Human Exposure to Short- and Medium-Chain Chlorinated Paraffins

Subscriber access provided by Fudan University

Article

Human Exposure to Short- and Medium-Chain Chlorinated Paraffins via Mothers’ Milk in Chinese Urban Population Dan Xia, Lirong Gao, Minghui Zheng, Jingguang Li, Lei Zhang, Yongning Wu, Qichang Tian, Huiting Huang, and Lin Qiao Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.6b04246 • Publication Date (Web): 08 Dec 2016 Downloaded from http://pubs.acs.org on December 8, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 29

Environmental Science & Technology

Human Exposure to Short- and Medium-Chain Chlorinated Paraffins via Mothers’ Milk in Chinese Urban Population

1 2 3 4

Dan Xia,†,‡ Lirong Gao,*,† Minghui Zheng,† Jingguang Li,§,║ Lei Zhang,§,║ Yongning Wu*§,║

5

Qichang Tian,† Huiting Huang,†,‡ and Lin Qiao†,‡

6

†

7

Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

8

‡

University of Chinese Academy of Sciences, Beijing 100085, China

9

§

The Key Laboratory of Food Safety Risk Assessment, Ministry of Health, China National

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for

10

Center of Food Safety and Risk Assessment, Beijing 100021, China

11

║

12

Prevention, 29 Nanwei Road, Beijing 100050, China

13

*Corresponding author: Lirong Gao, Tel.: +861062849356, Fax: +861062923563, E-mail

14

address: [email protected]; Yongning Wu, Tel. & Fax: +861052165589, E-mail address:

15

[email protected]

National Institute of Nutrition and Food Safety, Chinese Center for Disease Control and

16

1

ACS Paragon Plus Environment


17

ABSTRACT: Chlorinated paraffins (CPs) are high production volume synthetic chemicals,

18

found ubiquitously in various environmental matrices. However, little information is

19

available on CP contamination in mothers’ milk. In this study, 1,370 urban mothers’ milk

20

samples were collected from 12 Chinese provinces in 2007 and 16 provinces in 2011. CP

21

geographical distribution and congener group profiles were studied to assess the CP levels

22

and figure out the source of exposure in humans. Twenty-eight pooled samples were analyzed

23

for 48 short-chain CP (SCCP) and medium-chain CP (MCCP) congener groups using the

24

GC×GC-ECNI-HRTOFMS method. The median concentrations of SCCPs were 681 and 733

25

ng/g lipid in 2007 and 2011, respectively; median concentrations of MCCPs were 60.4 and

26

64.3 ng/g lipid in 2007 and 2011, respectively. Variations of more than 2 orders of magnitude

27

in CP exposure levels were found between different provinces. The levels of CPs increased

28

from 2007 to 2011, which indicates that CP production and use may be an important exposure

29

source. This is the first global comprehensive and large-scale investigation of CPs in mothers’

30

milk, and it lays foundations for improving our understanding of the metabolism of CPs in

31

humans. The high CP concentrations found in Chinese mothers’ milk should raise concern

32

about potential toxic effects in both mothers and breastfeeding infants.

33

2


Page 2 of 29

Page 3 of 29


34

INTRODUCTION

35

Chlorinated paraffins (CPs) are known as the most complex groups of organohalogen

36

pollutants in the environment, with homologues and isomers far exceeding 10,000.1

37

Commercial mixtures of CPs are produced by chlorination of n-alkane feedstocks and are

38

classified into short-chain CPs (SCCPs, C10–13), medium-chain CPs (MCCPs, C14–17), and

39

long-chain CPs (LCCPs, C18–30) based on their carbon chain length, with chlorination degree

40

varying from 30% to 70%. CPs are used in many applications, mainly as lubricant, cutting

41

fluid, flame retardants and plasticizers in PVC, rubber, paints, coatings, and sealants.2

42

Persistent organic pollutants (POPs) are toxic chemicals that persist in the environment and

43

adversely affect human health and the environment.3 Studies have shown that CPs persist in

44

the environment and could be prone to long-range atmospheric transport because of their

45

semi-volatile properties. SCCPs can bioaccumulate and biomagnify through food webs, likely

46

posing ecological and health risks to wildlife and humans.4-6 SCCPs have been listed as

47

candidate POPs under the Stockholm Convention,3 and have also been placed on the Toxics

48

Release Inventory (TRI) in the European Union, Japan, and Canada, and classified as priority

49

toxic substances in the United States.6

50

The global cumulative production of CPs has been approximately seven million tons

51

since the 1930s, and no other anthropogenic persistent organic chemical has been produced in

52

such quantities.7 Although some information is available on the global occurrence of CPs in

53

various environmental matrices, human exposure data remain scarcer, mainly because of the

54

complexity of CP mixtures and analytical difficulties encountered when studying them.8,9

55

Mothers’ milk is a unique biological matrix for investigating the human exposure pathways 3



56

of certain environmental contaminants, because it can provide exposure information for both

57

the mother and breastfeeding infant.10 The significance of mothers’ milk as an exposure

58

medium for humans has been shown for polychlorinated dibenzodioxins/furans (PCDD/Fs),11

59

polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs).12,13

60

However, human exposure to CPs though mothers’ milk has rarely been investigated. A study

61

on three mothers’ milk samples from Quebec, Canada, was the first to show the presence of

62

SCCPs in mothers’ milk.14 Thomas et al. reported levels of SCCPs and MCCPs in mothers’

63

milk samples from Lancaster and London, U.K..15 The sampling was limited geographically,

64

and the congener group patterns and exposure sources of CPs remain unclear. Moreover, no

65

comprehensive and large-scale investigation of CPs exposure levels in mothers’ milk has yet

66

been conducted.

67

China is the largest producer and consumer of CP-based products in the world. CP

68

production volume has been continuously and rapidly growing during the past decade, from

69

about 0.6 million tons in 2007 to about 1 million tons in 2010.7,16 Three main commercial CP

70

mixtures (CP-42, CP-52, and CP-70) are produced and used on a large scale.17 In recent years,

71

CPs have been found to be prevalent in the environment in China. One study indicated that

72

relatively high SCCPs concentrations were found in aquatic organisms from Liaodong Bay,

73

North China.18 Zhou et al. also reported high levels of CPs in wildlife in Yangtze River

74

Delta.19 Harada et al. found, by analyzing composite food samples (a sample being all the

75

food and drinks a participant consumed in a 24 h period), that dietary intakes of SCCPs in

76

Beijing increased by two orders of magnitude between 1993 and 2009, and may be related to

77

the increasing production and use of CPs in China.20 Human exposure for CPs though 4


Page 4 of 29

Page 5 of 29


78

mothers’ milk may also be great in this country with continued heavy production and

79

consumption of CPs. To better understand the occurrence, sources, and accumulation of CPs

80

in mothers’ milk, this study focused on CP exposure status in China, the most typical

81

CP-polluted country.

82

In this study, 1,370 individual urban mothers’ milk samples were collected and analyzed

83

for SCCPs and MCCPs simultaneously using the comprehensive two dimensional gas

84

chromatography coupled to electron capture negative ionization high-resolution time-of-flight

85

mass spectrometry (GC×GC-ECNI-HRTOFMS) method for the first time.21 With increased

86

chromatographic separation and high resolution of mass spectrometry, this method can

87

effectively exclude interference from other CP congeners and organohalogen compounds,

88

thus providing more accurate and precise analytical results for concentrations and congener

89

group profiles of CPs in mothers’ milk.

90

The objective of this study was to conduct the first comprehensive and large-scale

91

investigation of CP exposure in mothers’ milk. The national geographical distribution and

92

congener profiles of CPs were studied to assess the levels, and figure out the sources of CPs

93

exposure in humans. In addition, the CP concentrations in mother’s milk in 2007 and 2011

94

were compared, and the changes were assessed in relation to CP production and use.

95

EXPERIMENTAL SECTION

96

Sample collection. Individual mothers’ milk samples were collected from urban areas in

97

12 Chinese provinces in 2007 and 16 provinces in 2011. The approach for mothers selection

98

and mothers’ milk sampling followed the “Guidelines for Developing a National Protocol” of

99

the Fourth WHO-Coordinated Survey of Mothers’ milk for Persistent Organic Pollutants in 5



Page 6 of 29

100

Cooperation with UNEP.22,23 The locations of the 16 provinces in China are shown in Figure

101

1, and the 12 provinces from 2007 were also part of sampling provinces in 2011. Other

102

relevant sampling information regarding donor ages and sample collection is detailed in the

103

Table 1. Fifty donors were selected in urban sites in each province, and at least 50 mL of milk

104

for each participant, was collected directly to the pre-washed glass jars. A total of 570

105

mothers’ milk samples from 12 provinces in 2007 and 800 samples from 16 provinces in

106

2011 were obtained. The samples were stored at −20°C until analysis. The fifty individual

107

samples from each province were pooled to give one pooled sample before analysis, resulting

108

in 12 pooled samples in 2007 and 16 pooled samples in 2011.

109

Sample preparation. Briefly, approximately 30 mL of pooled mothers’ milk sample 13

110

was freeze-dried and spiked with 2.5 ng of

111

Cambridge Isotope Laboratories), then extracted with a 1:1 mixture of dichloromethane and

112

n-hexane using an ASE 350 extraction unit (Dionex, Sunnyvale, CA, USA). Lipid content

113

was determined gravimetrically after solvent evaporation. Gel permeation chromatography

114

was used to remove lipids from the extract, which was then cleaned through a multi-layered

115

column, from bottom to top, 3 g of activated Florisil, 2 g of activated silica gel, 5 g of

116

acidified silica gel (containing 30% w/w of concentrated sulfuric acid), and 4 g of anhydrous

117

sodium sulfate. The cleaned extract was concentrated, solvent-exchanged into cyclohexane,

118

evaporated to approximately 50 µL in a vial containing 2.5 ng of ε-hexachlorocyclohexane

119

(obtained from Dr. Ehrenstorfer). Sample extraction and cleanup procedures of CPs are

120

detailed in the Supplemental Material.

121

Analytical

quantification.

C10-labeled trans-chlordane (purchased from

Instrumental

analysis

6


was

conducted

using

Page 7 of 29


122

GC×GC-ECNI-HRTOF-MS (a GC instrument (Agilent, Santa Clara, CA, USA) coupled to a

123

HRTOF-MS instrument (Tofwerk, Thun, Switzerland) which operated in ECNI mode).

124

Forty-eight SCCPs (C10−13Cl5−10) and MCCPs (C14−17Cl5−10) formula congener groups were

125

quantified in one injection. Detailed information about the identification and quantification

126

procedures was given in our previous work about the GC×GC-ECNI-HRTOF-MS method

127

development,21 and detailed in the Supplemental Material.

128

Quality assurance/quality control. To minimize contamination, all glassware used in

129

this study was heated to 450°C before usage. Seven mothers’ milk samples were analyzed in

130

each batch, and one procedural blank was also performed in each batch. These procedural

131

blanks were extracted and analyzed in the same way as the samples. Levels in blanks were on

132

average 8.1 ng/sample for SCCPs and 2.4 ng/sample for MCCPs. The method detection limit

133

(MDL) for SCCPs and MCCPs was calculated by tripling the standard deviation of the

134

average levels of seven blanks samples. The MDLs were estimated to about 5.6 ng/g lipid for

135

SCCPs and 2.0 ng/g lipid for MCCPs, respectively. As the mean concentrations of the blanks

136

were lower than one-tenth of the SCCP and MCCP concentrations in mothers’ milk samples,

137

results were not blank corrected. The recoveries of

138

milk samples were in the range of 57%−119%, with an average of 92%.

13

C10-labeled trans-chlordane from the

139

Statistical analysis. Statistical analysis was performed with IBM SPSS Statistics 22.0,

140

and statistical significance was accepted at p-Values < 0.05. Correlations between the

141

concentrations of SCCPs and MCCPs were analyzed using the spearman correlation analysis.

142

RESULTS AND DISCUSSION

143

CP levels in mothers’ milk. The concentrations of total SCCPs, MCCPs, and different 7



144

carbon chain length homologues (C10-17) are summarized in Table 2. SCCPs and MCCPs

145

were detectable in all mothers’ milk samples. Total SCCP concentrations measured in 2007

146

ranged from 170 ng/g lipid (in Sichuan Province) to 6,150 ng/g lipid (in Hebei Province),

147

with a median value of 681 ng/g lipid. MCCP concentrations were between 18.7 ng/g lipid (in

148

Sichuan Province) and 350 ng/g lipid (in Hebei Province), with median of 60.4 ng/g lipid. In

149

2011, the median SCCP concentration was 733 ng/g lipid, and values ranged from 131 ng/g

150

lipid (in Neimenggu Province) to 16,100 ng/g lipid (in Hebei Province). MCCP concentration

151

were in the range of 22.3 ng/g lipid (in Neimenggu Province) and 1,501 ng/g lipid (in Hebei

152

Province), with a median value of 137 ng/g lipid. The ubiquitous detection of CPs in mothers’

153

milk suggested that both SCCPs and MCCPs can reach to human to a large extent.

154

The CP concentrations we found in mothers’ milk were typically present at the highest

155

levels compared with other POPs reported in mothers’ milk in China. These CPs levels were

156

higher than levels reported for dichloro-diphenyl-trichloroethanes (DDTs) (mean, 526 ng/g

157

lipid), and are 1–3 orders of magnitude higher than those found for PBDEs (median, 1.49

158

ng/g lipid) and indicator PCBs concentrations (median, 10.5 ng/g lipid) in mothers’ milk from

159

the same 2007 samples.23,24 Globally, higher PCBs levels were found in mothers’ milk from

160

Europe and Northern America than those in other areas, which may related to the PCBs

161

production and usage.25 The large amounts of CPs produced and used in China could partly

162

explain why the SCCP and MCCP concentrations in the samples were much higher than the

163

concentrations of other POPs that have been found in mothers’ milk.

164

Difficulties in analyzing complex CP mixtures are responsible for the lack of data on

165

SCCP and MCCP levels in human mothers’ milk. SCCP levels in human mothers’ milk were 8


Page 8 of 29

Page 9 of 29


166

determined only in two countries (Canada and the U.K.), while MCCP levels were measured

167

only in the U.K..14,15 Compared with these two studies, CP levels in this study are up to 1–2

168

orders of magnitude higher than those found in Canada (11.0–17.0 ng/g lipid) and the U.K.

169

(49–820 ng/g lipid) for SCCPs, and 0.81–14.0 ng/g lipid for MCCPs in the U.K. The high CP

170

concentrations we found in mothers’ milk were in line with the high CP concentrations that

171

have been found in sediment (320 to 6,600 ng/g dry weight (dw) for SCCPs and 880 to

172

38,000 ng/g dw for MCCPs) and biota (280 to 3,900 ng/g dw for SCCPs and 530 to 23,000

173

ng/g dw for MCCPs) in China.16,26

174

Generally, significant correlations between SCCP and MCCP concentrations were found

175

in Chinese mothers’ milk samples (R2 = 0.82, 2007; R2 = 0.85, 2011, p < 0.001). This

176

suggests that the two contaminants groups may have similar sources and undergo similar

177

uptake pathways. Similar positive correlations between SCCP and MCCP concentrations

178

were also found in dolphins and porpoises in the South China Sea.26 The possible reason for

179

these observations is that n-alkane feedstocks used to produce CPs are not strictly grouped by

180

carbon chain length, meaning that commercial products used in China are mixtures of SCCPs

181

and MCCPs with different carbon chain lengths.17

182

SCCP concentrations were much higher than those of MCCPs in all mothers’ milk

183

samples in the two sampling years. Higher SCCP concentrations were also found in samples

184

in the U.K. mothers’ milk samples and indoor air and dust samples in Sweden.15,27 The

185

transfer of contaminants to humans is the result of exposure from various sources, including

186

emissions during production, processing and use, food, and in vivo metabolism processes.15

187

The results of modeling and laboratory studies indicate that SCCPs and MCCPs are 9



188

hydrophobic (with log octanol–water partition coefficients of 5.9–8.1) that can

189

bioaccumulate.28 Exposure experiments using fish have indicated that CP bioaccumulation

190

potentials generally increase with the chain length and chlorine content of the CP.29 Humans

191

could be exposed to CPs through the diet and the inhalation of indoor air and dust. Human

192

exposure to CPs through inhaling indoor air and dust could be an important reason for the

193

SCCP concentrations being higher than the MCCP concentrations in the mothers’ milk

194

samples. Differences in the metabolisms of humans and other biota and differences in the

195

overall transfer efficiencies of SCCPs and MCCPs in humans could also account for these

196

results. Overall, this topic deserves further investigation.

197

Geographical distribution differences. We collected samples from 12 provinces in

198

2007 and 16 provinces in 2011. Spatial distribution of SCCPs and MCCPs in mothers’ milk

199

samples is important, as for the assessment of its sources. Figure 2 shows that variations of

200

more than 2 orders of magnitude in SCCP and MCCP concentrations were found among

201

different provinces.

202

The highest SCCP levels were found in Hebei and Henan provinces in both sampling

203

years. Based on background distribution information of CP-manufacturing plants in China,30

204

Hebei and Henan provinces are the major Chinese production bases of CPs, and are

205

characterized by high industrialization. Overall, there is a good correlation between the

206

regional distribution of CP production and the high CPs levels found in this study. With most

207

of the CPs manufacturing plants located in eastern China, high CP concentrations were found

208

in eastern parts, such as Jiangxi province, Liaoning province, and the city of Shanghai. The

209

release of CPs into the environment could occur during production, storage, transportation, 10


Page 10 of 29

Page 11 of 29


210

and industrial use of manufactured products.31 CPs can enter the aquatic environment in

211

runoff, biomagnify through the food chain, and finally be transferred to humans. The release

212

of CPs from materials in which they are present is a source of CPs to humans in the indoor

213

environment. 27 Increases in the production and use of CPs will increase the amounts of CPs

214

released into the environment in urban areas. The production and use of CPs in urban areas

215

may therefore be important sources of CPs found in mothers’ milk in those areas.

216

Levels of SCCPs and MCCPs from Neimenggu, Qinghai, Sichuan, and Ningxia

217

Provinces were much lower than those in other provinces. There are few or no CP

218

manufacturing plants and industrial activities in these provinces. Low CP levels in these areas

219

may result from long-range atmospheric transport of CPs. For future studies, these locations

220

may be regarded as background areas for national POPs monitoring.

221

Congener group profiles of SCCPs and MCCPs. Figures 3 show the SCCP and

222

MCCP congener patterns of 28 pooled mothers’ milk samples from different provinces for

223

both sampling years. Both the carbon and chlorine congener group profiles are shown. In

224

general, the congener group patterns of SCCP and MCCP in all samples were similar among

225

the sampling provinces, although the SCCPs and MCCPs concentrations varied between

226

provinces. The most abundant SCCP congener groups were C10 and C11, which accounted for

227

approximately 47% and 31% of total SCCPs, respectively. For MCCPs, the most abundant

228

group was C14, accounting for approximately 70% of total MCCPs. For the chlorine congener

229

group profiles of SCCPs, Cl6-CPs and Cl7-CPs dominated in most mothers’ milk samples,

230

contributed to the total abundance of SCCPs were 31% and 43%. For MCCPs, the main

231

congeners Cl7-CPs and Cl8-CPs showed notably higher mean abundance than other chlorine 11



232

atom congeners, accounting for approximately 34% and 40% of total MCCPs.

233

Congener patterns of SCCPs and MCCPs in mothers’ milk are a function of exposure

234

and metabolism processes. The SCCP congener group patterns we found were different from

235

those reported in mothers’ milk samples in the U.K.,15 where CPs were dominated by C11 and

236

C12 homologues. The difference indicates that exposure sources may differ between the U.K.

237

and China. The SCCP congener group patterns were similar to those in dolphins and

238

porpoises collected from Chinese marine areas, where C10-CPs and C11-CPs predominated.26

239

Congener patterns in the environment can also reflect those in commercial CP mixtures.32

240

Consistent with this, SCCP congener profiles identified in the present study reflect the two

241

major industrial CP mixtures manufactured in China, CP-42 and CP-52, which are dominated

242

by C10-CPs and C11-CPs;33 while in the U.K., the technical mixtures were dominated by

243

C11-CPs and C12-CPs.

244

For lower CP exposure areas, such as Guangdong and Qinghai provinces, the congeners

245

of the carbon chains was dominated by C10, accounting for 60.75% and 69.75%, respectively.

246

The Cl6 and Cl7 groups were the most abundant chlorine congener groups. CPs with fewer

247

carbon chains and lower chlorine numbers have relatively higher vapor pressures, and are

248

more favorable for long-range atmospheric transport. This further suggests that long-range

249

atmospheric transport of CPs may be the most important source for areas that lack industrial

250

CP production plants. Meanwhile, the release of CPs from materials containing CPs is also a

251

source of CP exposure in the indoor environment.27 Compared with the low-CP exposure

252

areas, the abundance of longer-chain SCCPs (C11-CPs, C12-CPs and C13-CPs) and higher

253

chlorinated congeners (Cl7−10) significantly increased in the high-CP exposure areas such as 12


Page 12 of 29

Page 13 of 29


254

Hebei and Liaoning provinces. These specific congener distributions may be influenced by

255

the difference in constitution of CP technical mixtures produced and used in China. The

256

relative contribution of carbon chain groups to SCCP totals in mothers’ milk in Hebei

257

Province in 2011 (C10 = 35%, C11 = 33%, C12 = 16%, C13 = 15%) is similar to results reported

258

for technical CP-52 samples (C10 = 35%, C11 = 34%, C12 = 24%, C13 = 7%).34 This pattern

259

from other mothers’ milk samples further indicate that production is a source of CP exposure

260

in Chinese human mothers’ milk.

261

Comparison of CP concentrations in mothers’ milk in 2007 and 2011. Between the

262

two sampling years, the SCCPs and MCCPs concentrations in 2007 samples were lower than

263

those measured in 2011 samples (Figure 4). SCCP and MCCP median concentrations increase

264

between 2007 (681 ng/g lipid for SCCPs and 60.4 ng/g lipid for MCCPs) and 2011 (733 ng/g

265

lipid for SCCPs and 64.3 ng/g lipid for MCCPs) with rates of increase of 7.1% and 6.1%,

266

respectively.

267

The increase in CP levels found in mothers’ milk are in accordance with the increasing

268

production volumes and use of CPs during this period. These results are also in good

269

agreement with increasing CP deposition concentrations found in sediment cores in China,35

270

and the significant increase observed in marine mammals (porpoises and dolphins) over the

271

past decade in the South China Sea.26 In addition, the increases in CP concentrations in

272

mothers’ milk were consistent with the increases in the concentrations of other POPs, such as

273

PBDEs and perfluorinated compounds, in various environmental matrices related to marked

274

increases in the production and use of those compounds. 36,37

275

SCCPs have been listed as priority hazardous substances by the European Union, and 13



276

the production of SCCPs has been voluntarily reduced from 13,000 tons in 1994 to 4,000 tons

277

in 1998 by the European industrial sector.9 Although SCCPs have been under review by the

278

Stockholm Convention as candidate POPs since 2007, the production and use of CPs in

279

China is currently not restricted in industrial activity. Annual production output grew

280

five-fold between 2004 and 2009, and reached a new high in 2015.30 The increase of SCCP

281

and MCCP levels in Chinese mothers’ milk are in good agreement with the history of CP

282

production and use in China over the past decade. Meanwhile, it can be inferred that

283

increasing production and use of CPs would further increase environmental release in regions

284

with rapid economic development and industrial activities.

285

Variations in both SCCP and MCCP carbon chain lengths and congener group profiles in

286

the samples were also observed between the two sampling periods (Figure 3). An increase

287

was observed for total abundances of C10 and C11 SCCPs in 2011 relative to 2007 in high-CP

288

exposure areas, such as Hebei and Henan provinces. This finding may be linked to the

289

continuing production of CP-42 and CP-52 in technical mixtures during this period. There

290

were no significant changes in the MCCP homologue pattern observed in the samples. C14

291

was the most abundant MCCP homologue group in both sampling years. Overall, the increase

292

in CP concentrations in Chinese mothers’ milk, combined with the prevalence of C10 and C11

293

SCCPs in both sampling years may indicate that emissions from urban production and use

294

may still be the most important source of CP exposure in China.

295

Environmental implications. This is the first comprehensive and large-scale

296

investigation of CP exposure levels in mothers’ milk, and also the first report of SCCPs and

297

MCCPs in mothers’ milk in China. Concentrations of SCCPs and MCCPs in Chinese mothers’ 14


Page 14 of 29

Page 15 of 29


298

milk were much higher than those reported in other countries, and higher than other

299

contaminants of concern, such as OCPs, PBDEs, PCDD/Fs, and PCBs in the same samples.

300

SCCPs have been found to be hepatotoxic in trout at high levels of exposure.38 Carcinogenic

301

effects in rats and mice have also been observed for SCCPs.39 Considering the persistence

302

and bioaccumulative properties of these contaminants, detection of high levels CPs in

303

Chinese mothers’ milk should raise concern for potential toxicity to both the mother and

304

breastfeeding infant.

305

Nationwide geographical differences of SCCP and MCCP exposure levels in urban

306

mothers’ milk were observed in 16 provinces. CP production may be an important source of

307

CP exposure in some urban areas, while the atmospheric transport of CPs is likely the source

308

in low-CP exposure areas. SCCP and MCCP levels in 2011 samples were higher than those in

309

2007 samples. This may be explained by increasing CP production and related urban

310

industrial activities. Increasing levels of these contaminants may pose a risk, especially to the

311

developing fetus and breastfeeding infant. Therefore, regulatory actions governing these

312

contaminants may be needed to reduce emissions of CPs and human exposure in China. In

313

the meantime, more detailed studies are required to determine the major human exposure

314

pathways in the general population, such as indoor air, dust and food, along with an

315

evaluation of the metabolic pathways and possible biological effects involved at these levels

316

of exposure.

317

ASSOCIATED CONTENT

318

Supporting Information

15



319

Additional information is available as noted in the text. This material is available free of

320

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

321

AUTHOR INFORMATION

322

Corresponding Author

323

*E-mail: [email protected]; [email protected]

324

Notes

325

The authors declare no competing financial interest.

326

ACKNOWLEDGMENTS

327

This research was funded by the National 973 program (No. 2015CB453100), the National

328

Natural Science Foundation of China (Nos. 21377140, 21361140359, 21577152, 21537001

329

and 21321004) and the Strategic Priority Research Program of the Chinese Academy of

330

Sciences (No. XDB14010100 and XDB14020102).

331

REFERENCES

332

(1) Eljarrat, E.; Barcelo, D. Quantitative analysis of polychlorinated n-alkanes in

333 334 335

environmental samples. TrAC, Trends. Anal. Chem. 2006, 25 (4), 421–434. (2) Feo, M. L.; Eljarrat, E.; Barceló, D. Occurrence, fate and analysis of polychlorinated n-alkanes in the environment. TrAC, Trends Anal. Chem. 2009, 28 (6), 778–791.

336

(3) Persistent Organic Pollutants Review Committe (PORC). Revised draft risk profile:

337

short-chain chlorinated paraffins; United Nations Environment Programme (UNEP),

338

Geneva, Switzerland, 2011. 16


Page 16 of 29

Page 17 of 29


339

(4) Jansson, B.; Andersson , R.; Asplund, L.; Litzen, K.; Nylund, K.; Sellstrom, U.; Uvemo,

340

U. B.; Wahlberg, C.; Wideovist, U.; Odsjo, T.; Olsson, M. Chlorinated and brominated

341

persistent organic-compounds in biological samples from the environment. Environ.

342

Toxicol. Chem. 1993, 12 (7), 1163−1174.

343

(5) Houde, M.; Muir, D. C. G.; Tomy, G. T.; Whittle, D. M.; Teixeira, C.; Moore, S.

344

Bioaccumulation and trophic magnification of short- and medium-chain chlorinated

345

paraffins in food webs from Lake Ontario and Lake Michigan. Environ. Sci. Technol.

346

2008, 42 (10), 3893−3899.

347

(6) de Boer, J.; El-Sayed Ali, T.; Fiedler, H.; Legler, J.; Muir, D. C.; Nikiforov, V. A.; Tomy,

348

G. T.; Tsunemi, K. Chlorinated Paraffins. In The Handbook of Environmental Chemistry,

349

Chlorinated Paraffins; De Boer, J., Ed.; Springer-Verlag Berlin: Berlin 2010; Vol. 10.

350

(7) van Mourik, L. M.; Gaus, C.; Leonards, P. E. G.; de Boer, J. Chlorinated paraffins in the

351

environment: A review on their production, fate, levels and trends between 2010 and

352

2015. Chemosphere 2016, 155, 415–428.

353

(8) Sverko, E.; Tomy, G. T.; Marvin, C. H.; Muir, D. C. Improving the quality of

354

environmental measurements on short chain chlorinated paraffins to support global

355

regulatory efforts. Environ. Sci. Technol. 2012, 46 (9), 4697–4698.

356

(9) van Mourik, L. M.; Leonards, P. E.; Gaus, C.; de Boer, J. Recent developments in

357

capabilities for analysing chlorinated paraffins in environmental matrices: A review.

358

Chemosphere 2015, 136, 259–272.

359

(10) Fiedler, H.; Abad, E.; van Bavel, B.; de Boer, J.; Bogdal, C.; Malisch, R. The need for

360

capacity building and first results for the Stockholm Convention Global Monitoring Plan. 17



361 362 363

TrAC, Trends Anal. Chem. 2013, 46, 72–84. (11) Hedley, A. J.; Wong, T. W.; Hui, L. L.; Malisch, R.; Nelson, E. A. S. Breast milk dioxins in Hong Kong and pearl River Delta. Environ. Health Perspect. 2006, 114 (2), 202–208.

364

(12) Gladen, B. C.; Monaghan, S. C.; Lukyanova, E. M.; Hulchiy, O. P.; Shkyryak-Nyzhnyk,

365

Z. A.; Sericano, J. L.; Little, R. E. Organochlorines in breast milk from two cities in

366

Ukraine. Environ. Health Perspect. 1999, 107 (6), 459–462.

367

(13) Schecter, A.; Pavuk, M.; Papke, O.; Ryan, J. J.; Birnbaum, L.; Rosen, R.

368

Polybrominated diphenyl ethers (PBDEs) in US mothers' milk. Environ. Health Perspect.

369

2003, 111 (14), 1723–1729.

370

(14) Tomy, G. T. The mass spectrometric characterization of polychlorinated n-alkanes and

371

the methodology for their analysis in the environment. University of Manitoba, winnipeg.

372

1997.

373

(15) Thomas, G. O.; Farrar, D.; Braekevelt, E.; Stern, G.; Kalantzi, O. I.; Martin, F. L.; Jones,

374

K. C. Short and medium chain length chlorinated paraffins in UK human milk fat.

375

Environ. Int. 2006, 32 (1), 34–40.

376

(16) Chen, M. Y.; Luo, X. J.; Zhang, X. L.; He, M. J.; Chen, S. J.; Mai, B. X. Chlorinated

377

paraffins in sediments from the Pearl River Delta, South China: Spatial and temporal

378

distributions and implication for processes. Environ. Sci. Technol. 2011, 45 (23),

379

9936–9943.

380 381 382

(17) Tang, E. T.; Yao, L. Q. Industry status of chlorinated paraffin and its development trends. China. Chlor-Alkali. 2005, 2, 1–3. (in Chinese) (18) Ma, X. D; Zhang, H. J.; Wang, Z.; Yao, Z. W.; Chen, J. W.; Chen, J. P. Bioaccumulation 18


Page 18 of 29

Page 19 of 29


383

and trophic transfer of short chain chlorinated paraffins in a marine food web from

384

Liaodong Bay, North China. Environ. Sci. Technol. 2014, 48 (10), 5964–5971.

385

(19) Zhou, Y.; Asplund, L.; Yin, G.; Athanassiadis, I.; Wideqvist, U.; Bignert, A.; Qiu, Y.;

386

Zhu, Z.; Zhao, J.; Bergman, A., Extensive organohalogen contamination in wildlife from

387

a site in the Yangtze River Delta. Sci. Total. Environ. 2016, 554-555, 320–328.

388

(20) Harada, K. H.; Takasuga, T.; Hitomi, T.; Wang, P.; Matsukami, H.; Koizumi, A. Dietary

389

exposure to short-chain chlorinated paraffins has increased in Beijing, China. Environ. Sci.

390

Technol. 2011, 45 (16), 7019–7027.

391

(21) Xia, D.; Gao, L. R.; Zheng, M. H.; Tian, Q, C.; Huang, H. T.; Qiao, L. A novel method

392

for profiling and quantifying short- and medium chain chlorinated paraffins in

393

environmental

394

chromatography−electron capture negative ionization high-resolution time-of-flight mass

395

spectrometry. Environ. Sci. Technol. 2016, 50, 7601–7609.

samples

using

comprehensive

two-dimensional

gas

396

(22) WHO. Fourth WHO-coordinated survey of human milk for persistent organic pollutants

397

in cooperation with UNEP. Guidelines for developing a national protocol, World Health

398

Organization. 2007.

399

(23) Li, J. G.; Zhang, L.; Wu, Y. N.; Liu, Y. P.; Zhou, P. P.; Wen, S.; Liu, J.; Zhao, Y. F.; Li, X.

400

A national survey of polychlorinated dioxins, furans (PCDD/Fs) and dioxin-like

401

polychlorinated biphenyls (dl-PCBs) in human milk in China. Chemosphere 2009, 75 (9),

402

1236–1242.

403

(24) Zhang, L.; Li, J. G.; Zhao, Y. F.; Li, X. W.; Yang, X.; Wen, S.; Cai, Z.; Wu, Y. N. A

404

national survey of polybrominated diphenyl ethers (PBDEs) and indicator polychlorinated 19



405

biphenyls (PCBs) in Chinese mothers' milk. Chemosphere 2011, 84 (5), 625–633.

406

(25) Fang, J.; Nyberg, E.; Winnberg, U.; Bignert, A.; Bergman, A. Spatial and temporal

407

trends of the Stockholm Convention POPs in mothers' milk - a global review. Environ. Sci.

408

Pollut. R. 2015, 22 (12), 8989-9041.

409

(26) Zeng, L. X.; Lam, J. C. W.; Wang, Y. W.; Jiang, G. B.; Lam, P. K. S. Temporal trends and

410

pattern changes of short- and medium-chain chlorinated paraffins in marine mammals

411

from the South China Sea over the past decade. Environ. Sci. Technol. 2015, 49 (19),

412

11348–11355.

413

(27) Friden, U. E.; McLachlan, M. S.; Berger, U. Chlorinated paraffins in indoor air and dust:

414

Concentrations, congener patterns, and human exposure. Environ. Int. 2011, 37 (7),

415

1169–1174.

416

(28) Environment Canada. Follow-up report on a PSL1 substance for which there was

417

insufficient information to conclude whether the substance constitutes a danger to the

418

environment. Chlorinated Paraffins; Environment Canada, Existing Substances Division:

419

Ottawa, ON, 2004.

420

(29) Fisk, A. T.; Tomy, G. T.; Cymbalisty, C. D.; Muir, D. C. G. Dietary accumulation and

421

quantitative structure-activity relationships for depuration and biotransformation of short

422

(C10), medium (C14), and long (C18) carbon-chain polychlorinated alkanes by juvenile

423

rainbow trout (Oncorhyncus mykiss). Environ. Toxicol. Chem. 2000, 19, 1508–1516.

424

(30) Zeng, L. X.; Wang, T.; Ruan, T.; Liu, Q.; Wang, Y. W., Jiang, G. B. Levels and

425

distribution patterns of short chain chlorinated paraffins in sewage sludge of wastewater

426

treatment plants in China. Environ. Pollut. 2012, 160, 88–94. 20


Page 20 of 29

Page 21 of 29


427

(31) Tomy, G. T.; Stern. G. A.; Lockhart, W. L.; Muir, D. C. G. Occurrence of C10–C13

428

polychlorinated n-alkanes in Canadian mid-latitude and arctic lake sediments. Environ.

429

Sci. Technol. 1999, 33, 2858–2863.

430

(32) Peters, A.; Tomy, G.; Stern, G.; Jones, K. Polychlorinated alkanes in the atmosphere of

431

the United Kingdom and Canada—analytical methodology and evidence of the potential

432

for long-range transport. Organohalogen Compd. 1998, 35, 439–442.

433

(33) Gao, Y.; Zhang, H. J.; Su, F.; Tian, Y. Z.; Chen, J. P. Environmental occurrence and

434

distribution of short chain chlorinated paraffins in sediments and soils from the Liaohe

435

River Basin, P. R. China. Environ. Sci. Technol. 2012, 46 (7), 3771–3778.

436

(34) Wei, G. L.; Liang, X. L.; Li, D. Q.; Zhuo, M. N.; Zhang, S. Y.; Huang, Q. X.; Liao, Y. S.;

437

Xie, Z. Y.; Guo, T. L.; Yuan, Z. J. Occurrence, fate and ecological risk of chlorinated

438

paraffins in Asia: A review. Environ. Int. 2016, 92-93, 373–387.

439

(35) Zeng, L. X.; Chen, R.; Zhao, Z. S.; Wang, T.; Gao, Y.; Li, A.; Wang, Y. W.; Jiang, G. B.;

440

Sun, L. G. Spatial distributions and deposition chronology of short chain chlorinated

441

paraffins in marine sediments across the Chinese Bohai and Yellow Seas. Environ. Sci.

442

Technol. 2013, 47 (20), 11449–11456.

443 444

(36) Hites, R. A. Polybrominated diphenyl ethers in the environment and in people: A meta-analysis of concentrations. Environ. Sci. Technol. 2004, 38 (4), 945−956.

445

(37) Holmstrom, K. E.; Johansson, A. K.; Bignert, A.; Lindberg, P.; Berger, U. Temporal

446

Trends of Perfluorinated Surfactants in Swedish Peregrine Falcon Eggs (Falco

447

peregrinus), 1974−2007. Environ. Sci. Technol. 2010, 44 (11), 4083−4088.

448

(38) Cooley, H. M.; Fisk, A. T.; Wiens, S. C.; Tomy, G. T.; Evans, R. E.; Muir, D. C. G. 21



449

Examination of the behavior and liver and thyroid histology of juvenile rainbow trout

450

(Oncorhynchus mykiss) exposed to high dietary concentrations of C-10-, C-11-, C-12-

451

and C-14-polychlorinated N-alkanes. Aquat. Toxicol. 2001, 54, 81–99.

452 453

(39) Wyatt, I.; Coutts, C. T.; Elcombe, C. R. The effect of chlorinated paraffins on hepatic enzymes and thyroid hormones. Toxicology 1993, 77, 81–90.

454

22


Page 22 of 29

Page 23 of 29


455 456 457

Figure 1. The sampling provinces in 2007 and 2011 in China.

23



458

459

Figure 2. Spatial distributions of SCCP and MCCP concentrations (ng/g lipid) in urban

460

mothers’ milk from 16 provinces in China. (Two colors were indicated for two contaminant

461

groups in both years. Blue was indicated for SCCPs and yellow for MCCP in 2007; green

462

was indicated for SCCPs and red for MCCP in 2007)

463

24


Page 24 of 29

Page 25 of 29


464 465

Figure 3. Carbon and chlorine congener group profiles of SCCPs (A) and MCCPs (B) in 28

466

pooled Chinese urban mothers’ milk samples from 16 provinces in 2007 and 2011.

467

25



468

469

Figure 4. Boxes-and whiskers plot of SCCP and MCCP concentrations (ng/g lipid) in

470

Chinese urban mothers’ milk samples in 2007 and 2011.

471

26


Page 26 of 29

Page 27 of 29

472 473


Table 1. Characteristics and description of the participants (the number of participants and the age range in each province) Provinces 2007 Heilongjiang Liaoning Hebei Ningxia Henan Shanxi Shanghai Sichuan Hubei Jiangxi Fujian Guangxi Mean 2011 Heilongjiang Jilin Liaoning Neimenggu Hebei Ningxia Qinghai Henan Shanxi Shanghai Sichuan Hubei Jiangxi Fujian Guangxi Guangdong Mean

Number of participants

Age Average age

Age range

50 50 40 50 50 50 50 30 50 50 50 50 -

25.8 26.4 27.7 25.2 27.6 26.9 27.1 24.2 25.7 23.9 26.0 28.1 26.2

21-30 20-31 21-35 20-36 21-35 21-35 23-35 20-29 19-30 18-33 21-29 23-34 -

50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 -

29.4 28.0 28.1 26.2 26.5 24.6 27 22.5 25.6 26.8 24.9 26.8 24.3 27.0 27.5 28.2 26.5

22-37 22-35 22-35 21-35 20-32 18-35 20-36 20-35 20-29 22-35 18-39 22-36 17-29 22-35 21-34 22-36 -

474

27



Page 28 of 29

475

Table 2. Concentrations (ng/g lipid) of SCCPs, MCCPs, and congener groups in mothers’

476

milk samples from 12 Chinese provinces in 2007 and 16 provinces in 2011 Provinces

2007 Heilongjiang Liaoning Hebei Ningxia Henan Shanxi Shanghai Sichuan Hubei Jiangxi Fujian Guangxi Minimum Maximum Mean Median 2011 Heilongjiang Jilin Liaoning Neimenggu Hebei Ningxia Qinghai Henan Shanxi Shanghai Sichuan Hubei Jiangxi Fujian Guangxi Guangdong Minimum Maximum Mean Median

Percent lipid

∑SCCPs

∑MCCPs

SCCPs concentration ∑C10

∑C11

∑C12

∑C13

MCCPs concentration ∑C14

∑C15

∑C16

∑C17

3.5 3.3 3.0 4.5 2.8 3.9 3.5 2.7 3.0 4.1 3.9 5.0 2.7 5 3.6 3.5

366 1550 6150 175 3010 721 1140 170 215 1230 641 263 170 6150 1300 681

213 677 2180 106 1740 375 460 35.6 112 607 225 174 35.6 2180 575 300

111 392 2040 48.1 796 261 326 75.5 45.4 393 222 63.9 45.4 2040 397 241

32.9 278 1010 15.1 276 64.5 194 42.7 36.4 140 104 15.1 15.1 1010 184 84.2

8.72 202 905 6.39 195 21.0 157 16.0 21.0 91.4 89.9 9.53 6.39 905 143 55.4

21.4 170 350 19.5 243 91.3 107 18.7 26.7 76.0 44.9 26.6 18.7 350 99.6 60.4

17.76 153 274 17.0 184 62.3 97.4 13.8 22.9 57.5 40.2 16.8 13.8 274 79.7 48.8

2.30 11.7 58.3 1.80 46.0 16.6 7.78 2.64 3.02 14.4 3.34 3.78 1.80 58.3 14.3 6.48

0.64 2.75 14.8 0.56 10.4 1.50 1.22 1.25 0.55 3.43 0.62 3.18 0.55 14.8 3.41 2.12

0.21 2.07 2.73 0.17 1.82 10.8 0.38 1.00 0.22 0.72 0.70 2.77 0.17 10.8 1.97 1.08

3.5 3.2 3.4 4.3 3.2 4.4 4.5 3.0 3.9 3.5 2.9 3.0 3.9 3.9 4.5 4.0 2.9 4.5 3.7 3.7

489 368 2180 131 16100 478 203 7060 977 2530 465 1180 1981 1650 342 355 131 16100 2280 733

342 204 1230 16.9 6820 252 124 4210 501 607 135 370 983 613 175 248 16.9 6820 1050 356

126 108 681 26.3 5870 162 50.1 2270 318 839 206 504 541 644 98.2 82.0 26.3 5870 783 262

17.1 37.8 155 33.3 2170 34.5 18.3 453 126 699 88.6 230 290 199 44.0 17.3 17.1 2070 288 107.3

3.43 18.8 114 31.4 1230 29.1 11.4 190 32.2 389 34.5 75.7 167 193 23.8 8.13 3.43 1230 159 33.3

28.5 63.9 409 22.3 1501 40.2 47 736 64.8 355.7 37.3 108 126 102 43.5 47.5 22.3 1501 233 64.3

22.8 41.4 321 13.4 1110 27.5 35.0 651 50.6 327.4 24.7 88.2 91.2 80.2 26.2 35.3 13.4 1110 184 46.0

4.28 10.4 43.6 5.20 171 6.15 5.36 72.8 8.79 20.1 5.57 13.0 21.8 16.9 7.12 5.42 4.28 171 26.0 9.59

1.14 7.42 23.5 2.88 102 2.63 3.19 10.6 3.10 5.70 3.95 4.38 9.18 3.56 5.64 3.22 1.14 102 12.0 5.40

0.29 4.68 23.5 0.85 113 3.96 3.55 2.07 2.33 2.51 3.09 2.40 3.95 0.80 4.50 3.59 0.29 113 10.9 3.57

28


Page 29 of 29

477


Abstract Graphic:

478 479

29


Human Exposure to Short- and Medium-Chain Chlorinated Paraffins

Recommend Documents