Grantee Research Project Results

2024 Progress Report: Innovative approach to assess the effect of metal mixtures from infant meconium associated with adverse infant outcomes by identifying methylation loci in mothers and infants

EPA Grant Number: R840454
Title: Innovative approach to assess the effect of metal mixtures from infant meconium associated with adverse infant outcomes by identifying methylation loci in mothers and infants
Investigators: Pavilonis, Brian , McDermott, Suzanne , Kavouras, Ilias , Cai, Bo , Cai, Guoshuai , Shin, Jin , Maroko, Andrew
Institution: Research Foundation of CUNY , Medgar Evers College , University of South Carolina at Columbia
EPA Project Officer: Aja, Hayley
Project Period: October 1, 2022 through May 12, 2025
Project Period Covered by this Report: October 1, 2023 through September 30,2024
Project Amount: $746,154
RFA: Development of Innovative Approaches to Assess the Toxicity of Chemical Mixtures Request for Applications (RFA) (2022) RFA Text |  Recipients Lists
Research Category: Children's Health , Health Effects , Genetics/Susceptibility/Metabolics , Urban Air Toxics , Endocrine Disruptors , Heavy Metal Contamination of Soil/Water , Human Health , Safer Chemicals , Mixtures , Chemical Safety for Sustainability , CSS

Objective:

The objectives of this research are: 1) developing a standardized methodology for assessing intrauterine exposure using meconium as a biomarker and quantify metal mixtures among an urban population and 2) explore and quantify the effect of metal mixture exposure on methylated genes for three adverse birth outcomes: small for gestational age (SGA), intellectual disability (ID), and autism spectrum disorders (ASD).

Progress Summary:

Our original study timeline aimed to recruit 300 participants across three New York City (NYC) hospitals and collect DNA and meconium samples from mothers and children during the first two years of the project. As of the second year, we have successfully collected and analyzed 301 meconium samples and 351 DNA samples (from both mothers and children). Recruitment has been completed at all three hospitals, achieving 100% progress across all sites. Our original grant aims remain unchanged, and we are on track to complete all proposed work within the project timeline.

Table 1: Quantification of selected metals in meconium (ppm)

Metal	N (%) < LOD	Mean	Min	Maximum
Al	0%	5.35	0.39	15.52
Cd	15.80%	0.008	0.0004	0.4
Cr	0.35%	0.26	0.002	9.14
Mo	1.06%	0.23	0.006	1.32
Ni	0%	0.48	0.06	26.04
Pb	14.40%	0.11	0.006	5.89

An overview of the measured concentrations of six metals in meconium samples are shown in Table 1 and show excellent analytical sensitivity. Notably, aluminum (Al) and nickel (Ni) were detectable in all samples, with Al exhibiting the highest mean concentration (5.35 ppm) and a maximum value of 152.52 ppm. Cadmium (Cd) and lead (Pb), known for their neurotoxicity, had only 15.8% and 14.4% of samples below the LOD, respectively, with lead reaching a maximum concentration of 5.89 ppm. Chromium (Cr) and molybdenum (Mo) were generally detectable, with only a small percentage of samples below the LOD. These data underscore the variability in prenatal exposure to metals and highlight the importance of further exploring their sources, potential effects on DNA methylation, and associations with maternal sociodemographic factors.

Preliminary analyses of sociodemographic factors associated with metals exposure has led to promising findings. Black mothers had significantly higher Cd concentrations (0.005 ppm) compared to White mothers (0.002 ppm; p = 0.006). Similarly, Asian mothers exhibited elevated levels of Pb (p = 0.018) and Ni (p = 0.016), with Ni concentrations nearly double those of White mothers. The elevated metal concentrations, particularly for Cd and Ni, may reflect environmental exposures specific to demographic groups, underscoring potential disparities in exposure sources.

Preliminary analysis of methylation data from a total of 197 children and 75 mothers has been conducted. Among these, 74 children and 57 mothers had complete data available for analysis. The primary aim was to investigate the correlation between methylation levels and metal exposure, and to identify any significant differences based on various demographic factors.

The data underwent several preprocessing steps to ensure accuracy and reliability. Initially, the data was normalized using the preprocessQuantile() function from the “minfi” package. Poor performing probes, as well as probes located on sex chromosomes or affected by SNPs, were filtered out. To correct for batch effects, the “Combat” function from the “sva” R package was employed. Differentially methylation analysis was conducted by fitting a linear model to each CpG site. Additionally, gene set enrichment analysis (GSEA) was performed on the top 300 differentially methylated genes to explore their biological significance.

 

 

 

Combined Analysis of Mothers and ChGene Set Enrichment Analysis- Children: The top 300 differentially methylated genes in children were significantly enriched in pathways related to fatty acid metabolism, KRAS signaling DN, L2 stat5 signaling, and responses to estrogen and androgen.

Children: The combined analysis indicated significant enrichment in pathways related to KRAS signaling UP and estrogen response.

 

 

Future Activities:

Since we have completed 100% of the data collection, we will focus our final year of the project on manuscript development and further data analyses. Our team’s biostatistician (B. Cai) and bioinformatics (G. Cai) leads are currently analyzing our preliminary data to determine the best methodology for carrying out the DNA methylation and metals mixture analysis.

Supplemental Keywords:

Meconium, metal mixture, epigenetics, small for gestational age, intellectual disability, autism, urban pollution, fetal exposure, New York City, EPA Region 2.

Progress and Final Reports:

Original Abstract

2023 Progress Report

Final