Ten years of progress in the Hokkaido birth cohort study on environment and children’s health: cohort profile—updated 2013

Abstract

The Hokkaido Study on Environment and Children's Health is an ongoing cohort study that began in 2002. The study consists of two prospective birth cohorts, the Sapporo cohort (n = 514) and the Hokkaido large-scale cohort (n = 20,940). The primary goals of this study are to first examine the potential negative effects of perinatal environmental chemical exposures on birth outcomes, including congenital malformations and growth retardation; second, to evaluate the development of allergies, infectious diseases and neurodevelopmental disorders and perform longitudinal observations of the children's physical development to clarify the causal relationship between these outcomes and environmental chemicals; third, to identify individuals genetically susceptible to environmental chemicals; finally, to identify the additive effects of various environmental factors in our daily life, such as secondhand smoke exposure or low folate intake during early pregnancy. In this paper, we introduce our recent progress in the Hokkaido study with a cohort profile updated in 2013. For the last ten years, we followed pregnant women and their offspring, measuring various environmental chemicals, i.e., PCB, OH-PCB and dioxins, PFCs (Perfluorinated Compounds), Organochlorine pesticides, Phthalates, bisphenol A and mercury. We discovered that the concentration of toxic equivalents (TEQ) of dioxin and other specific congeners of PCDF or PCDD have effects on birth weight, infants' neurodevelopment and immune function. There were significant gender differences in these effects; our results suggest that male infants have more susceptibility to those chemical exposures than female infants. Interestingly, we found maternal genetic polymorphisms in AHR, CYP1A1 or GSTs that significantly modified the dioxin concentrations in maternal blood, suggesting different dioxin accumulations in the bodies of individuals with these genotypes, which would lead to different dioxin exposure levels. These genetic susceptibility factors influenced the body size of children born from mothers that either smoked or were passively exposed to tobacco smoke. Further studies investigating the correlation between epigenetics, the effects of intrauterine exposure to environmental chemicals and developmental factors related to health and disease are warranted.

Association between prenatal exposure to perfluorinated compounds and symptoms of infections at age 1–4years among 359 children in the Odense Child Cohort

“…Five previous birth cohort studies have been conducted examining the adverse effects of prenatal PFAS exposure on clinical infectious or allergic disease (Fei et al 2010;Granum et al 2013;Kishi et al 2013;Okada et al 2012;Wang et al 2011). To our knowledge no previous studies have obtained information about fever as such but only about infectious diseases, as assessed by parental questionnaire or hospital diagnosis, and their findings appear to be somewhat inconsistent (Fei et al 2010;Granum et al 2013).…”

Prenatal exposure to bisphenol-A is associated with Toll-like receptor–induced cytokine suppression in neonates

“…To our knowledge, only two published studies implied BPA exposure to increase the risk of infectious diseases in the pediatric population. One study had suggested prenatal BPA exposure to increase the risk of respiratory tract infection in children; however, the association only became significant after adjusting for confounding factors (32,33). Furthermore, whether the effect of BPA on increased airway infection had resulted from direct immunosuppression or an indirect influence inflicted by hyperactive airway remains debatable, since they had concurrent results showing a strong association between BPA exposure and wheeze/asthma.…”

Combined effects of AHR , CYP1A1 , and XRCC1 genotypes and prenatal maternal smoking on infant birth size: Biomarker assessment in the Hokkaido Study

“…The study participants were Japanese mother-child pairs drawn from the birth cohort of The Hokkaido Study on Environmental and Children's Health begun in February 2003 [36][37]. The study protocol has been described [36][37].…”

“…The study protocol has been described [36][37]. In brief, this is a prospective ongoing birth cohort study.…”