Mercury Exposure in Healthy Korean Weaning-Age Infants: Association with Growth, Feeding and Fish Intake

Abstract

Low-level mercury (Hg) exposure in infancy might be harmful to the physical growth as well as neurodevelopment of children. The aim of this study was to investigate postnatal Hg exposure and its relationship with anthropometry and dietary factors in late infancy. We recruited 252 healthy Korean infants between six and 24 months of age from an outpatient clinic during the 2009/2010 and 2013/2014 seasons. We measured the weight and height of the infants and collected dietary information using questionnaires. The Hg content of the hair and blood was assessed using inductively coupled plasma mass spectroscopy. The geometric mean Hg concentration in the hair and blood was 0.22 (95% confidence interval: 0.20–0.24) µg/g and 0.94 (n = 109, 95% confidence interval: 0.89–0.99) µg/L, respectively. The hair Hg concentration showed a good correlation with the blood Hg concentration (median hair-to-blood Hg ratio: 202.7, r = 0.462, p < 0.001) and was >1 µg/g in five infants. The hair Hg concentration showed significant correlations with weight gain after birth (Z-score of the weight for age—Z-score of the birthweight; r = −0.156, p = 0.015), the duration (months) of breastfeeding as the dominant method of feeding (r = 0.274, p < 0.001), and the duration of fish intake more than once per week (r = 0.138, p = 0.033). In an ordinal logistic regression analysis with categorical hair Hg content (quartiles), dietary factors, including breastfeeding as the dominant method of feeding in late infancy (cumulative odds ratio: 6.235, 95% confidence interval: 3.086–12.597, p < 0.001) and the monthly duration of fish intake more than once per week (cumulative odds ratio: 1.203, 95% confidence interval: 1.034–1.401; p = 0.017), were significantly associated with higher hair Hg content. Weight gain after birth was not, however, significantly associated with hair Hg content after adjustment for the duration of breastfeeding as the dominant method of feeding. Low-level Hg exposure through breastfeeding and fish intake as a complementary food did not directly affect anthropometry in this population. If prolonged breastfeeding is expected, however, the Hg exposure through fish intake may need to be monitored for both mothers and infants.

Influence of Maternal Fish Intake on the Anthropometric Indices of Children in the Western Amazon

“…The implications of family Hg exposure resulting from fish consumption on young children’s anthropometric indices can be contradictory. While some authors reported negative [ 34 ] and positive [ 35 ] influence of Hg on childhood anthropometric indices, others have not inferred such a relationship in their reports [ 15 , 36 , 37 ]. Still, others have indicated that Hg has no influence on Z-scores of height and weight indices in children ≤6-years-old; however, an increase in Hg concentrations was associated with a higher body mass index (BMI) [ 38 ].…”

Mercury poisoning in a fisherman working on a pelagic fishing vessel due to excessive tuna consumption

“…Methylmercury can pass through the blood-brain barrier and placenta, potentially affecting the brain and/or fetus. Therefore, additional care is required for children and pregnant women to minimize exposure [24][25][26] . The present study reported the case of a 48-year-old deep-sea fisherman who presented to the hospital with paresthesia and pain in the lower limbs.…”

Low-Level Toxic Metal Exposure in Healthy Weaning-Age Infants: Association with Growth, Dietary Intake, and Iron Deficiency

“…The As, Cd, Hg, and Pb levels in the same venous whole blood samples of the infants were determined using Inductively-Coupled Plasma Mass Spectrometry (Agilent 7700, Santa Clara, CA, USA) at the Green Cross Reference Laboratory (Yongin-City, Kyunggi-do, Korea) as previously described [25]. …”

“…Exclusively/mostly breastfeeding and mostly formula feeding were defined as previously described [25]. The infants who were not classified as mostly breastfed or mostly formula fed were defined as have mixed feeding.…”

“…In addition, most studies investigated the effect of a single metal; only a few studies have simultaneously evaluated and compared the effect of low levels of multiple toxic metals on the growth of infants or children in the same population [22,23,24]. Factors such as different levels of exposure to toxic metals, differing amounts of materials that counteract or augment the harmful action of the toxic metals, or incomplete adjustment for other growth-affecting factors might contribute to the mixed results among previous studies [11,12,25,26]. …”