A study design to assess exposure levels of insecticides in 1.5-year-old children in Aichi Regional Subcohort of the Japan Environment and Children's Study

摘要

Background: A nationwide and government-funded birth cohort study in Japan named the Japan Environment and Children's Study (JECS) started from January 2011 to elucidate environmental factors that affect children's health and development. After 3-year recruitment period of pregnant women living in designated study areas including Aichi, Japan, the children to whom they gave birth are now followed until 13 years old. Objectives: This presentation aims to describe a study protocol of an adjunct study of JECS to assess exposure levels of insecticides in 1.5-year-old children in Aichi. Methods: For this adjunct study, we have recruited 1.5-year-old JECS participants since June 2015, which will be completed in June 2016. Their guardians are asked to take part in the study at health-care centers on the occasions of municipal checkups for children at the age, and informed consents for this study were obtained. Food intake questionnaire to assess exposure amount of insecticides from diets was developed based on data about permitted application of pesticides for registered crops in Japan. The intake of each crop is counted as a number of child-size spoons by the guardians at home for each of three meals during the day, and is recorded on the questionnaire. The questionnaire also asks them whether or not spraying insecticides during the preceding week. To collect urine, the children wear designated disposable diapers during the night following the three meals recorded, and the questionnaire and the used diapers are sent to our laboratory as refrigerated cargoes. Results: We collected the questionnaire and used diapers from 618 children from June 25 through December 31 in 2015 (consent rate was 79.1%). Their months of age were between 17 and 24 and the mode was 19 (54.9%). Three hundred and eighteen male and 300 female children were enrolled. One thousand children in total are expected to take part in this adjunct study by the end of the recruitment period. Age of the mothers at the delivery and the birth weights of the participating children are distributed from 18 to 44 (median, 33; interquartile range, 30-36) and from 815 to 4,400 (median, 3,044; interquartile range, 2,748-3,282), respectively. The rate of low birth weight (<2500 g) was 9.5%. These demographic data suggest that the subjects in this survey represent the population in Aichi regional subcohort of JECS and entire population in Aichi. Thus, it is expected that this study reveals exposure levels of insecticides in the area.