Environmental metal exposure and growth to 10 years of age in a longitudinal mother-child cohort in rural Bangladesh

The association of serum toxic metals and essential elements during early pregnancy with body mass index trajectory of infants during the first years: A prospective study

To the best of our knowledge, prior research has yet to delve into the combined and interactive relationships between maternal exposure to essential elements and toxic metals and infancy's continuous growth and trajectories. This study aims to discern infant growth trajectories in the first year of life and to determine the associations of maternal serum levels of essential elements and toxic metals with growth trajectory. Within a Chinese prospective cohort in 2019 - 2021, 407 mother-infant pairs were included, and the serum levels of five essential elements (zinc, calcium, copper, magnesium and iron) and two toxic metals (cadmium and lead) in early pregnancy were assessed. The growth trajectory of infants was followed until age one year. Raw BMI and height values were transformed to age- and sex-specific BMI and height standard deviation (SD) scores. Latent-class group-based trajectory models and piecewise linear mixed regression were estimated to determine infant growth trajectories and growth velocity, respectively. The individual relationship between maternal metallic element levels and infant growth trajectory was examined using multinomial logistic regression models and linear mixed regression, while joint associations and interactive relationships were explored using Bayesian kernel machine regression (BKMR) following confounder adjustments. Four distinct trajectory patterns based on BMI-z score (low-rapid BMI gain group, normal-stable BMI group, very low-rapid BMI gain group and normal-rapid BMI gain group) and length-for-age (high-stable length group, low-stable length group, normal-rapid length gain group, very low-rapid length gain group) were identified during the first year post-birth, respectively. In single-metal and multiple-metal models, infants born to mothers with higher serum Zn and lower serum Cu levels were associated with a normal-rapid BMI gain trajectory during the first year. Serum Cu exhibited a positive correlation with the rate of BMI change solely in infants aged 6-12 months. Further, the BKMR analysis revealed a statistically significant and negative joint effect of the five essential elements on the likelihood of normal-rapid BMI/length gain trajectory when serum levels of these elements fell below the 70th percentile compared to median levels. In addition, high levels of serum copper and calcium interactively affect the rates of BMI change during 6-12 months old (β: -0.21, 95% CI: -0.44, -0.03, P = 0.04, P-interaction=0.04). In conclusion, maternal trace elements at early pregnancy are linked to infant growth patterns and growth velocity in the first year of life.

Update of the risk assessment of inorganic arsenic in food

The European Commission asked EFSA to update its 2009 risk assessment on arsenic in food carrying out a hazard assessment of inorganic arsenic (iAs) and using the revised exposure assessment issued by EFSA in 2021. Epidemiological studies show that the chronic intake of iAs via diet and/or drinking water is associated with increased risk of several adverse outcomes including cancers of the skin, bladder and lung. The CONTAM Panel used the benchmark dose lower confidence limit based on a benchmark response (BMR) of 5% (relative increase of the background incidence after adjustment for confounders, BMDL05) of 0.06 μg iAs/kg bw per day obtained from a study on skin cancer as a Reference Point (RP). Inorganic As is a genotoxic carcinogen with additional epigenetic effects and the CONTAM Panel applied a margin of exposure (MOE) approach for the risk characterisation. In adults, the MOEs are low (range between 2 and 0.4 for mean consumers and between 0.9 and 0.2 at the 95th percentile exposure, respectively) and as such raise a health concern despite the uncertainties.

Cadmium reduces growth of male fetuses by impairing development of the placental vasculature and reducing expression of nutrient transporters

In utero exposure to the toxic metal cadmium (Cd) alters fetoplacental growth in rodents and has been inversely associated with birth weight and infant size in some birth cohorts. Moreover, studies suggest that Cd may have differential effects on growth and development according to offspring sex. The purpose of the current study was to evaluate changes in male and female fetoplacental development following a single injection of saline (5 ml/kg ip) or cadmium chloride (CdCl2, 2.5, 5 mg/kg, ip) on gestational day (GD) 9. By GD18, no changes in fetal or placental weights were observed after treatment with 2.5 mg/kg CdCl2. By comparison, the weight and length of male fetuses and their placentas were reduced following treatment with 5 mg/kg CdCl2 whereas no change was observed in females. In addition, the area of maternal and fetal blood vessels as well as the expression of the glucose transporters, Glut1 and Glut3, and the endothelial marker, CD34, were reduced in the placentas of CdCl2-treated male offspring compared to females. Interestingly, the placentas of females accumulated 80% more Cd than males after CdCl2 (5 mg/kg) administration. Female placentas also had higher concentrations of zinc and the zinc transporter Znt1 compared to males which may explain the limited changes in fetal growth observed following CdCl2 treatment. Taken together, disruption of vasculature development and reduced expression of glucose transporters in the placenta provide potential mechanisms underlying reduced fetal growth in male offspring despite the greater accumulation of Cd in female placentas.

Polycyclic aromatic hydrocarbon (PAH) exposure during pregnancy and child anthropometry from birth to 10 years of age: Sex-specific evidence from a cohort study in rural Bangladesh

Polycyclic aromatic hydrocarbons (PAHs) have endocrine disrupting properties and they cross the placental barrier, but studies on gestational exposure and child anthropometry are inconclusive. We aimed to elucidate the impact of early gestational PAH exposure on anthropometry from birth to 10 years of age in 1295 mother-child pairs from a nested sub-cohort of the MINIMat trial in Bangladesh. Several PAH metabolites [1-hydroxyphenanthrene (1-OH-Phe), Σ2-,3-hydroxyphenanthrene (Σ2-,3-OH-Phe), 4-hydroxyphenanthrene (4-OH-Phe), 1-hydroxypyrene (1-OH-Pyr), Σ2-,3-hydroxyfluorene (Σ2-,3-OH-Flu)] were quantified in spot urine collected around gestational week 8 using LC-MS/MS. Child weight and height were measured at 19 occasions from birth to 10 years. Multivariable-adjusted regression models were used to assess associations of maternal PAH metabolites (log₂-transformed) with child anthropometry. The median concentration of 1-OH-Phe, Σ2-,3-OH-Phe, 4-OH-Phe, 1-OH-Pyr and Σ2-,3-OH-Flu was 1.5, 1.9, 0.14, 2.5, and 2.0 ng/mL, respectively. All maternal urinary PAH metabolites were positively associated with newborn weight and length and all associations were more pronounced in boys than in girls (p interaction for all <0.14). In boys, the strongest associations were observed with Σ2-,3-OH-Phe and Σ2-,3-OH-Flu for which each doubling increased mean birth weight by 41 g (95% CI: 13; 69 and 12; 70) and length by 0.23 cm (0.075; 0.39) and 0.21 cm (0.045; 0.37), respectively. Maternal urinary PAH metabolites were not associated with child anthropometry at 10 years. In longitudinal analysis, however, maternal urinary PAH metabolites were positively associated with boys' weight-for-age (WAZ) and height-for-age Z-scores (HAZ) from birth to 10 years, but only the association of 4-OH-Phe with HAZ was significant (B: 0.080 Z-scores; 95% CI 0.013, 0.15). No associations were observed with girls' WAZ or HAZ. In conclusion, gestational PAH exposure was positively associated with fetal and early childhood growth, especially in boys. Further studies are needed to confirm causality and to explore long-term health effects.

Urinary Levels of 14 Metal Elements in General Population: A Region-Based Exploratory Study in China

Metal pollution may lead to a variety of diseases; for this reason, it has become a matter of public concern worldwide. However, it is necessary to use biomonitoring approaches to assess the risks posed to human health by metals. In this study, the concentrations of 14 metal elements in 181 urine samples obtained from the general population of Gansu Province, China, were analyzed using inductively coupled plasma mass spectrometry. Eleven out of fourteen target elements had detection frequencies above 85%, namely, Cr, Ni, As, Se, Cd, Al, Fe, Cu and Rb. The concentrations of most metal elements in the urine of our subjects corresponded to the medium levels of subjects in other regional studies. Gender exerted a significant influence (p < 0.05) on the concentrations of Tl, Rb and Zn. The concentrations of Ni, As, Pb, Sr, Tl, Zn, Cu and Se showed significant differences among different age groups and the age-related concentration trends varied among these elements. There were significant differences in the urine concentrations of Zn and Sr between those subjects in the group who were frequently exposed to soil (exposed soil > 20 min/day) and those in the group who were not, indicating that people in regular contact with soil may be more exposed to metals. This study provides useful information for evaluating the levels of metal exposure among general populations.

Early Life Environmental Exposure to Cadmium, Lead, and Arsenic and Age at Menarche: A Longitudinal Mother-Child Cohort Study in Bangladesh

BACKGROUND

Several metals act as endocrine disruptors, but there are few large longitudinal studies about associations with puberty onset.

OBJECTIVES

We evaluated whether early life cadmium, lead, and arsenic exposure was associated with timing of menarche.

METHODS

In a mother-child cohort in rural Bangladesh (n=935), the exposure was assessed by concentrations in maternal erythrocytes in early pregnancy and in girls' urine at 5 and 10 years of age using inductively coupled plasma mass spectrometry. The girls were interviewed twice, at average ages 13.3 [standard deviation (SD)=0.43] and 13.8 (SD=0.43) y, and the date of menarche, if present, was recorded. Associations were assessed using Kaplan-Meier analysis and multivariable-adjusted Cox regression.

RESULTS

In total, 77% of the girls (n=717) had reached menarche by the second follow-up. The median age of menarche among all girls was 13.0 y (25th-75th percentiles: 12.4-13.7 y). At 10 years of age, median urinary cadmium was 0.25μg/L (5th-95th percentiles: 0.087-0.72μg/L), lead 1.6μg/L (0.70-4.2μg/L), and arsenic 54μg/L (19-395μg/L). Given the same age, girls in the highest quartile of urinary cadmium at 5 and 10 years of age had a lower rate of menarche than girls in the lowest quartile, with an adjusted hazard ratio of (HR) 0.80 (95% CI: 0.62, 1.01) at 5 years of age, and 0.77 (95% CI: 0.60, 0.98) at 10 years of age. This implies that girls in the highest cadmium exposure quartile during childhood had a higher age at menarche. Comparing girls in the highest to the lowest quartile of urinary lead at 10 years of age, the former had a higher rate of menarche [adjusted HR = 1.23 (95% CI: 0.97, 1.56)], implying lower age at menarche, whereas there was no association with urinary lead at 5 years of age. Girls born to mothers in the highest quartile of erythrocyte arsenic during pregnancy were less likely to have attained menarche than girls born to mothers in the lowest quartile [adjusted HR= 0.79 (95% CI: 0.62, 0.99)]. No association was found with girls' urinary arsenic exposure.

DISCUSSION

Long-term childhood cadmium exposure was associated with later menarche, whereas the associations with child lead exposure were inconclusive. Maternal exposure to arsenic, but not cadmium or lead, was associated with later menarche. https://doi.org/10.1289/EHP11121.

Association between exposure to cadmium and risk of all-cause and cause-specific mortality in the general US adults: A prospective cohort study

BACKGROUND

Cadmium has been suggested to accumulate in the body over a lifetime, posing a great threat to human health. So far, few studies have studied the association between cadmium exposure and long-term health outcomes in adults.

OBJECTIVES

To investigate the risk of mortality with blood cadmium level in adults (participants of NHANES, 1999-2014).

METHODS

We evaluated the associations between cadmium and risk of mortality. Data on mortality and cadmium exposure were collected in NHANES database including 39,865 participants. Multivariate Cox regression models were established for calculating hazard ratios (HRs) and 95%CI between cadmium exposure and all-cause and specific-cause mortality outcomes.

RESULTS

Totally, 39,865 individuals with 19,260 males (48.3%) and 20,605 females (51.7%) were included in the study. During a total of 341,017 person-years of follow-up 5,094 deaths were documented, including 1,067 cardiovascular disease (CVD) and 890 cancers. Compared with the lowest quantile of cadmium exposure level group, the adjusted HRs in the highest quantile cadmium exposure level group were 1.73 (95%CI: 1.52-1.97) for all-cause mortality, 1.72 (95%CI: 1.28-2.30) for CVD mortality and 1.87 (95%CI: 1.49-2.36) for cancer mortality, respectively (P for trend: <0.001). Additionally, significant interactions with smoking status in the stratified analyses of all-cause mortality and cancer mortality, age in the stratified analyses of cancer mortality were found (P for interaction: 0.002, <0.001 and 0.012).

CONCLUSIONS

In this nationwide representative sample of the population, we found that higher blood cadmium concentration was associated with increased risks of all-cause and specific-cause mortality. These data further evidence the link between mortality and cadmium concentration. It is of great importance for both policy makers and the public to minimize cadmium exposure, and to reduce long-term adverse health effects.

Toxic metal exposures from infant diets: Risk prevention strategies for caregivers and health care professionals

Concerns are growing regarding the presence of toxic elements such as arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in the ingredients and prepared foods for infants and young children. There are few clear, evidence-based, guidelines on the maximum tolerable limits of toxicants in foods and little understanding of toxicant exposure or adverse health effects attributable to dietary exposure. Caregivers are faced with the burden of making decisions about which foods to select, how often to feed them to their children, and what foods to limit. This article reviews the current literature and existing recommendations on dietary exposure to toxic elements in children under 2 years of age, and their health effects in early childhood-focusing on growth, neurodevelopment, and immune function. The article also outlines best practices for healthcare providers to address the concerns of toxic element exposure through the diet in young children. Several foods consistently appear in the literature as potential sources of toxic element exposure. Contaminated drinking and cooking water, including water used to prepare infant formula, could also be a major exposure source. In the absence of stronger evidence on effects of dietary modification, exclusive breastfeeding until six months of age, followed by a diverse diet are some strategies to reduce dietary toxic element exposure while ensuring an adequate and balanced nutrient intake. Healthcare providers can support families by sharing information and encouraging blood Pb testing, the only element for which such testing is currently recommended.

Gestational and childhood urinary iodine concentrations and children's cognitive function in a longitudinal mother-child cohort in rural Bangladesh

BACKGROUND

Severe iodine deficiency adversely affects neurodevelopment; however, evidence regarding the association of non-severe deficiency and child cognitive functioning is inconclusive.

METHODS

This prospective mother-child cohort study was nested in a population-based nutritional supplementation trial in Bangladesh (Maternal and Infant Nutrition Interventions in Matlab [MINIMat]). Participants with data on cognitive abilities at 5 and 10 years of age (n = 1530) and at least one measurement of urinary iodine concentration (UIC) (gestational week 8, 5, and 10 years) were selected. Cognitive abilities were assessed using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) and Wechsler Intelligence Scale for Children (WISC-IV). UICs were measured with inductively coupled plasma mass spectrometry and thereafter adjusted for specific gravity.

RESULTS

Median UICs in our population: (282 μg/L [pregnancy]; 406 μg/L [5 years]; 294 μg/L [10 years]) indicated that iodine intake corresponded to above 'adequate' or even 'excessive', according to the WHO classification. Maternal 'UIC <150 μg/L' was associated with lower full-scale and verbal scores at 5 and 10 years, although the associations were weakened in the fully adjusted models. A tendency of decreased verbal scores was also observed for maternal 'UIC ≥500 μg/L' but not for the corresponding child iodine category (≥300 μg/L). Child 'UIC <100 μg/L' was associated with lower processing speed (B=-3.1, 95% CI [-6.2, -0.1]; P-value = 0.041) compared with the reference group (100 μg/L≤ UIC <300 μg/L).

CONCLUSIONS

Current findings add to the growing evidence of a causal association of early-life iodine intake with cognitive development, indicating that low iodine intake during childhood is associated with reduced processing speed and non-optimal gestational iodine intake is weakly associated with slightly poorer verbal development outcomes.

Maternal exposure to cadmium during pregnancy is associated with changes in DNA methylation that are persistent at 9 years of age

BACKGROUND

Cadmium (Cd) exposure during gestation has been associated with altered DNA methylation at birth, but it is not known if the changes in methylation persist into childhood.

OBJECTIVES

To evaluate whether gestational Cd-related changes of DNA methylation persist from birth to 9 years of age.

METHODS

We studied mother-child dyads in a longitudinal cohort in rural Bangladesh. Cadmium concentrations in maternal blood (erythrocyte fraction; Ery-Cd) at gestational week 14 and in child urine (U-Cd, long-term exposure marker) at 9 years were measured using inductively coupled plasma mass spectrometry. The epigenome-wide DNA methylation was measured in mononuclear cells (PBMCs) prepared from cord blood and peripheral blood at 9 years in 71 children (hereafter referred to as the explorative group) by Infinium HumanMethylation450K BeadChip. Replication of one differentially methylated region (DMR; 9 CpG sites) was performed in PBMCs of 160 9-year-old children (validation group) by EpiTyper MALDI-TOF mass spectrometry.

RESULTS

The median maternal Ery-Cd concentration was 1.24 µg/kg (range 0.35, 4.55) in the explorative group and 0.83 µg/kg (0.08, 2.97) in the validation group. The median U-Cd concentration in the 9-year-old children was 0.26 µg/L (0.09, 1.06) in the explorative group and 0.32 µg/L (0.07, 1.33) in the validation group. In the explorative group, we identified ten DMRs, both in cord blood and in PBMCs at 9 years, that were associated with maternal Ery-Cd. Eight out of the ten DMRs were hypomethylated and three of the hypomethylated DMRs were located in the HLA region on chromosome 6. One of the DMRs (hypomethylated) in the HLA region (upstream of the zinc finger protein 57 homolog, ZFP57 gene) was replicated in the validation group, and we found that it was hypomethylated in relation to maternal Ery-Cd, but not child U-Cd.

CONCLUSION

Gestational exposure to Cd appears to be associated with regional changes, especially hypomethylated, in DNA methylation that linger from birth up to prepubertal age.