Methylmercury in the breast milk of Japanese mothers and lactational exposure of their infants

Iwai-Shimada, Miyuki; Satoh, Hiroshi; Nakai, Kunihiko; Tatsuta, Nozomi; Murata, Katsuyuki; Akagi, Hirokatsu

doi:10.1016/j.chemosphere.2014.12.086

Cited by 30 publications

(24 citation statements)

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“…The research took place in two areas, an urban area (i.e., Sendai city of Miyagi prefecture) and a coastal area (i.e., the Sanriku coastal area of the same prefecture) in the Tohoku district of Japan (Nakamura et al 2008;Iwai-Shimada et al 2015;. In this study, only the subjects in the coastal area were examined because they were considered to eat more fish than those in the urban area.…”

Section: Study Design and Subjectsmentioning

confidence: 99%

“…Total mercury (THg) concentrations in hair and whole blood were measured using cold vapor atomic absorption spectrometry (CVAAS, HG-201, Sanso Seisakusho Co. Ltd., Tokyo, Japan). The analytical method of CVAAS has been fully described elsewhere (Iwai-Shimada et al 2015). Accuracy was ensured using a certified reference material (Seronorm Trace Elements Whole Blood L-2, Lot 0503109, Sero, Norway) for quality control.…”

Section: Exposure Biomakersmentioning

confidence: 99%

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

Tatsuta

Murata

Iwai-Shimada

et al. 2017

Tohoku J. Exp. Med.

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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.

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Section: Study Design and Subjectsmentioning

confidence: 99%

Section: Exposure Biomakersmentioning

confidence: 99%

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

Tatsuta

Murata

Iwai-Shimada

et al. 2017

Tohoku J. Exp. Med.

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“…[62][63][64][65][66] The average concentrations of MeHg in breast milk were found to be 0.17 μg/L (n=182) in Italy, 0.68 μg/L (n=11) in Slovenia, and 0.45 μg/L (n=27) in Japan. [63][64][65][66][67] The mean concentration of MeHg in fish-based infant food reported was 6.1 μg/kg. 68 Rice cereals have been largely overlooked when considering infant MeHg through diets, probably because of limited information on Hg and MeHg in rice and rice products.…”

Section: Postnatal Dietary Mehg Exposurementioning

confidence: 98%

“…Two of the 79 rice-based infant cereals exceeded the MeHg RfD, suggesting potential MeHg exposure of infants through cereal diet. Considering that cereal diet is not the only MeHg exposure pathway for infants and that breast milk has been regarded as an important source of MeHg in infants, 63,66 we further estimated the MeHg daily intake through both cereals and breastfeeding. The concentrations of MeHg in breast milk were found to be 0.17 μg/L (n = 182) in Italy, 0.68 μg/L (n = 11) in Slovenia, and 0.45 μg/L (n = 27) in Japan.…”

Section: Estimation Of Daily Intake Of Mehgmentioning

confidence: 99%

“…Traditionally, prenatal exposure was considered as the main source of accumulation of MeHg in infants, while postnatal exposure was primarily related to consumption of breast milk and fish-based food. [62][63][64][65][66] However, as a vital part of infant diet, rice-based cereals have been largely neglected because of the perception of low Hg in rice and rice products. As elevated MeHg has been observed in rice and rice-based cereals, 95 Qingdao (QD, n = 13), Nanjing (NJ, n = 6) and Wuhan (WH, n = 21).…”

Section: Introductionmentioning

confidence: 99%

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Comparative Evaluation on Human Infants Dietary Mercury Exposure through Consumption of Fish and Rice Products

Cui¹

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Human exposure to methylmercury (MeHg) through diets (e.g., fish and rice) is a global health concern. Although MeHg exposure through fish consumption has long been considered the major route of mercury health risks, studies concerning the long-term changes in MeHg exposure from fish remain lacking. In sharply contrast to the fish MeHg issue, the presence of MeHg in rice has only been reported recently and its implications on MeHg exposure, albeit probably important, are still in infancy. Focusing on the discrepancies in the studies of MeHg exposure through fish and rice consumption, this study was aimed to assess the MeHg exposure of human infants through consumption of rice cereals and to evaluate the long-term changes in fish MeHg. The presence of MeHg in rice prompted the studies on MeHg concentrations and bioaccessibility in rice cereals and potential infant dietary exposure to MeHg through cereal consumption, which is believed to be the first of its kind. The analysis of a variety of infant cereals sampled from the common markets in the United States and China showed that the concentrations of MeHg in the cereals ranged from 0.07 to 13.9 µg/kg with a mean of 1.61 µg/kg. On the basis of these MeHg concentrations, the daily intake vii of MeHg through rice cereal consumption for infants was estimated to be 4-122% of the reference dose (RfD). The MeHg bioaccessibility in the cereals, determined using an in vitro digestion method, ranged from 25 to 74% with a mean of 48±16%. A further examination on these results, however, revealed the occurrence of MeHg re-adsorption during extraction steps, which leads to the underestimation of MeHg bioaccessibility and warrants cautions to be exercised when using these procedures to evaluate bioaccessibility in general. The long-term changes in fish MeHg were investigated through conducting a comprehensive data analysis on datasets for the Everglades, a well-studied aquatic ecosystem for Hg contamination. The results showed a clear decline of MeHg in mosquitofish in the Everglades during the past two decades, which was probably related to changes in environmental conditions (e.g., periphyton, dissolve organic matter, and sulfate) instead of mercury deposition. viii

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Toxic Metals

Poulos¹

2021

The Secret Life of Chemicals

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Methylmercury in the breast milk of Japanese mothers and lactational exposure of their infants

Cited by 30 publications

References 29 publications

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

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

Comparative Evaluation on Human Infants Dietary Mercury Exposure through Consumption of Fish and Rice Products

Toxic Metals

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