Combined effects of prenatal exposure to polycyclic aromatic hydrocarbons and material hardship on child ADHD behavior problems

Abstract

Importance Polycyclic aromatic hydrocarbons (PAH) are carcinogenic and neurotoxic combustion by-products commonly found in urban air. Exposure to PAH is disproportionately high in low income communities of color who also experience chronic economic stress. Objective In a prospective cohort study in New York City (NYC) we previously found a significant association between prenatal PAH exposure and Attention Deficit Hyperactivity Disorder (ADHD) behavior problems at age 9. Here, we have evaluated the joint effects of prenatal exposure to PAH and prenatal/childhood material hardship on ADHD behavior problems. Materials and Methods We enrolled nonsmoking African-American and Dominican pregnant women in New York City between 1998 and 2006 and followed their children through 9 years of age. As a biomarker of prenatal PAH exposure, PAH-DNA adducts were measured in maternal blood at delivery and were dichotomized at the limit of detection (to indicate high vs. low exposure). Maternal material hardship (lack of adequate food, housing, utilities, and clothing) was self-reported prenatally and at multiple time points through child age 9. Latent variable analysis identified four distinct patterns of hardship. ADHD behavior problems were assessed using the Conners Parent Rating Scale-Revised. Analyses adjusted for relevant covariates. Results Among 351 children in our sample, across all hardship groups, children with high prenatal PAH exposure (high adducts) generally had more symptoms of ADHD (higher scores) compared to those with low PAH exposure. The greatest difference was seen among the children with hardship persisting from pregnancy through childhood. Although the interactions between high PAH exposure and hardship experienced at either period (“persistent” hardship or “any” hardship) were not significant, we observed significant differences in the number of ADHD symptoms between children with high prenatal PAH exposure and either persistent hardship or any hardship compared to the others. These differences were most significant for combined high PAH and persistent hardship: ADHD Index (p<0.008), DSM-IV Inattentive (p=0.006), DSM-IV Hyperactive Impulsive problems (p=0.033), and DSM-IV Index Total (p=0.009). Conclusion The present findings add to existing evidence that co-exposure to socioeconomic disadvantage and air pollution in early life significantly increases the risk of adverse neurodevelopmental outcomes. They suggest the need for multifaceted interventions to protect pregnant mothers and their children.

Combined association of BTEX and material hardship on ADHD‐suggestive behaviours among a nationally representative sample of US children

“…Material hardship exposure was defined as a composite score measuring food security, insurance coverage, medical care, and housing stability, consistent with previous studies . Specifically, material hardship scores were calculated based on parent responses at 9 months of age including (1) receiving food stamps; (2) categorical measure of household food security scale based on standard methods; (3) child insurance coverage; (4) child seen by physician; (5) receiving help with housing; and (6) having moved in the previous 2 years.…”

“…Characterised by behaviours including hyperactivity, impulsivity, and inattention, attention‐deficit/hyperactivity disorder (ADHD) has a prevalence of 11% in children aged 4‐17 years in the United States . Typically, diagnosis occurs in children older than 7 years of age due to difficulty ascertaining ADHD‐related behaviours in younger children.…”

“…Previous research suggests ADHD aetiology and degree of severity involves genetic, environmental, and social factors . Risk factors associated with ADHD are pregnancy and delivery complications, mother's use of tobacco and alcohol, exposure to lead, ambient air pollution, socio‐economic stressors, and psychosocial hardship . These findings have influenced the growing literature involving ADHD and ambient air pollution .…”

“…These findings have influenced the growing literature involving ADHD and ambient air pollution . There is growing interest in understanding how exposure to pollutants may interact with the socio‐economic factors that are highly prevalent in disadvantaged populations …”

“…Thus, material hardship must be taken into consideration in the context of environmental pollution due to the disparities in exposure to air pollution that exist across neighbourhoods . The relationship between prenatal air pollution, material hardship, and ADHD has been explored previously in an urban population . However, there remains a gap in the literature illuminating whether the relationships between ambient air pollutants, material hardship, and neurocognitive outcomes also occur in the broader United States paediatric population.…”