title: Exposure to organophosphorus and organochlorine pesticides, perfluoroalkyl substances, and polychlorinated biphenyls in pregnancy and the association with impaired glucose tolerance and gestational diabetes mellitus: The MIREC Study.
abstract: BACKGROUND
  Studies report increases in rates of gestational diabetes mellitus (GDM) over recent decades. Environmental chemicals may increase the risk of diabetes through impacts on glucose metabolism, mitochondrial dysfunction, and endocrine-disrupting mechanisms including effects on pancreatic β-cell function and adiponectin release.
  
  
  OBJECTIVE
  To determine the associations between pesticides, perfluoroalkyl substances (PFASs) and polychlorinated biphenyls (PCBs) measured in early pregnancy and impaired glucose tolerance (IGT) and GDM in a Canadian birth cohort.
  
  
  METHODS
  Women enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study were included if they had a singleton delivery and did not have pre-existing diabetes. Exposure variables included three organophosphorus (OP) pesticide metabolites detected in first-trimester urine samples, as well as three organochlorine (OC) pesticides, three PFASs, and four PCBs in first-trimester blood samples. Gestational IGT and GDM were assessed by chart review in accordance with published guidelines. Adjusted logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CI) for the association between quartiles of environmental chemicals and both gestational IGT and GDM.
  
  
  RESULTS
  Of the 2001 women recruited into the MIREC cohort, 1274 met the inclusion criteria and had outcome and biomonitoring data available. Significantly lower odds of GDM were observed in the third and fourth quartiles of dimethylphosphate (DMP) and in the fourth quartile of dimethylthiophosphate (DMTP) in adjusted analyses (DMP Q3: OR=0.2, 95% CI=0.1-0.7; DMP Q4: OR=0.3, 95% CI=0.1-0.8; DMTP: OR=0.3, 95% CI=0.1-0.9). Significantly elevated odds of gestational IGT was observed in the second quartile of perfluorohexane sulfonate (PFHxS) (OR=3.5, 95% CI=1.4-8.9). No evidence of associations with GDM or IGT during pregnancy was observed for PCBs or OC pesticides.
  
  
  CONCLUSIONS
  We did not find consistent evidence for any positive associations between the chemicals we examined and GDM or IGT during pregnancy. We observed statistical evidence of inverse relationships between urine concentrations of DMP and DMTP with GDM. We cannot rule out the influence of residual confounding due to unmeasured protective factors, such as nutritional benefits from fruit and vegetable consumption, also associated with pesticide exposure, on the observed inverse associations between maternal OP pesticide metabolites and GDM. These findings require further investigation.
authors: McGill University, Montreal, QC, Canada; CHU Sainte-Justine Research Centre, Université de Montréal, Montreal, QC, Canada.
authors: Gabriel D
authors: GD
authors: Shapiro
authors: Dalhousie University, Halifax, NS, Canada. Electronic address: L.Dodds@dal.ca.
authors: Linda
authors: L
authors: Dodds
authors: Health Canada, Ottawa, ON, Canada.
authors: Tye E
authors: TE
authors: Arbuckle
authors: Dalhousie University, Halifax, NS, Canada.
authors: Jillian
authors: J
authors: Ashley-Martin
authors: Yale University, New Haven, CT, USA.
authors: Adrienne S
authors: AS
authors: Ettinger
authors: Health Canada, Ottawa, ON, Canada.
authors: Mandy
authors: M
authors: Fisher
authors: University of Manitoba, Winnipeg, MB, Canada.
authors: Shayne
authors: S
authors: Taback
authors: CHU Sainte-Justine Research Centre, Université de Montréal, Montreal, QC, Canada.
authors: Maryse F
authors: MF
authors: Bouchard
authors: McGill University, Montreal, QC, Canada.
authors: Patricia
authors: P
authors: Monnier
authors: Laval University, Québec City, QC, Canada.
authors: Renée
authors: R
authors: Dallaire
authors: Laval University, Québec City, QC, Canada.
authors: Anne-Sophie
authors: AS
authors: Morisset
authors: CHU Sainte-Justine Research Centre, Université de Montréal, Montreal, QC, Canada; Centre de recherche du CHUS, Sherbrooke, QC, Canada; Université de Sherbrooke, Sherbrooke, QC, Canada.
authors: William
authors: W
authors: Fraser
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D016640:Diabetes, Gestational / Q000139:chemically induced / Q000453:epidemiology*; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D005466:Fluorocarbons / Q000633:toxicity*; D018149:Glucose Intolerance / Q000139:chemically induced / Q000453:epidemiology*; D006801:Humans; D016015:Logistic Models; D018811:Maternal Exposure; D008875:Middle Aged; D016017:Odds Ratio; D010575:Pesticides / Q000633:toxicity*; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D011247:Pregnancy; D011792:Quebec / Q000453:epidemiology; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D005466:Fluorocarbons; D010575:Pesticides; D011078:Polychlorinated Biphenyls
keywords: Gestational diabetes mellitus; Perfluoroalkyl substances; Pesticides; Polychlorinated biphenyls; Pregnancy