title: Lower placental telomere length may be attributed to maternal residential traffic exposure; a twin study.
abstract: BACKGROUND
  High variation in telomere length between individuals is already present before birth and is as wide among newborns as in adults. Environmental exposures likely have an impact on this observation, but remain largely unidentified. We hypothesize that placental telomere length in twins is associated with residential traffic exposure, an important environmental source of free radicals that might accelerate aging. Next, we intend to unravel the nature-nurture contribution to placental telomere length by estimating the heritability of placental telomere length.
  
  
  METHODS
  We measured the telomere length in placental tissues of 211 twins in the East Flanders Prospective Twin Survey. Maternal traffic exposure was determined using a geographic information system. Additionally, we estimated the relative importance of genetic and environmental sources of variance.
  
  
  RESULTS
  In this twin study, a variation in telomere length in the placental tissue was mainly determined by the common environment. Maternal residential proximity to a major road was associated with placental telomere length: a doubling in the distance to the nearest major road was associated with a 5.32% (95% CI: 1.90 to 8.86%; p=0.003) longer placental telomere length at birth. In addition, an interquartile increase (22%) in maternal residential surrounding greenness (5 km buffer) was associated with an increase of 3.62% (95% CI: 0.20 to 7.15%; p=0.04) in placental telomere length.
  
  
  CONCLUSIONS
  In conclusion, we showed that maternal residential proximity to traffic and lower residential surrounding greenness is associated with shorter placental telomere length at birth. This may explain a significant proportion of air pollution-related adverse health outcomes starting from early life, since shortened telomeres accelerate the progression of many diseases.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium; Department of Complex Genetics, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
authors.forename: Esmée
authors.initials: E
authors.lastname: Bijnens
authors.affiliation: Department of Complex Genetics, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
authors.forename: Maurice P
authors.initials: MP
authors.lastname: Zeegers
authors.affiliation: Department of Complex Genetics, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
authors.forename: Marij
authors.initials: M
authors.lastname: Gielen
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium.
authors.forename: Michal
authors.initials: M
authors.lastname: Kicinski
authors.affiliation: Department of Toxicology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
authors.forename: Geja J
authors.initials: GJ
authors.lastname: Hageman
authors.affiliation: Department of Toxicology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Pachen
authors.affiliation: Centre of Human Genetics, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Catherine
authors.initials: C
authors.lastname: Derom
authors.affiliation: Centre of Human Genetics, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Robert
authors.initials: R
authors.lastname: Vlietinck
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium; Department of Public Health, Leuven University (KU Leuven), Kapucijnenvoer 35, 3000 Leuven, Belgium. Electronic address: tim.nawrot@uhasselt.be.
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects* / Q000706:statistics & numerical data; D001530:Belgium; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005609:Free Radicals / Q000633:toxicity; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D011446:Prospective Studies; D059506:Telomere Shortening / Q000502:physiology*; D001335:Vehicle Emissions / Q000633:toxicity*; D055815:Young Adult
chemical_list: D005609:Free Radicals; D001335:Vehicle Emissions
keywords: Placenta; Telomeres; Traffic; Twin