Anthropometric measures at birth and early childhood are associated with neurodevelopmental outcomes among Bangladeshi children aged 2-3years

Association between maternal exposure to polycyclic aromatic hydrocarbons and birth anthropometric outcomes: A systematic review and meta-analysis

BACKGROUND

Previous research has proposed that exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy could potentially lead to a higher risk of adverse birth anthropometric outcomes. However, the current evidence on this connection remains inconclusive, as various studies have presented conflicting results.

OBJECTIVE

This systematic review and meta-analysis seeks to synthesize the available research on the potential link between maternal PAHs exposure and birth anthropometric outcomes.

METHODS

A comprehensive search of Scopus, PubMed/MEDLINE, Web of Science, and the Cochrane Library up to July 1, 2024, was conducted to identify studies investigating the impact of maternal PAHs exposure during pregnancy on birth anthropometric measures, including small gestational age (SGA), low birth weight (LBW), birth weight (BW), birth length (BL), birth head circumference (BHC), and birth chest circumference (BCC). Quality assessment was performed using the Newcastle-Ottawa Scale (NOS) and the GRADE framework, and a random-effects meta-analysis was conducted to consolidate association estimates.

RESULTS

Out of 5499 articles initially screened, 27 studies were included in the review. The meta-analysis revealed no significant association between maternal PAHs exposure and LBW (OR: 1.02, 95 % CI: 0.96-1.08), with moderate heterogeneity (I²: 25.8 %, P=0.37). Notably, PAHs exposure was significantly associated with BW (β: -9.79 g, 95 % CI: -16.71 to -2.87), along with high heterogeneity (I²: 99.9 %, P<0.001), and shorter BL (β: -0.04 cm, 95 % CI: -0.07 to -0.01), also with high heterogeneity (I²: 84.3 %, P<0.001). Additionally, a borderline significant decrease in BHC was observed (β: -0.01 cm, 95 % CI: -0.02 to -0.00) with no significant heterogeneity among studies. The results SGA were inconsistent across the studies.

CONCLUSION

Maternal exposure to PAHs was associated with adverse birth anthropometric outcomes, particularly lower BW and BL. The borderline significant reduction in BHC suggests a potential impact worth further investigation, although this finding remains inconclusive and not yet actionable. Results for SGA varied significantly among studies, underscoring the complexity of these associations. Collectively, these findings highlight the necessity for additional research to elucidate the effects of specific PAH metabolites on birth anthropometric outcomes and to explore potential interventions aimed at mitigating the identified risks.

Gait and sEMG characteristics of lower limbs in children with unilateral spastic cerebral palsy during walking

BACKGROUND

Children with unilateral spastic cerebral palsy (USCP) have muscle hypertonia, balance, and coordination defects that affect gross motor skills, especially walking. Understanding the gait characteristics and lower limb muscle activation patterns of USCP children can provide an objective and quantitative basis for patient assessment and treatment plan formulation.

OBJECTIVE

This study compared the gait and lower limb muscle activation characteristics of children with USCP and with typical development (TD) during walking.

METHODS

We recorded gait and sEMG data of 20 children with USCP, and 20 with typical development. sEMG signals were acquired from the bilateral tibialis anterior (TA) and lateral gastrocnemius muscles (LG) during walking. The root mean square (RMS) value, integrated electromyographic (iEMG) value and co-contraction ratio (CR) were used to evaluate muscle activity. Student's t Test and non-parametric rank sum Test were used to compare the differences between the data groups (significance level of 0.05).

RESULTS

The stance time, step length, speed, single leg support time ratio, ground impact, pre-swing angle, and muscle strength of the affected side were significantly decreased compared to those of the unaffected side in children with USCP (P < 0.05), while the swing phase, muscle tonus of LG were significantly prolonged (P < 0.05). Compared with TD children, children with USCP exhibited reduced bilateral walking ability, particularly noticeable in their smaller pre-swing angle(P < 0.05), diminished muscle strength of the TA and LG, as well as LG spasms(P < 0.05).

SIGNIFICANCE

Children with USCP have decreased ambulatory gait stability. Step length, pull acceleration, pre-swing angle, and CR can be used as sensitive indicators for gait assessment. Strengthening the TA muscle and reducing ankle spasm may help improve gait and postural stability in children with USCP.

Exposure of preterm neonates to toxic metals during their stay in the Neonatal Intensive Care Unit and its impact on neurodevelopment at 2 months of age

BACKGROUND

Premature neonates might be exposed to toxic metals during their stay in the neonatal intensive care unit (NICU), which could adversely affect neurodevelopment; however, limited evidence is available. The present study was therefore designed to assess the exposure to mercury, lead, cadmium, arsenic, and manganese of preterm neonates who received total parenteral nutrition (TPN) and/or red blood cell (RBC) transfusions during their NICU stay and the risk of neurodevelopment delay at the age of 2 months.

METHODS

We recruited 33 preterm neonates who required TPN during their NICU admission. Blood samples were collected for metal analysis at two different time points (admission and before discharge). Metals in the daily TPN received by preterm neonates were analyzed. Neurodevelopment was assessed using the Ages and Stages Questionnaire Edition 3 (ASQ-3).

RESULTS

All samples of TPN had metal contamination: 96% exceeded the critical arsenic limit (0.3 μg/kg body weight/day); daily manganese intake from TPN for preterm neonates exceeded the recommended dose (1 µg/kg body weight) as it was added intentionally to TPN solutions, raising potential safety concerns. All samples of RBC transfusions exceeded the estimated intravenous reference dose for lead (0.19 µg/kg body weight). Levels of mercury, lead and manganese in preterm neonates at discharge decreased 0.867 µg/L (95% CI, 0.76, 0.988), 0.831 (95%CI, 0.779, 0.886) and 0.847 µg/L (95% CI, 0.775, 0.926), respectively. A decrease in ASQ-3-problem solving scores was associated with higher levels of blood lead in preterm neonates taken at admission (ß = -0.405, 95%CI = -0.655, -0.014), and with plasma manganese (ß = -0.562, 95%CI = -0.995, -0.172). We also observed an association between decreased personal social domain scores with higher blood lead levels of preterm neonates before discharge (ß = -0.537, 95%CI = -0.905, -0.045).

CONCLUSION

Our findings provide evidence to suggest negative impacts on the neurodevelopment at 2 months of preterm infants exposed to certain metals, possibly related to TPN intake and/or blood transfusions received during their NICU stay. Preterm neonates may be exposed to levels of metals in utero.

The associations between stunting and wasting at 12 months of age and developmental milestones delays in a cohort of Cambodian children

Worldwide, over 250 million children under 5 years do not reach their developmental potential due to several causes, including malnutrition. In Cambodia, the prevalence of stunting and wasting among children remains high. This prospective cohort study aimed to assess acquisition of motor and cognitive developmental milestones in early childhood and their associations with stunting and wasting. Children aged from 0 to 24 months were recruited from three provinces in Cambodia and followed up to seven times from March 2016 to June 2019, until their 5 years. Data collection included anthropometry and developmental milestones. Seven motor and seven cognitive milestones were evaluated using the Cambodian Development Milestone Assessment Tool. Associations were assessed with parametric survival models. Hazard ratios (HR) below 1 stood for lower probabilities for achieving developmental milestones. Data were available for 7394 children. At 12 months, the prevalence of stunting and wasting were 23.7% and 9.6% respectively. Both were consistently associated with delays in most motor and cognitive milestones. Stunting was strongly associated with delays in gross motor milestones (HR < 0.85; p < 0.001). Wasting was more strongly associated with delays in fine motor development and most cognitive milestones (HR < 0.75; p < 0.001). Promoting nutritional programs in the first 1000 days to prevent malnutrition is essential to further the optimal growth and motor and cognitive development of Cambodian children.

Factors determining cognitive, motor and language scores in low birth weight infants from North India

BACKGROUND

Children born with low birth weight (LBW) tend to have lower neurodevelopmental scores compared to term normal birth weight children. It is important to determine factors that influence neurodevelopment in these low birth weight children especially in the first 2-3 years of life that represents a period of substantial brain development.

METHODS

This secondary data analysis was conducted using data from LBW infants enrolled soon after birth in an individually randomized controlled trial (RCT) and followed up till end of 1st year. Neurodevelopmental assessment was done at 12 months of corrected age by trained psychologists using Bayley Scales of Infant and Toddler Development 3rd edition (Bayley-III). Factors influencing cognitive, motor and language scores were determined using multivariable linear regression model.

RESULTS

Linear growth (i.e., length for age z score, LAZ) [cognitive: Standardized ẞ-coefficient = 2.19, 95% CI; 1.29, 3.10; motor: 2.41, 95% CI; 1.59, 3.23; language: 1.37, 95% CI; 0.70, 2.04], stimulation at home [cognitive: 0.21, 95% CI; 0.15, 0.27; motor: 0.12, 95% CI; 0.07, 0.17; language: 0.21, 95% CI; 0.16, 0.25] and number of diarrhoeal episodes [cognitive: -2.87, 95% CI; -4.34, -1.39; motor: -2.62, 95% CI; -3.93, -1.29; language: -2.25, 95% CI; -3.32, -1.17] influenced the composite scores in all three domains i.e., cognitive, language and motor. While increase in LAZ score and stimulation led to increase in composite scores; an increase in number of diarrhoeal episodes was associated with decrease in scores. Weight for height z scores (WHZ) were associated with motor and language but not with cognitive scores. Additionally, a negative association of birth order with cognitive and language scores was noted.

CONCLUSIONS

The findings indicate the possible importance of promoting nutrition and preventing diarrhoea as well as ensuring optimal stimulation and nurturance at home for enhancing child development in LBW infants.

Stunting and lead: using causal mediation analysis to better understand how environmental lead exposure affects cognitive outcomes in children

BACKGROUND

Many children in Bangladesh experience poor nutritional status and environmental lead exposure, both of which are associated with lower scores on neurodevelopmental assessments. Recent studies have suggested that part of lead's adverse effects on neurodevelopment are caused in part by lead's effect on growth. New statistical methods are now available to evaluate potential causal pathways in observational studies. This study used a novel statistical method to test the hypothesis that stunting, a measure of linear growth related to poor nutrition, is a mediator and/or an effect modifier of the lead exposure's adverse effect on cognitive development.

METHODS

Participants were 734 children from a longitudinal birth cohort established in rural Bangladesh to study the health effects of prenatal and early childhood environmental metal exposures. Lead exposure was estimated using umbilical cord blood samples obtained at birth and blood obtained via venipuncture at age 20-40 months. Stunting was determined using the World Health Organization's standards. Neurodevelopment was assessed at age 20-40 months years using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III). We evaluated the effect of lead on stunting and whether the effect of lead on cognitive scores is modified by stunting status in multivariable regression analyses. We then conducted a novel 4-way mediation analysis that allows for exposure-mediator interaction to assess how much of the effect of lead on cognitive scores is explained by the pathway through stunting (mediation) and how much is explained by the interaction between lead and stunt (effect modification).

RESULTS

Stunting was not a mediator of the effect of lead in our analyses. Results suggested effect modification by stunting. In an area of Bangladesh with lower lead exposures (median umbilical cord blood lead concentration, 1.7 μg/dL), stunting modified the relationship between prenatal blood lead concentrations and cognitive score at age 2-3 years. A 1-unit increase in natural log cord blood lead concentration in the presence of stunting was associated with a 2.1-unit decrease in cognitive scores (β = - 2.10, SE = 0.71, P = 0.003). This interaction was not found in a second study site where lead exposures were higher (median umbilical cord blood lead concentration, 6.1 μg/dL, β = - 0.45, SE = 0.49, P = 0.360).

CONCLUSIONS

We used a novel method of mediation analysis to test whether stunting mediated the adverse effect of prenatal lead exposure on cognitive outcomes in Bangladesh. While we did not find that stunting acted as mediator of lead's effect on cognitive development, we found significant effect modification by stunting. Our results suggest that children with stunting are more vulnerable to the adverse effects of low-level lead exposure.

Effects of early and recent mercury and lead exposure on the neurodevelopment of children with elevated mercury and/or developmental delays during lactation: A follow-up study

This follow-up study of 82 children investigated the potential impact of early and recent exposure to mercury and lead on their neurodevelopmental performance at 5-8 years of age (2017-2018). Early exposure of these children to mercury, methylmercury, and lead was assessed during lactation at 3-12 months old, as well as their mother's exposure using measurements from a cross-sectional study (2011-2013). Only infants who failed to pass the neurodevelopment screening tools and/or had elevated mercury were included in this study. Urine and hair were sampled during the follow-up study to assess the children's recent exposure to mercury, methylmercury, and lead. Their cognitive performance and visual-motor integration were also measured using the Test of Non-Verbal Intelligence (TONI) and the Beery-Visual-Motor Integration (Beery VMI), respectively. The association between alterations in urinary porphyrins excretion and exposure to metals was analyzed and their influence on the children's neurodevelopment was explored. Linear regression models revealed a significant negative association between the infants' mercury exposure during lactation and the TONI Quotient (β = -0.298, 95%CI = -4.677, -0.414) and Beery VMI Age Equivalent scores at age 5-8 (β = -0.437, 95%CI = -6.383, -1.844). The mothers' blood methylmercury was inversely and significantly associated with their children's TONI Quotient (β = -0.231, 95%CI = -8.184, -0.331). In contrast, the children's Beery VMI Age Equivalent scores were positively and significantly associated with the hair methylmercury of the mothers (β = 0.214, 95%CI = 0.088, 3.899) and their infants (β = 0.256, 95%CI = 0.396, 4.488). These relationships suggest the presence of negative confounding that we did not take into account. Unlike mercury, there was some evidence that lead in breast milk had an inverse relationship with the children's visual-motor coordination skills. Our study did not show a clear association between children's recent exposure to metals and neurodevelopment. However, a significant inverse association was observed between the TONI Quotient and the interaction of hair methylmercury × ∑porphyrins (ß = -0.224, 95%CI = -0.86, -0.049), implying that porphyrins are a sensitive measure of low body-mercury burden. Although lead induced higher ∑porphyrins excretion in urine (β = 0.347, 95%CI = 0.107, 0.525), their interaction did not influence children's neurodevelopmental scores. The interactions between metals and porphyrins might provide insights into their potential contributory role in the pathogenesis associated with neurological disorders or other diseases. Despite the small sample size of the present study, its findings about the association between toxic metal exposure and the high risk of poor neurodevelopmental performance are worrying, particularly at an early age, and additional research is needed using larger sample sizes.

Arsenic in a groundwater environment in Bangladesh: Occurrence and mobilization

Groundwater with an excessive level of Arsenic (As) is a threat to human health. In Bangladesh, out of 64 districts, the groundwater of 50 and 59 districts contains As exceeding the Bangladesh (50 μg/L) and WHO (10 μg/L) standards for potable water. This review focuses on the occurrence, origin, plausible sources, and mobilization mechanisms of As in the groundwater of Bangladesh to better understand its environmental as well as public health consequences. High As concentrations mainly was mainly occur from the natural origin of the Himalayan orogenic tract. Consequently, sedimentary processes transport the As-loaded sediments from the orogenic tract to the marginal foreland of Bangladesh, and under the favorable biogeochemical circumstances, As is discharged from the sediment to the groundwater. Rock weathering, regular floods, volcanic movement, deposition of hydrochemical ore, and leaching of geological formations in the Himalayan range cause As occurrence in the groundwater of Bangladesh. Redox and desorption processes along with microbe-related reduction are the key geochemical processes for As enrichment. Under reducing conditions, both reductive dissolution of Fe-oxides and desorption of As are the root causes of As mobilization. A medium alkaline and reductive environment, resulting from biochemical reactions, is the major factor mobilizing As in groundwater. An elevated pH value along with decoupling of As and HCO₃^- plays a vital role in mobilizing As. The As mobilization process is related to the reductive solution of metal oxides as well as hydroxides that exists in sporadic sediments in Bangladesh. Other mechanisms, such as pyrite oxidation, redox cycling, and competitive ion exchange processes, are also postulated as probable mechanisms of As mobilization. The reductive dissolution of MnOOH adds dissolved As and redox-sensitive components such as SO₄^2- and oxidized pyrite, which act as the major mechanisms to mobilize As. The reductive suspension of Mn(IV)-oxyhydroxides has also accelerated the As mobilization process in the groundwater of Bangladesh. Infiltration from the irrigation return flow and surface-wash water are also potential factors to remobilize As. Over-exploitation of groundwater and the competitive ion exchange process are also responsible for releasing As into the aquifers of Bangladesh.

Exposures to chemical mixtures during pregnancy and neonatal outcomes: The HOME study

INTRODUCTION

Exposure to mixtures of environmental chemicals are prevalent among pregnant women and may be associated with altered fetal growth and gestational age. To date, most research regarding environmental chemicals and neonatal outcomes has focused on the effect of individual agents.

METHODS

In a prospective cohort of 380 pregnant women from Cincinnati, OH (enrolled 2003-2006), we used biomarkers to estimate exposure to 43 phenols, phthalates, metals, organophosphate/pyrethroid/organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, perfluoroalkyl substances (PFAS), and environmental tobacco smoke. Using three approaches, we estimated covariate-adjusted associations of chemical mixtures or individual chemicals with gestational-age-specific birth weight z-scores, birth length, head circumference, and gestational age: k-means clustering, principal components (PC), and one-chemical-at-a-time regression.

RESULTS

We identified three chemical mixture profiles using k-means clustering. Women in cluster 1 had higher concentrations of most phenols, three phthalate metabolites, several metals, organophosphate/organochlorine pesticides, polychlorinated biphenyls, and several PFAS than women in clusters 2 and 3. On average, infants born to women in clusters 1 (-1.2 cm; 95% CI: -1.9, -0.5) and 2 (-0.5 cm; 95% CI: -1.1, 0.1) had lower birth length than infants in cluster 3. Six PCs explained 50% of the variance in biomarker concentrations and biomarkers with similar chemical structures or from shared commercial/industrial settings loaded onto commons PCs. Each standard deviation increase in PC 1 (organochlorine pesticides, some phenols) and PC 6 (cadmium, bisphenol A) was associated with 0.2 cm (95% CI: -0.4, 0.0) and 0.1 cm (95% CI: -0.4, 0.1) lower birth length, respectively. Organochlorine compounds, parabens, and cadmium were inversely associated with birth length in the one-chemical-at-a-time analysis. Cluster membership, PC scores, and individual chemicals were not associated with other birth outcomes.

CONCLUSION

All three methods of characterizing multiple chemical exposures in this cohort identified inverse associations of select organochlorine compounds, phenols, and cadmium with birth length, but not other neonatal outcomes.

Magnitude of the mixture hormetic response of soil alkaline phosphatase can be predicted based on single conditions of Cd and Pb

In soil ecosystems, it is very challenging to predict mixture hormesis effects. In the present study, soil alkaline phosphatase (ALP) was selected to investigate and predict its potential hormetic responses under Cd and Pb stresses. Typical reverse U-shaped dose-response relationships between ALP activities and the single and combined Cd and Pb were observed, showing a hormetic response of soil itself. The maximum stimulatory magnitudes ranged in 8.0 - 8.6% under 0.004 - 0.2 mg/kg Cd and 80 - 400 mg/kg Pb, respectively. An enhanced stimulation of 15.7% occurred under the binary mixtures of 0.6 mg/kg Cd and 200 mg/kg Pb. In addition, a dosage-independent binary linear regression model was proposed based on an assumption of a linear relationship between the single and combined hormetic responses under Cd and Pb. Our model can well predict ALP's responses in the presence of the two metals' mixtures (p < 0.1). Our findings provided new understandings to hormesis in soil.

Selenium status in lactating mothers-infants and its potential protective role against the neurotoxicity of methylmercury, lead, manganese, and DDT

A total of 206 lactating mothers and their infants (3-12 months) were included in this study to evaluate postnatal exposure to neurotoxic pollutants such as methylmercury (MeHg), lead (Pb), manganese (Mn), dichlorodiphenyltrichloroethane (DDT) and its metabolites [dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE)] and their association with delayed neurological development and to explore the protective role of selenium (Se) against chemical neurotoxicity. Neurodevelopmental performance was evaluated using Denver Developmental Screening Test II and Parents' Evaluation of Developmental Status (PEDS). Multivariate log-binomial regression modeling was applied for both single and multiple exposures to chemicals using a principal component analysis that generated six principal components. Both mothers and their infants had been exposed to metals and DDT metabolites, with some exceeding the accepted permissible limits. The geometric means of MeHg, Pb, Mn, DDD, DDE and DDT levels in breast milk were 1.333, 45.327, 15.576, 0.069, 0.542 and 1.08 μg/l, respectively. A single-exposure model identified a high risk of reduced PEDS performance significantly associated with DDD in breast milk [relative risk (RR) = 1.484; 95% confidence interval (95%CI) = 1.091-2.019] and marginally significantly associated with Pb in the mothers' blood (RR = 2.164; 95%CI = 0.87-5.382). We did not find a protective role of Se in neurodevelopment due to its high levels in the mothers. Models of multi-chemical exposure indicated that Mn in blood and breast milk, Se in blood and Pb in the mothers' urine were marginally significantly associated with a high risk of reduced PEDS performance (RR = 0.424; 95%CI = 0.176-1.022). The use of multi-chemical exposure approach in early life risk assessments is important because it indicates real-world exposure. Our results were not conclusive because the sample size was small, so future studies examining the implications to health of the impact of prenatal/postnatal exposure to a mixture of chemicals in the Saudi population are merited.

Growth parameters at birth mediate the relationship between prenatal manganese exposure and cognitive test scores among a cohort of 2- to 3-year-old Bangladeshi children

Background

Our previous study demonstrated that prenatal manganese exposure is associated with cognitive test scores among a cohort of 2- to 3-year-old Bangladeshi children. This study tested the hypothesis that the adverse effects of manganese are mediated through poor prenatal growth.

Methods

Pregnant mothers were enrolled in a birth cohort in Bangladesh between 2008 and 2011, and children were followed at birth and age 20-40 months. Manganese concentration was measured in umbilical cord blood. Anthropometric measurements (weight, length, head circumference) were assessed at delivery. Children's cognitive development was assessed at age 20-40 months using the Bayley Scales of Infant and Toddler Development-Third Edition. Using recently developed statistical approaches that estimate mediation and interaction effects simultaneously, we evaluated whether the association between cord blood manganese and cognitive score was mediated through anthropometric measures at birth.

Results

This analysis included 764 mother-child pairs. Higher manganese concentration was associated with lower cognitive score [β=-0.61, standard error (SE)=0.23, p = 0.009]. Among the birth measures, we found a significant indirect effect only through birth length (β =-0.10, SE = 0.03, p = 0.001). We also found evidence of mediated interaction (both mediation and interaction, β =-0.03, SE = 0.01, p = 0.01) with birth length in the association between cord blood manganese and cognitive score. The overall proportion mediated by birth length was 33% (p = 0.02) and the proportion attributed to interaction was 11% (p = 0.04). We did not find evidence of a mediating effect through birth weight or head circumference.

Conclusions

Our findings confirm that prenatal growth, particularly birth length, contributes to the overall effect of environmental manganese exposure on a child's cognitive development.

Hearing loss in children with e-waste lead and cadmium exposure

Environmental chemical exposure can cause neurotoxicity and has been recently linked to hearing loss in general population, but data are limited in early life exposure to lead (Pb) and cadmium (Cd) especially for children. We aimed to evaluate the association of their exposure with pediatric hearing ability. Blood Pb and urinary Cd were collected form 234 preschool children in 3-7years of age from an electronic waste (e-waste) recycling area and a reference area matched in Shantou of southern China. Pure-tone air conduction (PTA) was used to test child hearing thresholds at frequencies of 0.25, 0.5, 1, 2, 4 and 8kHz. A PTA≥25dB was defined as hearing loss. A higher median blood Pb level was found in the exposed group (4.94±0.20 vs 3.85±1.81μg/dL, p<0.001), while no significance was found for creatinine-adjusted Cd. Compared with the reference group, the exposed group had a higher prevalence of hearing loss (28.8% vs 13.6%, p<0.001). The PTA in the left, right and both ears, and hearing thresholds at average low and high frequency, and single frequency of 0.5, 1 and 2kHz were all increased in the exposed group. Positive correlations of child age and nail biting habit with Pb, and negative correlations of parent education level and child washing hands before dinner with Pb and Cd exposure were observed. Logistic regression analyses showed the adjusted OR of hearing loss for Pb exposure was 1.24 (95% CI: 1.029, 1.486). Our data suggest that early childhood exposure to Pb may be an important risk factor for hearing loss, and the developmental auditory system might be affected in e-waste polluted areas.