Next Article in Journal
Development of the Children and Adolescents Physical Activity and Sedentary Questionnaire (CAPAS-Q): Psychometric Validity and Clinical Interpretation
Next Article in Special Issue
Rubber Antioxidants and Their Transformation Products: Environmental Occurrence and Potential Impact
Previous Article in Journal
An Examination of Child Pedestrian Rule Compliance at Crosswalks around Parks in Montreal, Canada
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Associations between Maternal Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Serum Concentrations and Pulse Pressure in Early Pregnancy: A Cross-Sectional Study

Hubei Provincial Key Laboratory for Applied Toxicology, Hubei Provincial Center for Disease Control and Prevention, Wuhan 430079, China
*
Authors to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2022, 19(21), 13785; https://doi.org/10.3390/ijerph192113785
Submission received: 21 September 2022 / Revised: 19 October 2022 / Accepted: 20 October 2022 / Published: 23 October 2022

Abstract

:
Pulse pressure (PP) is the difference between systolic blood pressure (SBP) and diastolic blood pressure (DBP), and an independent predictor of cardiovascular risk. Previous research suggests, with different conclusions, that exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) could affect blood pressure (BP). We conducted a cross-sectional study to determine the association of dioxin exposure with PP in early pregnancy. A total of 305 pregnant women in early pregnancy in Yingcheng, China, recruited from May 2018 to February 2021, were included in this study. We measured 17 congeners of PCDD/Fs in maternal serum via high-resolution gas chromatography tandem high-resolution mass spectrometry. A generalized linear regression model was used to analyze the influencing factors of dioxin exposure and their relationships with PP. The levels of total PCDD/Fs (∑PCDD/Fs) ranged from 163.52 pg/g lipid to 1,513,949.52 pg/g lipid, with a mean of 10,474.22 pg/g lipid. The mean toxicity equivalent (TEQ) of total PCDD/Fs (∑TEQ-PCDD/Fs) was 42.03 pg/g lipid. The ratio of tetrachlorinated to octa-chlorinated congeners in maternal serum was enriched with an increasing number of chlorines. Pregnant women with college and above education had higher concentrations of ∑PCDD/Fs than those with education levels of junior high school and below (β = 0.34, 95% CI: 0.01, 0.67). The adjusted model for ∑TEQ-PCDD/Fs was significantly and negatively associated with PP (β = −1.79, 95% CI: −2.91, −0.68). High levels of dioxins were found in this area, and exposure to dioxins may affect the PP of women in early pregnancy, with health risks.

1. Introduction

Current guidelines for the diagnosis and management of hypertension have defined cardiovascular risk by the elevation of systolic blood pressure (SBP) and/or the elevation of diastolic blood pressure (DBP) [1]. However, the value of pulse pressure (PP) in the clinical assessment of cardiovascular risk has become increasingly evident [2]. PP is defined as the difference between SBP and DBP, and various studies have verified PP as an independent predictor of cardiovascular risk [3]. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) compounds are ubiquitous in the environment and bioaccumulate and biomagnify through the food chain due to their persistence and lipophilicity [4,5]. They were shown to induce carcinogenicity, endocrinopathy, neurotoxicity, and immunotoxicity [6]. A handful of studies suggest that exposure to dioxins may also be associated with an increased risk of chronic diseases, such as hypertension, ischemic heart disease, stroke, diabetes, and hyperlipidemia [7,8,9,10].
Pregnant women are a special group of people who may intake more food of animal origin, which contributes to more than 90% of dioxins body burden [11]. Studies undertaken on maternal participants highlighted epidemiological evidence of short- and long-term effects of in utero exposure. These include associations between maternal exposure, diet, and age with hormonal disruptions in children and impacts on estrogenic metabolism [12,13,14,15,16]. Additionally, investigative studies on fetal exposure to dioxins provide evidence of an association between maternal serum and fetal abortion, birth defects, and low birth weight [17]. Although higher concentrations of dioxins have been detected in the placenta and umbilical cord blood, venous blood samples during pregnancy are considered the most representative to evaluate maternal or fetal body burdens [18,19]. In recent years, numerous studies have supported increasing evidence of adverse effects of PCDD/Fs in pregnant women. These include the populations in Mexico [20], Japan [12,21], Vietnam [22], Taiwan [23], Beijing [24], Tianjin [6], Tema and Accra [25].
Moreover, emerging data support the plausible contribution of specific environmental toxicants to BP, including dioxins and dioxin-like compounds. A number of studies conducted in populations have shown significant associations between dioxin-like compounds and increased BP or hypertension, although the associations with individual congeners are not consistent across studies [7,9,26,27]. Animal studies show that 2,3,7,8-TCDD exposure can affect the BP of experimental animals, but the effect may be related to the dose or the species of the animals tested [28,29,30]. Gestational hypertension during pregnancy is a common obstetric disease, accounting for 5~10% of all pregnancies and causing approximately 10~16% of all pregnancy-related deaths [31]. However, no reports have been found on the relationship between PCDD/F exposure and PP during early pregnancy. In the present study, we addressed this issue by conducting a cross-sectional study to assess the risks of dioxin exposure and the association with PP in early pregnancy.

2. Materials and Methods

2.1. Study Design and Population

We conducted a birth cohort study (H-YCCS) in Yingcheng, Hubei Province, China, from May 2018 to February 2021 to investigate the associations between dioxin exposure in early pregnancy and adverse health outcomes. Healthy pregnant women were recruited, and prenatal examinations were conducted in Yingcheng People’s Hospital, China.
A total of 722 pregnant women were recruited, and 605 (83.8%) of them completed the questionnaire. The questionnaire included general demographic characteristics (age, height, weight, ethnicity, education level, monthly household income, occupation, occupational exposure to hazard factors, alcohol consumption, active and passive smoking, reproductive history, drug use, and disease). BP (SBP and DBP) measurements of pregnant women were obtained by an automatic standard sphygmomanometer beginning after the patient had been sitting for 5 min. Finally, 305 (50.4%) women provided sufficient blood samples for PCDD/F measurements. Our study was approved by the Ethics Committee of Hubei Center for Disease Control and Prevention.

2.2. Blood Collection and Chemical Analysis

Fasting venous blood samples were collected from the participants by nurses. The whole blood sample was centrifuged immediately, and the serum was segregated and preserved at −40 °C until further analysis. PCDD/Fs in serum were extracted and determined as previously described [6]. Briefly, approximately 2 mL of serum was mixed with diatomite and then spiked with 13C-labeled internal standards (EPA-1613LCS, Wellington Laboratories Inc., Guelph, ON, Canada). The mixture was extracted by an accelerated solvent extractor (ASE-914, BÜCHI, Switzerland) at 130 °C and 100 bar. The extract was concentrated to near one milliliter and then purified using an acid silica gel column and carbon column under a pressure of 0.1 MPa (F12, CAPE Technologies, South Portland, ME, USA). Then, the PCDD/F fraction was collected and concentrated to near dryness and redissolved in approximately 20 microliters of nonane. The 13C-labeled recovery standards for PCDD/Fs (EPA-1613ISS, Wellington Laboratories Inc., Guelph, ON, Canada) were injected before instrumental analysis. Concentrations of PCDD/Fs were analyzed by high-resolution gas chromatography tandem high-resolution mass spectrometry (HRGC-HRMS, DFS, Thermo Fisher Scientific, Waltham, MA, USA), equipped with a capillary column (DB-5 MS, 60 m × 0.25 mm ID × 0.25 μm, Agilent Technologies, Santa Clara, CA, USA). The total lipids of each maternal serum sample were detected by an enzymatic summation method [32]. All data were reported on a lipid basis.

2.3. Quality Control

One procedure blank test was carried out for every eight serum samples to examine contamination of the analysis system, and one test of standard reference material (Organic Contaminants in Non-Fortified Human Serum, SRM-1957) purchased from the U.S. National Institute of Standards and Technology. Procedure blank and SRM-1957 were analyzed to identify potential system contamination and as a quality control to assess laboratory precision during the entire analytical process. The precision and accuracy of measurements for PCDD/Fs in SRM-1957 were within the certified reference ranges recommended by the manufacturer. The method detection limits (MDLs) were 0.05–0.16 pg/g lipid. Recoveries of internal standards ranged from 47% to 99%, thus meeting the requirements of U.S. Environmental Protection Agency (EPA) method 1613.

2.4. Statistical Analysis

The values below the detection limit were assigned as half of the MDLs for statistical calculations. Toxicity equivalents (TEQs) were calculated using the World Health Organization (WHO) 2005 toxicity equivalence factors (TEFs) [33]. All statistical analyses were performed using Empower stats software (Available online: www.empowerstats.com (accessed on 17 March 2021), X&Y Solutions, Inc., Boston, MA, USA) and R software, version 3.2.0 (Available online: http://www.R-project.org/ (accessed on 17 March 2021)). Since the value of PCDD/Fs did not conform to a normal distribution, natural logarithm transformation (ln) was carried out. PCDDs (7 species, including 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD, 1,2,3,4,6,7,8-HpCDD, and OCDD), PCDFs (10 species, including 2,3,7,8-TCDF, 1,2,3,7,8-PeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF, 1,2,3,4,7,8,9-HpCDF, and OCDF) and PCDD/Fs (7 PCDDs and 10 PCDFs) concentrations and TEQs were included in the analysis. ∑PCDDs and ∑TEQ-PCDDs are the sum of 7 PCDD concentrations and TEQs, respectively, ∑PCDFs and ∑TEQ-PCDFs are the sum of 10 PCDF concentrations and TEQs, and ∑PCDD/FS and ∑TEQ-PCDD/FS are the sum of 17 concentrations and TEQs. We considered multiple covariates and potential confounders for the association of PCDD/F exposure with influencing factors and BP, and factors with p < 0.1 were included in the final multiple linear regression models. The following variables were considered for use: maternal age (years), body mass index (BMI, kg/m2), days of pregnancy, education level (junior high school, high school, college and above), average monthly family income (<5000 yuan, ≥5000 yuan), parity (0, ≥1), alcohol consumption (No, Yes), active smoking (No, Yes), passive smoking (No, Yes), occupation (worker, farmer, others), and nationality (Han nationality, others). Values were considered statistically significant when p ≤ 0.05.

3. Results

3.1. Demographic Characteristics of the Study Participants

The demographic characteristics of the study participants are shown in Table 1. The mean with standard deviations (SD) of maternal age, pregnancy BMI, and days of pregnancy were 27.98 ± 3.55 years old, 21.55 ± 3.29 kg/m2, and 84.12 ± 8.71 days, respectively. More than half of the mothers (54.8%) were having their first pregnancy. The majority of the mothers (56.7%) had a high school education. Nearly one-third (36.4%) of the mothers did not work during pregnancy. Few mothers were active smokers (2.0%) or consumed alcohol (16.4%), but 43.3% of mothers passively smoked more than 15 min per day.

3.2. PCDD/Fs Concentrations in Maternal Serum

The concentrations and detection rates of PCDD/Fs in maternal serum are shown in Table 2. The detection rates ranged from 32% (2,3,7,8-TCDD) to 100% (OCDD), ∑PCDD/F concentrations in maternal serum ranged from 163.52 pg/g lipid to 1,513,949.52 pg/g lipid, with a mean of 10,474.22 pg/g lipid, and OCDD (10,111.19 pg/g lipid) was the highest concentration. ∑PCDD concentrations (10,321.86 pg/g lipid) were significantly higher than ∑PCDFs (152.36 pg/g lipid). The mean ∑TEQ-PCDD/Fs was 42.3 pg/g lipid, and the ∑PCDDs were two-fold higher than the ∑PCDFs.

3.3. PCDD/Fs Congeners in Maternal Serum

Level and TEQ contributions of congeners to total PCDD/Fs are shown in Figure 1. Among the PCDD/F levels, OCDD was the predominant congener, accounting for 96.5%. The ratios of PCDDs and PCDFs to total PCDD/Fs were 98.6% and 1.4%, respectively. The ratios of tetra- (0.3%), penta- (0.4%), hexa- (0.9%), hepta- (1.7%), and octa-chlorinated (96.6%) congeners were enriched with increasing amounts of chlorine. For TEQs, 1,2,3,7,8-PeCDD was the dominant congener, accounting for 41.3%, followed by 2,3,4,7,8-PeCDF (11.8%). The mean contribution of PCDDs to ∑TEQs was 66.8%, and that of PCDFs was 33.2%.

3.4. Other Factors

Influencing factors on PCDD/F concentrations and TEQs [β, 95% confidence interval (CI)] are presented in Table 3. Pregnant women with college and above education had higher concentrations of ∑PCDD/Fs than those with junior high school and below (β = 0.34, 95% CI: 0.01, 0.67). No associations were observed between the ∑TEQ-PCDDs, ∑TEQ-PCDFs, ∑TEQ-PCDD/Fs, and influencing factors.

3.5. Relationships between PCDD/Fs in Maternal Serum and BP

The relationships between BP and the TEQs in maternal serum are shown in Table 4. ∑TEQ-PCDD/Fs in maternal serum was significantly and negatively correlated with PP in both crude and adjusted models (β = −1.62, 95% CI: −2.72, −0.52 and β = −1.79, 95% CI: −2.91, −0.68, respectively) and the same as ∑TEQ-PCDDs (β = −1.10, 95% CI: −1.94, −0.26, and β = −1.23, 95% CI: −2.08, −0.37, respectively). A significantly negative association between ∑TEQ-PCDFs and PP was found only in the adjusted model (β = −1.20, 95% CI: −2.39, −0.01). ∑TEQ-PCDFs were also found to be significantly and negatively correlated with SBP in both crude and adjusted models (β = −1.24, 95% CI: −2.40, −0.09 and β = −1.31, 95% CI: −2.47, −0.15, respectively). However, exposure to ∑TEQ-PCDDs was significantly and positively associated with DBP after adjustment (β = 0.79, 95% CI: 0.04, 1.54). No associations were observed between the concentrations of ∑PCDDs, ∑PCDFs, ∑PCDD/Fs, and BP.

4. Discussion

We measured the PCDD, PCDF, PCDD/F, and TEQ concentrations in maternal serum early in pregnancy for a Chinese birth cohort study (H-YCCS). The total TEQs of PCDDs, PCDFs, and PCDD/Fs in maternal serum between this study and other studies globally are shown in Table 5. Mean ∑TEQ-PCDDs, ∑TEQ-PCDFs, and ∑TEQ-PCDD/Fs in the present study were higher than most background concentrations reported in the serum of pregnant women in other locations of the world. ∑TEQ-PCDD/Fs in maternal serum were also compared with the biomonitoring equivalent (BE) for risk assessment. BE values are designed to be used as screening tools to assess whether chemicals have a large, small, or no margin of safety compared to existing health-based exposure guidelines [34]. On the basis of neurodevelopmental effects, ∑TEQs of 15 pg/g lipid in serum samples is consistent with the minimal risk level recommended by the Agency for Toxic Substances and Disease Registry [35]. Referring to the ∑TEQ-PCDD/Fs in our data, 175 (57.4%) of the participants showed higher levels than the BEs. Thus, future studies should address long-term exposure to dioxins in pregnant women.
Concentrations of tetrachlorinated to octa-chlorinated congeners in serum enriched with increasing amounts of chlorine. These accumulations of highly chlorinated congeners in serum might be attributed to their high molecular weight [18,36,37]. It has been reported that once higher chlorinated congeners enter serum, they are more likely to accumulate with time [38]. Both the number and position of chlorine substituted on the ring of PCDD/Fs was important for metabolism [39]. We found that pregnant women with a higher education had higher concentrations of ∑PCDD/Fs. Educational status may be a marker for socioeconomic status in this population, and both education and socioeconomic status have been positively associated with maternal dietary quality [40]. They have better conditions and tend to increase the consumption of animal-origin food [41]. It has been estimated that more than 90% of current human exposure to dioxins among the general population occurs via food consumption, primarily from animal-origin food [42]. PCDD/Fs are highly lipophilic, environmentally persistent, and more likely to be enriched in adipose tissues [43].
Only a few studies have reported the relationship between PCDD/Fs and BP. Vietnamese soldiers exposed to high levels of 2,3,7,8-TCDD may have an increased risk of hypertension but not other PCDD/F congeners [26]. It has been reported that high TEQs of PCDD/Fs in Japanese general populations may increase the risk of hypertension [7]. However, the relationship between dioxin exposure and PP during pregnancy has not been reported until now. In this study, high exposure to PCDD/Fs was associated with decreased PP in pregnant women. Our results differ from the conclusions reported by Cypel and Nakamoto. Animal studies have shown that dioxins could affect BP. Sustained aryl hydrocarbon receptor (AhR) activation by 2,3,7,8-TCDD exposure induces hypertension in adult male C57BL/6 mice. This model provides valuable insight into the mechanisms underlying 2,3,7,8-TCDD-induced cardiovascular pathogenesis, including the role of vascular reactive oxygen species (ROS) as potential mediators of 2,3,7,8-TCDDMinduced hypertension [29]. When C57BL/6J mice are continuously exposed to 2,3,7,8-TCDD, AHR regulates the expression of several genes, including CYP1A1 and cyclooxygenase (COX-2), which may influence BP through the production of vasoactive eicosanoids [30]. However, different results showed that BP in the infected group was lower than that in the control group after exposure to 2,3,7,8-TCDD in female rats [28]. These studies suggest that 2,3,7,8-TCDD exposure could affect the BP of experimental animals, but the effect may be related to the dose or the species of the tested animals.
Mechanisms that might be involved in the associations between PCDD/Fs and PP are currently largely unknown. Experimental evidence suggests that dioxin-like compounds can modulate endothelium-derived vasoactive factors in human primary endothelial cells and induce changes characteristic of endothelial dysfunction in human essential hypertension [44]. It can modulate the expression of vasoconstriction factors such as COX-2, prostaglandins, and reactive oxygen species (ROS) and change the production of nitric oxide (NO), a well-known vasodilator factor [45]. It has been reported that a decreased PP may be associated with hypovolemia, cardiac failure, cardiac arrhythmia, valvular heart disease, aortic dissection, or low BP [46]. Upon review of previous medical literature, a low PP has been shown to be an indicator of decreased cardiac function and poor outcomes in patients with myocardiac infarction and a predictor of cardiovascular death in patients with mild to advanced heart failure [47]. Although low PP was less apparent in pregnant women, if these associations are indeed present at relatively common serum PCDD/Fs concentrations, the public health significance of the relationships may be considerable. Clearly, it is very important that these possibilities should be tested systematically in a prospective investigation. There is also a need for investigations that can identify the mechanisms that might underlie these associations. For PP, a number of external factors can influence levels or performance, but the observation that serum PCDD/Fs levels can influence them indicates that PCDD/Fs levels may cause physiological changes and contribute to the development of diseases even when they are not the sole cause.
This study has several limitations. First and foremost is the limited sample size of our study population. As the serum dioxin concentration is at the pg/g level, sufficient serum is required. Only a subset of the population provided sufficient samples. Second, the current study on the relationship between dioxin exposure and PP is cross-sectional, which cannot prove causality regardless of how strong the associations are.

5. Conclusions

Our collective findings reveal that pregnant women may be at risk of exposure to PCDD/Fs. The ratio of tetrachlorinated to octa-chlorinated congeners in maternal serum was enriched with an increasing number of chlorines. Pregnant women with higher education had higher levels of ∑PCDD/Fs. We found that ∑TEQs were significantly and negatively associated with PP. These exploratory results require corroboration with further studies involving larger sample sizes and a wider range of exposure to establish the association between exposure to dioxins and maternal as well as offspring health.

Author Contributions

Methodology, X.L. (Xiao Liu); formal analysis, Y.Z.; investigation, W.C.; writing—original draft preparation, X.L. (Xiaofang Liu); writing—review and editing, S.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Key Research and Development Program of China (grant number 2017YFC1600500), the National Natural Science Foundation of China (grant number 81703194), and the Hubei Provincial Health and Family Planning Commission (grant number WJ2019Q054).

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Hubei Center for Disease Control and Prevention (protocol code 2018-006-02).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

Data are available upon request contacting [email protected] (Y.Z.).

Acknowledgments

We express our sincere gratitude to all technicians and interviewers who contributed to the present research. We also sincerely appreciate all participants for providing the maternal serum samples and their cooperation during the interviews.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Gillebert, T.C. Pulse pressure and blood pressure components: Is the sum more than the parts? Eur. J. Prev. Cardiol. 2018, 25, 457–459. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  2. Dart, A.M.; Kingwell, B.A. Pulse pressure—A review of mechanisms and clinical relevance. J. Am. Coll. Cardiol. 2001, 37, 975–984. [Google Scholar] [CrossRef] [Green Version]
  3. Çimen, T.; Sunman, H.; Efe, T.H.; Akyel, A.; Yayla, K.; Şahan, H.F.; Bilgin, M.; Asarcıklı, L.D.; Nallbani, A.; Doğan, M.; et al. Early changes in atrial conduction times in hypertensive patients with elevated pulse pressure. Rev. Port. Cardiol. 2017, 36, 453–459. [Google Scholar] [CrossRef] [PubMed]
  4. Schecter, A.; Birnbaum, L.; Ryan, J.J.; Constable, J.D. Dioxins: An overview. Environ. Res. 2006, 101, 419–428. [Google Scholar] [CrossRef]
  5. EFSA CONTAM Panel (EFSA Panel on Contaminants in the Food Chain); Knutsen, H.K.; Alexander, J.; Barregård, L.; Bignami, M.; Brüschweiler, B.; Ceccatelli, S.; Cottrill, B.; Dinovi, M.; Edler, L.; et al. Scientific Opinion on the risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food. EFSA J. 2018, 16, e05333. [Google Scholar] [CrossRef] [Green Version]
  6. Yu, D.; Liu, X.; Liu, X.; Cao, W.; Zhang, X.; Tian, H.; Wang, J.; Xiong, N.; Wen, S.; Wu, Y.; et al. Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Umbilical Cord Serum from Pregnant Women Living Near a Chemical Plant in Tianjin, China. Int. J. Environ. Res. Public Health 2019, 16, 2178. [Google Scholar] [CrossRef] [Green Version]
  7. Nakamoto, M.; Arisawa, K.; Uemura, H.; Katsuura, S.; Takami, H.; Sawachika, F.; Yamaguchi, M.; Juta, T.; Sakai, T.; Toda, E.; et al. Association between blood levels of PCDDs/PCDFs/dioxin-like PCBs and history of allergic and other diseases in the Japanese population. Int. Arch. Occup. Environ. Health 2013, 86, 849–859. [Google Scholar] [CrossRef]
  8. Pelcl, T.; Skrha, J., Jr.; Prazny, M.; Vlckova, S.; Fenclova, Z.; Navratil, T.; Malik, J.; Diblik, P.; Zikan, V.; Pelclova, D. Diabetes, Cardiovascular Disorders and 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Body Burden in Czech Patients 50 Years After the Intoxication. Basic Clin. Pharmacol. Toxicol. 2018, 123, 356–359. [Google Scholar] [CrossRef] [Green Version]
  9. Uemura, H.; Arisawa, K.; Hiyoshi, M.; Kitayama, A.; Takami, H.; Sawachika, F.; Dakeshita, S.; Nii, K.; Satoh, H.; Sumiyoshi, Y.; et al. Prevalence of metabolic syndrome associated with body burden levels of dioxin and related compounds among Japan’s general population. Environ. Health Perspect. 2009, 117, 568–573. [Google Scholar] [CrossRef]
  10. Warner, M.; Mocarelli, P.; Brambilla, P.; Wesselink, A.; Samuels, S.; Signorini, S.; Eskenazi, B. Diabetes, metabolic syndrome, and obesity in relation to serum dioxin concentrations: The Seveso women’s health study. Environ. Health Perspect. 2013, 121, 906–911. [Google Scholar] [CrossRef]
  11. Lignell, S.; Winkvist, A.; Bertz, F.; Rasmussen, K.M.; Glynn, A.; Aune, M.; Brekke, H.K. Environmental organic pollutants in human milk before and after weight loss. Chemosphere 2016, 159, 96–102. [Google Scholar] [CrossRef] [PubMed]
  12. Baba, T.; Ito, S.; Yuasa, M.; Yoshioka, E.; Miyashita, C.; Araki, A.; Sasaki, S.; Kobayashi, S.; Kajiwara, J.; Hori, T.; et al. Association of prenatal exposure to PCDD/Fs and PCBs with maternal and infant thyroid hormones: The Hokkaido Study on Environment and Children’s Health. Sci. Total Environ. 2018, 615, 1239–1246. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  13. Cao, Y.; Winneke, G.; Wilhelm, M.; Wittsiepe, J.; Lemm, F.; Fürst, P.; Ranft, U.; Imöhl, M.; Kraft, M.; Oesch-Bartlomowicz, B.; et al. Environmental exposure to dioxins and polychlorinated biphenyls reduce levels of gonadal hormones in newborns: Results from the Duisburg cohort study. Int. J. Hyg. Environ. Health 2008, 211, 30–39. [Google Scholar] [CrossRef] [PubMed]
  14. Miyashita, C.; Araki, A.; Mitsui, T.; Itoh, S.; Goudarzi, H.; Sasaki, S.; Kajiwara, J.; Hori, T.; Cho, K.; Moriya, K.; et al. Sex-related differences in the associations between maternal dioxin-like compounds and reproductive and steroid hormones in cord blood: The Hokkaido study. Environ. Int. 2018, 117, 175–185. [Google Scholar] [CrossRef] [PubMed]
  15. Nakajima, S.; Saijo, Y.; Miyashita, C.; Ikeno, T.; Sasaki, S.; Kajiwara, J.; Kishi, R. Sex-specific differences in effect of prenatal exposure to dioxin-like compounds on neurodevelopment in Japanese children: Sapporo cohort study. Environ. Res. 2017, 159, 222–231. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  16. Papadopoulou, E.; Kogevinas, M.; Botsivali, M.; Pedersen, M.; Besselink, H.; Mendez, M.A.; Fleming, S.; Hardie, L.J.; Knudsen, L.E.; Wright, J.; et al. Maternal diet, prenatal exposure to dioxin-like compounds and birth outcomes in a European prospective mother-child study (NewGeneris). Sci. Total Environ. 2014, 484, 121–128. [Google Scholar] [CrossRef]
  17. Le, T.N.; Johansson, A. Impact of chemical warfare with agent orange on women’s reproductive lives in Vietnam: A pilot study. Reprod. Health Matters 2001, 9, 156–164. [Google Scholar] [CrossRef]
  18. Suzuki, G.; Nakano, M.; Nakano, S. Distribution of PCDDs/PCDFs and Co-PCBs in human maternal blood, cord blood, placenta, milk, and adipose tissue: Dioxins showing high toxic equivalency factor accumulate in the placenta. Biosci. Biotechnol. Biochem. 2005, 69, 1836–1847. [Google Scholar] [CrossRef] [Green Version]
  19. Wang, S.L.; Lin, C.Y.; Guo, Y.L.; Lin, L.Y.; Chou, W.L.; Chang, L.W. Infant exposure to polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls (PCDD/Fs, PCBs)—Correlation between prenatal and postnatal exposure. Chemosphere 2004, 54, 1459–1473. [Google Scholar] [CrossRef]
  20. Rodríguez-Dozal, S.; Riojas Rodríguez, H.; Hernández-Ávila, M.; Van Oostdam, J.; Weber, J.P.; Needham, L.L.; Trip, L. Persistent organic pollutant concentrations in first birth mothers across Mexico. J. Expo. Sci. Environ. Epidemiol. 2012, 22, 60–69. [Google Scholar] [CrossRef]
  21. Todaka, T.; Hirakawa, H.; Kajiwara, J.; Hori, T.; Tobiishi, K.; Yasutake, D.; Onozuka, D.; Sasaki, S.; Miyashita, C.; Yoshioka, E.; et al. Relationship between the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in maternal blood and those in breast milk. Chemosphere 2010, 78, 185–192. [Google Scholar] [CrossRef] [PubMed]
  22. Boda, H.; Nghi, T.N.; Nishijo, M.; Thao, P.N.; Tai, P.T.; Van Luong, H.; Anh, T.H.; Morikawa, Y.; Nishino, Y.; Nishijo, H. Prenatal dioxin exposure estimated from dioxins in breast milk and sex hormone levels in umbilical cord blood in Vietnamese newborn infants. Sci. Total Environ. 2018, 615, 1312–1318. [Google Scholar] [CrossRef]
  23. Huang, C.Y.; Lee, C.C.; Chang, J.W.; Cheng, Y.Y.; Kuo, Y.C.; Guo, H.R.; Wu, C.L. Association Between Dioxin and Metabolic Syndrome by Age and Sex in an Endemic Area of Exposure in Taiwan. Epidemiology 2017, 28 (Suppl. 1), S82–S88. [Google Scholar] [CrossRef] [PubMed]
  24. Bao, Y.; Zhang, L.; Liu, X.; Shi, L.; Li, J.; Meng, G.; Zhao, Y.; Wu, Y. Dioxin-like compounds in paired maternal serum and breast milk under long sampling intervals. Ecotoxicol. Environ. Saf. 2020, 194, 110339. [Google Scholar] [CrossRef] [PubMed]
  25. Bruce-Vanderpuije, P.; Megson, D.; Jobst, K.; Jones, G.R.; Reiner, E.; Sandau, C.D.; Clarke, E.; Adu-Kumi, S.; Gardella, J.A., Jr. Background levels of dioxin-like polychlorinated biphenyls (dlPCBs), polychlorinated, polybrominated and mixed halogenated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, PBDD/Fs & PXDD/Fs) in sera of pregnant women in Accra, Ghana. Sci. Total Environ. 2019, 673, 631–642. [Google Scholar] [CrossRef]
  26. Cypel, Y.S.; Kress, A.M.; Eber, S.M.; Schneiderman, A.I.; Davey, V.J. Herbicide Exposure, Vietnam Service, and Hypertension Risk in Army Chemical Corps Veterans. J. Occup. Environ. Med. 2016, 58, 1127–1136. [Google Scholar] [CrossRef] [Green Version]
  27. Goncharov, A.; Pavuk, M.; Foushee, H.R.; Carpenter, D.O. Anniston Environmental Health Reseach Consortium. Blood pressure in relation to concentrations of PCB congeners and chlorinated pesticides. Environ. Health Perspect. 2011, 119, 319–325. [Google Scholar] [CrossRef]
  28. Hermansky, S.J.; Holcslaw, T.L.; Murray, W.J.; Markin, R.S.; Stohs, S.J. Biochemical and functional effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the heart of female rats. Toxicol. Appl. Pharmacol. 1988, 95, 175–184. [Google Scholar] [CrossRef]
  29. Kopf, P.G.; Huwe, J.K.; Walker, M.K. Hypertension, cardiac hypertrophy, and impaired vascular relaxation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin are associated with increased superoxide. Cardiovasc. Toxicol. 2008, 8, 181–193. [Google Scholar] [CrossRef] [Green Version]
  30. Dalton, T.P.; Kerzee, J.K.; Wang, B.; Miller, M.; Dieter, M.Z.; Lorenz, J.N.; Shertzer, H.G.; Nerbert, D.W.; Puga, A. Dioxin exposure is an environmental risk factor for ischemic heart disease. Cardiovasc. Toxicol. 2001, 1, 285–298. [Google Scholar] [CrossRef]
  31. Fenton, T.R.; Lyon, A.W.; Rose, M.S. Cord blood calcium, phosphate, magnesium, and alkaline phosphatase gestational age-specific reference intervals for preterm infants. BMC Pediatr. 2011, 11, 76. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  32. Covaci, A.; Voorspoels, S.; Thomsen, C.; van Bavel, B.; Neels, H. Evaluation of total lipids using enzymatic methods for the normalization of persistent organic pollutant levels in serum. Sci. Total Environ. 2006, 366, 361–366. [Google Scholar] [CrossRef] [PubMed]
  33. Van den Berg, M.; Birnbaum, L.S.; Denison, M.; De Vito, M.; Farland, W.; Feeley, M.; Fiedler, H.; Hakansson, H.; Hanberg, A.; Haws, L.; et al. The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicol. Sci. 2006, 93, 223–241. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  34. LaKind, J.S.; Aylward, L.L.; Brunk, C.; DiZio, S.; Dourson, M.; Goldstein, D.A.; Kilpatrick, M.E.; Krewski, D.; Bartels, M.J.; Barton, H.A.; et al. Biomonitoring Equivalents Expert Workshop. Guidelines for the communication of Biomonitoring Equivalents: Report from the Biomonitoring Equivalents Expert Workshop. Regul. Toxicol. Pharmacol. 2008, 51 (Suppl. 3), S16–S26. [Google Scholar] [CrossRef]
  35. Aylward, L.L.; Lakind, J.S.; Hays, S.M. Derivation of biomonitoring equivalent (BE) values for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds: A screening tool for interpretation of biomonitoring data in a risk assessment context. J. Toxicol. Environ. Health A 2008, 71, 1499–1508. [Google Scholar] [CrossRef]
  36. Mannetje, A.; Coakley, J.; Mueller, J.F.; Harden, F.; Toms, L.M.; Douwes, J. Partitioning of persistent organic pollutants (POPs) between human serum and breast milk: A literature review. Chemosphere 2012, 89, 911–918. [Google Scholar] [CrossRef]
  37. Wittsiepe, J.; Fürst, P.; Schrey, P.; Lemm, F.; Kraft, M.; Eberwein, G.; Winneke, G.; Wilhelm, M. PCDD/F and dioxin-like PCB in human blood and milk from German mothers. Chemosphere 2007, 67, S286–S294. [Google Scholar] [CrossRef]
  38. Consonni, D.; Sindaco, R.; Bertazzi, P.A. Blood levels of dioxins, furans, dioxin-like PCBs, and TEQs in general populations: A review, 1989–2010. Environ. Int. 2012, 44, 151–162. [Google Scholar] [CrossRef]
  39. Pluess, N.; Poiger, H.; Hohbach, C.; Schlatter, C. Subchronic toxicity of some chlorinated dibenzofurans (pcdfs) and a mixture of pcdfs and chlorinated dibenzodioxins (pcdds) in rats. Chemosphere 1988, 17, 973–984. [Google Scholar] [CrossRef]
  40. Rifas-Shiman, S.L.; Rich-Edwards, J.W.; Kleinman, K.P.; Oken, E.; Gillman, M.W. Dietary quality during pregnancy varies by maternal characteristics in Project Viva: A US cohort. J. Am. Diet Assoc. 2009, 109, 1004–1011. [Google Scholar] [CrossRef]
  41. Chen, L.W.; Low, Y.L.; Fok, D.; Han, W.M.; Chong, Y.S.; Gluckman, P.; Godfrey, K.; Kwek, K.; Saw, S.M.; Soh, S.E.; et al. Dietary changes during pregnancy and the postpartum period in Singaporean Chinese, Malay and Indian women: The GUSTO birth cohort study. Public Health Nutr. 2014, 17, 1930–1938. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  42. Uçar, Y.; Traag, W.; Immerzeel, J.; Kraats, C.; van der Lee, M.; Hoogenboom, R.; van der Weg, G.; Cakirogullari, G.C.; Oymael, B.; Kilic, D. Levels of PCDD/Fs, PCBs and PBDEs in butter from Turkey and estimated dietary intake from dairy products. Food Addit. Contam. Part B Surveill. 2011, 4, 141–151. [Google Scholar] [CrossRef] [PubMed]
  43. Baars, A.J.; Bakker, M.I.; Baumann, R.A.; Boon, P.E.; Freijer, J.I.; Hoogenboom, L.A.; Hoogerbrugge, R.; van Klaveren, J.D.; Liem, A.K.; Traag, W.A.; et al. Dioxins, dioxin-like PCBs and non-dioxin-like PCBs in foodstuffs: Occurrence and dietary intake in The Netherlands. Toxicol. Lett. 2004, 151, 51–61. [Google Scholar] [CrossRef]
  44. Valera, B.; Ayotte, P.; Poirier, P.; Dewailly, E. Associations between plasma persistent organic pollutant levels and blood pressure in Inuit adults from Nunavik. Environ. Int. 2013, 59, 282–289. [Google Scholar] [CrossRef] [PubMed]
  45. Andersson, H.; Garscha, U.; Brittebo, E. Effects of PCB126 and 17β-oestradiol on endothelium-derived vasoactive factors in human endothelial cells. Toxicology 2011, 285, 46–56. [Google Scholar] [CrossRef] [PubMed]
  46. Muller, M.; van der Graaf, Y.; Visseren, F.L.; Vlek, A.L.; Mali, W.P.; Geerlings, M.I.; SMART Study Group. Blood pressure, cerebral blood flow, and brain volumes. The SMART-MR study. J. Hypertens. 2010, 28, 1498–1505. [Google Scholar] [CrossRef]
  47. El-Menyar, A.; Zubaid, M.; Almahmeed, W.; Alanbaei, M.; Rashed, W.; Al Qahtani, A.; Singh, R.; Zubair, S.; Al Suwaidi, J. Initial hospital pulse pressure and cardiovascular outcomes in acute coronary syndrome. Arch. Cardiovasc. Dis. 2011, 104, 435–443. [Google Scholar] [CrossRef] [PubMed]
Figure 1. The contributions of congeners to total PCDD/Fs in maternal serum (%).
Figure 1. The contributions of congeners to total PCDD/Fs in maternal serum (%).
Ijerph 19 13785 g001
Table 1. Demographic characteristics among the study participants (n = 305).
Table 1. Demographic characteristics among the study participants (n = 305).
VariableStatisticsPPSBPDBP
Nationality
Han nationality302 (99.0%)47.81 ± 10.36120.99 ± 10.22 *73.18 ± 9.13
Others3 (1.0%)53.33 ± 5.51134.33 ± 4.5181.00 ± 7.21
Maternal education
Junior high school and blow132 (43.3%)47.95 ± 9.94122.22 ± 9.7274.27 ± 8.81
High school83 (27.2%)47.02 ± 10.99119.93 ± 9.5872.90 ± 9.77
College and above90 (29.5%)48.50 ± 10.34120.61 ± 11.5372.11 ± 8.94
Household income, RMB, per month
≤5000 Yuan155 (50.8%)47.33 ± 9.89120.62 ± 8.9273.29 ± 9.48
>5000 Yuan150 (49.2%)48.41 ± 10.78121.64 ± 11.5073.23 ± 8.80
Parity
0167 (54.8%)47.68 ± 9.98121.33 ± 10.0273.65 ± 9.20
≥1138 (45.2%)48.09 ± 10.77120.87 ± 10.5972.78 ± 9.06
Occupation
Worker152 (49.8%)47.25 ± 9.91119.70 ± 9.3872.45 ± 9.15 *
Farmer111 (36.4%)47.53 ± 9.89122.52 ± 10.4474.99 ± 9.11
Others42 (13.8%)50.95 ± 12.51122.55 ± 12.2371.60 ± 8.61
Active smoking
No299 (98.0%)47.88 ± 10.36121.29 ± 10.20 *73.41 ± 9.01 *
Yes6 (2.0%)47.00 ± 9.76112.83 ± 11.3065.83 ± 13.00
Passive smoking
No173 (56.7%)47.76 ± 10.71121.58 ± 10.4573.82 ± 9.14
Yes132 (43.3%)48.00 ± 9.86120.52 ± 10.0372.52 ± 9.11
Alcohol Drinking
No255 (83.6%)48.03 ± 10.31121.51 ± 10.3973.48 ± 9.32
Yes50 (16.4%)47.00 ± 10.54119.14 ± 9.4372.14 ± 8.15
Marital status
No2 (0.7%)53.00 ± 5.66122.50 ± 12.0269.50 ± 17.68
Yes303 (99.3%)47.83 ± 10.35121.11 ± 10.2873.28 ± 9.10
Previous history
No282 (92.5%)47.72 ± 10.38121.16 ± 10.4373.43 ± 9.24
Yes23 (7.5%)49.57 ± 9.84120.70 ± 8.2071.13 ± 7.65
Hazard factors
No283 (92.8%)47.93 ± 10.5073.29 ± 9.20121.22 ± 10.45
Yes22 (7.2%)47.00 ± 8.0272.86 ± 8.51119.86 ± 7.64
Maternal age (years)27.98 ± 3.550.16 (−0.16, 0.49)0.02 (−0.31, 0.34)−0.15 (−0.44, 0.14)
BMI (kg/m2)21.55 ± 3.290.28 (−0.08, 0.63)0.11 (−0.24, 0.46)−0.17 (−0.48, 0.14)
Days of pregnancy84.12 ± 8.710.08 (−0.05, 0.21)−0.02 (−0.15, 0.11)−0.10 (−0.22, 0.01)
* p < 0.05.
Table 2. Concentrations of PCDD/Fs in maternal serum, expressed as pg/g lipid (n = 305).
Table 2. Concentrations of PCDD/Fs in maternal serum, expressed as pg/g lipid (n = 305).
CompoundsMeanMinimumMedianMaximumDR (%)
2,3,7,8-TCDD2.180.050.0580.1632%
1,2,3,7,8-PeCDD17.350.073.96695.4561%
1,2,3,4,7,8-HxCDD12.180.022.12320.2268%
1,2,3,6,7,8-HxCDD16.940.024.13374.1083%
1,2,3,7,8,9-HxCDD11.080.021.94342.8173%
1,2,3,4,6,7,8-HpCDD150.940.0558.0012,557.3599%
OCDD10,111.1979.401273.921,501,331.77100%
∑PCDDs10,321.86112.841405.471,513,889.31
2,3,7,8-TCDF29.440.0422.10253.7480%
1,2,3,7,8-PeCDF10.990.084.15151.5770%
2,3,4,7,8-PeCDF16.570.077.47247.0085%
1,2,3,4,7,8-HxCDF16.660.057.03316.0992%
1,2,3,6,7,8-HxCDF14.420.044.18334.5887%
1,2,3,7,8,9-HxCDF8.110.032.02277.8676%
2,3,4,6,7,8-HxCDF14.720.042.55371.8383%
1,2,3,4,6,7,8-HpCDF23.840.0411.52548.3197%
1,2,3,4,7,8,9-HpCDF6.220.051.40391.5169%
OCDF11.400.036.05679.4486%
∑PCDFs152.369.1782.793279.23
tetra-chlorinated PCDD/Fs31.620.0924.38257.44
penta-chlorinated PCDD/Fs44.910.2217.28746.47
hexa-chlorinated PCDD/Fs94.113.4826.242165.06
hepta-chlorinated PCDD/Fs180.990.1480.9912,576.23
octa-chlorinated PCDD/Fs10,122.5984.811297.161,501,331.80
∑PCDD/Fs10,474.22163.521632.381,513,949.52
∑TEQ-PCDDs28.090.359.04767.3
∑TEQ-PCDFs13.940.607.48214.39
∑TEQ-PCDD/Fs42.032.0218.17786.11
DR, detection rate; TEQ: Toxicity equivalent; PCDD/Fs: Polychlorinated Dibenzo-p-Dioxins and dibenzofurans; TCDD: Tetrachlorodibenzo-p-dioxin; PeCDD: Pentachlorodibenzo-p-dioxin; HxCDD: Hexachlorodibenzo-p-dioxin; HpCDD: Heptachlorodibenzo-p-dioxin; OCDD: Octachlorodibenzodioxin; TCDF: Tetrachlorodibenzofuran; PeCDF: Hexachlorodibenzofuran; HxCDF: Hexachlorodibenzofuran; HpCDF: Heptachlorodibenzofuran; OCDF: Octachlorodibenzofuran; tetra-chlorinated PCDD/Fs: 2,3,7,8-TCDD + 2,3,78-TCDF; penta-chlorinated PCDD/Fs: 1,2,3,7,8-PeCDD + 1,2,3,7,8-PeCDF + 2,3,4,7,8-PeCDF; hexa-chlorinated PCDD/Fs: 1,2,3,4,7,8-HxCDD + 1,2,3,6,7,8-HxCDD + 1,2,3,4,7,8-HxCDF + 1,2,3,6,7,8-HxCDF + 1,2,3,7,8,9-HxCDF + 2,3,4,6,7,8-HxCDF; hepta-chlorinated PCDD/Fs: 1,2,3,4,6,7,8-HpCDD + 1,2,3,4,6,7,8-HpCDF + 1,2,3,4,7,8,9-HpCDF; octa-chlorinated PCDD/Fs: OCDD + OCDF.
Table 3. Results of the multivariate linear regression model for the groups of ln-transformed concentrations in maternal serum (n = 305).
Table 3. Results of the multivariate linear regression model for the groups of ln-transformed concentrations in maternal serum (n = 305).
Variable∑PCDDs∑PCDFs∑PCDD/Fs
Maternal age (years)0.02 (−0.00, 0.03)−0.01 (−0.02, 0.01)0.01 (−0.00, 0.03)
Days of pregnancy0.03 (−0.01, 0.08)0.02 (−0.00, 0.05)0.03 (−0.00, 0.07)
Maternal education
Junior high school and blow1.001.001.00
High school−0.07 (−0.44, 0.29)0.14 (−0.10, 0.37)−0.06 (−0.40, 0.28)
College and above0.35 (−0.00, 0.71)0.18 (−0.05, 0.41)0.34 (0.01, 0.67) *
Passive smoking
No1.001.001.00
Yes−0.09 (−0.39, 0.21)0.14 (−0.05, 0.34)−0.08 (−0.36, 0.21)
* p < 0.05.
Table 4. Regression coefficients [β (95% CI)] for BP associated with groups of ln-transformed TEQs in maternal serum (n = 305).
Table 4. Regression coefficients [β (95% CI)] for BP associated with groups of ln-transformed TEQs in maternal serum (n = 305).
AnalytesNonadjustedAdjusted a
PP
∑TEQ-PCDDs−1.10 (−1.94, −0.26) *−1.23 (−2.08, −0.37) **
∑TEQ-PCDFs−1.00 (−2.17, 0.16)−1.20 (−2.39, −0.01) *
∑TEQ-PCDD/Fs−1.62 (−2.72, −0.52) **−1.79 (−2.91, −0.68) **
SBP
∑TEQ-PCDDs−0.36 (−1.20, 0.48)−0.44 (−1.28, 0.41)
∑TEQ-PCDFs−1.24 (−2.40, −0.09) *−1.31 (−2.47, −0.15) *
∑TEQ-PCDD/Fs−0.86 (−1.97, 0.24)−0.91 (−2.01, 0.20)
DBP
∑TEQ-PCDDs0.74 (−0.01, 1.49)0.79 (0.04, 1.54) *
∑TEQ-PCDFs−0.24 (−1.27, 0.79)−0.11 (−1.16, 0.94)
∑TEQ-PCDD/Fs0.76 (−0.23, 1.74)0.89 (−0.10, 1.87)
a Adjusted by age, parity, drinking, smoking, occupation, income, education, BMI, days of pregnancy, and nationality; * p < 0.05; ** p < 0.01.
Table 5. A comparison of background TEQs with relevant studies.
Table 5. A comparison of background TEQs with relevant studies.
LocationSampling YearSample Size∑TEQs (pg/g Lipid)Reference
PCDDsPCDFsPCDD/Fs
Tianjin2017247.346.6214.0[6]
Hokkaido2002–20053797.262.539.79[12]
Mexico2005–20062405.01.36.3[20]
Sapporo2002–20051198.22.911.1[21]
Vietnam20121610.054.0614.5[22]
Beijing2013–2015554.15.79.8[24]
Tema/Accra2017342.100.993.09[25]
Yingcheng2018–202030528.0913.9442.03This Study
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Liu, X.; Cao, W.; Liu, X.; Zhou, Y.; Wen, S. Associations between Maternal Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Serum Concentrations and Pulse Pressure in Early Pregnancy: A Cross-Sectional Study. Int. J. Environ. Res. Public Health 2022, 19, 13785. https://doi.org/10.3390/ijerph192113785

AMA Style

Liu X, Cao W, Liu X, Zhou Y, Wen S. Associations between Maternal Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Serum Concentrations and Pulse Pressure in Early Pregnancy: A Cross-Sectional Study. International Journal of Environmental Research and Public Health. 2022; 19(21):13785. https://doi.org/10.3390/ijerph192113785

Chicago/Turabian Style

Liu, Xiaofang, Wencheng Cao, Xiao Liu, Yan Zhou, and Sheng Wen. 2022. "Associations between Maternal Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Serum Concentrations and Pulse Pressure in Early Pregnancy: A Cross-Sectional Study" International Journal of Environmental Research and Public Health 19, no. 21: 13785. https://doi.org/10.3390/ijerph192113785

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop