Adverse effects of prenatal mercury exposure on neurodevelopment during the first 3 years of life modified by early growth velocity and prenatal maternal folate level

Machine learning-based analysis on factors influencing blood heavy metal concentrations in the Korean CHildren's ENvironmental health Study (Ko-CHENS)

Heavy metal concentration in pregnant women affects neurocognitive and behavioral development of their infants and children. The majority of existing research focusing on pregnant women's heavy metal concentration has considered individual environmental factor. In this study, we aim to comprehensively consider lifestyle, food, and environmental factors to determine the most influential factor affecting heavy metal concentration in pregnant women. The Ko-CHENS (Korean CHildren health and ENvironmental Study) is a nationwide prospective birth cohort study in South Korea enrolling pregnant women from 2015 to 2020. A total of 5458 eligible pregnant women were included in this study, and 897 variables were included in questionnaire comprising: maternal general information, indoor and living environment, dietary habits, health behavior, exposure to chemicals. Lead, cadmium and mercury concentration on blood were measured in early, late pregnancy and in cord blood at birth. Variables that might be related to heavy metal concentrations were included in machine learning models. Random forest and XGBoost machine learning models were conducted for predictions. Both models had similar but better performance than multiple linear regression. Kimchi (β = 1.55), seaweed (β = 0.40), fatty fish (β = 1.55), intakes respectively affected lead, cadmium, and mercury exposure through early, late pregnancy and cord blood.

Which prenatal biomarker is most appropriate for methylmercury dose-response for neurodevelopmental effects?

Developmental neurotoxicity (DNT) is a well-established hazard attributed to methylmercury (MeHg) exposure. This evidence is based primarily upon includes studies that measured biomarkers of MeHg exposure in samples of maternal hair and blood, and cord blood. The aim of this review was to investigate which of these prenatal biomarkers is most appropriate for quantifying the DNT effects attributed to MeHg. A comprehensive literature search covered MeHg dose-response literature published 1998-2022. Studies were evaluated for risk of bias and study sensitivity using IRIS approach. Quantitative results of investigations were extracted and statistically compared. Seven studies were identified that measured both maternal hair and cord blood Hg levels. In these investigations, several DNT umbrella tests and their sub-tests results were modeled. Cord blood MeHg was more sensitive, producing larger estimates of MeHg potency, in most of the comparisons (91%) with maternal hair MeHg estimates for the same sub-tests in the same study. When comparing results from cord blood Hg to maternal hair Hg there was a 75% increase in sensitivity (range: 4-583%). In the two domains where results for maternal hair Hg were more sensitive, the rise was only 18% (Range: 7-29%). There were limited data (two studies) that compared maternal blood and maternal hair biomarkers (maternal blood Hg was more sensitive (mean 320% and range 43-855%) and cord blood biomarkers (maternal blood Hg was more sensitive by approximately 30%). Maternal hair Hg remains an appropriate biomarker for exposure monitoring in many populations, but these data suggest that cord blood Hg is more appropriate for dose-response modeling of MeHg DNT effects.

Maternal diet quality during pregnancy and biomarkers of potentially toxic trace element exposure: Data from the ELFE cohort

The contribution of the diet to potentially toxic trace element exposure in pregnancy has been rarely addressed. The objective of the present study was to determine the association between the maternal diet during pregnancy and biomarkers of exposure for arsenic (As), mercury (Hg) and lead (Pb) at delivery. As was assessed in maternal urine, Hg in maternal hair, and Pb in cord blood, as a proxy for in utero exposure. Based on 2995 women from the ELFE nationwide birth cohort, higher scores for dietary patterns considered healthy were associated with higher concentrations of As and Hg in maternal matrices. Levels of cord blood Pb were inconsistently associated with dietary patterns considered healthy, and lower with a dietary pattern driven by milk and breakfast cereals. Lower levels of Hg were associated with higher Western dietary pattern scores. In conclusion, higher levels of maternal urinary As and hair Hg are associated with diets considered as "Healthy", while cord blood Pb was not strongly correlated with dietary exposure.

Risk Assessment of Mercury-Contaminated Fish Consumption in the Brazilian Amazon: An Ecological Study

Mercury is one of the most dangerous contaminants on the planet. In recent years, evidence of mercury contamination in the Amazon has significantly increased, notably due to gold-mining activities. Although mercury contamination in fish has consistently been documented, little is known about the risk associated with fish consumption by populations in urban areas of the Amazon. We sampled 1010 fish sold in public markets in six state capitals and 11 additional cities. Mercury levels were determined for each specimen, and the evaluation of the health risks associated with consuming mercury-contaminated fish was conducted according to the methodology proposed by the World Health Organization (WHO). Our study reveals that more than one-fifth (21.3%) of the fish sold in urban centers had mercury levels above the safe limits (≥0.5 µg/g) established by the Brazilian Health Surveillance Agency (ANVISA). The prevalence of Hg contamination ≥0.5 µg/g was approximately 14 times higher in carnivorous than in noncarnivorous fish. The analysis of the risk attributable to fish consumption reveals that daily mercury intake exceeded the reference dose recommended by the U.S. EPA in all population groups analyzed, reaching up to 7 and 31 times in women of childbearing age and children from 2 to 4 years old, respectively. However, these risks are diverse depending on the type of fish consumed and must be considered to formulate appropriate nutritional guidelines for safe fish consumption by the local community.

Associations between biomarkers of prenatal metals exposure and non-nutritive suck among infants from the PROTECT birth cohort in Puerto Rico

Background/Aim

Infant non-nutritive suck (NNS) has been used as an early marker of neonatal brain function. Although there is an established relationship between prenatal exposure to certain metals and brain development, the association between metal exposure and NNS has not been explored. Therefore, in this study we assessed associations between maternal urinary metal(loid) concentrations and NNS measurements among infants from the Puerto Rico PROTECT birth cohort. We hypothesized that maternal urinary metal(loid) concentrations are significantly associated with infant NNS measures in a sex-dependent manner.

Methods

We measured urinary concentrations of 14 metal(loid)s in pregnant women at up to three time points in pregnancy. The geometric mean of each metal(loid) for each pregnant woman was calculated and used as an exposure measurement across gestation. NNS measurements (duration, frequency, amplitude, bursts/min, cycles/burst, cycles/min) were collected from infants between 4 and 6 (±2 weeks) weeks of age using our custom research pacifier. Linear regression was used to estimate associations between urinary metal(loid) concentrations across pregnancy and continuous NNS variables. Sex-specific effects were estimated using interaction terms between NNS variables and infant sex.

Results

We observed significant positive associations between mercury, manganese, and tin with NNS duration (mercury: %Δ = 1.08, 95% CI: 0.42, 1.74; manganese: %Δ = 0.67, 95% CI: 0.15, 1.20; tin: %Δ = 0.83, 95% CI: 0.17, 1.49) and NNS cycles/burst (mercury: %Δ = 1.85, 95% CI: 0.58, 3.11; manganese: (%Δ = 1.37, 95% CI: 0.40, 2.34; tin: %Δ = 1.68, 95% CI: 0.46, 2.91). Furthermore, the association between NNS cycles/min with cadmium (%Δ = 8.06, 95% CI: 3.33, 12.78), manganese (%Δ = 4.44, 95% CI: 1.40, 7.47), and tin (%Δ = 4.50, 95% CI: 0.81, 8.18) were in the opposite direction from its association with zinc (%Δ = -9.30, 95% CI: -14.71, -3.89), as well as with copper (%Δ = -6.58, 95% CI: -12.06, -1.10). For the sex-stratified analysis, the negative associations between metal(loid)s and NNS duration were predominantly driven by male infants; however, the negative associations between metal(loid)s and NNS bursts/min were mainly driven by female infants.

Conclusion

We observed significant associations between prenatal metal(loid) exposure and NNS measurements among infants from the ongoing Puerto Rico PROTECT cohort. Similar to previous studies that have demonstrated associations between NNS and subsequent neurodevelopment, this study highlights the potential of NNS as a quantitative index to measure altered neurodevelopment from prenatal metal(loid) exposures. We believe this study will inform future efforts aimed at reducing health risks related to early life metal exposures, such as developing early identification of metal-induced adverse outcomes in child neurodevelopment.

Improving Nutrition in the First 1000 Days in the United States: A Federal Perspective

The first 1000 days begins with pregnancy and ends at the child's second birthday. Nutrition throughout the life course, and especially during the first 1000 days, supports maternal health and optimal growth and development for children. We give a high-level summary of the state of nutrition in the first 1000 days in the United States. We provide examples where continued efforts are needed. We then discuss select opportunities to strengthen federal research and surveillance, programs, and communication and dissemination efforts aimed at improving nutrition and positively, and equitably, influencing the health and well-being of mothers and children. (Am J Public Health. 2022;112(S8):S817-S825. https://doi.org/10.2105/AJPH.2022.307028).

Prenatal Diet as a Modifier of Environmental Risk Factors for Autism and Related Neurodevelopmental Outcomes

PURPOSE OF REVIEW

Environmental chemicals and toxins have been associated with increased risk of impaired neurodevelopment and specific conditions like autism spectrum disorder (ASD). Prenatal diet is an individually modifiable factor that may alter associations with such environmental factors. The purpose of this review is to summarize studies examining prenatal dietary factors as potential modifiers of the relationship between environmental exposures and ASD or related neurodevelopmental outcomes.

RECENT FINDINGS

Twelve studies were identified; five examined ASD diagnosis or ASD-related traits as the outcome (age at assessment range: 2-5 years) while the remainder addressed associations with neurodevelopmental scores (age at assessment range: 6 months to 6 years). Most studies focused on folic acid, prenatal vitamins, or omega-3 fatty acids as potentially beneficial effect modifiers. Environmental risk factors examined included air pollutants, endocrine disrupting chemicals, pesticides, and heavy metals. Most studies took place in North America. In 10/12 studies, the prenatal dietary factor under study was identified as a significant modifier, generally attenuating the association between the environmental exposure and ASD or neurodevelopment. Prenatal diet may be a promising target to mitigate adverse effects of environmental exposures on neurodevelopmental outcomes. Further research focused on joint effects is needed that encompasses a broader variety of dietary factors, guided by our understanding of mechanisms linking environmental exposures with neurodevelopment. Future studies should also aim to include diverse populations, utilize advanced methods to optimize detection of novel joint effects, incorporate consideration of timing, and consider both synergistic and antagonistic potential of diet.

Maternal gestational mercury exposure in relation to cord blood T cell alterations and placental gene expression signatures

The immunotoxic impacts of mercury during early life is poorly understood. We investigated the associations between gestational mercury exposure and frequency of cord blood T cells as well as placental gene expression. Frequency of natural Treg cells was positively associated with prenatal and postpartum mercury toenail concentrations. Frequency of NKT and activated naïve Th cells was positively associated with prenatal toenail mercury concentrations and number of maternal silver-mercury dental amalgams, respectively. Placental gene expression analyses revealed distinct gene signatures associated with mercury exposure. Decreased placental expression of a histone demethylase, KDM4DL, was associated with both higher prenatal and postpartum maternal toenail mercury levels among male infants and remained statistically significant after adjustment for fish and seafood consumption. The results suggest that gestational exposure to mercury concentrations contribute to alterations in both T cells and gene expression in placenta at birth. These alterations may inform mechanisms of mercury immunotoxicity.

Associations between perfluoroalkyl acids in serum and lead and mercury in whole blood among US children aged 3-11 years

Data for 639 US children aged 3-11 years who participated in the National Health and Nutrition Examination Survey during 2013-2014 were analyzed by fitting regression models with log10-transformed values of blood lead and methyl and total mercury as dependent variables and log10-transformed values of perfluoroalkyl acids (PFAA) as one of the independent variables. PFAAs considered were 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (MPAH), linear isomer of perfluorooctanoic acid (NPFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonic acid (PFHxS), linear isomer of perfluorooctane sulfonic acid (NPFOS), and monomethyl branch isomer of perfluorooctane sulfonic acid (MPFOS). Adjusted regression slopes (β) indicating associations between the concentrations of PFAAs with blood lead and mercury were estimated. Statistically significant associations between concentrations of each PFAA and blood lead were observed. For 10% increases in concentrations of MPAH, NPFOA, PFNA, PFDA, PFHxS, NPFOS, and MPFOS, percent increases in the concentrations of blood lead were 0.45%, 1.59%, 0.78%, 0.32%, 0.65%, 1.32%, and 0.89% respectively. For 10% increases in concentrations of MPAH, PFNA, PFDA, and NPFOS, percent increases in the concentrations of total mercury in the blood were 1.62%, 1.44%, and 3.24% respectively. For 10% increases in concentrations of PFDA and NPFOS, percent increases in the concentrations of methyl mercury in the blood were 2.07% and 4.57% respectively. While concentrations of each of the seven PFAAs were positively associated with the concentrations of blood lead, concentrations of only PFDA and NPFOS were positively associated with increases in total and methyl mercury. PFAAs having positive associations with lead and mercury imply co-exposure and/or co-existence of high concentrations of PFAAs and lead/mercury. Since PFAAs as well as lead/mercury are known to be neurotoxic, nephrotoxic, and endocrine disruptors, their co-existence/co-exposure may lead to neurodevelopmental deficits that are additive/synergistic than neurodevelopmental deficits associated with exposures to PFAAs and lead/mercury alone. Future studies are needed to investigate additive/synergistic neurodevelopmental deficits associated with co-exposures to PFAAs and lead/mercury.