Tissue-specific Accumulation and Body Burden of Parabens and Their

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Ecotoxicology and Human Environmental Health

Tissue-specific Accumulation and Body Burden of Parabens and Their Metabolites in Small Cetaceans Yunsun Jeong, Jingchuan Xue, Gyum-Joon Park, Kurunthachalam Kannan, and Hyo-Bang Moon Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b04670 • Publication Date (Web): 05 Dec 2018 Downloaded from http://pubs.acs.org on December 8, 2018

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Environmental Science & Technology

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Tissue-specific Accumulation and Body Burden of Parabens and Their

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Metabolites in Small Cetaceans

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Yunsun Jeonga, Jingchuan Xueb, Kyum Joon Parkc, Kurunthachalam Kannanb,*, Hyo-Bang Moona,*

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a Department

of Marine Science and Convergence Engineering, Hanyang University, Ansan

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15588, Republic of Korea b

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

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Environmental Health Sciences, School of Public Health, State University of New York at

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Albany, NY, 12201-0509, USA

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c

Cetacean Research Institute (CRI), National Institute of Fisheries Science (NIFS), Ulsan

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44780, Republic of Korea

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*Co-Corresponding Authors: Kurunthachalam Kannan and Hyo-Bang Moon

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Tel.: +82-31-400-5534

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Fax: +82-31-408-6255

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E-mail: [email protected] (H.-B. Moon, Ph.D.)

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For submission to: Environmental Science & Technology

ACS Paragon Plus Environment


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TOC Art

Melon

Dietary intake

Kidney Muscle

Stomach Liver

Blubber

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Abstract Parabens have been of global concern due to their endocrine disrupting properties.

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However, few studies have reported tissue-specific distribution of parabens in wildlife. In this

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study, we measured parabens and their metabolites in organs and tissues (blubber, muscle,

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melon, stomach, kidney, liver, gonad, brain, uterus, and umbilical cord, total n=94) of

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common dolphins (Delphinus capensis) and finless porpoises (Neophocaena asiaeorientalis),

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to investigate tissue-specific accumulation and body burden. Among the target compounds,

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methyl paraben (MeP) and para-hydroxybenzoic acid (4-HB) were detected in all organs.

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Compared to common dolphins, finless porpoises had significantly higher concentrations of

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MeP and 4-HB due to their near-shore habitat. Higher concentrations of MeP and 4-HB were

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found in the kidney, liver, and stomach than in other organs, indicating selective

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accumulation of parabens in certain organs. Significant correlations between MeP and 4-HB

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in liver/kidney suggested metabolic transformation of the former to the latter. Detection of

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parabens in brains, umbilical cord, and uterus suggests that these chemicals cross biological

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barriers such as the blood-brain and placental barriers. The body burdens of total parabens

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were in the ranges of 13000–90600 μg and 19800–81500 μg for common dolphins and finless

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porpoises, respectively.

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Keywords: Methyl paraben; Maternal transfer; Placenta; Brain-blood barrier; Diet



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1. Introduction

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Parabens, esters of p-hydroxybenzoic acid, are synthesized by esterification between

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p-hydroxybenzoic acid and corresponding alcohols that results the formation of

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methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP). Parabens are widely

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used as antimicrobial preservatives in food, cosmetics, and pharmaceuticals due to their

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stability and low production cost.1–3 However, previous in vivo and in vitro studies reported

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estrogenic activities of methyl-, ethyl-, propyl-, and butyl-parabens in rats.4,5 Paraben

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exposures have been linked to breast cancer and were reported to occur in human breast

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tumors.6,7 The linkage of paraben exposure to breast cancer risk remains controversial.3,8

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Considering potential estrogenic effects, the European Union (EU) regulated parabens in

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cosmetic products, limiting them to 0.4% for single esters and 0.8% for mixtures of all

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parabens.9,10

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Parabens are hydrolytically metabolized by esterases after oral and dermal

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administration.3,10 The main metabolic product of paraben is p-hydroxybenzoic acid (4-HB).

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Parabens and their metabolites are conjugated with glucuronide or sulfate before excretion.11

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Other metabolites such as OH-parabens (e.g. OH-MeP and OH-EtP) and 3,4-

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dihydroxybenzoic acid (3,4-DHB) also form at relatively minor proportions in comparison to

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4-HB.12

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A major environmental source of parabens is discharge of effluent from wastewater

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treatment plants (WWTPs).7 According to previous studies, 90% of parabens in WWTP

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influents are removed through biological treatment.7,13 However, parabens, in particular MeP,

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are commonly detected at measurable levels in riverine sediments, estuarine systems, and

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even in marine environments.14-16 Xue et al. (2017) reported the occurrence and accumulation

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of parabens and their metabolites in seawater, sediment, plankton, invertebrates, and various

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fish species including sharks, indicating widespread contamination throughout the marine


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ecosystems.16 In addition to anthropogenic sources, In addition to anthropogenic sources, the

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natural formations of MeP have been reported for different plant species such as cloudberry,

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bourbon vanilla, and herbs.17,18 Several parabens, such as butylparaben (BuP), heptylparaben

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(HeP), nonylparaben (NoP), and 4-HB, are also formed from the activities of marine bacteria

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(Microbulbifer sp.).19

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Marine mammals are top predators in marine ecosystems. Due to their high trophic

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position and long lifespan, these species serve as sentinels of marine pollution by persistent

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contaminants. Xue et al. (2015) detected MeP and 4-HB in several body tissues including

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blubber, liver, kidney, and brain of dolphins, whales, and sea otters from the US coastal

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waters.20 However, our understanding of tissue-specific accumulation of parabens in marine

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mammals is limited due to the limited of availability of tissues and organs. Moreover,

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metabolic transformation and tissue-specific burdens of parabens are not well characterized

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in marine mammals. It is prudent to understand tissue-specific distributions of parabens to

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elucidate exposure pathways, bioaccumulation, and metabolic capacity/transformation of

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parabens in marine mammals.

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In the present study, blubber, brain, muscle, melon, kidney, liver, brain, gonad

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(testis/ovary), uterus, and umbilical cord were analyzed to measure the concentrations of

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parabens and their metabolites, and to investigate the occurrence, species- and sex-dependent

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accumulation, tissue-specific distribution, and total body burdens of these contaminants in

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common dolphins (Delphinus capensis) and finless porpoises (Neophocaena asiaeorientalis)

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collected from Korean coastal waters.

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2. Materials and methods

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Sample Collection

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Common dolphins (D. capensis) and finless porpoises (N. asiaeorientalis) were



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obtained as by-catch from the eastern (Pohang, Gyeongju, and Yeongdeok) and western

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(Taean) Korean coasts, respectively. Common dolphins were collected during 2012–2013 and

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of finless porpoises in 2015. The animals were transported to the Cetacean Research Institute,

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Ulsan, Korea, for necropsy. Six individuals from each species were chosen for analysis based

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on age and sex. The sampled individuals included immature male (n=1), immature female

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(n=1), mature male (n=2), and mature female (n=2) common dolphins (sample code: C1–C6)

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and finless porpoises (F1–F6). Biological parameters such as body length, body weight, sex,

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and sexual maturity were assessed during necropsy. Available biological information of each

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individual is presented in the Supporting Information (Table S1). In this study, common

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organs comprising blubber, muscle, liver, kidney, stomach, melon, and gonad (testis/ovary)

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were collected from all specimens. Additionally, brain (n=5), uterus (n=2), and umbilical

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cord (n=1) were collected from common dolphins and stomach contents (n=2) were collected

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from finless porpoises, on the basis of the availability (Table S1). Mature female common

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dolphins included lactating (C5) and pregnant (C6) animals. A total of 94 organ and tissue

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samples from common dolphins (n=50) and finless porpoises (n=44) were obtained for the

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analysis. All samples were stored at -24°C until analysis.

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Sample Preparation

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Analytical procedures used to determine parabens and their metabolites were similar

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to those described previously.16,20 In brief, tissue samples were homogenized in a mortar and

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then transferred to polypropylene (PP) tubes. Approximately 200-300 mg tissue samples were

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spiked with 50 ng each of internal standards of 13C-labeled-MeP, -EtP, -PrP, -BuP, and -4-HB

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(Cambridge Isotope Laboratories, Andover, MA, USA) and D4-heptyl paraben (HeP) and D4-

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benzyl paraben (BzP) (C/D/N Isotopes Inc., Pointe-Claire, QC, Canada). After equilibration

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for 30 min, 5 mL of acetone was added to the sample and homogenized using a pestle.


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Samples were then transferred to 15 mL PP tubes, which were rinsed with acetone (ACS

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grade), methanol (HPLC grade), and acetonitrile (ACS grade) (Mallinckrobt Baker,

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Phillipsburg, NJ, USA) prior to use. The extracts were shaken in an oscillator shaker for 1 h

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and then centrifuged at 5000 rpm for 10 min (Eppendorf Centrifuge 5804, Hamburg,

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Germany). The supernatants were transferred to another PP tube and concentrated to near

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dryness under a gentle nitrogen stream. After adding 1 mL of acetonitrile and methanol (1:1),

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samples were stored overnight in an incubator (-20°C) to separate the lipid layer from the

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organic solvent. During the sample storage, lipid changed to the solid state which is visible

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for separation. Samples were immediately centrifuged at 5000 rpm for 5 min after storage to

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separate the lipid and then extracts (~1 mL) were filtered through a nylon syringe filter (0.22

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μm) to dispense in vials for analysis.

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Instrumental Analysis An Agilent 1100 Series HPLC system (Agilent Technologies Inc., Santa Clara, CA,

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USA) equipped with Applied Biosystems API 2000 electrospray triple quadrupole mass

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spectrometry (ESI-MS/MS; Applied Biosystems, Foster City, CA, USA) was used for the

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identification and quantification of six parabens (MeP, EtP, PrP, BuP, BzP, and HeP) and

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four metabolites (4-HB, 3,4-DHB, OH-MeP, and OH-EtP). In our study, the forms of free

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and conjugated parent parabens or their metabolites were not separately measured in various

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organs and tissues. A Zorbax SB-Aq (Agilent Technologies Inc., 150 mm × 2.1 mm, 3.5 μm)

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column connected to a Javelin guard column (Betasil C18, 20 mm × 2.1 mm, 5 μm; Thermo

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Fisher Scientific, Waltham, MA, USA) was used for chromatographic separation. Ten

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microliters of sample were injected, and the mobile phase comprised of (A) methanol and (B)

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Milli-Q water that contained 0.4% (v/v) acetic acid. The elution gradient (flow: 300 μL/min)

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started from 5% (v/v) A, held for 3 min, increased to 85% A until 5 min, held for 1 min,



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increased to 98% A within 2 min (~8 min), held for 7 min, and reverted to 5% A at 16 min

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and held for 7 min (total run time: 23 min). The MS/MS was operated under negative ion

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multiple reaction monitoring (MRM) mode. Respective nitrogen flow rates for curtain and

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collision gas were 20 and 2 psi. The electrospray ionization voltage was -4500 V and the

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source heater temperature was set at 450°C. The nebulizer gas was set at 55 psi and the heater

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gas was set at 70 psi.

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Quality Assurance and Quality Control Prior to sample homogenization, the mortar and pestle were rinsed with Milli-Q

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water, acetone, hexane, and methanol and then baked at 450°C overnight. Procedural blanks

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were included in the analysis (two blanks for 20 samples) to monitor for background levels of

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contamination. Small amounts of ethyl paraben (0.1 ng/mL) and 3,4-DHB (1.8 ng/mL) were

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detected in two blank samples and the values were subtracted from the sample

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concentrations. Methanol was injected, to check for carryover of target chemicals, between

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every 10 samples. A mid-point calibration standard (50 ng/mL) containing native and internal

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standards of parabens was injected with every sample batch to confirm instrumental stability.

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Eleven to 13 point calibration curve, ranging in concentrations from 0.1 to 200 ng/mL (0.1 to

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1000 ng/mL for 4-HB and 3,4-DHB), was used for the quantification of target chemicals

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using isotope dilution method. Instrumental detection limits were 0.5 ng/mL for MeP, EtP,

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OH-MeP, and OH-EtP, 0.2 ng/mL for PrP, BuP, BzP, and HeP, and 5.0 ng/mL for 4-HB and

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3,4-DHB. To assess matrix effect, known amounts of native (100 ng) and internal (50 ng)

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standards were spiked into several tissues including blubber, liver, brain, muscle, stomach,

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testis, uterus, and stomach contents, and analyzed. The recoveries of target chemicals from

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matrix spiked samples were 86 ± 7.6% for MeP, 76 ± 7.0% for EtP, 73 ± 3.4% for PrP, 88 ±

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5.8% for BuP, 90 ± 5.8% for BzP, 89 ± 4.9% for HeP, and 107 ± 15% for 4-HB. However,


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3,4-DHB, OH-MeP, and OH-EtP showed low recoveries (< 30%) in most of the organs

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analyzed except for blubber and stomach. Nevertheless, use of isotope dilution method

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accounted for the low recoveries and that these compounds were rarely found in tissues, as

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has been reported earlier.16,20 Detailed information on the recoveries of matrix-spiked

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samples are presented in Table S2.

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Statistical Analysis

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Statistical analyses were conducted using SPSS 18.0 for Windows (Chicago, IL,

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USA) with the significance level set at p < 0.05. The concentrations of parabens in samples

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are presented on a wet weight basis. Among parabens and their metabolites, only MeP and 4-

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HB, which were detected in all organs and tissues, were used for statistical analysis. Data

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distribution (normality) was not tested due to the different sample types and limited sample

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numbers. Mann-Whitney U-tests and Kruskal-Wallis tests were used to assess significant

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differences in paraben concentrations between species, age, and sex. Spearman’s rank

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correlation analysis was performed between the concentrations of MeP and 4-HB in organs

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from dolphins and porpoises.

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3. Results and Discussion

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Occurrence and Concentration of MeP and 4-HB in Small Cetaceans

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Concentrations of parabens and their metabolites measured in organs of common

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dolphins and finless porpoises are summarized in Table 1. No significant age- or sex-

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dependent accumulation of parabens was found for either species (p > 0.05). This is different

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from what was reported for organochlorines (OCs) such as polychlorinated biphenyls (PCBs)

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and dichloro-diphenyl-trichloroethanes (DDTs).21,22

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Among 10 analytes measured in this study, MeP (min–max; 1.3–570 ng/g wet) and



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4-HB (54–10540 ng/g wet) were found in all organs, while other parabens were rarely

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detected in any samples (15% for EtP and < 5% for other parabens). In our study, 4-HB was

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found at 1–2 orders of magnitude higher than MeP, which could be derived from natural

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formation and/or final metabolic product of parabens (e.g. EtP, PrP, and BuP). The presence

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of MeP and 4-HB in all organs of marine mammals indicates widespread contamination in

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marine ecosystems. Although EtP was detected in only 13 organ samples, it was correlated

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significantly (r=0.68, p=0.01) with MeP concentrations in samples in which both compounds

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were detected. This implies that both compounds are likely to have similar exposure sources

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(e.g., diet) and/or similar bioaccumulation process among various organs/tissues of marine

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mammals (Figure S1).

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In comparison to previous studies, MeP concentrations (mean: 402 ng/g) found in

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liver tissues of finless porpoises in our study were higher than those reported for other

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cetacean species (98–188 ng/g; bottlenose dolphin, striped dolphin, rough-toothed dolphin,

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clymene dolphin, and pygmy sperm whale) collected from the US coasts, whereas MeP

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concentrations in common dolphin livers (118 ng/g) were within the ranges reported in the

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previous study.20 The concentrations of 4-HB in liver tissues of common dolphins (mean:

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1180 ng/g) and finless porpoises (3500 ng/g) were lower than those reported for other

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cetaceans from the US coasts (1450–11900 ng/g). In blubber, MeP concentrations (mean: 4.6

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ng/g for common dolphins; 12 ng/g for finless porpoises) measured in our study were about

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1–2 orders of magnitude lower than those reported for the US cetaceans. Although the

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residue levels of less-persistent contaminants such as parabens are influenced by species,

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sampling locations, and sampling years, our findings suggest bioaccumulation potential of

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parabens and their metabolites in marine mammals.

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Tissue-specific Accumulation of Parabens


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The highest MeP concentrations in common dolphins were found in the order of

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kidney (mean: 130 ng/g), liver (120 ng/g), and stomach (80 ng/g). Similarly, the highest MeP

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concentrations in finless porpoises were found in liver (mean: 400 ng/g), kidney (180 ng/g),

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and stomach (75 ng/g). The pattern of accumulation of 4-HB, the metabolite of MeP and

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other parabens, differed from that for MeP. 4-HB concentrations were the highest in

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stomachs of common dolphins (mean: 2130 ng/g) and finless porpoises (6880 ng/g), whereas

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the concentrations of 4-HB in liver and kidney were similar between the two species. The

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mean concentrations of 4-HB in liver and kidney of common dolphins were 1180 and 1090

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ng/g, respectively, and were 3500 and 3750 ng/g in liver and kidney of finless porpoises,

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respectively. Unlike lipophilic contaminants such as OCs, MeP concentrations in lipid-rich

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compartments such as blubber (mean: 4.6 ng/g for common dolphins; 12 ng/g for finless

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porpoises) and melon (8.5 ng/g and 42 ng/g) were approximately 2−3 orders of magnitude

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lower than those measured in liver, kidney, and stomach for both species. Similarly, 4-HB

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also showed lower concentration in blubber (130 ng/g and 400 ng/g) and melon (350 ng/g

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and 1070 ng/g) than in other organs. This indicates that MeP and 4-HB preferentially

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accumulate in metabolism-related or digestive organs such as kidney, liver, and stomach.

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Several additional organs such as brain (n=5), uterus (n=2), and umbilical cord (n=1)

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of common dolphins were also analyzed. Respective mean concentrations of MeP and 4-HB

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in brain were 25.4 ng/g and 370 ng/g, which were relatively lower than those measured in

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other organs. However, the presence of parabens in brains indicates that MeP and 4-HB can

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cross the blood-brain barrier (BBB) through transmembrane diffusion and saturable

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transporters.23 A previous human study reported the detection of MeP in brain tissues

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(hypothalamus).24 Presence of 372 ng/g of 4-HB in brain should not be ignored because

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endocrine disrupting chemicals such as parabens alter the hormone system in brain.24 In

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addition, the detection of MeP and 4-HB in uterus and umbilical cord tissues from mature



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female animals suggests maternal transfer of these contaminants.

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Species-specific Accumulation of Parabens in Dolphins and Porpoises

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We compared summed concentrations of MeP and 4-HB in organs (blubber, muscle,

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melon, stomach, kidney, and liver) of common dolphins and finless porpoises, to investigate

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species-specific accumulation of parabens (Figure 1). The overall concentrations of MeP and

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4-HB in finless porpoises (mean MeP: 900 ng/g; 4-HB: 17600 ng/g) were approximately 2–3

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times (p < 0.01) higher than those found in common dolphins (MeP: 400 ng/g; 4-HB: 5400

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ng/g). This is likely due to the differences in habitat and metabolic capacity between the two

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species. Finless porpoises inhabit near-shore waters such as estuaries, whereas common

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dolphins inhabit coastal and offshore waters of eastern Korea. In particular, the western coast,

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where finless porpoises were collected, is more urbanized with high WWTP discharges than

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the eastern coast of Korea. Xue et al. (2017) also found high concentrations of MeP and 4-HB

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in seawater and sediments collected from locations close to WWTPs.16 The diet (mostly

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shrimp and anchovy) of finless porpoises inhabiting the western coast may contain parabens,

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which resulted in greater accumulation than that those of common dolphins.

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A marginally significant correlation was found between the concentrations of MeP and

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4-HB in livers of common dolphins (r=0.81, p=0.05), whereas no such correlation was found

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in organs of finless porpoises (r=0.65, p=0.16) (Figure S2). This difference may be due to the

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greater metabolic capacity of finless porpoises in eliminating 4-HB than common dolphins. In

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our study, the partitioning ratios of 4-HB between organs/tissues (stomach, kidney, gonad,

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brain, muscle, blubber, and melon) and liver (blood-rich organs) were higher than MeP for all

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cases of finless porpoises, whereas no any trend was found for common dolphins (Figure S3).

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Our finding suggests that higher concentrations of 4-HB could be transported to the other

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organs/tissues after metabolism of parabens (e.g., MeP to 4-HB) in liver of finless porpoises


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rather. A previous study reported that harbor porpoises exhibited stronger metabolic capacity

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than common dolphins.25 However, other confounding factors such as diet, surrounding

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environment, and the contribution of other tissues (e.g., blood) should also be considered to

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understand tissue-specific accumulation of parabens between species.

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Body Distribution of MeP and 4-HB Spearman’s rank correlation analysis was performed to examine the relationship

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between MeP and 4-HB in individual organs of both species (Figures 2, S3, and S4). Overall,

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significant correlations (r = 0.74–0.93, p < 0.05) were found among the organs of each

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cetacean specimen (Figure S3–S4). Only lactating common dolphin (C5) did not show any

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correlation among organs due to the re-distribution of parabens during lactation. In contrast,

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pregnant specimen (C6) showed the highest correlation coefficient (r = 0.92, p < 0.01). Our

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finding suggests that lactation is an important determinant of body distribution of parabens.

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To examine the distribution of parabens in body tissues, samples were divided into

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functional groups as stomach (digestion), liver/kidney (metabolism), and others (blubber,

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brain, melon, muscle, gonad, uterus, and umbilical cord). Due to the different paraben

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distribution in lactating animal (C5), this specimen was excluded from this correlation

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analysis. Overall, the correlations between MeP and 4-HB concentrations showed similar

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trends (e.g., regression slopes) for the same organs between species. Detailed information on

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correlation coefficients between MeP and 4-HB in each organ is summarized in Tables S5

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and S6. Stomach showed high variations in concentrations of 4-HB among individuals of

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both the species. This implies that paraben exposure to marine mammals is mainly through

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diet. A previous study reported that hydrolysis in the stomach during digestion results in de-

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esterification of parent parabens.10 Interestingly, the highest concentrations of 4-HB were

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found in stomach contents (n=2; mean: 2250 ng/g), higher than in stomach, which supports



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our findings (Figure S5). For metabolism-related tissues (liver/kidney), common dolphins

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showed significant correlations (r=0.74, p=0.006) between concentrations of MeP and 4-HB,

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whereas no correlation (r=0.47, p=0.124) was found for finless porpoises. This could be

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related to differences in the metabolic capacity between species, as mentioned above. In

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addition, higher concentrations of MeP were found in liver/kidney tissues than in other

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organs, which might be explained by selective gastrointestinal absorption. Among other

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organs, brain tissues of common dolphins showed a significant correlation (r=0.90, p=0.037)

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between concentrations of MeP and 4-HB. This indicates that parabens cross the blood-brain

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barrier and accumulate in the brain. A significant correlation (r=0.94, p=0.005) was found

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between MeP and 4-HB concentrations in the gonad of finless porpoises.

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Body Burden of Parabens in Marine Mammals To date, limited studies have reported the body burdens of organic contaminants in

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marine mammals.26-28 In our study, the total body burdens of MeP and 4-HB were estimated

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using biometric parameters and tissue-specific concentrations. Because of the lack of body

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weight data for the common dolphins examined in this study, we estimated that using a

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regression equation describing body weight and length in common dolphins (Delphinus

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capensis) as reported in a previous study.29 Weights of individual organs were obtained from

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earlier studies of striped dolphins (Stenella coeruleoalba) and finless porpoises

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(Neophocaena phocaenoides).30,31 In this study, common organs, which accounted for 75% of

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the total body weight for both species, were used to estimate the body burden of parabens

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(Figure 3). The estimated body burdens of parabens in common dolphins ranged from 760 to

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7,520 (mean: 4,090) μg and from 12,300 to 83,900 (40,800) μg for MeP and 4-HB,

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respectively. For finless porpoises, the body burdens of MeP and 4-HB ranged from 840 to

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2,400 (1420) μg and 18,500 to 79,200 (43,000) μg, respectively. Although the total body


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burdens of parabens were similar between the two species, the body weight-normalized body

336

burdens of total parabens were in the ranges of 160–550 (mean: 400) μg/kg for common

337

dolphins and 340–2340 (mean: 1230) μg/kg for finless porpoises. Our finding suggests that

338

finless porpoises have higher exposure doses to parabens than common dolphins.

339

The contribution of each body tissue to the total body burdens of parabens was

340

different for each species, indicating tissue- and species-specific accumulation of parabens

341

(Figure 3). In common dolphins, muscle (> 80%) accounted for a higher proportion of the

342

total body burden of parabens, whereas the contributions of the other organs were small (
50%) high burdens of parabens in finless porpoises but

344

other organs such as blubber (mean: 19%) and liver (14%) also comprised moderate

345

proportions of total body burdens. In particular, liver tissues accounted for a greater

346

proportion of MeP burden (32%) to the total body burdens in finless porpoises, whereas in

347

common dolphin livers accounted for only a small proportion (4.9%). This discrepancy

348

further explains species-dependent metabolic capacities. In addition, the proportions of MeP

349

(13%) and 4-HB (19%) in blubber of finless porpoises were higher than those in common

350

dolphins (3.5% for MeP and 7.4% for 4-HB). Our finding suggests the possibility of paraben

351

exposure through skin absorption in porpoises. Earlier studies have reported the skin

352

absorption of parabens in rat, rabbit and human skin, which could support our findings.32-36

353

Despite the differences in sampling locations, collection year, and species

354

investigated, the estimated body burden of parabens was compared with those reported for

355

other organic contaminants. The body burdens of total parabens (mean: 44,800 μg for

356

common dolphins and 44,400 μg for finless porpoises) were an order of magnitude lower

357

than those of PCBs (460,000 μg) and DDTs (850,000 μg) in striped dolphins (Stenella

358

coeruleoalba) collected in Japanese coastal waters and higher than in bottlenose dolphins

359

(Tursiops truncatus, 19,814 μg for PCBs; 4,727 μg for DDTs) from Florida.26,27 Nevertheless,



360

it should be noted that parabens accumulate at high proportions in physiologically important

361

organs, which can have implications for health. A body burden of perfluorinated compounds

362

estimated at 2665 μg for harbor seals (Phoca vitulina) from Germany, was lower than that

363

found for parabens, in our study.28 Further studies are needed to assess the ecotoxicological

364

significance of parabens in marine mammals.

365 366

Acknowledgements

367

This study was supported by the ‘Development of Techniques for Assessment and

368

Management of Hazardous Chemicals in the Marine Environment’ program funded by the Ministry

369

of Oceans and Fisheries and a grant from the National Institute of Fisheries Science (NIFS,

370

RF2018026), Korea.


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toxicity, absorption, esterase and human exposure, and discussion of potential human

475

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476



477

Figure Captions

478 479

Figure 1. Concentrations of MeP and 4-HB in common dolphins and finless porpoises

480

collected from Korean coastal waters.

481 482

Figure 2. Correlations between the concentrations of MeP and 4-HB among all organs

483

analyzed in (a) common dolphins (n=50) and (b) finless porpoises (n=44). Bold line indicates

484

statistically significant correlations (p < 0.05); liver/kidney (y = 7x + 260, R2 = 0.53), and

485

brain (y = 12x + 76, R2 = 0.98) of common dolphins, and gonad (y = 8x + 573, R2 = 0.72) of

486

finless porpoises.

487 488

Figure 3. Relative body burdens (%) of MeP and 4-HB in each organ of (a) common dolphins

489

and (b) finless porpoises.

490


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Table 1. Concentrations (ng/g wet weight) of parabens and their metabolites in common dolphins and finless porpoises collected from Korean coastal waters Common dolphins n Blubber 6 Muscle 6 Melon 6 Stomach 6 Kidney 6 Liver 6 Testis/ovary 6 Brain 5 Uterus 2

Range 1.3–7.5 13–121 4.8–12 44–118 67–221 13–224 26–76 4.2–50 37–74

Methylparaben (MeP) Mean ± SD 4.6 ± 2.2 56 ± 40 8.5 ± 2.5 82 ± 27 133 ± 61 118 ± 85 51 ± 19 25 ± 20 55 ± 26

Median 4.7 50 8.6 86 133 147 53 25 37

Para-hydroxybenzoic acid (4-HB) Range Mean ± SD Median 54–241 128 ± 68 106 164–827 556 ± 305 691 90–713 346 ± 210 300 1140–3304 2132 ± 796 1971 446–2415 1090 ± 745 943 170–1904 1175 ± 666 1252 268–1654 730 ± 511 534 137–668 372 ± 237 299 425–3507 1967 ± 2179 426

Range 6.4–21 12–88 21–71 75–228 181–359 235–569 44.3–256

Methylparaben (MeP) Mean ± SD 12 ± 5.6 38 ± 35 42 ± 20 128 ± 55 283 ± 67 402 ± 110 155 ± 97

Median 11 22 43 118 288 413 171

Para-hydroxybenzoic acid (4-HB) Range Mean ± SD Median 104–929 399 ± 303 282 73–4071 1978 ± 2044 1795 748–2007 1073 ± 488 859 3300–10539 6882 ± 3164 6680 1918–5769 3751 ± 1355 4055 1725–5076 3504 ± 1290 3575 443–2996 1814 ± 912 1848

59, 76

67

na

Finless porpoises n 6 6 6 6 6 6 6

Blubber Muscle Melon Stomach Kidney Liver Testis/ovary Stomach 2 content ana=not available.


1123, 3373

2248

na


Concentration (ng/g wet weight)

Figure 1

105 Common dolphins Finless porpoises

104

103

102

MeP**


4-HB**

Page 24 of 26

Page 25 of 26


Figure 2

(a) Common dolphins

4-HB (ng/g wet weight)

4000 Liver/Kidney Stomach Brain Others

3000

2000

1000

0 0

50

100

150

200

250

MeP (ng/g wet weight)

(b)

Finless porpoises 14000 Liver/Kidney Stomach Gonad Others

4-HB (ng/g wet weight)

12000 10000 8000 6000 4000 2000 0 0

100

200

300

400

MeP (ng/g wet weight)


500

600


Page 26 of 26

Figure 3

(a)

(b)

Relative contribution (%)

100

80

60

40 Blubber Muscle Stomach Kidney Liver

20

0

MeP

4-HB

MeP


4-HB

Tissue-specific Accumulation and Body Burden of Parabens and Their

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