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Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Matched Maternal, Cord and Placenta Samples: a Study of Transplacental Transfer Fangfang Chen, Shanshan Yin, Barry C. Kelly, and Weiping Liu Environ. Sci. Technol., Just Accepted Manuscript • Publication Date (Web): 09 May 2017 Downloaded from http://pubs.acs.org on May 9, 2017

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Environmental Science & Technology

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Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Matched Maternal, Cord and Placenta

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Samples: a Study of Transplacental Transfer

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Fangfang Chen1, Shanshan Yin1, Barry C. Kelly2*, Weiping Liu1*

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Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health,

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College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058,

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China

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Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore

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Corresponding author. * College of Environmental and Resource Sciences, Zhejiang University,

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Hangzhou, China 310058.

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Tel. (+86-571-8898 2341); Fax (+86-571-8898 2341); Email: [email protected]

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* Department of Civil and Environmental Engineering, National University of Singapore, Block

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E1A, #07-03, No.1 Engineering Drive 2, Singapore 117576.

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Tel. (+65-6516 3764); Fax (+65-6779 1635); Email: [email protected]

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1 ACS Paragon Plus Environment


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Graphical Abstract for TOC

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ABSTRACT

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Currently, information regarding concentrations of chlorinated polyfluoroalkyl ether sulfonic

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acids (Cl-PFESAs) in human placenta does not exist. The main objective of the present study

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was to assess the occurrence and distribution of two Cl-PFESAs, 6:2 Cl-PFESA and 8:2 Cl-

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PFESA, in maternal serum, umbilical cord serum and placenta to better assess the transport

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pathways related to human prenatal exposure. The widely studied perfluorooctane sulfonate,

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PFOS, was studied for comparison. The study was a hospital-based survey involving quantitative

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determination of Cl-PFESAs and PFOS concentrations in maternal serum (n = 32), cord serum (n

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= 32) and placenta (n = 32) samples from women in Wuhan, China. The results indicate that Cl-

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PFESAs can efficiently transport across placenta, with median exposure levels of 0.60 and 0.01

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ng/mL of 6:2 Cl-PFESA and 8:2 Cl-PFESA in the cord sera, respectively. Concentrations of the

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target compounds in maternal sera, cord sera and placentas were ordered PFOS > 6:2 Cl-

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PFESA > 8:2 Cl-PFESA. Similar patterns were observed in maternal sera, cord sera and

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placentas for Cl-PFESAs, with concentrations ordered maternal sera > cord sera > placentas.

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Significant correlations were observed between 6:2 Cl-PFESA, 8:2 Cl-PFESA and PFOS

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concentrations in the maternal serum, cord serum, and placenta samples (r > 0.7, p < 0.001). The

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median value of RCM (ratio of concentration between cord serum and maternal serum) of 6:2 Cl-

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PFESA was 0.403, indicating a relatively high (~40%) placental transfer efficiency. 8:2 Cl-

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PFESA transported across placenta to a greater extent than 6:2 Cl-PFESA, likely due to higher

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hydrophobicity and lower plasma protein binding affinity. To the best of our knowledge, this is

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the first study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in

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human placenta. The findings help to better understand the mechanisms of the transplacental

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transfer and neonatal exposure to these important PFOS alternatives.



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Keywords: chlorinated polyfluoroalkyl ether sulfonic acids, placental transfer, cord serum,

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maternal serum


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INTRODUCTION

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The occurrence of perfluoroalkyl substances (PFASs) in the environment has raised

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concerns in decades. Multitudinous studies have demonstrated the occurrence, bioaccumulation

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and adverse effects of perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids

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(PFCAs) in wildlife and humans all over the world.1-4 While numerous studies regarding PFCAs

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and PFSAs have been done, investigations of subclasses of PFASs, including perfluorooctane

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sulfonamides

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sulfonates (FTSs), perfluoroalkyl phosphinic acids (PFPiAs), perfluoroalkyl phosphonic acids

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(PFPAs), polyfluoroalkyl phosphate diesters (diPAPs) and perfluoroalkyl ether sulfonic acids

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(PFESAs) are very limited.3, 5-7

(FOSAs),

perfluorooctane

sulfonamidoacetates

(FOSAAs),

fluorotelomer

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Since 3M announced to voluntarily phase out of perfluorooctanesulfonic acid (PFOS) due

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to environmental and human health concerns, there have been substantial efforts to find less

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hazardous alternatives.8 Major alternatives to PFOS used in the metal plating industry are

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perfluorobutanesulfonic acid (PFBS), 6:2 fluorotelomer sulfonate (6:2 FTS) and 6:2 chlorinated

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perfluoroalkyl ether sulfonic acids (6:2 Cl-PFESA) with commercial name F-53B.9 8:2 Cl-

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PFESA is the impurity of F-53B.9 Chemical structures and physicochemical properties of 6:2 Cl-

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PFESA and 8:2 Cl-PFESA are listed in Figure S1 and Table S1 of the supporting information

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(SI). Although F-53B was uniquely used as mist suppressant in metal plating industry in China

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for more than 30 years, information of its occurrence, fate and effects in the environment is

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extremely limited. Wang et al. were the first to report the 6:2 Cl-PFESA concentrations in

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wastewater of electroplating plant with the range of 65−112 µg/L in the influent and 43−78 µg/L

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in the effluent.10 6:2 Cl-PFESA is resistant to biodegradation and has moderate toxicity to



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zebrafish (Danio rerio) with LC50 (96 h) 15.5 mg/L.10 Further, 6:2 Cl-PFESA and 8:2 Cl-PFESA

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were recently found in samples of municipal sewage sludge throughout China with mean

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concentrations of 2.15 and 0.50 ng/g d.w., respectively.9 Bioaccumulation of 6:2 Cl-PFESA in

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crucian carp (Carassius carassius) was also investigated and was found with higher

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bioaccumulation potential compared to PFOS.11 More recently, a study of ubiquitous human

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exposure and slow elimination kinetics of 6:2 Cl-PFESA and 8:2 Cl-PFESA highlights the

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importance of advanced study and regulatory actions on these alternatives of PFOS.12 The study

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of 6:2 Cl-PFESA and 8:2 Cl-PFESA in maternal and cord sera indicated that exposure to Cl-

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PFESAs may be widespread among pregnant women and neonates in China.3 Nevertheless,

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distribution patterns, trends and fate of 6:2 Cl-PFESA and 8:2 Cl-PFESA in the environmental

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media remain unknown. Although PFOS is still allowed to be used in China, F-53B has potential

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to be consumed more with the phase-out of PFOS worldwide. However, the bioaccumulation

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potential and toxicity of 6:2 Cl-PFESA and 8:2 Cl-PFESA are greater than those of PFOS

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according to data from Table S1 implying the importance of including 6:2 Cl-PFESA and 8:2 Cl-

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PFESA in the phase-out process.

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Prenatal exposure to xenobiotics for neonates is of great concern as infants are much

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more sensitive to pollutants than adults.13-17 The environmental pollutants that have the ability to

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cross the placenta may have adverse effects on growth, development and reproduction of

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newborns.18-20 Investigations of the maternal–fetal transfer are necessary to fully understand the

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mechanisms and risks of prenatal exposure. Multiple studies have investigated the maternal–fetal

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transfer of PFASs including the linear and branched isomers of PFOS and perfluorooctanoic acid

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(PFOA).21-28 A consistent finding of these studies is that maternal serum has higher

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concentrations of PFASs than umbilical cord serum.27 However, to our knowledge, there is 6 ACS Paragon Plus Environment

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currently only one report of concentrations of Cl-PFESAs in the maternal and umbilical cord

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serum as well as the transplacental transfer of the Cl-PFESAs,3 and no report of concentrations

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of Cl-PFESAs in the human placenta.

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The objective of the present study is to (i) determine the range of concentrations of Cl-

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PFESAs in maternal serum, umbilical cord serum, and placenta, (ii) examine the pathways of

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human prenatal exposure. PFOS was also studied for comparison. The study provides novel

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information of Cl-PFESAs in human placenta and assists better understanding the mechanism of

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the transplacental transfer of these emerging contaminants of concern.

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MATERIALS AND METHODS

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Standards and reagents. PFOS,

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Wellington Laboratories Inc. (Ontario, Canada). 6:2 Cl-PFESA and 8:2 Cl-PFESA were donated

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by Dr. Ting Ruan which were laboratory-purified from mist suppressant product, which is

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marketed under the name of commercial F-53B. Details regarding the structural characterization

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of 6:2 Cl-PFESA and 8:2 Cl-PFESA are described elsewhere.9 Optima LC/MS grade methanol

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was purchased from Fisher Scientific Inc. (Loughborough, UK). The nomenclature of Cl-PFESA

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analogues was adopted from Ruan et al.9

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Collection of samples. Matched maternal serum, umbilical cord serum and placenta samples (n

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= 32) were analyzed in this study. All the samples were collected at Department of Obstetrics

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and Gynecology of the Wuhan No.1 Hospital from November 2015 to March 2016.

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Demographic information of the participants (including maternal age, pregnancy weight gain,

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pre-pregnancy body mass index, parity, abortion, drinking water source, smoking habit and diet

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preference, occupation of the mothers and the gender and gestational age of the neonates) was

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C4-PFOS, and

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C8-PFOS standards were obtained from



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gathered using completed structured questionnaires (Table 1). Maternal blood samples (n = 32)

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from pregnant women within 3 days prior to delivery, and cord blood samples (n = 32) and

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placenta (n = 32) were collected at delivery. Then the serum was separated by centrifugation. All

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samples were stored at –20 ºC. All participants have given written informed consent. The total

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protein (TP) and total albumin (ALB) were quantified by enzymatic method using a Beckman

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Coulter AU5800 biochem analytic station. Ethical clearance was approved by the medical ethics

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committees of the Wuhan No.1 Hospital and the Zhejiang University.

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Sample extraction. Following Kuklenyik et al. (2004),29 we utilized an extraction method for

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simultaneous determination of target PFSEAs and PFOS in serum samples. Briefly,

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approximately 1 mL of serum was spiked with 1.9 ng of isotopically-labeled internal standard

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(IS),

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extracted via sonication for 20 min. Solid phase extraction (SPE) was performed using Oasis-

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HLB cartridges (Waters, Milford, MA, USA; 60 mg/3 mL). The cartridges were conducted with

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2 mL of methanol followed by 2 mL of 0.1 M formic acid. Prepared serum extracts were passed

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through cartridges at a flow rate of 1 mL/min. The cartridges were then washed with 3 mL of 0.1

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M formic acid, 5 mL of 50% 0.1 M formic acid/50% methanol, and 1 mL of 1% ammonium

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hydroxide. Cartridges were drained using vacuum for 5 min, and chemicals were eluted with 1

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mL of 1% ammonium hydroxide in methanol. The eluates were then evaporated to dryness under

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gentle nitrogen and reconstitute with 500 µL of mixture of methanol: Milli-Q water (1:1, v/v).

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The above extracts were centrifuged at 15000 rpm before transferring to polypropylene vials.

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Lastly, 1.9 ng of

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prior to analysis.

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C4-PFOS, along with 3 mL of 0.1 M formic acid. Samples were vortex-mixed and

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C8-PFOS (injection internal standards, ISTD) was fortified into the extracts


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10 g of placenta (wet weight) was freeze-dried for 72 hr using Christ Beta 1-8 LD plus

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freeze-dryer (Osterode am Harz, Germany) and homogenized using mortar and pestle. These

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homogenates were spiked with1.9 ng of IS (13C4-PFOS), along with 20 mL of 0.01 M KOH in

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methanol. Samples were then shaken at 250 rpm for 24 hr on a shaker table. Homogenates were

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extracted with a second time using an additional 20 mL of 0.01 M KOH in methanol. Combined

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extracts were then centrifuged and the supernatants were concentrated to approximately 1 mL

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with a gentle stream of nitrogen. 5 mL of 0.1 M formic acid was added to the concentrated

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extracts and diluted to 14 mL with Milli-Q water. The extracts were vortex-mixed and sonicated

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(20 min) just prior to SPE extraction. SPE extraction and ISID spiking was same as for serum

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samples.

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Instrumental Analysis. Target analytes were quantified with a UPLC-tandem electrospray-triple

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quadrupole mass spectrometry system (Xevo TQ-S, Waters, Milford, MA, U.S.A.). Compounds

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were separated using Acquity UPLC BEH C18 column (2.1×100 mm, 1.7 µm, Waters, Ireland).

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The injected sample volume was 10 µL. Mobile phase of solvent (A) 10 mM ammonium acetate

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in Milli-Q water with pH adjusted to 8 using NH4OH, and solvent (B) 10 mM ammonium acetate

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in methanol with pH adjusted to 8 using NH4OH, was used for analytes chromatographic

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separation at a flow rate of 0.2 mL/min. The gradient elution was as follows: initial conditions,

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50% of B; 1-5 min, increase linearly to 100% of B; 5-10 min, 100% of B; 10-10.5 min, return to

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initial conditions; 10.5-15 min, 50% of B.

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Source-dependent parameters in ESI negative mode were: capillary voltage, 3 KV;

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desolvation temperature, 400 ºC; desolvation gas flow, 1000 L/hr; cone gas flow, 150 L/hr and

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collision gas flow, 0.15 mL/min. Compound-specific parameters are listed in Table S2.



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QA/QC. All labware was rinsed with HPLC grade methanol (Sigma-Aldrich, USA) twice prior

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to the experiment. One procedural blank (Milli-Q water) was analyzed for every 8 samples to

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check for any background contamination. The matrix spike-recoveries were conducted by

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spiking ~2 ng of native standards into 1 mL of newborn calf serum and subjected to the

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extraction method discussed above. Spike-recoveries (n = 3) and method matrix-specific

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quantification limits (MQLs) are provided in Table S3. All reported serum and placental

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concentrations were corrected for recovery. MQL was defined as concentration responding to

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signal to noise ratio of 10 in the sample matrix. An isotope dilution calibration approach was

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employed for quantification of Cl-PFESAs and PFOS in samples. In detail, a series of 5

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calibration standard solutions (CS1-CS5, ranged from 0.02-25 ng/mL) were prepared, with

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variable concentrations of the target compounds and a constant concentration of the surrogates.

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Mean relative response (RR) values for the 5 calibration solutions were employed for

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quantification of each analyte only if the relative standard deviation (RSD) of the computed RR

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values was less than 20%, therefore implying good linearity. Instrumental drift was monitored as

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well by injecting a calibration standard solution CS 2 for every 10 samples. No instrumental drift

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was observed if the RSD of RRs was lower than 20%. However, if the RSD of RRs was greater

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than 20%, a new calibration of RR was employed for quantitation.

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Data Analysis. The cord-maternal concentration ratio (RCM) is used to assess the extent of

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transplacental transfer,30 meanwhile the placenta-maternal concentration ratio (RPM) is an

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estimate of retention /accumulation in the placenta.28 Placental transfer efficiency was estimated

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by computing of the concentration ratios of paired cord-maternal sera (RCM) and paired

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placental-maternal sera (RPM) for each compound on ng/mL and ng/g wet weight. The equations

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for RCM (dimensionless) and RPM (dimensionless) were listed below, 10 ACS Paragon Plus Environment

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RCM = Ccord / CMaternal

(1)

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RPM = CPlacenta / (CMaternal / 1.025 g/mL )

(2)

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where CCord is the umbilical cord serum concentration, CMaternal is the maternal serum

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concentration, CPlacenta is the placental concentration, and the density of human blood plasma,

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1.025 g/mL, was brought into the formula to make RPM dimensionless for comparison with

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RCM.31

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Statistical analyses were conducted using the IBM SPSS statistics 16.0 software (SPSS Inc.,

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2007). The significance threshold level was α = 0.05. Only analytes with detection frequencies

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greater than 50% in maternal / cord serum and placenta samples were calculated for summary

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statistics. Concentrations below MQL were set to be half of MQL in the statistical analysis.

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Correlations of 6:2 Cl-PFESA, 8:2 Cl-PFESA and PFOS in maternal, cord serum and placenta

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samples were calculated by Spearman’s rho values.

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RESULTS AND DISCUSSION

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Demographic characteristics of the study population. The characteristics for the mother-

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infant pairs are shown in Table 1. The average age, BMI before the pregnancy, and weight gain

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during pregnancy of the mothers were 27.1 years (SD = 2.8), 20.4 kg/m3 (SD = 2.5), and 20.5 kg

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(SD = 5.7), respectively. Among all the participants, 53.1% had given birth to child before, and

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48.4% of them had a history of abortion. Most of the mothers chose tap water (81.2%) as their

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main water source. Only 2 (6.3%) of the mothers were smoking and 1 (3.1 %) of them were

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drinking alcohol chronically. There were more boys (53.1%) than girls included in the samples.



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The selected newborns were born at term at an average of 38.9 weeks (SD = 1.6) and their

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average weight and head circumference were 3.4 kg (SD = 0.5), 34.0 cm (SD = 1.8), respectively.

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The association between Cl-PFESAs and PFOS concentrations and maternal /fetal indices

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was also investigated as part of the present study. Indices included parity, abortion numbers,

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maternal age, pregnancy weight gain, pre-pregnancy BMI, serum total protein, serum albumin,

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drinking water source, smoking habit, alcohol drinking habit, diet preference and occupation of

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mothers, as well as gender, weight, head circumference and gestational age of neonates (Table 1).

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No correlations were observed between Cl-PFESAs or PFOS concentrations and these

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maternal/fetal indices. It may be due to the limited sample size.

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Concentrations of Cl-PFESAs in maternal, cord serum and placenta. Table 2 shows the

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concentrations of 6:2 Cl-PFESA, 8:2 Cl-PFESA and PFOS in the maternal sera, cord sera and

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placentas. 6:2 Cl-PFESA and PFOS were detected in all of the maternal sera, cord sera, and

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placentas. 8:2 Cl-PFESA was detected less frequently in maternal sera, cord sera, and placentas

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with detection frequencies of 84.4%, 81.3%, and 28.1%, respectively. The main source of 6:2 Cl-

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PFESA and 8:2 Cl-PFESA is from commercial F-53B mist suppressant, which has been shown

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to contain approximately 77.6% of 6:2 Cl-PFESA.9 Concentrations of 6:2 Cl-PFESA in

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environmental samples have been shown to be much higher than those of 8:2 Cl-PFESA. For

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example, mean concentrations of 6:2 Cl-PFESA and 8:2 Cl-PFESA in wastewater treatment

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plant (WWTP) sludge samples were previously found to be 2.15 and 0.5, respectively.9

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Figure 1 illustrates the concentration of 6:2 Cl-PFESA is orders of magnitude higher than

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that of 8:2 Cl-PFESA in the maternal sera, cord sera and placentas. The magnitude difference

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between 6:2 Cl-PFESA and 8:2 Cl-PFESA from the environment to human beings went higher


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may be due to the selective uptake rates of these compounds through different routes as they

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have different hydrophobicity. The 6:2 Cl-PFESA and 8:2 Cl-PFESA concentrations in the

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maternal serum samples were ranged from 0.23-4.44 and < MQL-0.209 ng/mL. This is

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consistent with previous studies in Wuhan City, which have reported

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concentrations in the human sera were between 1.87 and 5.94 ng/mL (n=8, background group),

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while 8:2 Cl-PFESA concentrations were between 0.04 and 0.11 ng/mL (n=8, background

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group).12 PFOS concentrations in maternal serum were also consistent with this previous study.12

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The 6:2 Cl-PFESA and 8:2 Cl-PFESA concentrations in the maternal serum samples were also

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consistent with previous placental transfer study in Wuhan City.3

6:2 Cl-PFESA

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Figure 1 also shows that concentrations of 6:2 Cl-PFESA in serum and placenta were

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constantly lower than those of PFOS, which may be related to differences in environmental

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levels of these two compounds. The estimated annual usage of PFOS for electroplating around

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China was 30 to 40 tons, based on data from the Chinese Electroplating Association.10 The total

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usage of PFOS in China is estimated to be 100 tons per year.32 The annual consumption of F-53B

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in China is approximately 13 tons, according to Shanghai Synica Corporation Ltd., the primary

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manufacturer.33

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The 6:2 Cl-PFESA and 8:2 Cl-PFESA concentrations in the cord serum samples were 0.6

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(median) and 0.01 (median), respectively, which were consistent with previous placental transfer

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study in Wuhan City with the median cord serum concentrations of 0.8 and 0.03, respectively.3

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The composition profiles of 6:2 Cl-PFESA, 8:2 Cl-PFESA and PFOS were similar in maternal

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sera, cord sera and placentas, with concentrations ordered maternal sera > cord sera > placentas

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(Figure 1). The occurrence of these organofluorine contaminants in cord sera demonstrates the

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potential for prenatal exposure to fetus. Fetus is much more sensitive to chemical exposure 13 ACS Paragon Plus Environment


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during embryonic and fetal development, where low level contaminant exposure may lead to

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irreversible damage or risk of diseases later in life.13-16 The results from the present study clearly

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show that 6:2 Cl-PFESA, 8:2 Cl-PFESA, as well as PFOS can substantially accumulate in fetal

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cord blood.

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Placental transfer. The occurrence of 6:2 Cl-PFESA, 8:2 Cl-PFESA and PFOS residues in

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placentas and cord sera indicated that these chemicals can be transported through the placenta

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into the cord blood with retention in the placenta. For the 6:2 Cl-PFESA, the RCM values were in

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the range of 0.273−0.554 (first to third quartiles), while the median RCM was 0.403 which

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indicates relatively high (~50%) transfer to cord blood (Table 3). The median RPM for the 6:2 Cl-

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PFESA was 0.201, suggesting that about 20% retention of 6:2 Cl-PFESA in the placenta. The

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RCM values of 8:2 Cl-PFESA were in the range of 0.438-0.783 (first to third quartiles),

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consistently greater than that of the 6:2 Cl-PFESA (p 0.7, p < 0.001). Similarly, significant correlations were

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also observed between the 6:2 Cl-PFESA and 8:2 Cl-PFESA concentrations in the maternal and

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cord serum (r > 0.6, p < 0.001). Weak correlations were observed between the Cl-PFESAs and

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the PFOS concentrations in the serum and placenta.

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Strong linear relationships between log-transformed concentrations of Cl-PFESAs and

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PFOS between the maternal-cord sera and maternal-placenta were observed (Table 4, Figure S2).

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Using this relationship it may be possible to assess prenatal exposure of neonates by estimating

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concentrations in cord sera or placentas based on maternal concentrations. Conversely, it may be

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possible to estimate Cl-PFESAs and PFOS concentrations in the maternal sera using the

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concentrations in the cord sera, which is a relatively more non-invasive approach. Further,

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investigations of internal sera/ tissues and urine would be useful to allow better noninvasive

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screening for internal exposure to these and other environmental contaminants.


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Implications for human health risk assessment. To the best of our knowledge, this is the first

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study to report the occurrence and distribution of 6:2 Cl-PFESA and 8:2 Cl-PFESA in placenta

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in humans. The findings help to better understand the mechanisms of the transplacental transfer

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of these emerging contaminants of concern.

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One limitation of the present study is the relatively small sample size, which consisted of 32

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maternal-fetal pairs. However, based on these findings, expanded studies with larger sample size

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are warranted. Proteins and phospholipids in the sera and placentas may have an influence on

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both the distribution and mechanism of placental transfer of these chemicals.5, 43, 44 Thus, future

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studies of protein binding and phospholipid partitioning behavior in sera and tissues would

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undoubtedly help to better understand the placental transfer and prenatal exposure risks of these

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emerging contaminants of concern.

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ASSOCIATED CONTENT

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Supporting Information. Additional information including supplemental tables (Tables S1-S4),

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supplemental figure (Figures S1-S2) and supplemental references are available free of charge via

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the Internet at http://pubs.acs.org.

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Acknowledgments. This work was supported by the National Natural Science Foundation of

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China (Key Program Grant No. 21427815 and International Cooperation Grant No.

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21320102007) and the China Postdoctoral Science Foundation (Grant No. 2015M580514). We

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thank the medical staffs at Wuhan No.1 Hospital for collecting the serum and placenta samples.

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Dr. Ting Ruan is acknowledged for donation of the standards of 6:2 Cl-PFESA and 8:2 Cl-

329

PFESA.



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Figure Captions Figure 1. Box chart of Cl-PFESA and PFOS concentrations in matched maternal, cord serum (ng/mL) and placenta (ng/g). The boxes represent the 25th, 50th and 75th percentiles. The whiskers mark the maximum and minimum values excluding outliers.



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Table 1. Demographic characteristics of the mothers and neonates in this study. Characteristics

Pairs

Maternal characteristics Maternal Age (year) Pregnancy weight gain (kg) Pre-Pregnancy Body mass index (BMI) (kg m-3) Maternal serum total protein (g/L) Maternal serum albumin (g/L) Parity Primiparous Multiparous Abortion 0 1 2 3 Drinking water source Tap Water Filtered tap water Smoking habit Non-Smoking Smoking Alcohol drinking habit Non-drinking Drinking Diet preference Vegetables Meat Seafood Occupation Technicians Public servants Business owners Management stuff Industrial workers Unemployed Others Neonatal characteristics Gender Male Female Weight (kg) Head circumference (cm) Gestational age (week)

Counts

32 24 24 31 31 31

% or (Mean ± SD) 27.1 20.5 20.4 70.4 35.8

± 2.8 ± 5.7 ± 2.5 ± 7.9 ± 3.5

15 16

46.8 53.1

16 12 1 2

51.6 37.5 3.1 6.3

26 6

81.2 18.8

30 2

93.8 6.3

31 1

96.9 3.1

17 13 3

53.1 40.6 9.4

3 2 5 3 2 8 8

9.7 6.5 16.1 9.7 6.5 25.8 25.8

17 14

53.1 46.9 3.4 ± 0.5 34.0 ± 1.8 38.9 ± 1.6

31

32

32

32

31

32

31

30 30 30


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Table 2. Concentrations of Cl-PFESAs and PFOS in matched maternal serum, cord serum and placenta (n = 32, ng/mL for serum and ng/g wet weight for placenta). 6:2 Cl-PFESA 8:2 Cl-PFESA Maternal Cord Maternal Cord Serum Serum Placenta Serum Serum Placenta n = 32 n = 32 n = 32 N (% > MQL*) 100 100 100 84.4 81.3 28.1 Max 4.44 2.64 1.78 0.21 0.08 0.07 Min 0.23 0.10 0.04 < MQL < MQL < MQL Mean 1.88 0.78 0.42 0.02 0.01 0.01 Median 1.54 0.60 0.34 0.01 0.01 < MQL SD** 1.19 0.57 0.32 0.04 0.02 0.01 * MQL: matrix-specific quantitation limits ** SD: standard deviation


Maternal Serum

PFOS Cord Serum

Placenta

100 22.9 1.73 8.67 7.01 5.27

100 12.7 0.54 3.67 3.64 2.51

100 1.38 0.06 0.42 0.35 0.30


Table 3. Summary statistics of the cord-maternal and placental-maternal ratios (dimensionless) for Cl-PFESAs and PFOS. 6:2 Cl-PFESA 8:2 Cl-PFESA PFOS RCM RPM RCM RPM RCM RPM n = 32 n = 32 n = 18 n = 32 n = 32 Max 0.828 0.431 0.941 NA* 0.770 0.091 Min 0.130 0.117 0.308 NA 0.186 0.032 Mean 0.436 0.240 0.617 NA 0.431 0.048 1st Quartile 0.273 0.185 0.438 NA 0.322 0.037 Median 0.403 0.201 0.557 NA 0.399 0.045 3rd Quartile 0.554 0.273 0.783 NA 0.534 0.056 * Due to the detection frequency of 8:2 Cl-PFESA in placenta was less than 50%, the RPM was absent in the statistics.


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Table 4. Linear relationships between logC-logMa and logP-logMa for Cl-PFESAs and PFOS. Compound Equation (C-M) R2 p-value Equation (P-M) 6:2 Cl-PFESA logC = 0.91 logM -0.39 0.65 p < 0.001 logP = 0.88 logM -0.64 8:2 Cl-PFESA logC = 0.76 logM -0.58 0.81 p < 0.001 NAb PFOS logC = 0.97 logM -0.36 0.77 p < 0.001 logP = 1.08 logM -1.42 a C: cord serum concentration; M: maternal serum concentration; P: placental concentration b NA: not available due to detection frequency of 8:2 Cl-PFESA in placenta was < 50%.


R2 0.73 NA 0.86

p-value p < 0.001 NA p < 0.001


Figure 1.


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Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in ... - ACS Publications

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