Occurrence and Distribution of Organophosphate Flame Retardants

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Characterization of Natural and Affected Environments

Occurrence and Distribution of Organophosphate Flame Retardants/Plasticizers in Surface Waters, Tap Water, and Rainwater – Implications for Human Exposure Un-JUng Kim, and Kurunthachalam Kannan Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b00727 • Publication Date (Web): 16 Apr 2018 Downloaded from http://pubs.acs.org on April 19, 2018

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Environmental Science & Technology

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Occurrence and Distribution of Organophosphate

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Flame Retardants/Plasticizers in Surface Waters,

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Tap Water, and Rainwater – Implications for Human

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Exposure

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Un-Jung Kima and Kurunthachalam Kannana,b*

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a

Wadsworth Center, New York State Department of Health, and Department of Environmental

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Health Sciences, School of Public Health, State University of New York at Albany, Empire

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State Plaza, P.O. Box 509, Albany, New York 12201-0509, United States

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b

Biochemistry Department, Faculty of Science and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia

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*Corresponding author: [email protected]

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For submission to: ES&T

1 Environment ACS Paragon Plus


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ABSTRACT

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The occurrence and profiles of 14 triester organophosphate flame retardants (OPFRs) and

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plasticizers were investigated in surface water, tap water, rainwater, and seawater collected from

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New York State. In total, 150 samples collected from rivers (n = 35), lakes (n = 39), tap water (n

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= 58), precipitation/rainwater (n = 15) and seawater (n = 3) were analyzed for 14

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organophosphate esters (OPEs). An additional nine Hudson River water samples were collected

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periodically to delineate seasonal trends in OPE levels. The total concentrations of OPEs were

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found at part-per-trillion ranges, with average concentrations that ranged from 0.01 ng/L for

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tripropyl phosphate (TPP) in river water to 689 ng/L for tris(2-butoxyethyl)phosphate (TBOEP)

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in lake water. Tris(1-chloro-2-propyl)phosphate (TCIPP) was the most abundant compound

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among the investigated OPEs in all types of water. The concentrations of OPEs in river-, lake-,

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and rainwater were similar, but >3 times higher than those found in tap water. Chlorinated alkyl

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OPFRs accounted for a major proportion of total concentrations. TCIPP, TBOEP, and triethyl

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phosphate (TEP) were found in >90% of the samples analyzed. Wet deposition fluxes for 14

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OPFRs were estimated, based on the concentrations measured in rainwater in Albany, New

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York, and the values were between 440 and 5250 ng/m2. Among several surface water bodies

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analyzed, samples from the Hudson River and Onondaga Lake contained elevated concentrations

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of OPEs. Estimated daily intake of OPEs via the ingestion of drinking water was up to 9.65

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ng/kg body weight/day.

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INTRODUCTION

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Although organophosphate esters (OPEs) have been used for more than 150 years, these

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chemicals have received considerable attention in recent years due to their increasing usage as


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flame retardants in consumer products.1,2 OPEs are currently used as flame retardants/plasticizers

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in consumer products, as anti-foaming agents in industrial processes, and as additives in paints,

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glues, lubricants, lacquers, and floor polishes.2,3 Although OPEs are generally considered to be

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less persistent than are halogenated flame retardants, they have been reported to occur in the

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environment.2,4 Based on their chemical structures and functions, OPEs are categorized as

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chlorinated alkyl-, non-chlorinated alkyl-, aryl-, and “other phosphates.” Chlorinated alkyl

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phosphates

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propyl)phosphate (TCIPP), and tris(2-chloroethyl)phosphate (TCEP), which are reported to be

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toxic and carcinogenic.5-7 TCEP, triphenyl phosphate (TPhP), and tributyl phosphate (TnBP)

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have been reported to be neurotoxic.5,8-10 TPhP and TnBP are bioaccumulative and have been

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found in the tissues of fish and birds.11-13

include

tris(1,3-dichloro-2-propyl)phosphate

(TDCIPP),

tris(1-chloro-2-

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Organophosphate flame retardants (OPFRs) are not chemically bound to polymeric substrates

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and, therefore, can leach into the surrounding environment.6,14,15 In addition, TCEP, TCIPP, and

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tris(2-butoxyethyl)phosphate (TBOEP) are semi-volatile compounds and possess moderate to

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high water solubility (TCEP = 7.0×103 mg/L, TCIPP = 1.6×103 mg/L, TBOEP = 1.2×103

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mg/L).2,16-18 Due to their water solubility, these chemicals were expected to occur in aquatic

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environments at concentrations higher than those of halogenated flame retardants, which have

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much lower water solubility.13,19 OPFRs and related plasticizers can enter into the aquatic

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environment through various pathways, including the discharge of wastewater and/or

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atmospheric deposition.2,20-22

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Studies have reported the occurrence of OPFRs in indoor air, house dust, and surface

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waters.2,22 In comparison with studies of other regions across the globe, only a few studies have

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reported the occurrence of chlorinated-alkyl OPEs in surface water and/or drinking water in the



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USA.23-26 Only one study reported the occurrence of OPEs in the Great Lakes water,26 and other

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studies from the USA focused mostly on chlorinated-alkyl OPEs.23-25 Thus far, no

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comprehensive monitoring surveys that cover a wide range of surface waters and other aquatic

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matrices, including rainwater, drinking water, and seawater, are available. Studies on the

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occurrence, spatial distribution, and congener profiles of OPFRs and related plasticizers in

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aquatic media are essential to elucidate sources and to assess potential health risks.

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Our recent study showed that OPEs were not completely removed in wastewater treatment

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processes.27 Therefore, the release of OPEs into surface waters is a potential source for these

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chemicals in drinking water. In this study, therefore, we determined 14 OPFRs/plasticizers in

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various types of water samples, including surface water from lakes and rivers, drinking (tap)

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water, rainwater, and seawater collected from various locations in New York State. The

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distribution profile and seasonal variation in concentrations of OPEs in waters were examined.

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Based on the concentration of OPEs measured in rainwater from Albany, New York, fluxes of

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OPEs through wet deposition were calculated. Human exposure to OPEs through drinking water

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ingestion was estimated. This is the first study to describe the occurrence, distribution profile,

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and human exposure to 14 OPFR/plasticizer triesters from various types of water in the USA.

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MATERIALS AND METHODS

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Chemicals and Reagents.

TPhP, TnBP, TBOEP, TCEP, TCIPP, TDCIPP,

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tris(methylphenyl) phosphate (known as tricresyl phosphate, or TMPP), triethyl phosphate

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(TEP),

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ethylhexyl)phosphate (TEHP), and p,p’-1,3-phenylene p,p,p’,p’-tetraphenyl ester phosphate (also

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known as resorcinol bis(diphenyl phosphate), or PBDPP) were purchased from AccuStandard

tripropyl

phosphate

(TPP),

tris(2,3-dibromopropyl)phosphate


(TDBPP),

tris(2-

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(New Haven, CT, USA). Tri-isobutyl phosphate (TiBP) and 2-ethylhexyl diphenyl phosphate

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(EHDPP) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Eight deuterated OPEs

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were used as internal standards. Of these, TnBP-d27, TPP-d21, TCEP-d12, TCIPP-d18, TDCIPP-d15,

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and TPhP-d15 were purchased from Cambridge Isotope Laboratories (Tewksbury, MA, USA),

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and TEHP-d51 and TEP-d15 were purchased from Toronto Research Chemicals (North York, ON,

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Canada) and Sigma-Aldrich, respectively. All standard solutions were prepared in HPLC grade

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acetonitrile or dissolved in a mixture of acetonitrile:methanol (1:1 v/v).

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Sampling. In total, 159 water samples, comprising 35 river water, 39 lake water, 15

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rainwater, 3 seawater, and 58 tap water samples, were collected from various locations in New

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York State. In addition, 9 Hudson River water samples were collected from June 2016 to

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September 2017 at monthly intervals in Albany, New York, to examine seasonal trends in the

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concentrations of OPEs. The surface river water samples were collected from the Hudson,

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Hoosic, and Mohawk Rivers and various creeks in New York State (see SI 1, Supporting

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Information, for specific details of sampling locations). Lake water samples were collected from

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Lake Ontario, Lake Erie, Lake Champlain, Finger Lakes, Onondaga Lake, and Oneida Lake as

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well as from ponds and water reservoirs in New York State. Water samples were collected in

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solvent-cleaned amber glass bottles (2-4 L) that were rinsed twice with water from the sampling

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site prior to collecting water. Rainwater samples were collected in Albany, New York, by

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deploying a wide-mouth funnel placed on top of an amber glass bottle during eight different rain

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events from April to August 2017. Surface water samples were collected from a fixed location on

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the Hudson River in Albany between June 2016 and September 2017 to monitor seasonal trends

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in OPE concentrations. Tap water samples were collected from drinking water fountains and

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faucets from individual homes and public areas after opening the tap for more than one minute.



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The tap water samples originated in 16 different counties in New York State, including Albany

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and New York City. All samples were collected in pre-cleaned amber glass bottles, shipped to

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the laboratory, and kept in a refrigerator (4º C) until analysis. Sample extraction was performed

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as quickly as possible, and samples were not held for more than 60 days. Further details of

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samples and sampling locations have been described in the supporting information (SI 1).

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Sample Extraction. Water samples were mixed thoroughly, and 300 mL was taken for

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extraction by a solid-phase extraction (SPE) method with Oasis HLB cartridges (60 mg, 3cc;

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Waters, Milford, MA, USA), as described earlier.27 All water samples were not filtered and

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reported for whole water concentrations of OPEs (i.e., both dissolved and particulate phase). In

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brief, HLB cartridges were conditioned with 5 mL of methanol (MeOH), and 5 mL of HPLC

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grade water. Water samples were spiked with 20 µL of the internal standard mixture (eight

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deuterated OPE mixture at 500 ng/mL) and loaded onto the cartridge at a rate of 2 mL/min, dried

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under a vacuum for 20 min, and eluted each time with 3 mL MeOH thrice. The eluent was

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evaporated under a gentle nitrogen stream at 37º C to 0.5 mL and micro-centrifuged (0.2 µm

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nylon filter, Spin-X, Costar, Corning Inc., Corning, NY, USA) prior to analysis by

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HPLC/MS/MS. Prior to extraction, polypropylene (PP) tubes, SPE vacuum manifold, and all

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other materials that come into contact with samples were rinsed with hexane, acetone, MeOH,

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acetonitrile, and HPLC grade water in sequence to remove any potential background

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contamination of OPEs.

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Instrumental Analysis.

The extracts were analyzed by high-performance liquid

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chromatography (Agilent 1100 series HPLC; Agilent Technologies, Santa Clara, CA, USA)

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coupled with electrospray triple quadrupole mass spectrometry (API 2000, ESI-MS/MS; Applied

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Biosystems, Foster City, CA, USA). The chromatographic separation of 14 triester OPEs and 8


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deuterated compounds was accomplished by a Luna C18 column (150 mm × 4.6 mm, 3 µm;

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Phenomenex, Torrance, CA, USA), serially connected to a Betasil C18 guard column (20 mm ×

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2.1 mm, 5 µm; Thermo, Waltham, MA, USA). The mobile phase consisted of methanol and

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HPLC grade water (1:9) with 0.15% formic acid (A) and methanol with 0.2% formic acid (B).

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Electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM) modes were

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used for the identification and quantification of target OPEs. Detailed information of the

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analytical method is described elsewhere.27

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Quality Assurance/Quality Control. An 11-point calibration standard, encompassing

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concentrations that ranged from 0.1 to 400 ng/mL, was used in the calculation of OPE

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concentrations in samples. The regression coefficients of the quadratic calibration curves were

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>0.997. Internal standards (mixture of eight deuterated OPEs) were spiked into each calibration

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standard and sample to yield a final concentration of 20 ng/mL. The limits of quantitation

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(LOQs) were set at a signal-to-noise ratio of 10 in sample extracts and were determined to be

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0.2–1 ng/L. Procedural blank, field blank, travel blank, laboratory blank, duplicate, and matrix

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spike samples were analyzed (SI 2). To avoid potential degradation of OPEs during sample

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storage, samples were extracted as soon as possible. In addition, randomly chosen water samples

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(n = 2 per sample type) were extracted at a monthly interval to confirm that there was no

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degradation/loss during storage of samples (target chemical concentrations varied by 100 ng/L were found in small lakes located within

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parks in Albany and Long Island. TBOEP (Fig. 3-E) was the predominant compound at points

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located between the mid-Hudson River and New York City. Wastewater discharge can be a

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major source of OPEs in the Hudson River (SI 4).27,38,47

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Seasonal Variation in OPEs in the Hudson River. Seasonal variation in OPE concentrations

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was examined in water samples collected from a location along the Hudson River in Albany,

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New York. During the 14-month sampling campaign that covered all four seasons, the observed

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concentration profile of total OPEs was compared with the monthly mean atmospheric

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temperature (Fig. 4). Although no significant seasonal trend in individual OPE concentrations

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could be discerned in surface river water (Fig. S2), higher concentrations of ∑14OPEs were

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found in warmer seasons than colder seasons. This may be related to the temperature-dependent

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emission of OPEs from consumer products and building materials.15,21 Short chain alkylated

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OPEs can evaporate easily with an increase in atmospheric temperature. Seasonal variation in


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OPE levels in river water from the Elbe has been reported.30 Nevertheless, the most abundant

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OPEs found in the Hudson River (TBOEP, TDCIPP, and TPhP) have low vapor pressure

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(TBOEP: 2.1×10-7 mm Hg, TDCIPP: 7.4×10-8 mm Hg, TPhP: 1.2×10-6 mm Hg) and high water

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solubility.2

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Human Exposure to OPEs Through Water. The EDI of OPEs was calculated based on

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normal- and high-exposure scenarios (see Supporting Information, Fig. S3, for details). Under

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the normal-exposure scenario, the EDI of ∑14OPEs ranged between 0.22 ng/kg-bw/day and 1.25

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ng/kg-bw/day. Under the high-exposure scenario, the EDI of ∑14OPEs ranged between 1.17

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ng/kg-bw-day and 9.65 ng/kg-bw/day. Among various age groups, newborns were the highly

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exposed group. Among 14 OPEs, >50% of the total EDIs were contributed by TCIPP and

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TBOEP. The indirect water ingestion during swimming can contribute to a total OPE exposure

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of up to 15.8 ng/event for children and 9.28 ng/event for adults (Fig. S4). The EDI of OPEs

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through tap water ingestion in the USA was 2–10 times lower than those calculated for South

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Korea.33 In comparison to the dietary intakes of OPEs, intake from tap water ingestion was at

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least two orders of magnitude lower.48-50 Previous studies have reported that dust ingestion is a

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dominant exposure pathway to OPEs.51 In comparison to the reported EDI of OPEs through dust

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ingestion from Belgium,50 the EDI via water ingestion was 2–5 times lower. This study

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establishes baseline values for OPFRs/plasticizers in surface waters in New York State. The

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consumption of OPFRs is expected to increase in the future due to the regulations on brominated

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flame retardants in consumer products, and, therefore, further studies are needed to elucidate

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future trends of contamination by OPEs.

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FIGURES

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Fig. 1. Concentrations of total (sum of 14) organophosphate esters (OPEs) and plasticizers in

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water samples from New York State (A). Location specific difference in OPE concentrations in

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tap water (B), rivers (C), and lakes (D) in New York State.

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Fig. 2. Composition of 14 organophosphorus flame retardants (OPFRs) and plasticizers in

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various types of water samples collected from river, lakes, seawater, rain water and tap water

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from New York State (*: cited from Kim et al., 2017; OPFRs were categorized as aryl, non-

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chlorinated alkyl, chlorinated-alkyl and others)

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Fig. 3. Geographical distribution of 14 organophosphorus flame retardants/plasticizers (A) and

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TCIPP (B), TDCIPP (C), TCEP (D) and TBOEP (E) in river and lake waters in New York State

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(bar graph unit was set at 500 ng/L, 150 ng/L, 50 ng/L, 50 ng/L, and 250 ng/L in that order)

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Fig. 4. Seasonal variation in the concentrations of 14 organophosphorus esters in the Hudson River water collected in Albany, New York

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Table 1. Concentrations of organophosphate flame retardants in river, lake, rain, sea and tap waters from New York State, USA TCEP

TCIPP

TDBPP

TDCIPP

TEHP

EHDPP

PBDPP

TBP*

∑14OPEs

Occurrence and Distribution of Organophosphate Flame Retardants

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