1
|
Björvang RD, Hassan J, Stefopoulou M, Gemzell-Danielsson K, Pedrelli M, Kiviranta H, Rantakokko P, Ruokojärvi P, Lindh CH, Acharya G, Damdimopoulou P. Persistent organic pollutants and the size of ovarian reserve in reproductive-aged women. ENVIRONMENT INTERNATIONAL 2021; 155:106589. [PMID: 33945905 DOI: 10.1016/j.envint.2021.106589] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/07/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
Industrial chemicals such as persistent organic pollutants (POPs) have been associated with reduced fertility in women, including longer time-to-pregnancy (TTP), higher odds for infertility, and earlier reproductive senescence. Fertility is highly dependent on the ovarian reserve, which is composed of a prenatally determined stock of non-growing follicles. The quantity and quality of the follicles decline with age, thereby eventually leading to menopause. In the clinical setting, assessing ovarian reserve directly through the histological analysis of follicular density in ovaries is not practical. Therefore, surrogate markers of ovarian reserve, such as serum anti-Müllerian hormone (AMH) are typically used. Here, we studied associations between chemical exposure and ovarian reserve in a cohort of pregnant women undergoing elective caesarean section (n = 145) in Stockholm, Sweden. Full data (histological, clinical, serum) were available for 50 women. We estimated the size of the reserve both directly by determining the density of follicles in ovarian cortical tissue samples, and indirectly by measuring AMH in associated serum samples. Concentrations of 9 organochlorine pesticides (OCPs), 10 polychlorinated biphenyls (PCBs), 3 polybrominated diphenylethers (PBDEs) and 9 perfluoroalkyl substances (PFAS) were determined in serum, and clinical data were retrieved from electronic medical records. Healthy follicle densities (median 0, range 0-193 follicles/mm3) and AMH levels (median 2.33 ng/mL, range 0.1-14.8 ng/mL) varied substantially. AMH correlated with the density of growing follicles. Twenty-three chemicals detected in more than half of the samples were included in the analyses. None of the chemicals, alone or as a mixture, correlated with AMH, growing or atretic follicles. However, HCB, transnonachlor, PCBs 74 and 99 were associated with decreased non-growing follicle densities. HCB and transnonachlor were also negatively associated with healthy follicle density. Further, mixture of lipophilic POPs (PBDE 99, p,p'-DDE, and PCB 187) was associated with lower non-growing follicle densities. In addition, exposure to HCB, p,p'-DDE, and mixture of OCPs were significantly associated with higher odds of infertility. The results suggest that exposure to chemicals may reduce the size of ovarian reserve in humans, and strongly encourage to study mechanisms behind POP-associated infertility in women in more detail.
Collapse
Affiliation(s)
- Richelle D Björvang
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
| | - Jasmin Hassan
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
| | - Maria Stefopoulou
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
| | - Kristina Gemzell-Danielsson
- Department of Women's and Children's Health, Karolinska Institutet and Karolinska University Hospital Solna, 171 76 Stockholm, Sweden.
| | - Matteo Pedrelli
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Huddinge, 141 52 Stockholm, Sweden.
| | - Hannu Kiviranta
- Department of Health Security, Finnish Institute for Health and Welfare, 70701 Kuopio, Finland.
| | - Panu Rantakokko
- Department of Health Security, Finnish Institute for Health and Welfare, 70701 Kuopio, Finland.
| | - Päivi Ruokojärvi
- Department of Health Security, Finnish Institute for Health and Welfare, 70701 Kuopio, Finland.
| | - Christian H Lindh
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, 223 61 Lund, Sweden.
| | - Ganesh Acharya
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
| | - Pauliina Damdimopoulou
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital Huddinge, 141 86 Stockholm, Sweden.
| |
Collapse
|
2
|
Putative adverse outcome pathways for female reproductive disorders to improve testing and regulation of chemicals. Arch Toxicol 2020; 94:3359-3379. [PMID: 32638039 PMCID: PMC7502037 DOI: 10.1007/s00204-020-02834-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/30/2020] [Indexed: 12/12/2022]
Abstract
Modern living challenges female reproductive health. We are witnessing a rise in reproductive disorders and drop in birth rates across the world. The reasons for these manifestations are multifaceted and most likely include continuous exposure to an ever-increasing number of chemicals. The cause–effect relationships between chemical exposure and female reproductive disorders, however, have proven problematic to determine. This has made it difficult to assess the risks chemical exposures pose to a woman’s reproductive development and function. To address this challenge, this review uses the adverse outcome pathway (AOP) concept to summarize current knowledge about how chemical exposure can affect female reproductive health. We have a special focus on effects on the ovaries, since they are essential for lifelong reproductive health in women, being the source of both oocytes and several reproductive hormones, including sex steroids. The AOP framework is widely accepted as a new tool for toxicological safety assessment that enables better use of mechanistic knowledge for regulatory purposes. AOPs equip assessors and regulators with a pragmatic network of linear cause–effect relationships, enabling the use of a wider range of test method data in chemical risk assessment and regulation. Based on current knowledge, we propose ten putative AOPs relevant for female reproductive disorders that can be further elaborated and potentially be included in the AOPwiki. This effort is an important step towards better safeguarding the reproductive health of all girls and women.
Collapse
|
3
|
Oostingh EC, Hall J, Koster MPH, Grace B, Jauniaux E, Steegers-Theunissen RPM. The impact of maternal lifestyle factors on periconception outcomes: a systematic review of observational studies. Reprod Biomed Online 2018; 38:77-94. [PMID: 30424937 DOI: 10.1016/j.rbmo.2018.09.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 12/20/2022]
Abstract
The main risk factors for important reproductive health issues such as subfertility and perinatal mortality largely originate in the periconception period. To evaluate associations between modifiable maternal lifestyle factors and periconception outcomes, a systematic search was conducted for relevant studies published from 1990 to February 2017 on Embase, Medline, Web of Science, Cochrane database, PubMed and Google Scholar. The initial search identified 6166 articles, of which 49 studies were eligible for inclusion. Fecundity (the capacity to have a live birth) showed significant inverse associations with smoking, alcohol use and poor diet. Studies regarding time to pregnancy showed a decline in fecundity ratios (the monthly conception rate among exposed relative to unexposed couples) with increasing body mass index (BMI). Furthermore, risk of first-trimester miscarriage was found to be increased in smokers, alcohol and caffeine consumers, and with increasing BMI. Vitamin supplement use showed a decrease in this risk. This review demonstrates that maternal modifiable lifestyle factors affect periconception outcomes. If couples planning a pregnancy are more aware and supported to adopt healthy lifestyles during the periconceptional 'window of opportunity', short-term reproductive health as well as health in later life and even of future generations can be further improved.
Collapse
Affiliation(s)
- Elsje C Oostingh
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Jennifer Hall
- Research Department of Reproductive Health, EGA Institute for Women's Health, Faculty of Population Health Sciences, University College London (UCL), London, United Kingdom
| | - Maria P H Koster
- Department of Obstetrics and Gynecology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Bola Grace
- Research Department of Reproductive Health, EGA Institute for Women's Health, Faculty of Population Health Sciences, University College London (UCL), London, United Kingdom
| | - Eric Jauniaux
- Research Department of Reproductive Health, EGA Institute for Women's Health, Faculty of Population Health Sciences, University College London (UCL), London, United Kingdom
| | | |
Collapse
|
4
|
Bastos AMX, Souza MDCBD, Almeida Filho GLD, Krauss TM, Pavesi T, Silva LED. Organochlorine compound levels in fertile and infertile women from Rio de Janeiro, Brazil. ACTA ACUST UNITED AC 2013; 57:346-53. [DOI: 10.1590/s0004-27302013000500003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 01/29/2013] [Indexed: 11/22/2022]
Abstract
OBJECTIVE: The aim of the study was quantify organochlorine compounds in women seeking for infertility treatment (n = 15) and in spontaneously pregnant ones (n = 21). MATERIALS AND METHODS: A questionnaire was applied regarding lifestyle, occupational and reproductive history. Blood samples were collected from both groups. RESULTS: From the pesticides studied, pp'DDE was detected in 100% of infertile women, at higher mean levels than in pregnant women (3.02 mcg/L vs. 0.88 mcg/L; p = 0.001; power of 69%), without correlation with the etiology of infertility. Levels of the polychlorinated biphenyls (PCBs) were low, with positive samples in 100% in the infertile women for PCBs 138, 153, 180, while in pregnant women, they were 85.7% for congeners 138 and 153. Only PCB180 showed significance, with frequency of 71.4% (p = 0.019). CONCLUSIONS: The risk factors for female infertility were: age, consumption of untreated water and of canned foods. Exposure to the most prevalent organochlorine compounds described in literature was confirmed in the study, indicating that pp'DDE may adversely influence female fertility.
Collapse
|
5
|
Organochlorine Pesticides, Polychlorinated Biphenyls, Seafood Consumption, and Time-to-Pregnancy. Epidemiology 2013; 24:251-60. [DOI: 10.1097/ede.0b013e31827f53ec] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
6
|
Meeker JD, Maity A, Missmer SA, Williams PL, Mahalingaiah S, Ehrlich S, Berry KF, Altshul L, Perry MJ, Cramer DW, Hauser R. Serum concentrations of polychlorinated biphenyls in relation to in vitro fertilization outcomes. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:1010-6. [PMID: 21345762 PMCID: PMC3222973 DOI: 10.1289/ehp.1002922] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 02/09/2011] [Indexed: 05/22/2023]
Abstract
BACKGROUND Human exposure to polychlorinated biphenyls (PCBs) remains widespread. PCBs have been associated with adverse reproductive health outcomes including reduced fecundability and increased risk of pregnancy loss, although the human data remain largely inconclusive. OBJECTIVE Our goal was to explore the relationship between serum PCB concentrations and early pregnancy loss among a large cohort of women undergoing in vitro fertilization (IVF) between 1994 and 2003. METHODS Concentrations of 57 PCB congeners were measured in serum samples collected during 827 IVF/intracytoplasmic sperm injection cycles from 765 women. Joint statistical models that accommodate multiple outcomes and multiple cycles per woman were used to assess the relationship between serum PCB quartiles and implantation failure, chemical pregnancies (human chorionic gonadotropin level > 5.0 mIU/mL) that did not result in clinical pregnancy, or spontaneous abortion, while also adjusting for confounders. RESULTS PCB-153 was the congener present in the highest concentration (median, 46.2 ng/g lipid). Increasing quartiles of PCB-153 and the sum of all measured PCB congeners (ΣPCBs) were associated with significantly elevated dose-dependent odds of failed implantation. Adjusted odds ratios (95% confidence interval) for highest versus lowest quartile were 2.0 (1.2-3.4) for PCB-153 and 1.7 (1.0-2.9) for ΣPCBs. There were suggestive trends for increased odds of implantation failure for PCB-118 and cytochrome P450-inducing congeners (p-values for trend = 0.06). No statistically significant associations between PCBs and chemical pregnancy or spontaneous abortion were found. CONCLUSIONS Serum PCB concentrations at levels similar to the U.S. general population were associated with failed implantation among women undergoing IVF. These findings may help explain previous reports of reduced fecundability among women exposed to PCBs.
Collapse
Affiliation(s)
- John D Meeker
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan 48109, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Cohn BA, Cirillo PM, Sholtz RI, Ferrara A, Park JS, Schwingl PJ. Polychlorinated biphenyl (PCB) exposure in mothers and time to pregnancy in daughters. Reprod Toxicol 2011; 31:290-6. [PMID: 21296657 DOI: 10.1016/j.reprotox.2011.01.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 01/08/2011] [Accepted: 01/21/2011] [Indexed: 02/04/2023]
Abstract
Developmental exposure to polychlorinated biphenyls (PCBs) disrupts reproduction in animals. Human data are lacking. We measured PCBs in preserved mothers' serum samples collected during 1960-1963, 1-3 days after their daughters' birth. We recorded time to pregnancy (TTP) in 289 daughters 28-31 years later. PCB congeners 187, 156, and 99 in mother's serum were associated with longer TTP in their daughters while PCB congeners 105, 138 and 183 were associated shorter TTP. Probability of pregnancy fell by 38% (95% CI 17-53%) and infertility was higher (30% not pregnant after 13 cycles versus 11% not pregnant after 13 cycles) among women whose mothers had a higher proportion of PCB congeners associated with longer TTP (75th percentile versus 25th percentile). This study demonstrates, for the first time, that developmental exposure to PCBs may disrupt pregnancy in humans.
Collapse
Affiliation(s)
- Barbara A Cohn
- The Center for Research on Women and Children's Health, The Child Health and Development Studies, Public Health Institute, Berkeley, CA 94709, United States.
| | | | | | | | | | | |
Collapse
|
8
|
Oberson D, Lafon D. Pollutions environnementales et effets sur la reproduction : un regard sur le passé. ARCH MAL PROF ENVIRO 2010. [DOI: 10.1016/j.admp.2010.02.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
9
|
Buck Louis GM, Dmochowski J, Lynch C, Kostyniak P, McGuinness BM, Vena JE. Polychlorinated biphenyl serum concentrations, lifestyle and time-to-pregnancy. Hum Reprod 2008; 24:451-8. [PMID: 18940895 DOI: 10.1093/humrep/den373] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Consumption of fish contaminated with polychlorinated biphenyls (PCBs) and prenatal PCB serum concentrations have been associated with a longer time-to-pregnancy (TTP). However, the relationship between preconception serum PCBs concentrations and TTP has not been previously studied. METHODS Eighty-three women (contributing 442 menstrual cycles) planning pregnancies completed daily diaries regarding menstruation, intercourse, home pregnancy test results, and reported use of alcohol and cigarettes. TTP denoted the number of observed menstrual cycles required for pregnancy. Preconception blood specimens underwent toxicologic analysis for 76 PCB congeners via gas chromatography with electron capture; serum lipids were quantified with enzymatic methods. A priori, PCB congeners were summed into a total and three groupings-estrogenic, anti-estrogenic and other-and entered into discrete analogs of Cox models with time-varying covariates to estimate fecundability odds ratios (FOR) and corresponding 95% confidence intervals (CIs). RESULTS Estrogenic and anti-estrogenic PCB concentrations (ng/g serum) conferred reduced FORs in fully adjusted models (0.32; 95% CI 0.03, 3.90 and 0.01: 95% CI < 0.00, 1.99, respectively). Reduced FORs (0.96) were observed for alcohol consumption standardized to a 28-day menstrual cycle in the same adjusted model (FOR = 0.96; 95% CI 0.93, 1.00). CONCLUSIONS These data suggest that environmental exposures including those amenable to change, such as alcohol consumption, may impact female fecundity. The findings are sensitive to model specification and PCB groupings, underscoring the need to further assess the impact of chemical mixtures on sensitive reproductive outcomes, such as TTP, especially in the context of lifestyle factors which are amenable to change, thereby improving reproductive health.
Collapse
Affiliation(s)
- G M Buck Louis
- Epidemiology Branch, Division of Epidemiology, Statistics and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, 6100 Executive Blvd, Rm. 7B03, Rockville, MD 20852, USA
| | | | | | | | | | | |
Collapse
|
10
|
Axmon A, Rylander L, Rignell-Hydbom A. Reproductive toxicity of seafood contaminants: prospective comparisons of Swedish east and west coast fishermen's families. Environ Health 2008; 7:20. [PMID: 18507855 PMCID: PMC2438351 DOI: 10.1186/1476-069x-7-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 05/28/2008] [Indexed: 05/26/2023]
Abstract
Cohorts comprising fishermen's families on the east coast of Sweden have been found to have a high consumption of contaminated fish as well as high body burdens of persistent organochlorine pollutants (POPs). Their west coast correspondents are socio-economically similar, but with considerably lower POP exposure since the fish caught on the west coast is far less contaminated. The rationale for this was that the cohorts residing on the east coast of Sweden have been found to have a high consumption of contaminated fish as well as high body burdens of POPs, whereas their west coast correspondents are socio-economically similar, but with considerably lower POP exposure since the fish caught on the west coast is far less contaminated. Among the reproductive outcomes investigated are included both male and female parameters, as well as couple fertility and effects on the fetus. A range of exposure measures, including both questionnaire assessments of fish consumption and biomarkers, have been used. The most consistent findings of the studies are those related to the fetus, where a decreased birth weight was found across all measures of exposure, which is in agreement with studies from other populations. Some markers for male reproduction function, i.e. sperm motility, sperm chromatin integrity, and Y:X chromosome ratio, were associated with POP exposure, whereas others, such as sperm concentration and semen volume, were not. With respect to couple fertility and female reproductive parameters, no support was given for associations with POP exposure. Although some associations may have been affected by beneficial effects of essential nutrients in seafood, the overall findings are meaningful in the context of reproductive toxicity and support the usefulness of the epidemiological design.
Collapse
Affiliation(s)
- Anna Axmon
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, University Hospital, SE-221 85 Lund, Sweden
| | - Lars Rylander
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, University Hospital, SE-221 85 Lund, Sweden
| | - Anna Rignell-Hydbom
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, University Hospital, SE-221 85 Lund, Sweden
| |
Collapse
|
11
|
Yang CY, Wang YJ, Chen PC, Tsai SJ, Guo YL. Exposure to a mixture of polychlorinated biphenyls and polychlorinated dibenzofurans resulted in a prolonged time to pregnancy in women. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:599-604. [PMID: 18470317 PMCID: PMC2367681 DOI: 10.1289/ehp.10715] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 01/22/2008] [Indexed: 05/04/2023]
Abstract
BACKGROUND Polychlorinated biphenyls (PCBs), dibenzofurans (PCDFs), and dibenzodioxins (PCDDs) may affect the female reproductive system in animals and humans. In 1978-1979, a mass poisoning occurred in central Taiwan due to PCB/PCDF-contaminated cooking oil; this incident was called Yucheng ("oil disease" in Chinese). OBJECTIVE The purpose of our study was to determine whether PCB/PCDF exposure affected fertility in exposed women. METHODS After the event, we followed the exposed individuals and a reference group who were sex-, age-, and community-matched. In 2003, we obtained fertility histories from Yucheng and reference women by telephone interview. We used Kaplan-Meier survival curves and multivariable Cox regression to compare time to pregnancy (TTP) between Yucheng and reference women, and we performed multiple logistic regression to determine whether PCB/PCDF exposure caused infertility. RESULTS In total, 412 women responded, with a median TTP of 4 months in Yucheng women and 3 months in reference women (p = 0.019). After adjusting for confounders by Cox regression, we found a fecundability ratio of 0.90 [95% confidence interval (CI), 0.80-1.00] for Yucheng women. Among the 408 women who had non-contraceptive sexual activity for > 12 months, 19.7% of Yucheng women and 9.7% of reference women did not become pregnant (i.e., they were infertile). After we adjusted for confounders by logistic regression, the infertility odds ratio was 2.34 (95% CI, 1.23-4.59) for Yucheng women compared with the reference group. CONCLUSIONS We found prolonged TTP and reduced fertility among women previously exposed to PCBs/PCDFs. Because of the limited sample size and the relatively small decrease in the fertility rate, these effects require cautious interpretation and further investigation for confirmation.
Collapse
Affiliation(s)
- Chiu-Yueh Yang
- The Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan
- Department of Health Business Administration, Hung-Kuang University, Taichung, Taiwan
| | - Ying-Jan Wang
- Department of Environmental and Occupational Health, National Cheng Kung University Medical College, Tainan, Taiwan
| | - Pau-Chung Chen
- Department of Occupational Medicine and Industrial Hygiene, National Taiwan University, Taipei, Taiwan
| | - Shaw-Jenq Tsai
- The Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan
| | - Yueliang Leon Guo
- Department of Occupational Medicine and Industrial Hygiene, National Taiwan University, Taipei, Taiwan
- Department of Environmental and Occupational Medicine, National Taiwan University (NTU) and NTU Hospital, Taipei, Taiwan
- Address correspondence to Y.L. Guo, Department of Environmental and Occupational Medicine, National Taiwan University (NTU) and NTU Hospital, 17, Syujhou Rd., Taipei 100, Taiwan, ROC. Telephone: 886-2-33228216. Fax: 886-2-33228214. E-mail:
| |
Collapse
|
12
|
Mendola P, Messer LC, Rappazzo K. Science linking environmental contaminant exposures with fertility and reproductive health impacts in the adult female. Fertil Steril 2008; 89:e81-94. [PMID: 18308071 DOI: 10.1016/j.fertnstert.2007.12.036] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
STUDY OBJECTIVE To broadly review the recent literature linking environmental factors and adult female reproductive health for the UCSF-CHE Summit on Environmental Challenges to Reproductive Health and Fertility. DESIGN Reviewed articles indexed in PubMed from 1999-2007 addressing environment and puberty, menstrual and ovarian function, fertility, and menopause. RESULT(S) The strongest evidence of environmental contaminant exposures interfering with healthy reproductive function in adult females is for heavy metals, particularly lead. Compounds that can influence hormone function, including pesticides and persistent pollutants, are also associated with risk. The pattern of effects for these endocrine-active compounds is often complex, with no clear dose response, but alterations in function and poor reproductive health outcomes are observed. From a clinical perspective, most modifiable risk appears to be associated with exposures in unique populations (contaminated fish consumers) or occupational groups (farmworkers). Many compounds have demonstrated increased risks for reproductive health impairment in women, but the literature is largely cross-sectional in nature and too sparse or inconclusive to support causal inference. CONCLUSION(S) Reproductive function in adult females is impaired by lead exposure. Pesticides and persistent pollutants can alter hormone function resulting in adverse reproductive health effects. Coordinated research is needed to address contaminant effects across the life span.
Collapse
Affiliation(s)
- Pauline Mendola
- US EPA, Human Studies Division, National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina 27711, USA.
| | | | | |
Collapse
|
13
|
Axmon A. Menarche in women with high exposure to persistent organochlorine pollutants in utero and during childhood. ENVIRONMENTAL RESEARCH 2006; 102:77-82. [PMID: 16458286 DOI: 10.1016/j.envres.2005.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 12/09/2005] [Accepted: 12/15/2005] [Indexed: 05/06/2023]
Abstract
In animal studies, exposure to persistent organochlorine pollutants (POPs) in utero and through mother's milk has been suggested to affect the onset of puberty. However, human studies are scarce and ambiguous. In the present study, information on age at menarche was collected from 545 women who had been brought up in a fishing village/family on the Swedish east coast, off the Baltic Sea, and therefore were assumed to have been exposed to POPs in utero, through breast feeding, and/or through dietary habits during their childhood. The average age at menarche for these women was compared to that of three referent groups: (a) 1252 women who also had been brought up in a fishing village/family, but on the Swedish west coast, where the fish had been considerably less contaminated; (b) 634 women from the east coast, but who had not grown up in a fishing village/family; and (c) 869 women from the west coast who had not grown up in a fishing village/family. Based on previous studies, all groups were regarded as having similar socioeconomic circumstances. Data were analyzed using analysis of variance (ANOVA). In an attempt to account for variations in environmental concentrations of POPs over time, all analyses were adjusted for year of birth. Exposed women were found to be slightly older at menarche than referent women from the same coastal area (mean age 13.0 vs 12.8 yr). No differences were found between the exposed women and the two other referent groups (mean age 13.0 yr in all groups).
Collapse
Affiliation(s)
- Anna Axmon
- Division of Occupational and Environmental Medicine and Psychiatric Epidemiology, Department of Laboratory Medicine, Lund University, University Hospital, SE-221 85 Lund, Sweden.
| |
Collapse
|
14
|
Axmon A, Rignell-Hydbom A. Estimations of past male and female serum concentrations of biomarkers of persistent organochlorine pollutants and their impact on fecundability estimates. ENVIRONMENTAL RESEARCH 2006; 101:387-94. [PMID: 16352301 DOI: 10.1016/j.envres.2005.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 09/27/2005] [Accepted: 10/07/2005] [Indexed: 05/05/2023]
Abstract
Persistent organochlorine pollutants (POPs) have been suggested to have negative effects on a number of hormonal systems. Several studies performed retrospectively have reported a possible association between POP exposure and fertility, measured as time to pregnancy (TTP). However, these studies lack biomarkers of exposure at the time when the women tried to conceive. It has previously been found that past female serum concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) can be estimated using a complex decay model, assuming that the biological half-life is 5 years, the yearly environmental reduction of the compound has been 3% since 1976, and the reduction of body burden due to lactation is 20% for periods up to 6 months and 30% for periods exceeding 6 months. In the present study, it is established that the model is valid also for estimations of past male serum concentrations of CB-153. Furthermore, the complex decay model was found to be useful also for estimating past serum concentrations of 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE), assuming that the biological half-life of the compound is 8 years, the yearly reduction between 1971 and 1981 was 20% and after that 9%, and the reduction of body burden due to lactation is the same as that for CB-153. However, even though the estimated past serum concentrations of CB-153 and p,p'-DDE were found to be better proxy measures of actual past concentrations than current serum concentrations, there was little change in the rank order of the population investigated. Thus, the effect estimate for TTP was similar for both proxy measures when using categorized measures of exposure.
Collapse
Affiliation(s)
- Anna Axmon
- Division of Occupational and Environmental Medicine and Psychiatric Epidemiology, Lund University Hospital, Lund 221 85, Sweden.
| | | |
Collapse
|
15
|
Axmon A, Hagmar L. Time to pregnancy and pregnancy outcome. Fertil Steril 2006; 84:966-74. [PMID: 16213851 DOI: 10.1016/j.fertnstert.2005.04.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 04/18/2005] [Accepted: 04/18/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To investigate whether the outcome of a pregnancy is related to the time required to achieve that pregnancy (TTP). DESIGN The distribution of the TTP for pregnancies ending in multiple birth, early (before week 12) and late (weeks 12-28) miscarriage, stillbirth, and extrauterine pregnancy was compared to that of pregnancies ending in singleton birth. Furthermore, the distribution of the TTP for preterm singleton births was compared to that of full-term singleton births. SETTING Sweden. PATIENT(S) Information from three previous studies on reproduction was used: Women chosen for exposure to persistent organochlorine pollutants, or exposure as a hairdresser, and their respective controls. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Self-reported pregnancy outcome. RESULT(S) An increased TTP (i.e., decreased fecundability) was associated with pregnancies ending in miscarriage (early as well as late) and extrauterine pregnancies. Pregnancies ending in multiple live birth tended to have shorter TTPs than those ending in single live birth. No association between TTP and stillbirths was found. Among women whose pregnancies ended in singleton birth, a prolonged TTP was associated with preterm delivery. CONCLUSION(S) The TTP of a pregnancy seemed to be associated with the outcome of that pregnancy. The mechanisms behind this phenomenon are, however, unclear.
Collapse
Affiliation(s)
- Anna Axmon
- Division of Occupational and Environmental Medicine and Psychiatric Epidemiology, University Hospital, Lund, Sweden.
| | | |
Collapse
|
16
|
Axmon A, Thulstrup AM, Rignell-Hydbom A, Pedersen HS, Zvyezday V, Ludwicki JK, Jönsson BAG, Toft G, Bonde JP, Hagmar L. Time to pregnancy as a function of male and female serum concentrations of 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE). Hum Reprod 2005; 21:657-65. [PMID: 16361295 DOI: 10.1093/humrep/dei397] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Persistent organochlorine pollutants (POP) may affect both the female and male reproductive system in animals as well as in humans. METHODS Blood samples were collected from pregnant women and their partners from Greenland, Warsaw and Kharkiv, and from a cohort of Swedish fishermen's wives. Blood samples were analysed for 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE). Information on the participants' fertility, measured as time to pregnancy (TTP), was collected. In total, 778 men and 1505 women were included in the analyses. RESULTS The data from Warsaw, Kharkiv and the Swedish fishermen's wives indicated no effect of either male or female exposure to POP on TTP. However, among men and women from Greenland, there seemed to be an association between serum concentrations of CB-153 and p,p'-DDE and prolonged TTP. Due to the strong intra-individual correlation between CB-153 and p,p'-DDE in the Greenlandic population, it was not possible to determine whether the risk was associated with CB-153 or p, p'-DDE or was an interaction between the two compounds. CONCLUSIONS The overall results of the present study create a somewhat ambiguous pattern, but give some support to the idea that dietary POP exposure might be harmful for couple fertility.
Collapse
Affiliation(s)
- A Axmon
- Division of Occupational and Environmental Medicine and Psychiatric Epidemiology, Lund University Hospital, SE-221 85 Lund, Sweden.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Law DCG, Klebanoff MA, Brock JW, Dunson DB, Longnecker MP. Maternal serum levels of polychlorinated biphenyls and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and time to pregnancy. Am J Epidemiol 2005; 162:523-32. [PMID: 16093292 DOI: 10.1093/aje/kwi240] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polychlorinated biphenyls (PCBs), once used widely in transformers and other applications, and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), the main metabolite of the pesticide 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), are hormonally active agents. Changes in menstrual cycle functioning associated with PCBs and DDE, and increased odds of spontaneous abortion associated with DDE, suggest that these compounds could affect fertility. The authors investigated the association between PCB and DDE exposure and time to pregnancy by using serum levels measured in 390 pregnant women in the Collaborative Perinatal Project enrolled at 12 study centers in the United States from 1959 to 1965. They estimated adjusted fecundability odds ratios by using Cox proportional hazards modeling for discrete time data. Compared with time to pregnancy for women in the lowest exposure category (PCBs < 1.24 microg/liter, DDE < 14 microg/liter), time to pregnancy increased for women in the highest exposure category in terms of both PCBs (fecundability odds ratio for PCBs > or = 5.00 microg/liter = 0.65, 95% confidence interval: 0.36, 1.18) and DDE (fecundability odds ratio for DDE > or = 60 microg/liter = 0.65, 95% confidence interval: 0.32, 1.31). Overall, time to pregnancy increased with increasing serum PCB levels but was less suggestive of an association with DDE. Both trends were imprecise and attenuated when expressed on a lipid basis. Overall, evidence of an association between PCB or DDE exposure and time to pregnancy was weak and inconclusive.
Collapse
Affiliation(s)
- Dionne C Gesink Law
- Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | | | | | | | | |
Collapse
|
18
|
Toft G, Hagmar L, Giwercman A, Bonde JP. Epidemiological evidence on reproductive effects of persistent organochlorines in humans. Reprod Toxicol 2004; 19:5-26. [PMID: 15336708 DOI: 10.1016/j.reprotox.2004.05.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Revised: 02/17/2004] [Accepted: 05/11/2004] [Indexed: 11/15/2022]
Abstract
Organochlorines are widespread pollutants in humans. Concern about adverse reproductive effects of these compounds arises from accidental exposure of humans and experimental studies. Recently, this issue has been addressed by a number of studies of exposed populations and hospital-based case-referent studies. These studies indicate that high concentrations of persistent organochlorines may adversely affect semen quality and cause testicular cancer in males, induce menstrual cycle abnormalities and spontaneous abortions in females, and cause prolonged waiting time pregnancy, reduced birth weight, skewed sex ratio, and altered age of sexual development. However, most effects have been demonstrated at exposure levels above the present day exposure level in European and North American populations. Due to inherent methodological problems in several of the available studies, additional research is needed to fully elucidate the possible adverse effects of organochlorines on human reproductive health.
Collapse
Affiliation(s)
- Gunnar Toft
- Department of Occupational Medicine, Aarhus University Hospital, Noerrebrogade 44, Build. 2C, 8000 Aarhus C, Denmark.
| | | | | | | |
Collapse
|
19
|
Axmon A, Rylander L, Strömberg U, Jönsson B, Nilsson-Ehle P, Hagmar L. Polychlorinated biphenyls in serum and time to pregnancy. ENVIRONMENTAL RESEARCH 2004; 96:186-195. [PMID: 15325879 DOI: 10.1016/j.envres.2003.10.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 10/06/2003] [Accepted: 10/09/2003] [Indexed: 05/24/2023]
Abstract
Polychlorinated biphenyls (PCBs) may affect the female reproductive system in both animals and humans. In Sweden, a main exposure source to PCBs is consumption of fatty fish from the Baltic Sea. From 165 female consumers of such fish (fishermen's sisters), information on time to pregnancy (TTP) and miscarriages was collected, blood was drawn, and serum was analyzed for 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153), a biomarker for total PCB exposure. TTP and miscarriage data, as well as plasma CB-153 concentrations, for 121 fishermen's wives were available from previous studies. Thus, information on 286 women was available for investigation of whether a high exposure to PCB affects fertility negatively by increasing the TTP. The concentrations of CB-153 at the time of conception were estimated and trichotomized into low, medium, and high exposure groups. When we analyzed the joint data set of fishermen's wives and fishermen's sisters, a decrease rather than an increase in TTP was indicated for women in the medium (fecundability ratio 1.27 [95% confidence interval 0.89-1.82]) and high (fecundability ratio 1.42 [0.99-2.03]) exposure groups compared to those in the low exposure group. Similar results were found when we stratified on the original data set (fishermen's wives and fishermen's sisters) or childhood exposure. Women with miscarriages had lower estimated past CB-153 concentrations than women with live births. Our data provide no evidence of a hazardous effect associated with CB-153 concentration in the exposure range assessed. The exposure levels found in the fishermen's families, although high compared to that in the general Swedish population, may not be high enough to negatively affect fertility.
Collapse
Affiliation(s)
- Anna Axmon
- Department of Occupational and Environmental Medicine, Institute of Laboratory Medicine, University Hospital, Lund SE-221 85, Sweden.
| | | | | | | | | | | |
Collapse
|
20
|
Axmon A, Rylander L, Strömberg U, Hagmar L. Altered menstrual cycles in women with a high dietary intake of persistent organochlorine compounds. CHEMOSPHERE 2004; 56:813-819. [PMID: 15251296 DOI: 10.1016/j.chemosphere.2004.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Revised: 02/05/2004] [Accepted: 03/01/2004] [Indexed: 05/24/2023]
Abstract
Dietary exposure to persistent organochlorine compounds (POCs) has been found to affect the menstrual cycle in both animals and humans. In Sweden, the major exposure route for POCs is the consumption of fatty fish from the Baltic Sea. Thus, women who eat relatively large amounts of this fish constitute a suitable study group when investigating a possible association between dietary exposure to POC and menstrual cycle disruption. Questionnaires were sent to the exposed women, as well as to a socioeconomically similar cohort of controls, and information was collected on their menstrual cycles. Since the exposed women tended to smoke more than the controls, all results were adjusted for smoking habits. A cohort comparison found that the exposed women on average had 0.46 (95% confidence interval: 0.03, 0.89) days shorter menstrual cycles than controls. However, within the exposed cohort no effects were found of the proxy variables early life exposure and high consumption of Baltic Sea fatty fish. The results give some support to previous results from studies on women with similar exposure, but are not conclusive with respect to whether there is a causal association between POC exposure and menstrual cycle disruption.
Collapse
Affiliation(s)
- Anna Axmon
- Department of Occupational and Environmental Medicine, University Hospital, SE-221 85 Lund, Sweden.
| | | | | | | |
Collapse
|
21
|
Gregoraszczuk EL, Grochowalski A, Chrzaszcz R, Wegiel M. Congener-specific accumulation of polychlorinated biphenyls in ovarian follicular wall follows repeated exposure to PCB 126 and PCB 153. Comparison of tissue levels of PCB and biological changes. CHEMOSPHERE 2003; 50:481-488. [PMID: 12685747 DOI: 10.1016/s0045-6535(02)00637-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
OBJECTIVE Small (SF), medium (MF) and large (LF) preovulatory porcine follicles were isolated and incubated in an Erlenmeyer flask containing 5 ml of medium with addition of PCB 126 or PCB 153 to test differences in their accumulation in the follicular wall. METHODS; The follicles were incubated in M199 medium at 37 degrees C with constant shaking at 70 rpm, for 6 days. The media were changed every day and repeated dose 25 pg/ml of PCB 126 or 25 ng/ml of PCB 153 was added each day till 6 days of culture. Media were collected every day and frozen for steroid analysis by RIA. 24 h after the last treatment follicles were frozen for further polychlorinated biphenyls (PCB) content analysis. PCB concentrations in the follicular wall were analysed by mass spectrometry. RESULTS 3.3%; 3.6% and 5.6% of total PCB 126 dose, and 71%; 71.4% and 30.4% of total PCB 153 dose accumulated in SF, MF and LF follicles, respectively. The accumulative effect of PCB was manifested by the disruption of estradiol (E2) secretion. In SF antiestrogenic action of PCB 126 was observed during the whole time of exposure while PCB 153 decreased E2 till 4 days of culture and then estrogenic action was observed. In MF, both these congeners decreased E2 till 5 days of exposure and then estrogenic actions were noted with the highest magnification in the case of PCB 126. In LF both PCB studied increased E2 till 3 days of exposure with the highest magnification of PCB 126, then antiestrogenic action was noted. Testosterone secretion was generally affected in a pattern oposite to that of E2 suggesting action on P450arom activity. CONCLUSION The results of these studies demonstrated that disruption of aromatization process in the follicles following repeated exposure to both congeners is not directly correlated with the bioaccumulation or amount of PCB within the follicular wall.
Collapse
Affiliation(s)
- E L Gregoraszczuk
- Laboratory of Physiology and Toxicology of Reproduction, Department of Animal Physiology, Institute of Zoology, Jagiellonian University, Ingardena 6, Krakow 30-060, Poland.
| | | | | | | |
Collapse
|
22
|
Buck GM, Vena JE, Greizerstein HB, Weiner JM, McGuinness B, Mendola P, Kostyniak PJ, Swanson M, Bloom MS, Olson JR. PCB congeners and pesticides and female fecundity, New York State Angler Prospective Pregnancy Study. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2002; 12:83-92. [PMID: 21782627 DOI: 10.1016/s1382-6689(02)00026-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Consumption of PCB-contaminated sport fish from Lake Ontario has been reported to be associated with diminished female fecundity. To identify Polychlorinated biphenyl (PCB) congeners and other pesticides that might be associated with reduced fecundity, we followed 102 women aged 20-34 years attempting pregnancy who completed daily diaries for 12 at risk menstrual cycles. Fecundity referred to time-to-pregnancy (TTP) or the number of at risk menstrual cycles required for pregnancy. Blood specimens were obtained for 88 (86%) women and were analyzed using gas chromatography and electron capture for 66 PCB congeners and seven pesticides. Laboratory values were recovery, background and fat corrected prior to natural log transformation. Using stepwise discriminant analysis, congeners IUPAC #205 and #206 and hexaclorobenzene were significantly and positively associated with increasing TTP when women were categorized as becoming pregnant in the first or first three at risk menstrual cycles, respectively. Congeners #205 and #206 are reported to have (anti) estrogenic structural activity.
Collapse
Affiliation(s)
- Germaine M Buck
- Departments of Social and Preventive Medicine and Pharmacology and Toxicology, University at Buffalo, State of New York, Buffalo, NY 14214, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Axmon A, Rylander L, Strömberg U, Dyremark E, Hagmar L. Polychlorinated biphenyls in blood plasma among Swedish female fish consumers in relation to time to pregnancy. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2001; 64:485-498. [PMID: 11732699 DOI: 10.1080/152873901753215948] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The purpose of this study was to assess the association between 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in plasma, a biomarker of exposure to polychlorinated biphenyls (PCB), and time to pregnancy (TTP) in a group of women with a varying dietary exposure to PCB. For 121 Swedish east coast fishermen's wives (median year of birth 1956, range 1945-1968), information on selt-reported TTP for the first planned pregnancy (median 2 mo, range 0-48) and CB-153 concentrations from blood samples drawn in 1995 (median 144 ng/g lipid, range 16-566) were available. Each woman's CB-153 concentration in plasma at the time immediately preceding her pregnancy was estimated, taking into account reduction of body burden of CB-153 due to lactation, the yearly reduction of PCB in Baltic Sea fish, as well as the biological half-life of CB-153. Based on the estimated CB-153 concentrations, subjects were categorized into tertiles as low (37-206 ng/g lipid), medium (207-330 ng/g lipid), and high (331-,1036 ng/g lipid) exposure groups. TTP in the medium- and high-exposure groups were then compared to TTP in the low-exposure group by estimating the corresponding success rate (i.e., the number of pregnancies per person month) ratios (SuRR) using discrete Cox regression, taking into account essential confounders. No obvious association between estimated CB-153 concentration and TTP was observed (medium vs. low: SuRR 0.77 [95% CI 0.47-1.28] and high vs. low: SuRR 0.95 10.74-1.23]). The present data give no support for a negative association between the plasma CB-153 concentrations observed in the present study and TTP. It should, however, be borne in mind that the study group was rather small and mainly included relatively young women, likely to have been only moderately exposed.
Collapse
Affiliation(s)
- A Axmon
- Department of Occupational and Environmental Medicine, Institute of Laboratory Medicine, University Hospital, Lund, Sweden.
| | | | | | | | | |
Collapse
|