Chemicals found in food packaging, toys and cosmetics may increase risk of ADHD in teenagers, warn scientists
Chemicals used to make consumer products, including food packaging, cosmetics, fragrances and pharmaceuticals, has been linked to an increased risk of attention-deficit/hyperactivity disorder (ADHD)-related behaviors in children. The researchers from the US measured a range of different chemicals in the urine of teenagers and adolescents and assessed their behavior using data from parents and teachers. They found that ADHD-like behaviors were linked with high exposure to certain phthalates: while 40% had scores consistent with a significant behavioral problem, 19% had an ADHD diagnosis. These chemicals, termed endocrine disruptors, can act as hormones, and the high-risk phthalates can act to curb the normal activity of male hormones called androgens, the team warns.
Endocrine-disrupting chemicals (EDCs) are chemicals capable of interfering with hormone action and which thereby contribute to disease and disability across the lifespan. Phthalates are a group of chemicals used in hundreds of products, such as toys, vinyl flooring and wall covering, detergents, lubricating oils, food packaging, pharmaceuticals, blood bags and tubing and personal care products, such as nail polish, hair sprays, aftershave lotions, soaps, shampoos, perfumes and other fragrance preparations. Evidence has doubled in the last five years about the negative impact of endocrine-disrupting chemicals in plastics, pesticides and flame retardants on people’s health. The results of the current study support the importance of adolescent exposure to EDCs, particularly phthalates, as a potential risk factor for significant ADHD-related behavior problems, explain researchers.
“ADHD is a common and costly neurobehavioral disorder. US healthcare and education expenditures associated with ADHD in children and adolescents are estimated to be $38 billion to $72 billion annually. Costs associated with ADHD in adults, including lost wages, are much higher, ranging from $143 billion to $266 billion annually. The identification of modifiable risk factors for ADHD is of great public health importance,” writes authors in their analysis published in JAMA Network Open.
The team includes experts from Harvard Medical School, Brigham and Women’s Hospital, Harvard TH Chan School of Public Health, Boston University School of Public Health, and the Centers for Disease Control and Prevention (CDC), among others. “Endocrine-disrupting chemicals are used in a wide variety of consumer products resulting in ubiquitous exposure. The study findings suggest that exposure to some of these endocrine-disrupting chemicals, particularly certain phthalates, during adolescence may be associated with behaviors characteristic of ADHD,” they emphasize.
The findings
ADHD is the most common neurobehavioral disorder of childhood, affecting approximately 9.4% of children in the US. It is characterized by difficulty maintaining attention, controlling impulses and regulating activity level and may be associated with academic and social problems as well as difficulties throughout adulthood, say experts. “The objective of this study is to examine the association of adolescent exposure to EDCs, specifically phthalates, phenols, and triclocarban, with ADHD-related behaviors. We hypothesize that exposure to certain EDCs during adolescence is particularly detrimental to adolescent behavior given the rapid brain development that occurs during this time,” says the team.
For the cross-sectional analysis, data were collected from 205 adolescents and teenagers in the New Bedford Cohort, an ongoing prospective birth cohort, between June 18, 2011, and June 10, 2014. The average age of the participants was 15.3 years, with 112 girls (55%) and 124 non-Hispanic White participants (61%). The findings reveal that 82 (40%) had scores consistent with a significant behavioral problem, whereas 39 (19%) had an ADHD diagnosis, which is higher than US population estimates (approximately 10%).
“A two-fold increase in antiandrogenic phthalates was associated with a 1.34 increased risk of significant ADHD-related behavior problems, whereas a two-fold increase in DEHP metabolites was associated with a 1.29 increased risk. A smaller 1.16 increased risk was observed with a two-fold increase in personal care products. Adverse associations were observed with each individual phthalate metabolite. We observed stronger associations for hyperactive behaviors compared with inattentive behaviors for antiandrogenic phthalates,” say investigators.
According to the scientists, associations tended to be stronger among male adolescents than among female adolescents, “most notably with respect to the DEHP metabolites,” in which a two-fold increase corresponded to a 1.62 increased risk of significant ADHD-related behavior problems in male adolescents compared with a 1.06 increased risk in female adolescents. “A two-fold increase in dichlorophenols was also associated with an increased risk of ADHD-related behaviors. These findings support the potential importance of exposures to endocrine-disrupting chemicals, especially phthalates, during adolescence as correlates of ADHD-related behaviors,” the researchers conclude.