Wang,a, b and Kurunthachalam Kannana, c, *

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aWadsworth

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States

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bMOE

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Center, New York State Department of Health, Albany, New York 12201, United

Key Laboratory of Pollution Processes and Environmental Criteria, College of

Environmental Science and Engineering, Nankai University, Tianjin 300350, China cDepartment

of Environmental Health Sciences, School of Public Health, State University of

New York at Albany, Albany, New York 12201, United States

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Corresponding Author:

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*Wadsworth Center, Empire State Plaza, P.O. Box 509, Albany, New York 12201, United States.

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Tel.: +1 518 474 0015; fax: +1 518 473 2895. E-mail: [email protected] (K.

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Kannan).

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For submission to: Journal of Agricultural and Food Chemistry

1 ACS Paragon Plus Environment


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TOC

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ABSTRACT

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Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, but little is

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known about their occurrence in foodstuffs, an important source of human exposure. In this study,

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15 OPEs were measured in foodstuffs and food-packing materials collected from local markets in

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Albany, New York, United States, for the first time. Among the foodstuffs analyzed, median

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concentrations of ∑OPEs (sum of 15 OPEs) in meat (6.76 ng/g wet weight; ww) and fish/seafood

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(7.11 ng/g ww) were higher than those in other food categories. ∑OPEs were found in food

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packaging at a median concentration of 132 ng/g. The estimated daily dietary intakes (EDIs) of

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OPE were of 37.9, 135, 56.6, 32.2, and 25.1 ng/kg body weight (bw)/day for infants, toddlers,

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children, teenagers, and adults, respectively. Meat was a major source (47%) of dietary OPEs

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exposure in adults, whereas dairy products accounted for 52% of OPE exposures in toddlers.

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Keywords: organophosphate esters, foodstuffs, occurrence, dietary exposure

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INTRODUCTION

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Organophosphate esters (OPEs) have been widely used in many commercial products, including

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electronics, plastics, paints, furniture, and building materials since the 1970s due to their flame

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retardation and plasticization properties.1, 2 OPEs are deemed as suitable substitutes for brominated

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flame retardants (BFRs), which are restricted in use and are being phased out gradually. The global

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production of OPEs in 2015 was estimated at 680,000 metric tons and has been increasing

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gradually.3 A few recent studies have reported carcinogenic and neurotoxic potentials of

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chlorinated OPEs and tris(2-butoxyethyl) phosphate (TBOEP),3, 4 and exposure to OPEs has been

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linked to reproductive effects in humans.5 Further, OPEs have been found to be ubiquitous in

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various environmental matrices, such as outdoor air,6-8 indoor air,9, 10 indoor dust,11-13 water,14-16

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sediment,17, 18 soil,19 and biota.20-22

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The widespread occurrence of OPEs in the environment can instigate food chain transfer,23, 24

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resulting in contamination of foodstuffs. Further, OPEs are used as plasticizers in many products

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that are used in food treatment processes and packaging.25 Information on the occurrence of OPEs

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in foodstuffs, however, is limited. A few studies have reported the occurrence of OPEs at median

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total concentrations (∑OPE) of 0.1–50 ng/g in meat, fish, cereals, dairy products, fruits, and

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vegetables from Sweden, Belgium, China, Philippines, and Canada.26-30 A high concentration of

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∑OPE was found in rice (7.59–55.9 ng/g) from China28 and in cereal products (4.1–9.8 ng/g) from

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China and Sweden.26, 27 The occurrence of OPEs in foodstuffs produces human dietary exposure

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to these chemicals, which is a public concern. The estimated daily dietary intakes (EDIs) of ∑OPE

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were 5–600 ng/kg body weight (bw)/day through various foods for the general population in

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China,26, 28 and Belgium.27 An estimated daily intake (EDI) of 5.9 ng/kg bw/day was calculated


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through fish consumption in the Philippines.31 Further, studies have shown that exposure dose of

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OPEs through food ingestion is comparable to that of dust ingestion11, 32, 33 and air inhalation.34, 35

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The migration of plastic additives, such as bisphenol A, and phthalates from food packaging

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and plastic containers into foodstuffs36-39 and the consequential human dietary exposure40, 41 have

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been well documented. The migration of OPEs, which also are used as additive plasticizers, from

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paper and plastic packaging into various food items, is predicted. The measurement of OPE

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concentrations and profiles in food packaging is important to understanding the magnitude and

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sources of contamination in foods. Information on the occurrence of OPEs in foodstuffs, food

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packaging, and dietary exposure in the United States (US), however, is still unknown.

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In this study, 15 OPEs were measured in a wide range of foodstuffs and food packaging

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collected from local markets in the US, with the objectives of investigating occurrence in

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foodstuffs and food packaging materials and assessing human dietary exposures. To the best of

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our knowledge, this is the first study on the concentrations and profiles of OPEs as well as human

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dietary exposure to OPEs in the US.

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MATERIALS AND METHODS

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Sample Collection. A total of 106 food items and 18 food packaging samples were randomly

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collected from several food markets in Albany, New York, US, during August and September

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2018. Food samples were stratified into five categories: meat (beef, chicken, pork, and turkey);

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fish/seafood; dairy products (butter, cheese, milk, and yogurt); cereal products (bread, cereal, flour,

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pasta, and rice); and cooking oil. The food packaging was classified into plastic and paper materials.

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Further details of the food samples analyzed are presented in the Supplementary Information (SI)

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Table S1. All samples were stored frozen (-20° C) until analysis.



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Chemicals and Reagents. Triethyl phosphate (TEP), tripropyl phosphate (TPP), tri-n-butyl

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phosphate (TNBP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-ethylhexyl) phosphate (TEHP),

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tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), tris(1,3-

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dichloro-2-propyl) phosphate (TDCIPP), triphenyl phosphate (TPHP), trimethylphenyl phosphate

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(TMPP), cresyl diphenyl phosphate (CDPP), and isodecyl diphenyl phosphate (IDDP) were

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purchased from AccuStandard (New Haven, CT, US). Trimethyl phosphate (TMP), tri-iso-butyl

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phosphate (TIBP) and 2-ethylhexyl diphenyl phosphate (EHDPP) were purchased from Sigma-

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Aldrich (St. Louis, MO, US). Nine deuterated compounds were used as internal standards. TPP-

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d21, TNBP-d27, TCEP-d12, TCIPP-d18, TDCIPP-d15, and TPHP-d15 were purchased from

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Cambridge Isotope Laboratories (Tewksbury, MA, US). TMP-d9 and TEHP-d51 were purchased

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from Toronto Research Chemicals (North York, ON, Canada), and TEP-d15 was purchased from

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Sigma-Aldrich. High-performance liquid chromatography (HPLC)-grade water, formic acid

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(88%), acetic acid (glacial, 99.7%), and HPLC-grade acetonitrile were purchased from J. T. Baker

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(Center Valley, PA, US), and HPLC-grade methanol was purchased from Fisher Scientific (Fair

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Lawn, NJ, US). Anhydrous magnesium sulfate (MgSO4) was purchased from Sigma-Aldrich, and

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a dispersive solid-phase extraction (d-SPE) tube that contained 150 mg MgSO4, 50 mg primary

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secondary amine (PSA), and 50 mg C18 was purchased from RESTEK (Bellefonte, PA, US). An

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Oasis HLB cartridge (60 mg, 3 cm3) was purchased from Waters (Milford, MA, US). All standard

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stock solutions were prepared in HPLC-grade acetonitrile and stored at -20° C. The

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physicochemical properties of target analytes are presented in the SI (Table S2).

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Sample Preparation. The method for the extraction of OPEs from foods has been described in

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a previous study.26 For the analysis of dairy products (milk, yogurt), cereal products, and cooking

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oil, 1.0 g of the homogenized sample was transferred into a polypropylene (PP) tube (precleaned


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with methanol) and fortified with 5 ng (of each target analyte) of an internal standard mixture.

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After the addition of 5 mL 0.5% formic acid in acetonitrile (ACN), the sample was shaken in an

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orbital shaker (2 h), followed by ultrasonication (30 min). Then 500 mg of MgSO4 was added into

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the tube and vortexed for 1 min for the removal of water. The sample was then centrifuged at 3,500

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g for 10 min. The supernatant was carefully transferred into a precleaned PP tube, followed by

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transfer of d-SPE sorbents, comprising150 mg MgSO4, 50 mg PSA, and 50 mg C18. The tube was

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vortexed for 1 min and then centrifuged at 3,500 g for 5 min. The supernatant was collected and

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evaporated to near dryness under a gentle stream of nitrogen and reconstituted in a 200-µL

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water/methanol mixture (4/6; v/v) prior to HPLC-tandem mass spectrometry (MS/MS) analysis.

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For the analysis of meat, fish/seafood, and dairy products (butter and cheese), 1.0 g of the

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homogenized sample was transferred into a precleaned PP tube and fortified with 5 ng each of the

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internal standard mixture. The sample was extracted with 5 mL of 0.5% formic acid in ACN by

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shaking in an orbital shaker (2 h) and ultrasonication (30 min). After centrifugation (3,500 g; 10

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min), the supernatant was carefully transferred into a precleaned PP tube. Then d-SPE sorbents,

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comprising 150 mg MgSO4, 50 mg PSA, and 50 mg C18, were added. The tube was vortexed for

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1 min and then centrifuged at 3,500 g for 5 min. The supernatant was collected and then purified

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by passage through Oasis HLB cartridges (60 mg, 3 cm3). The cartridges were preconditioned with

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2.5 mL of ACN, loaded with the sample extract (Fraction 1), and then eluted with 1.5 mL of ACN

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(Fraction 2). The purified extracts (Fractions 1 and 2) were evaporated to near dryness and

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reconstituted with 200 µL of a water/methanol mixture (4/6; v/v) prior to analysis using HPLC-

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MS/MS.

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For the analysis of food packaging, 0.2 g of the material was cut into small pieces, transferred

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into a precleaned PP tube, and spiked with the internal standard mixture (5 ng each). After



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extraction with 5 mL of 0.5% formic acid in ACN by shaking mechanically for 12 h and

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ultrasonication for 1 h, the extract was centrifuged at 3,500 g for 10 min. The supernatant was

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carefully transferred into a precleaned PP tube. Extraction was repeated twice, and the combined

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extracts were purified by passage through Oasis HLB cartridges, as described above. Purified

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extracts were evaporated to near dryness and reconstituted with 200 µL of the water/methanol

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mixture (4/6; v/v) prior to instrumental analysis.

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Instrumental Analysis. Quantitative analysis of target OPEs in foods and food packages was

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performed by HPLC (Agilent 1100 series; Agilent Technologies, Santa Clara, CA), coupled with

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an electrospray triple quadrupole mass spectrometry system (API 2000; Applied Biosystems,

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Foster City, CA) in electrospray positive ionization with multiple reaction monitoring mode. A

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Betasil C18 column (100 mm × 2.1 mm, 5 μm; Thermo, Waltham, MA), connected to a Betasil C18

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guard column (20 mm × 2.1 mm, 5 μm; Thermo), was used for the chromatographic separation of

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chemicals. The mobile phase, comprising HPLC-grade water with 0.1% acetic acid (v/v) (A) and

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methanol with 0.1% acetic acid (v/v) (B), was used at a flow rate of 200 μL/min. The initial mobile

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phase flow was set at 40% A and held for 2 min, then decreased linearly to 1% in 5.5 min and held

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for 9.5 min, then reverted to 40% A in 0.5 min, and held for 7.5 min for column equilibration. The

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MS/MS transitions of all target chemicals are presented in the SI (Table S3).

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Quality Assurance (QA) and Quality Control (QC). Quantification of target analytes was

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performed, using a calibration curve that ranged in concentrations from 0.05 to 100 ng/mL

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(regression coefficients > 0.99). The instrumental limits of quantitation (LOQs) were set at a

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signal-to-noise ratio of 10 at the lowest point of the calibration standard (Table S4). Trace levels

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of TNBP (0.08 ng/g ww), TIBP (0.07 ng/g ww), and TBOEP (0.06 ng/g ww) were found in

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procedural blanks. The concentrations were reported after subtraction from the procedural blank


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values. The method detection limits (MDLs) of OPEs were in the range of 0.01–0.17 ng/g ww,

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which were calculated from LOQs, procedure blank values, sample concentration factor, and

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sample mass used for extraction (Table S4). The average recoveries of internal standards (spiked

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5 ng each) were 57.1±5.1–85.6±7.8%, and the average recoveries of OPEs spiked into foodstuffs

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and packaging materials (5 ng each) were in the range of 64.9±6.7–120±10.9% for meat, 63.3±7.0–

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121±11.3% for fish/seafood, 51.2±4.9–117±14.6% for dairy products, 57.0±9.1–137±14.0% for

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cereal products, 56.0±6.6–128±12.0% for cooking oil, and 62.4±6.2–117±12.1% for packaging

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materials (Table S5). A midpoint calibration standard and a pure solvent (methanol) were injected

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after every 20 sample injections to monitor for the drift in instrumental response. Detailed QA/QC

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data are presented in the SI (Tables S4 and S5).

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Data Analysis. Concentrations of OPEs below the MDLs were assigned a value at 1/2 MDLs.

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OPE compounds with detection frequencies (DFs) below 20% were not included in the statistical

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analysis. The Spearman rank correlation analysis and one-way ANOVA (to test differences in

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concentrations between food categories) were conducted using SPSS software (version 22.0, SPSS

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Inc., Armonk, NY). All data are presented on a wet weight (ww) basis.

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Daily dietary intakes of OPEs were calculated for different age groups of the general

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population.40 The total intakes of OPEs were calculated by summing the intakes from all food

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categories, as shown in equation 1:

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𝐸𝐷𝐼 =

∑𝐶 × 𝐹𝐼𝑅 𝑖

𝑖

(1)

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where EDI (ng/kg bw/day) is the estimated daily dietary intake, Ci (ng/g ww) is the OPE

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concentration measured in food samples (median and 95th percentile values were used to represent

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average- and high-exposure scenarios, respectively), and FIRi (g/kg bw/day) is the daily food



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ingestion rate. The FIRi values for various age groups (Table S6) have been suggested in the US

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Environmental Protection Agency’s (EPA) Exposure Factors Handbook 2011.42

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The exposure risks of OPEs were estimated as hazard quotients (HQ) as shown in equation 2:43 𝐸𝐷𝐼 𝑅𝑓𝐷

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𝐻𝑄 =

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where RfD is the reference dose of OPE (ng/kg bw/d), described in a previous study and by the US

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EPA.43, 44 The potential risk is considerable when HQ value is ≥ 1. The hazard index (HI) was

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calculated by summing HQs of several OPEs.

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RESULTS AND DISCUSSION

(2)

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Concentrations of OPEs in Foodstuffs. DFs of 15 OPEs were generally low in all food

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categories (Table 1). Only TNBP, TIBP, TBOEP, and TCIPP were found in over 50% of the food

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samples analyzed, whereas other OPEs were detected in

Concentrations and Dietary Exposure to Organophosphate Esters in

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