47
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Maternal exposure to perfluorinated chemicals and reduced fecundity: the MIREC study

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          STUDY QUESTION

          What is the effect of maternal exposure to perfluorooctane sulfonate (PFOS), perflurooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) on female fecundity?

          SUMMARY ANSWER

          Increasing concentrations of PFOA or PFHxS in maternal plasma were associated with reduced fecundability and infertility.

          WHAT IS KNOWN ALREADY

          Perfluorinated chemicals (PFCs) are a group of synthetic compounds used in industrial production. There is a concern about the effect of PFCs on fecundity, as measured by time-to-pregnancy (TTP). Although some recent studies suggest that increasing concentrations of PFCs may decrease fecundity, divergence in the methodological approaches used to evaluate this association have prevented firm conclusions being reached.

          STUDY DESIGN, SIZE, DURATION

          The Maternal-Infant Research on Environmental Chemicals (MIREC) Study is a cohort study of 2,001 women recruited before 14 weeks of gestation in 10 cities across Canada between 2008 and 2011.

          PARTICIPANTS/MATERIALS, SETTING, METHODS

          A questionnaire was administered and medical chart data and biospecimens were collected from participants. After excluding women who withdrew, those for whom data were incomplete, those whose pregnancies followed birth control failure, and accounting for male fertility, 1743 participants remained. TTP was defined as the number of months of unprotected intercourse needed to become pregnant in the current pregnancy, as self-reported in the first trimester of pregnancy. Plasma concentrations of PFOA, PFOS and PFHxS measured in the first trimester were considered as a surrogate of preconception exposure. Fecundability odds ratios (FORs) were estimated using Cox proportional hazard models for discrete time. FOR < 1 denote a longer TTP and FORs >1 denote a shorter TTP. The odds of infertility (TTP > 12 months or infertility treatment in the index pregnancy) were estimated using logistic regression. Each chemical concentration (ng/ml) was log-transformed and divided by its SD.

          MAIN RESULTS AND THE ROLE OF CHANCE

          The cumulative probabilities of pregnancy at 1, 6 and 12 months were 0.42 (95% confidence interval (CI) 0.40–0.45), 0.81 (95% CI 0.79–0.83) and 0.90 (95% CI 0.89–0.92), respectively. The mean maternal age was 32.8 (SD 5.0) years. The geometric means (ng/ml) of PFOA, PFOS and PFHxS were 1.66 (95% CI 1.61–1.71), 4.59 (95% CI 4.46–4.72) and 1.01 (95% CI 0.97–1.05), respectively. After adjustment for potential confounders, PFOA and PFHxS were associated with a 11 and 9% reduction in fecundability per one SD increase (FOR = 0.89; 95% CI 0.83–0.94; P < 0.001 for PFOA and FOR = 0.91; 95% CI 0.86–0.97; P = 0.002 for PFHxS), while no significant association was observed for PFOS (FOR = 0.96; 95% CI 0.91–1.02; P = 0.17). In addition, the odds of infertility increased by 31% per one SD increase of PFOA (odds ratio (OR) = 1.31; 95% CI 1.11–1.53; P = 0.001) and by 27% per one SD increase of PFHxS (OR = 1.27; 95% CI 1.09–1.48; P = 0.003), while no significant association was observed for PFOS (OR = 1.14; 95% CI 0.98–1.34; P = 0.09).

          LIMITATIONS, REASONS FOR CAUTION

          Women with the highest concentrations of PFCs might have been excluded from the study if there is a causal association with infertility. The MIREC study did not assess concentrations of PFCs in males, semen quality, menstrual cycle characteristics or intercourse frequency.

          WIDER IMPLICATIONS OF THE FINDINGS

          Our results add to the evidence that exposure to PFOA and PFHxS, even at lower levels than previously reported, may reduce fecundability.

          STUDY FUNDING/COMPETING INTEREST(S)

          The MIREC study is supported by the Chemicals Management Plan of Health Canada, the Canadian Institutes for Health Research (CIHR, grant no. MOP – 81285) and the Ontario Ministry of the Environment. M.P.V. was supported by a CIHR Fellowship Award, and a CIHR-Quebec Training Network in Perinatal Research (QTNPR) Ph.D. scholarship. W.D.F. is supported by a CIHR Canada Research Chair. There are no conflicts of interest to declare.

          Related collections

          Most cited references33

          • Record: found
          • Abstract: found
          • Article: not found

          Quantifying biases in causal models: classical confounding vs collider-stratification bias.

          It has long been known that stratifying on variables affected by the study exposure can create selection bias. More recently it has been shown that stratifying on a variable that precedes exposure and disease can induce confounding, even if there is no confounding in the unstratified (crude) estimate. This paper examines the relative magnitudes of these biases under some simple causal models in which the stratification variable is graphically depicted as a collider (a variable directly affected by two or more other variables in the graph). The results suggest that bias from stratifying on variables affected by exposure and disease may often be comparable in size with bias from classical confounding (bias from failing to stratify on a common cause of exposure and disease), whereas other biases from collider stratification may tend to be much smaller.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Trends in exposure to polyfluoroalkyl chemicals in the U.S. Population: 1999-2008.

            Since 2002, practices in manufacturing polyfluoroalkyl chemicals (PFCs) in the United States have changed. Previous results from the National Health and Nutrition Examination Survey (NHANES) documented a significant decrease in serum concentrations of some PFCs during 1999-2004. To further assess concentration trends of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA), we analyzed 7876 serum samples collected from a representative sample of the general U.S. population ≥12 years of age during NHANES 1999-2008. We detected PFOS, PFOA, PFNA, and PFHxS in more than 95% of participants. Concentrations differed by sex regardless of age and we observed some differences by race/ethnicity. Since 1999-2000, PFOS concentrations showed a significant downward trend, because of discontinuing industrial production of PFOS, but PFNA concentrations showed a significant upward trend. PFOA concentrations during 1999-2000 were significantly higher than during any other time period examined, but PFOA concentrations have remained essentially unchanged during 2003-2008. PFHxS concentrations showed a downward trend from 1999 to 2006, but concentrations increased during 2007-2008. Additional research is needed to identify the environmental sources contributing to human exposure to PFCs. Nonetheless, these NHANES data suggest that sociodemographic factors may influence exposure and also provide unique information on temporal trends of exposure.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Perfluorinated compounds--exposure assessment for the general population in Western countries.

              Perfluorinated compounds (PFCs) can currently be detected in many environmental media and biota, as well as in humans. Because of their persistence and their potential to accumulate they are of toxicological concern. The present review presents the current knowledge of PFC monitoring data in environmental media relevant for human exposure. In this context, PFC concentrations in indoor and ambient air, house dust, drinking water and food are outlined. Furthermore, we summarize human biomonitoring data of PFC levels in blood, breast milk, and human tissues. An estimate of the overall exposure of the general adult population is provided and compared with tolerable intake values. Using a simplified model, the average (and upper) level of daily exposure including all potential routes amounts to 1.6 ng/kg(body weight) (8.8 ng/kg(body weight)) for PFOS and 2.9 ng/kg(body weight) (12.6 ng/kg(body weight)) for PFOA in adults in the general population. The majority of exposure can be attributed to the oral route, mainly to diet. Overall, the contribution of PFOS and PFOA precursors to total exposure seems to be limited. Besides this background exposure of the general population, a specific additional exposure may occur which causes an increased PFC body burden. This has been observed in populations living near PFC production facilities or in areas with environmental contamination of PFCs. The consumption of highly contaminated fish products may also cause an increase in PFC body burdens.
                Bookmark

                Author and article information

                Journal
                Hum Reprod
                Hum. Reprod
                humrep
                humrep
                Human Reproduction (Oxford, England)
                Oxford University Press
                0268-1161
                1460-2350
                March 2015
                07 January 2015
                07 January 2015
                : 30
                : 3
                : 701-709
                Affiliations
                [1 ]Sainte-Justine University Hospital Research Centre, University of Montreal , Montreal, Canada
                [2 ]Population Studies Division, Healthy Environments and Consumer Safety Branch, Health Canada , Ottawa, Canada
                Author notes
                [* ]Correspondence address. E-mail: mdp.velez.gomez@ 123456umontreal.ca
                Article
                deu350
                10.1093/humrep/deu350
                4325673
                25567616
                fc7e86d7-43d0-472d-96b4-42b11b8d130a
                © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

                History
                : 11 September 2014
                : 28 October 2014
                : 8 December 2014
                Categories
                Original Articles
                Reproductive Epidemiology

                Human biology
                time to pregnancy,fecundity,perfluorooctane sulfonate,perflurooctanoic acid,perfluorohexane sulfonate

                Comments

                Comment on this article