Exposure to Endocrine-Disrupting Chemicals Linked to ADHD in Adolescents

Data from a study of more than 200 adolescents from a birth cohort study suggests exposure to endocrine-disrupting chemicals could be linked to attention-deficit/hyperactivity disorder (ADHD).

Analysis of urinary biomarker concentrations revealed increases in certain endocrine-disrupting chemicals were associated with increased risk of developing ADHD-related behavior problems with this association appearing to be stronger in male patients than their female counterparts.

“Our findings support an association of adolescent exposure to EDCs, particularly select phthalates, with an increased risk of significant ADHD-related behavior problems at exposure biomarker concentrations typical of adolescents in the general US population,” wrote study investigators.

With a growing source of evidence suggest exposure to endocrine-disrupting chemicals could influence a child’s risk of developing ADHD or ADHD-related behavior problems later in life, investigators sought to investigate these potentials association using data from the New Bedford Cohort. Of note, the New Bedford Cohort is an ongoing prospective birth cohort study examining mother-infant pairs from Massachusetts enrolled from 1993-1998.

While the original study aimed to examine association of prenatal organochlorine and metal exposures to neurodevelopment in children, an assessment of exposure to endocrine-disrupting chemicals was performed midway through the 15-year follow-up period. Of those invited to provide urine samples, 205 provided at least 1 sample and were included in the study. Investigators assessed the urine concentrations of 28 specific biomarker.

Investigators noted urine concentrations were quantified at the Centers for Disease Control and Prevention laboratory in Atlanta in 2 sprat batches. In the first batch, investigators assessed concentrations of 11 phthalate metabolites and 8 phenols. In the second batch, investigators assess 5 additional biomarkers of phthalates or the phthalate substitute cyclohexane-1,2-dicarboxylic acid, monohydroxy isononyl ester (MHINCH), 3 additional phenols, and triclocarban.

Of the 205 participants included, mean age at assessment was 15.3 (0.7) years, 55% were girls, and 61% were non-Hispanic White participants. Additionally, 40% of the study had scores consistent with a significant behavioral problem, which was defined as at least 1 BASC-2 or CADS ADHD-related measure, and 19% had an ADHD diagnosis. Investigators pointed out the incidence of diabetes noted in the study was nearly double the US estimate of approximately 10%.

The median urine concentrations among the study population were 0.45 μmol/L of antiandrogenic phthalates, 0.13 μmol/L of DEHP metabolites, 0.49 μmol/L of personal care product phthalates, 0.35 μmol/L of parabens, 0.02 μmol/L of bisphenols, and 0.02 μmol/L of dichlorophenols. Results of the investigators' analysis indicated each 2-fold increase in the sum of antiandrogenic phthalate concentration was associated with a 34% increase in the risk of significant ADHD-related behavior problems (RR, 1.34; 95% CI, 1.00-1.79). Similarly, each 2-fold increase in sum of dichlorophenols was associated with a 15% increase in risk (RR, 1.34; 95% CI, 1.01-1.32)

“US health care and education expenditures associated with ADHD in children and adolescents are estimated to be $38 billion to $72 billion annually, while costs associated with ADHD in adults, including lost wages, are much higher, ranging from $143 billion to $266 billion annually,” noted study investigators. “The identification of modifiable risk factors for ADHD is of great public health importance. These findings contribute new insights into the potential detrimental neurobehavioral outcomes of EDC exposure during adolescence.”

This study, “Association of Exposure to Endocrine-Disrupting Chemicals During Adolescence With Attention-Deficit/Hyperactivity Disorder–Related Behaviors,” was published in JAMA Network Open.