Occurrence and Profile Characteristics of the Pesticide Imidacloprid

Nov 16, 2015 - In this study, 295 urine samples collected from subjects in rural and urban areas in China were analyzed for imidacloprid and four para...
0 downloads 9 Views 1012KB Size
Subscriber access provided by UNIV OF LETHBRIDGE

Article

Occurrence and profile characteristics of the pesticide imidacloprid, the preservative parabens, and their metabolites in human urine from rural and urban China Lei Wang, Tianzhen Liu, Fang Liu, Junjie Zhang, Yinghong Wu, and Hongwen Sun Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b04037 • Publication Date (Web): 16 Nov 2015 Downloaded from http://pubs.acs.org on November 20, 2015

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 34

Environmental Science & Technology

1

Occurrence and profile characteristics of the pesticide imidacloprid,

2

the preservative parabens, and their metabolites in human urine

3

from rural and urban China

4 5

Lei Wang†,*, Tianzhen Liu†, Fang Liu†, Junjie Zhang†, Yinghong Wu‡, Hongwen

6

Sun†

7 8 9 10 11



Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300071, China



Tianjin Centers for Disease Control and Prevention, Tianjin 300171, China

12 13 14 15 16 17 18 19 20 21

*Corresponding author: L. Wang Nankai University 94 Weijin Road Tianjin, China 300071 Tel: 86-22-2350-9241 Fax: 86-22-2350-8807 E-mail: [email protected]

22

For submission to: Environmental Science & Technology

ACS Paragon Plus Environment

Environmental Science & Technology

23

Abstract

24

Knowledge of human exposure to imidacloprid, the most extensively used

25

insecticide, and para-hydroxybenzoic acid esters (parabens), the most extensively

26

used preservative, is insufficient. In this study, 295 urine samples collected from rural

27

and urban areas in China were analyzed for imidacloprid and four parabens, namely,

28

methyl paraben, ethyl paraben, propyl paraben, and butyl paraben, as well as their

29

major metabolites, namely, 6-chloronicotinic acid (6-ClNA) and para-hydroxybenzoic

30

acid (p-HB). Imidacloprid was detected in 100% of the urine samples from rural

31

Chinese and 95% of the urine samples from urban Chinese. Concentrations of urinary

32

imidacloprid detected in rural Chinese (geometric mean (GM) = 0.18 ng/mL) were

33

slightly higher than those detected in urban Chinese (GM = 0.15 ng/mL) when the

34

effect of pesticide spraying was excluded. However, concentrations of urinary

35

imidacloprid detected in rural adults increased significantly in the subsequent days of

36

pesticide spraying (GM = 0.62 ng/mL), which could return to the normal levels within

37

3 days. By contrast, concentrations of urinary parabens detected in rural Chinese (GM

38

= 6.90 ng/mL) were lower than that in urban Chinese (GM = 30.5 ng/mL). In addition,

39

the metabolism characteristics of imidacloprid to 6-ClNA and parabens to p-HB were

40

discussed preliminarily.

ACS Paragon Plus Environment

Page 2 of 34

Page 3 of 34

Environmental Science & Technology

41

INTRODUCTION

42

With the increasing application of artificial chemicals, human exposure to these

43

compounds is of significant concern, due to the potential association of some

44

compounds with some adverse healthy effects.1,2 A total of 265 chemicals have been

45

included in the newest National Report on Human Exposure to Environmental

46

Chemicals published by the United States Centers for Disease Control and

47

Prevention3 based on the National Health and Nutrition Examination Survey of the

48

US. Nevertheless, knowledge of the exposure levels and metabolism characteristics of

49

chemicals is still insufficient compared with the rapid growth of the application of

50

new chemicals.

51

Imidacloprid [1-6(chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine]

52

is a typical neonicotinoid insecticide, which was launched to the market in the early

53

1990s.4 Imidacloprid is currently the most extensively used insecticide in the world,

54

which represents approximately 20% of the global pesticide market,5 and is

55

distributed in more than 120 countries.6 Imidacloprid exhibits a lower acute toxicity in

56

mammals than insects.6 However, the affinity of imidacloprid to mammalian nicotinic

57

acetylcholine receptors (nAChRs) and its toxicity to mammals have been observed.7

58

Most recently, imidacloprid was reported to induce changes to the biochemical

59

parameters of the kidney of male rats, at no observed adverse effect level.8 Adverse

60

effects, such as thyroid disturbance, neurobehavioral impairments, and lipid

61

peroxidation induced by exposure to low subchronic doses of imidacloprid, were also

62

reported in birds9 and aquatic organisms.10,11

ACS Paragon Plus Environment

Environmental Science & Technology

63

Although the use of imidacloprid has been gaining popularity in agricultural

64

settings, human exposure to imidacloprid has not been fully evaluated. 12-15 China is a

65

major producer and user of imidacloprid, with an annual capacity of 25,000 tons and a

66

domestic demand of 3,000 tons per year to 4,000 tons per year.16 As such, the Chinese

67

population might be subject to high exposure risk.

68

Parabens (para-hydroxybenzoic acid esters) are the most extensively used

69

preservatives in packaged foods, cosmetics, and personal care products. 17 After the

70

estrogenic activities of methyl paraben (MeP), ethyl paraben (EtP), propyl paraben

71

(PrP), and butyl paraben (BuP) were reported in 1998,18 increasing evidence of

72

endocrine and reproductive toxicities has been reported in numerous in vitro and in

73

vivo assays.19–23 The potential bioaccumulation of parabens in humans was also

74

proposed in several studies,24–26 and their exposure was associated with several

75

adverse health outcomes in epidemiological studies.2,27 Widespread exposure of

76

humans to parabens has been identified in certain populations of different countries,

77

including China.3,28–36 However, knowledge of the exposure of the rural Chinese

78

population to parabens is scarce, even if over 600 million Chinese live in rural areas.

79

In this study, the concentrations of imidacloprid and its metabolite,

80

6-chloronicotinic acid (6-ClNA), as well as four major paraben analytes, i.e., MeP, EtP,

81

PrP, and BuP, and their metabolite, para-hydroxybenzoic acid (p-HB), were

82

determined in 295 urine samples, including 120 samples collected from rural adults,

83

58 samples from rural children, 57 samples from rural elders, 48 samples from urban

84

adults, and 12 samples from urban children in China. The objectives of this study

ACS Paragon Plus Environment

Page 4 of 34

Page 5 of 34

Environmental Science & Technology

85

were to (i) determine the concentrations of urinary imidacloprid in the Chinese

86

population and evaluate the effects of pesticide spraying; (ii) elucidate the rural–urban

87

differences in human exposure to imidacloprid and parabens; and (iii) conduct a

88

preliminary discussion of the metabolism characteristics of imidacloprid and parabens

89

in humans.

90

MATERIALS AND METHODS

91

Reagents and standards. Standards of imidacloprid, p-HB, MeP, EtP, and PrP

92

were purchased from Sigma-Aldrich (St. Louis, MO, USA). Standards of 6-ClNA and

93

BuP were purchased from Alfa Aesar (Tianjin, China). The structures and

94

physicochemical properties of the target analytes are shown in Table 1 and Figure S1

95

(in the Supporting Information). The isotope-labelled standard d4-imidacloprid was

96

purchased from Sigma-Aldrich (St. Louis, MO, USA), whereas

97

13

98

Laboratories (Andover, MA, USA). β-Glucuronidase from Helix pomatia (145,700

99

units/mL β-glucuronidase and 887 units/mL sulfatase) was purchased from

100

C6-BuP (99%), and

13

C6-MeP (99%),

13

C6-p-HB (99%) were purchased from Cambridge Isotope

Sigma-Aldrich (St. Louis, MO, USA).

101

Sample collection. During April and May 2014, 10 rural families, including 20

102

adults (named Group RA, including 9 males and 11 females aged 25 years to 60

103

years), 10 children (named Group RC, including 8 males and 2 females aged 4 years

104

to 9 years), and 11 elders (named Group RE, including 4 males and 7 females aged 65

105

years to 85 years) (Table S1 in the Supporting Information), from a village in

106

Shandong Province in China, which is known for fruit cultivation, were invited as

ACS Paragon Plus Environment

Environmental Science & Technology

107

rural volunteers. Three days before and three days after the spraying of imidacloprid

108

pesticide in their orchards, the first morning urine specimens from the adult farmers

109

who sprayed the pesticides and the children and elders in their family were collected

110

daily. More detailed information of pesticide spraying is provided in Table S2.

111

In the same period, urine specimens were also collected from healthy urban

112

volunteers in a nearby town (~25 km far from the village). Concretely, 16 adults who

113

never engaged in pesticide-related work (named Group UA, including 8 males and 8

114

females aged 23 years to 60 years) and 4 children (named Group UC, including 4

115

males aged 4 years to 9 years) were randomly selected. The first morning urine

116

specimens were collected daily for three days. All urine specimens were collected in

117

polypropylene (PP) tubes and stored at −80 °C prior to analysis. The urine collection

118

was approved by the Institutional Review Board of Nankai University. Detailed

119

information of the volunteers is shown in Table S1.

120

Sample preparation. A liquid–liquid extraction method, similar to that reported

121

in our previous study33 with minor modifications, was employed for the extraction of

122

imidacloprid, parabens, and their metabolites. Briefly, 2 mL of urine was transferred

123

into a 15 mL PP tube and spiked with 100 µL of methanol containing 10 ng

124

d4-imidacloprid, 10 ng 13C6-MeP, 10 ng 13C6-EtP, and 50 ng 13C6-p-HB. Then, 300 µL

125

of hydrolytic enzyme buffer solution containing 77 units of β-glucuronidase was

126

transferred into the PP tube and enzymolyzed for 12 h at 37 °C. Afterward, the

127

specimens were extracted two times with 8 and 5 mL of ethyl acetate. For each

128

extraction, the mixture was shaken in an oscillator shaker for 60 min and centrifuged

ACS Paragon Plus Environment

Page 6 of 34

Page 7 of 34

Environmental Science & Technology

129

at 3,000 r/min for 5 min. The supernatants were combined and washed with 1 mL of

130

Milli-Q water, shaken in an oscillator shaker for 10 min, and centrifuged at 3,000

131

r/min for 5 min. The supernatant was transferred into a glass tube and concentrated to

132

dryness under a gentle nitrogen stream. Finally, 0.5 mL of methanol was added and

133

vortex mixed for analysis by ultra-performance liquid chromatography–tandem mass

134

spectrometry (UPLC-MS/MS).

135

Instrumental Analysis. Separation and detection of imidacloprid, parabens, and

136

their metabolites were accomplished by using the Waters 7100C Series

137

UPLC-MS/MS (Waters Corporation, Milford, MA, USA) interfaced with a triple

138

quadrupole mass spectrometer Xevo TQ-S (Waters Corporation, Milford, MA, USA).

139

Ten microliters of the extract was injected into an analytical column (Waters BEH

140

Shield C18, 100 × 3.0 mm, 1.7 µm; Waters Corporation, Milford, MA, USA)

141

connected serially to a Javelin guard column (Waters BEH Shield C18, 20 × 2.1 mm,

142

1.7 µm; Waters Corporation, Milford, MA, USA). The mobile phase comprised 100%

143

acetonitrile (A) and Milli-Q water that contained 0.01% formic acid (B). A gradient

144

elution at a flow rate of 0.4 mL/min was used for the analysis, with detailed

145

information shown in Table S3. The MS/MS was operated in multiple reaction

146

monitoring, with the negative and positive modes used, respectively. Imidacloprid and

147

d4-imidacloprid were operated in positive ionization mode, while the others were

148

operated in negative ionization mode. The parameters were optimized by infusion of

149

individual analytes. The results are shown in Table S4.

150

Quality assurance and quality control. Procedural blanks were analyzed in

ACS Paragon Plus Environment

Environmental Science & Technology

151

every batch of 25 specimens. Duplicate analysis of selected specimens showed a

152

coefficient of variation of