Publications by authors named "Ghassan Hamra"
Article Synopsis
- A study examined the link between pesticide use and the risk of rheumatoid arthritis (RA) among licensed pesticide applicators, primarily white male farmers in North Carolina and Iowa, observing data from 1993 to 2016.
- Out of over 22,000 applicators aged 67 and older, 161 developed RA after not having claims for at least a year, with nine specific pesticides showing increased risk.
- Notable pesticides associated with elevated RA risk include malathion, carbaryl, and various herbicides and fungicides, indicating a potential health concern for older adults exposed to these chemicals.
Article Synopsis
- Phthalates, synthetic chemicals found in consumer products, are linked to preterm births, but previous studies have methodological flaws and insufficient data on the effects of alternative phthalate compounds like di-2-ethylhexyl phthalate (DEHP).
- Using data from the NIH's ECHO Program spanning from 1998 to 2022, researchers analyzed the impact of 20 phthalate metabolites on birth outcomes such as gestational age and birth weight, focusing on mother-child pairs with phthalate measurements during pregnancy.
- The study found strong associations between certain phthalates (like phthalic acid and diisononyl phthalate) and negative birth outcomes,
Prenatal Metal Exposures and Child Social Responsiveness Scale Scores in 2 Prospective Studies.
Environ Health Insights
February 2024
Article Synopsis
- Prenatal exposure to metals like lead, mercury, manganese, and selenium was studied for potential links to autism by analyzing urine samples from mothers during pregnancy.
- The research used data from two autism-risk cohorts (EARLI and MARBLES), employing complex statistical methods to assess the relationships between metal levels and child social responsiveness scores.
- Results showed no consistent associations between overall metal exposure or individual metals and the social responsiveness scores at 36 months, suggesting the effects could vary based on child sex and study cohort.
Article Synopsis
- Synthetic chemicals like bisphenols, parabens, and triclosan may contribute to preterm birth (PTB) and low birth weight (LBW) due to their ability to disrupt hormones and cause oxidative stress.
- A study with 3,619 mother-infant pairs found that higher concentrations of benzophenone-3 and methylparaben during pregnancy were linked to lower birth weight and increased odds of being small for gestational age (SGA).
- The findings suggest that while the effects are concerning, certain compounds like 2,4-dichlorophenol showed an unexpected association with lower odds of low birth weight, indicating complex interactions that need further investigation.
Article Synopsis
- Phthalates are chemicals that pregnant individuals might be exposed to, which could potentially affect fetal brain development and contribute to autism spectrum disorder (ASD).
- The study used data from two groups of pregnant participants (one general population and one with higher ASD risk) to analyze the effects of six phthalate metabolites on children's behavior, specifically looking at Social Responsiveness Scale (SRS) scores as indicators of ASD traits.
- Results showed weak and varying associations between phthalate exposure and SRS scores in the two cohorts, indicating more research with larger sample sizes is needed to understand these effects accurately.
Article Synopsis
- * Conducted over 14 years across multiple U.S. sites, it analyzed data from 2,174 pregnant individuals who provided urine samples and completed depression screenings within a year after childbirth.
- * Results showed that virtually all participants had detectable levels of several harmful chemicals, highlighting a potential area for reducing PPD risk through dietary and lifestyle changes.
Article Synopsis
- Prenatal nutrient intake may have a relationship with autism, but this study aimed to analyze a broader range of nutrients and foods through a comprehensive Bayesian approach.
- Data was collected from two cohorts: women with a child with autism (Early Autism Risks Longitudinal Investigation) and female nurses (Nurses' Health Study II), focusing on their reported prenatal diets and child autism-related traits.
- The results showed no significant overall mixture effects on autism traits in children, although some associations were found, such as lower Social Responsiveness Scale (SRS) scores linked to higher intake of certain vegetables and n-6 polyunsaturated fatty acids in some cohorts.
Article Synopsis
- The study investigates the potential link between gestational exposure to PFAS (per- and polyfluoroalkyl substances) and the likelihood of obesity in children by analyzing data from 1,391 mother-child pairs in eight U.S. cohorts.* -
- Findings indicate that higher concentrations of specific PFAS during pregnancy are associated with increased BMI-scores and a higher risk of overweight or obesity in children, though the associations are subtle and vary depending on the type of PFAS.* -
- Results suggest that the associations do not differ based on the child's sex, and while some PFAS show clearer connections to obesity risk, the overall impact of PFAS mixtures remains less certain.*
Background: Vitamin D deficiency is common in pregnancy. Vitamin D plays an important role in the developing brain, and deficiency may impair childhood behavioral development.
Objectives: This study examined the relationship between gestational 25(OH)D concentrations and childhood behavior in the Environmental influences on Child Health Outcomes (ECHO) Program.
Article Synopsis
- The study investigates the impact of maternal exposure to a mix of persistent organic pollutants (POPs) on children's neurodevelopment, particularly autism-related traits.
- The analysis involves examining maternal serum samples for 17 different POPs and assessing their effects on social, cognitive, and behavioral traits in children at 36 months using various scales.
- Results indicate some POPs are linked to deficits in social behavior and cognitive performance, but no overall mixture effect was found, suggesting that individual POPs may have varying influences rather than a combined impact.
Article Synopsis
- The ECHO-Wide Cohort Study (EWC) is a big research project started in 2016 to help improve children's health in the U.S. by looking at different factors that affect their well-being.
- It collects lots of data from 69 groups and has information on over 60,000 kids, with some kids also giving new info and samples for research.
- Researchers study five main health areas, like how kids develop and their weight, while considering things like air pollution and family health.
Background: Per- and polyfluoroalkyl substances (PFAS) are persistent and ubiquitous chemicals associated with risk of adverse birth outcomes. Results of previous studies have been inconsistent. Associations between PFAS and birth outcomes may be affected by psychosocial stress.
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- The prevalence of obesity among US youths aged 2 to 19 was 19.3% from 2017 to 2018, and previous studies linked school lunches to increased obesity rates, prompting the Healthy, Hunger-Free Kids Act of 2010 (HHFKA) to enhance nutritional standards for school meals.
- This study aimed to assess the impact of the HHFKA on youth body mass index (BMI) by analyzing data from a national cohort of children aged 5 to 18 over a period from January 2005 to March 2020.
- Results indicated that after the HHFKA's implementation, there was a significant decrease in annual BMI z-scores, particularly among youths aged 12 to
The COVID-19 pandemic-and its associated restrictions-have changed many behaviors that can influence environmental exposures including chemicals found in commercial products, packaging and those resulting from pollution. The pandemic also constitutes a stressful life event, leading to symptoms of acute traumatic stress. Data indicate that the combination of environmental exposure and psychological stress jointly contribute to adverse child health outcomes.
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- This study investigated the link between prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and autism-related traits in children using data from 1,429 participants across 10 cohorts in the NIH-funded ECHO program.
- The analysis showed that most PFAS in maternal blood had no significant association with child autism traits, but higher levels of perfluorononanoic acid (PFNA) were linked to increased autism-related traits.
- The findings suggest a potential connection between PFNA levels during pregnancy and modest increases in autism traits, indicating the need for further research on various PFAS and their impacts on child development.
Importance: The primary outcomes of the COVID-19 pandemic on the mental health of women with children remain largely unknown.
Objectives: To identify and describe clusters of mothers of children participating in the Environmental influences on Child Health Outcomes (ECHO) Program that characterize pandemic-associated hardships, coping mechanisms, and behaviors, and to evaluate associations between pandemic-associated hardships, coping strategies, and behavior changes with pandemic-associated traumatic stress symptoms.
Design, Setting, And Participants: This multicenter cohort study investigated experiences during the COVID-19 pandemic between April 2020 and August 2021 among maternal caregivers of children participating in the ECHO Program.
Article Synopsis
- - Yland et al. challenge the widely accepted idea that "nondifferential misclassification biases results towards the null," arguing that this notion is often incorrect and oversimplified.
- - The article reviews the historical context of this heuristic, explaining how it gained popularity and why it remains influential in epidemiological discussions.
- - The authors highlight the specific situations where this heuristic might be applicable, emphasizing its limitations in broader contexts.
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.
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- Neighborhood greenspace may lead to demographic and housing changes in large U.S. cities, particularly affecting income and employment among residents.
- The study analyzed data from the largest metropolitan areas, examining the impact of greenspace on factors like education level, job types, and economic status from 1990 to 2010.
- Findings showed that areas with more greenspace saw increases in professional jobs and median income between 1990-2000, but trends were less significant in later years and did not differ significantly by racial/ethnic composition.
Article Synopsis
- Meta-analysis combines data from various studies, but it’s crucial to ensure that these studies are unbiased and comparable, which involves careful selection of confounders using directed acyclic graphs (DAGs).
- The study compared the effectiveness of different statistical methods, including linear, log-binomial, logistic regression, and inverse probability weighting, on estimates derived from varying minimally sufficient sets identified via a DAG.
- Results indicated that most methods yielded similar estimates with minor differences, but logistic regression produced inconsistent results and larger errors, suggesting it’s unreliable for collaborative meta-analysis.
Article Synopsis
- Linear regression is commonly used to analyze the relationship between chemical exposure and neurodevelopment, but this study explores how these associations vary across different levels of neurodevelopmental outcomes, particularly for those at the extremes.
- Using quantile regression, researchers assessed the impact of gestational phthalate exposure on Autism Spectrum Disorder (ASD)-related behaviors in children by combining data from two studies, the EARLI Study and the HOME Study, focusing on urine samples from pregnant mothers and caregiver reports of children's behaviors.
- Findings revealed that in the EARLI Study, most associations were either negative or non-existent; however, in the HOME Study, stronger positive associations between certain phthalate levels and ASD behaviors were found among children with more severe ASD-related
Bayesian Weighted Sums: A Flexible Approach to Estimate Summed Mixture Effects.
Int J Environ Res Public Health
February 2021
Objectives: Methods exist to study exposure mixtures, but each is distinct in the research question it aims to address. We propose a new approach focused on estimating both the summed effect and individual weights of one or multiple exposure mixtures: Bayesian Weighted Sums (BWS).
Methods: We applied BWS to simulated and real datasets with correlated exposures.
Article Synopsis
- The study investigated how eating fish during pregnancy affects autism traits in children, using data from two pregnancy cohorts in the U.S.
- Results showed that mothers who ate more fish in the second half of pregnancy had children with higher autism traits, especially with certain types of fish like shellfish and large fish increasing scores, while salmon seemed to decrease them.
- The research suggests the need for further studies to explore the timing of fish intake during pregnancy and how different fish types may influence autism-related outcomes in children.