Rationale and study design of the Japan environment and children's study (JECS).

BACKGROUND: There is global concern over significant threats from a wide variety of environmental hazards to which children face. Large-scale and long-term birth cohort studies are needed for better environmental management based on sound science. The primary objective of the Japan Environment and Children's Study (JECS), a nation-wide birth cohort study that started its recruitment in January 2011, is to elucidate environmental factors that affect children's health and development. METHODS/DESIGN: Approximately 100,000 expecting mothers who live in designated study areas will be recruited over a 3-year period from January 2011. Participating children will be followed until they reach 13 years of age. Exposure to environmental factors will be assessed by chemical analyses of bio-specimens (blood, cord blood, urine, breast milk, and hair), household environment measurements, and computational simulations using monitoring data (e.g. ambient air quality monitoring) as well as questionnaires. JECS' priority outcomes include reproduction/pregnancy complications, congenital anomalies, neuropsychiatric disorders, immune system disorders, and metabolic/endocrine system disorders. Genetic factors, socioeconomic status, and lifestyle factors will also be examined as covariates and potential confounders. To maximize representativeness, we adopted provider-mediated community-based recruitment. DISCUSSION: Through JECS, chemical substances to which children are exposed during the fetal stage or early childhood will be identified. The JECS results will be translated to better risk assessment and management to provide healthy environment for next generations.

[Epidemiological research on children's environmental health].

In accordance with the Declaration of the Environment Leaders of the Eight on Children's Environmental Health (Miami Declaration) in 1997, the Japanese government (the Ministry of Environment, Japan) organized a commission tasked to discuss issues related to the present situation of the environmental health of children (Advisory Commission for Children's Environmental Health). Epidemiological research on children's environmental health has been recommended as one of the priority projects by the commission because the effects of environmental factors on children's health are clarified by only studies using children as subjects, particularly, a birth cohort study, and not by animal experiments. The Advisory Committee of Epidemiological Research on Children's Environmental Health was established in 2007 and decided to start a nationwide birth cohort study following up children from pregnancy to 12 years old. Under the Advisory Committee, a working group composed of scientific experts, including epidemiologists, toxicologists, obstetricians, orthopedists, and statisticians, was organized in 2008. Pilot studies are going to be conducted in several areas in Japan with the support of the working group. Study hypotheses will also be decided by the working group soon. The full-scale survey will start in 2010.