Human Early Life Exposome (HELIX) study: a European population-based exposome cohort
Authors: Maitre Léa , de Bont Jeroen , Casas Maribel , Robinson Oliver , Aasvang Gunn Marit , Agier Lydiane , Andrušaitytė Sandra , Ballester Ferran , Basagaña Xavier , Borràs Eva , Brochot Céline , Bustamante Mariona , Carracedo Angel , de Castro Montserrat , Dedele Audrius , Donaire-Gonzalez David , Estivill Xavier , Evandt Jorunn , Fossati Serena , Giorgis-Allemand Lise , R Gonzalez Juan , Granum Berit , Grazuleviciene Regina , Bjerve Gützkow Kristine , Småstuen Haug Line , Hernandez-Ferrer Carles , Heude Barbara , Ibarluzea Jesus , Julvez Jordi , Karachaliou Marianna , Keun Hector C , Hjertager Krog Norun , Lau Chung-Ho E , Leventakou Vasiliki , Lyon-Caen Sarah , Manzano Cyntia , Mason Dan , McEachan Rosemary , Meltzer Helle Margrete , Petraviciene Inga , Quentin Joane , Roumeliotaki Theano , Sabido Eduard , Saulnier Pierre-Jean , Siskos Alexandros P , Siroux Valérie , Sunyer Jordi , Tamayo Ibon , Urquiza Jose , Vafeiadi Marina , van Gent Diana , Vives-Usano Marta , Waiblinger Dagmar , Warembourg Charline , Chatzi Leda , Coen Muireann , van den Hazel Peter , Nieuwenhuijsen Mark J , Slama Rémy , Thomsen Cathrine , Wright John , Vrijheid Martine 
Published: September 2018

PurposeEssential to exposome research is the collection of data on many environmental exposures from different domains in the same subjects. The aim of the Human Early Life Exposome (HELIX) study was to measure and describe multiple environmental exposures during early life (pregnancy and childhood) in a prospective cohort and associate these exposures with molecular omics signatures and child health outcomes. Here, we describe recruitment, measurements available and baseline data of the HELIX study populations.ParticipantsThe HELIX study represents a collaborative project across six established and ongoing longitudinal population-based birth cohort studies in six European countries (France, Greece, Lithuania, Norway, Spain and the UK). HELIX used a multilevel study design with the entire study population totalling 31 472 mother-child pairs, recruited during pregnancy, in the six existing cohorts (first level); a subcohort of 1301 mother-child pairs where biomarkers, omics signatures and child health outcomes were measured at age 6–11 years (second level) and repeat-sampling panel studies with around 150 children and 150 pregnant women aimed at collecting personal exposure data (third level).Findings to dateCohort data include urban environment, hazardous substances and lifestyle-related exposures for women during pregnancy and their offspring from birth until 6–11 years. Common, standardised protocols were used to collect biological samples, measure exposure biomarkers and omics signatures and assess child health across the six cohorts. Baseline data of the cohort show substantial variation in health outcomes and determinants between the six countries, for example, in family affluence levels, tobacco smoking, physical activity, dietary habits and prevalence of childhood obesity, asthma, allergies and attention deficit hyperactivity disorder.Future plansHELIX study results will inform on the early life exposome and its association with molecular omics signatures and child health outcomes. Cohort data are accessible for future research involving researchers external to the project.