Maternal blood manganese level and birth weight: a MOCEH birth cohort study

Assessment of ten trace elements in umbilical cord blood and maternal blood: association with birth weight

BACKGROUND

Trace elements are an essential nutritional component for humans and inadequate tissue-concentrations may have a significant effect on fetal size.

OBJECTIVE

To measure ten trace elements in blood samples from mothers and their newborns, and assess their association with anthropometric characteristics at birth. The effects of other factors on fetal growth, such as biologic characteristics of the infant and mother, were analysed.

METHODS

A cross-sectional study was conducted in the Hospital general, University of Valencia, Spain. Healthy pregnant women, and their full-term infants were selected (n = 54 paired samples). Infants were grouped according to birth weight: small for gestational age (SGA n = 11), appropriate (AGA n = 30), and large (LGA n = 13). Anthropometric and biologic characteristics of the infant and mother were recorded. Levels of ten essential elements: arsenic (As), barium (Ba), cobalt (Co), copper (Cu), chrome (Cr), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se) and zinc (Zn), in maternal and cord plasma samples were determined. Samples were obtained from the umbilical cord immediately after delivery and the samples of their mothers were drawn at 2-4 h after delivery.

RESULTS

The analysis identified that cord blood Cu (p = 0.017) and maternal blood Ba and Mg (p = 0.027 and p = 0.002, respectively) concentrations were significantly higher among SGA infants compared to AGA and LGA infants. A multiple linear regression analysis showed that increased umbilical cord Cu concentration (adjusted β -146.4 g, 95% CI -255 to -37.7; p = 0.009), maternal smoking during pregnancy (adjusted β -483.8 g, 95% CI -811.7 to -155.9; p = 0.005), shorter gestational age (adjusted β 350.1 g, 95% CI 244.5 to 455.8; p = 0.000), and female sex (adjusted β -374 g, 95% CI -648 to -100; p = 0.009) were significantly associated with decreased birth weight. Maternal anaemia was positively associated with birth weight (adjusted β 362 g, 95% CI 20.8 to 703.1; p = 0.038). No significant associations were found between maternal trace elements and birth weight in multivariate analysis.

CONCLUSIONS

We did not observe significant associations of cord blood trace elements other than Cu and maternal trace elements with birth weight in the multivariate analyses.

Urgent need to reevaluate the latest World Health Organization guidelines for toxic inorganic substances in drinking water

The World Health Organization (WHO) has established guidelines for drinking-water quality that cover biological and chemical hazards from both natural and anthropogenic sources. In the most recent edition of Guidelines for Drinking-water Quality (2011), the WHO withdrew, suspended, did not establish, or raised guidelines for the inorganic toxic substances manganese, molybdenum, nitrite, aluminum, boron, nickel, uranium, mercury, and selenium. In this paper, we review these changes to the WHO drinking-water guidelines, examining in detail the material presented in the WHO background documents for each of these toxic substances. In some cases, these WHO background documents use literature reviews that do not take into account scientific research published within the last 10 or more years. In addition, there are instances in which standard WHO practices for deriving guidelines are not used; for example, rounding and other mathematical errors are made. According to published meeting reports from the WHO Chemical Aspects Working Group, the WHO has a timetable for revising some of its guidelines for drinking-water quality, but for many of these toxic substances the planned changes are minimal or will be delayed for as long as 5 years. Given the limited nature of the planned WHO revisions to the inorganic toxic substances and the extended timetable for these revisions, we suggest that governments, researchers, and other stakeholders might establish independent recommendations for inorganic toxic substances and possibly other chemicals to proactively protect public health, or at the very least, revert to previous editions of the Guidelines for Drinking-water Quality, which were more protective of public health.

Manganese Is Essential for Neuronal Health

The understanding of manganese (Mn) biology, in particular its cellular regulation and role in neurological disease, is an area of expanding interest. Mn is an essential micronutrient that is required for the activity of a diverse set of enzymatic proteins (e.g., arginase and glutamine synthase). Although necessary for life, Mn is toxic in excess. Thus, maintaining appropriate levels of intracellular Mn is critical. Unlike other essential metals, cell-level homeostatic mechanisms of Mn have not been identified. In this review, we discuss common forms of Mn exposure, absorption, and transport via regulated uptake/exchange at the gut and blood-brain barrier and via biliary excretion. We present the current understanding of cellular uptake and efflux as well as subcellular storage and transport of Mn. In addition, we highlight the Mn-dependent and Mn-responsive pathways implicated in the growing evidence of its role in Parkinson's disease and Huntington's disease. We conclude with suggestions for future focuses of Mn health-related research.

High Intake of Manganese During Second Trimester, Increases the Risk of Preterm Delivery: A Large Scale Cohort Study

Evidence indicates that nutrients and minerals might play an important role in preterm delivery (PTD). The aim of this study was to determine maternal nutritional status during second trimester of pregnancy and its association with preterm delivery (<34 weeks gestation) in Iranian women. In a large scale longitudinal study, 1033 pregnant women were recruited from prenatal clinics since December 2012 to June 2013. Dietary intake was assessed by Food Frequency Questionnaire (FFQ) in pregnant women of 14 to 20 weeks gestational age. The participants were followed up until delivery. Dietary intake of women with preterm delivery was compared with women who had term delivery. The results show that 61.2% of women were primiparous and that the incidence of preterm delivery was 7%. Manganese dietary intake was significantly higher in mothers with preterm delivery than those with term delivery (P=.03). Manganese was the only micronutrient correlated with preterm delivery after adjustment for maternal characteristics during second trimesters of pregnancy (OR=1.12; P=.01). These results suggest that high maternal manganese dietary intake during the second trimester of pregnancy may be associated with the risk of preterm delivery in Iranian pregnant women.

Maternal blood and hair manganese concentrations, fetal growth, and length of gestation in the ISA cohort in Costa Rica

BACKGROUND

Animal studies have shown that both deficiency and excess manganese (Mn) may result in decreased fetal size and weight, but human studies have reported inconsistent results.

METHODS

We examined the association of blood and hair Mn concentrations measured at different times during pregnancy with fetal growth among term births and length of gestation in a cohort of 380 mother-infant pairs living near banana plantations aerially sprayed with Mn-containing fungicides in Costa Rica. We used linear regression and generalized additive models to test for linear and nonlinear associations

RESULTS

Mean (± SD) blood Mn concentration was 24.4 ± 6.6 μg/L and geometric mean (geometric SD) hair Mn concentration was 1.8 (3.2) μg/g. Hair Mn concentrations during the second and third trimesters of gestation were positively related to infant chest circumference (β for 10-fold increase = 0.62 cm; 95% CI: 0.16, 1.08; and β = 0.55 cm; 95% CI: -0.16, 1.26, respectively). Similarly, average maternal hair Mn concentrations during pregnancy were associated with increased chest circumference (β for 10-fold increase = 1.19 cm; 95% CI: 0.43, 1.95) in infants whose mothers did not have gestational anemia, but not in infants of mothers who had gestational anemia (β = 0.39 cm; 95% CI: -0.32, 1.10; pINT=0.14). All these associations were linear. Blood Mn concentrations did not show consistent linear nor nonlinear relationships with any of the birth outcomes

CONCLUSIONS

Mn plays an important role in fetal development, but the extent to which environmental exposures may cause adverse health effects to the developing fetus is not well understood. Among women living near banana plantations in Costa Rica, we did not observe linear or nonlinear associations of Mn concentrations with lowered birth weight or head circumference, as reported in previous studies. However, we did find positive linear associations between maternal hair Mn concentrations during pregnancy and infant chest circumference.