Psychomotor Ability in Children Prenatally Exposed to Methylmercury: The 18-Month Follow-Up of Tohoku Study of Child Development

Abstract

Fish contain nutrients essential to the developing fetal brain, but they are contaminated with methylmercury. The Tohoku Study of Child Development, now underway in the Sanriku coastal area of Miyagi prefecture, Japan, follows mother-child pairs to examine the risks and benefits of fish consumption during pregnancy, especially the effects of prenatal exposures to methylmercury, selenium, and docosahexaenoic acid (DHA) on child neurodevelopment. Children aged 18 months were administered the Bayley Scales of Infant Development second edition (BSID-II) and Kyoto Scale of Psychological Development (KSPD) in [2004][2005][2006][2007][2008]. Complete data of cord-blood total mercury (THg), cord-plasma selenium, maternal-plasma DHA, the above test scores, and confounders for 566 mother-child pairs were available. The median cord-blood THg level was 15.7 (range, 2.7-96.1) ng/g. Since the BSID-II and KSPD scores were significantly lower in the 285 boys than in the 281 girls, analyses were conducted separately. The Psychomotor Development Index (PDI) of BSID-II was significantly correlated with cord-blood THg only in the boys, and significance of the association remained unchanged after adjusting for possible confounders; i.e., a 10-fold increase in cordblood THg was associated with a 8.3-point decrease in the score of the PDI. Other significant correlations of THg were not seen in the boys or girls. Selenium and DHA showed no significant correlations with the BSID-II or KSPD scores in either sex. In conclusion, intrauterine methylmercury exposure may affect psychomotor development, and boys appear to be more vulnerable to the exposure than girls.

Psychometric profile of the Ages and Stages Questionnaires, Japanese translation

“…In support of this, a study that compared the KSPD with the Bayley-2, an older version of the Bayley-3, found that the KSPD score was higher than the Bayley-2 score, suggesting that the children identified as delayed on the KSPD were more severely delayed than those identified on the Bayley-2. 21 This supports our explanation of why the alternative criterion for the J-ASQ-3 worked better than the original criterion for distinguishing children who needed specialized support from those who did not in the present study.…”

Maternal selenium status and neuropsychological development in Spanish preschool children

“…However, other studies failed to find any significant association with these and other assessed aspects of neuropsychological development in children from Greece (Kippler et al, 2016), USA (Oken et al, 2016), Poland (Polanska et al, 2016) and Japan (Tatsuta et al, 2017). Se levels (mean ± standard deviation) observed in these studies were 23 ± 8.6 µg/L in maternal urine at the first trimester of pregnancy in Greece (Kippler et al, 2016), 205.6 ± 34.6 ng/mL in erythrocytes at mid-pregnancy in USA (Oken et al, 2016), and 66.3 ± 10.2 and 67.0 ± 9.6 ng/g (for boys and girls, respectively) in cord plasma in Japan (Tatsuta et al, 2017). Conversely, Saint-Amour et al (2006) observed that prenatal Se levels were associated with alterations in the visual evoked potentials of Inuit children (cord blood Se was 4.44 ± 2.08 µmol/L) (Saint-Amour et al, 2006).…”

The Nuclear Protein HOXB13 Enhances Methylmercury Toxicity by Inducing Oncostatin M and Promoting Its Binding to TNFR3 in Cultured Cells

“…Excessive consumption of methylmercury-contaminated fish causes severe central nervous system injury, such as Minamata disease [2]. Recent epidemiological studies have suggested that excessive intake of 2 of 17 methylmercury during pregnancy has an adverse effect on fetal neural development [3,4]. However, the molecular mechanisms underlying methylmercury-induced central nervous system injury are still poorly understood.…”