Nozomi Tatsuta1, Kunihiko Nakai2, Yuichi Kasanuma3, Miyuki Iwai-Shimada4, Mineshi Sakamoto1, Katsuyuki Murata5, Hiroshi Satoh6. 1. Development and Environmental Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan. 2. Development and Environmental Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan. Electronic address: nakaik@med.tohoku.ac.jp. 3. Kesen-numa City Hospital, Kesen-numa 988-0181, Japan; Minami-Kesennuma Medical Clinic 988-0025, Japan. 4. Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba 305-8506, Japan. 5. Akita University Graduate School of Medicine, Akita 010-8543, Japan. 6. Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
Abstract
BACKGROUND: Low-level lead exposure during childhood is associated with deficit in child IQ. However, the association between prenatal lead exposure and child IQ remains inconsistent. The objective of our study was to examine the association between prenatal/postnatal lead exposure and child IQ at the age of 12. METHODS: We obtained data pertaining to cord-blood and child-blood lead levels and IQ for 286 children from a prospective birth cohort study (Tohoku Study of Child Development). IQ was assessed using the Wechsler Intelligence Scale for Children-Fourth Edition. Simultaneously, the Boston Naming Test (BNT) was used to assess the children's language ability. RESULTS: The median lead level in the cord blood was 0.8 μg/dL (5th-95th percentiles, 0.4-1.4 μg/dL), and that in the blood of 12-year-old children was 0.7 μg/dL (0.4-1.1 μg/dL). IQ and BNT scores were significantly lower in boys than in girls; therefore, multiple regression analysis was conducted separately for boys and girls. Among boys, IQ was associated with child-blood lead (B = -16.362, p = 0.033) but not cord-blood lead (B = -6.844, p = 0.309). When boys were divided into four groups according to the child-blood lead levels, there was a significant decreasing trend for IQ. The score with cues of the BNT was associated with both cord-blood (B = -5.893, p = 0.025) and child-blood (B = -7.108, p = 0.022) lead concentrations in boys. Among girls, there was no significant association of the outcomes with cord-blood or child-blood lead level. CONCLUSIONS: These findings suggest that postnatal lead exposure adversely affects the intellectual ability in boys. Furthermore, the language ability is sensitive to prenatal/postnatal lead exposure in boys.
BACKGROUND: Low-level lead exposure during childhood is associated with deficit in child IQ. However, the association between prenatal lead exposure and child IQ remains inconsistent. The objective of our study was to examine the association between prenatal/postnatal lead exposure and child IQ at the age of 12. METHODS: We obtained data pertaining to cord-blood and child-blood lead levels and IQ for 286 children from a prospective birth cohort study (Tohoku Study of Child Development). IQ was assessed using the Wechsler Intelligence Scale for Children-Fourth Edition. Simultaneously, the Boston Naming Test (BNT) was used to assess the children's language ability. RESULTS: The median lead level in the cord blood was 0.8 μg/dL (5th-95th percentiles, 0.4-1.4 μg/dL), and that in the blood of 12-year-old children was 0.7 μg/dL (0.4-1.1 μg/dL). IQ and BNT scores were significantly lower in boys than in girls; therefore, multiple regression analysis was conducted separately for boys and girls. Among boys, IQ was associated with child-blood lead (B = -16.362, p = 0.033) but not cord-blood lead (B = -6.844, p = 0.309). When boys were divided into four groups according to the child-blood lead levels, there was a significant decreasing trend for IQ. The score with cues of the BNT was associated with both cord-blood (B = -5.893, p = 0.025) and child-blood (B = -7.108, p = 0.022) lead concentrations in boys. Among girls, there was no significant association of the outcomes with cord-blood or child-blood lead level. CONCLUSIONS: These findings suggest that postnatal lead exposure adversely affects the intellectual ability in boys. Furthermore, the language ability is sensitive to prenatal/postnatal lead exposure in boys.
Authors: Radu Ionut Neamtu; Marius Craina; George Dahma; Alin Viorel Popescu; Adelina Geanina Erimescu; Ioana Citu; Amadeus Dobrescu; Florin George Horhat; Dan Dumitru Vulcanescu; Florin Gorun; Elena Silvia Bernad; Andrei Motoc; Ioan Cosmin Citu Journal: Exp Ther Med Date: 2021-12-03 Impact factor: 2.447