Tohoku J. Exp. Med., 2004, 202(3)

The Tohoku Study of Child Development: A Cohort Study of Effects of Perinatal Exposures to Methylmercury and Environmentally Persistent Organic Pollutants on Neurobehavioral Development in Japanese Children

KUNIHIKO NAKAI, KEITA SUZUKI, TOMOKO OKA, KATSUYUKI MURATA,¹ MINESHI SAKAMOTO,² KUNIHIRO OKAMURA,³ TORU HOSOKAWA,⁴ TAKEO SAKAI,⁵ TOMOYUKI NAKAMURA,⁶ YOSHINORI SAITO,⁶ NAOYUKI KUROKAWA, SATOMI KAMEO and HIROSHI SATOH

Department of Environmental Health Sciences, Tohoku University Graduate School of Medicine, Sendai 980-8575,
¹Division of Environmental Health Science, Akita University School of Medicine, Akita 010-8543,
²National Institute for Minamata Disease, Minamata 867-0008,
³Department of Obstetrics, Tohoku University Graduate School of Medicine, Sendai 980-8575,
⁴Department of Human Development, Faculty of Education, Tohoku University, Sendai 980-8576,
⁵Miyagi Children's Hospital, Sendai 989-3126, and
⁶Miyagi Prefectural Institute of Public Health and Environment, Sendai 983-8666

Several birth cohort studies have shown adverse effects of perinatal exposures to methylmercury (MeHg) and environmentally persistent organic pollutants (POPs). These chemicals are ingested mainly through fish consumption, but little is known about the hazardous effects in Japanese, whose fish consumption is high. The present study, the Tohoku Study of Child Development, was designed to examine the effects of perinatal exposures to MeHg, polychlorinated biphenyls (PCB), dioxins, pesticides, and other chemicals in Japanese children. Six hundred eighty-seven pregnant women were participated in this study with their written informed consent. Maternal peripheral blood, cord blood, cord tissue, placenta, and breast milk samples were collected for chemical analysis. Maternal hair was also taken for MeHg analysis. Infants born at full term were assessed by neurobehavioral tests: the Brazelton Neonatal Behavioral Assessment Scale at three days old, the Kyoto Scale of Psychological Development and the Bayley Scales of Infant Development at 7 and 18 months old, and the Fagan Test of Infant Intelligence at 7 months old. The children will be continuously followed up to ages 6-7 years. Maternal food intake frequency, maternal IQ, socioeconomic status, and home environment were assessed as covariates. The results of this cohort study will allow us to evaluate associations between the neurobehavioral development of children and perinatal exposures to MeHg and environmentally POPs in Japan.

keywords —— cohort; development; dioxin; methylmercury; polychlorinated biphenyls

© 2004 Tohoku University Medical Press

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Address for reprints : Kunihiko Nakai, V.M.D., Ph.D., Department of Environmental Health Sciences, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai 980-8575, Japan.

e-mail: nakaik@mail.tains.tohoku.ac.jp

Some results from this study were presented at the NIMD Forum 2003 held at Niigata, Japan, on November 20, 2003.