Mount Sinai finds prenatal exposure to certain chemicals affects childhood neurodevelopment


A new study led by Mount Sinai researchers in collaboration with scientists from Cornell University and the U.S. Centers for Disease Control and Prevention, has found higher prenatal exposure to phthalates—manmade chemicals that interfere with hormonal messaging—to be connected with disruptive and problem behaviors in children between the ages of 4 and 9 years. The study, which is the first to examine the effects of prenatal phthalate exposure on child neurobehavioral development, will be published January 28, on the Environmental Health Perspectives website.

“There is increasing evidence that phthalate exposure is harmful to children at all stages of development,” said Stephanie Engel, PhD, lead study author and Associate Professor of Preventive Medicine at Mount Sinai School of Medicine. “We found a striking pattern of associations between low molecular weight phthalates – which are commonly found in personal care products – and disruptive childhood behaviors, such as aggressiveness and other conduct issues, and problems with attention. These same behavioral problems are commonly found in children diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder, or Conduct Disorder.”

Phthalates are part of a group of chemicals known as endocrine disruptors, that interfere with the body’s endocrine, or hormone system. They are a family of compounds found in a wide range of consumer products such as nail polishes, to increase their durability and reduce chips, and in cosmetics, perfumes, lotions and shampoos, to carry fragrance. Other phthalates are used to increase the flexibility and durability of plastics such as PVC, or included as coatings on medications or nutritional supplements to make them timed-release.

“Recently, the government instituted regulations limiting certain phthalates in things like child care articles or toys that a young child might put in their mouth,” continued Dr. Engel. “But it’s their mother’s contact with phthalate-containing products that causes prenatal exposure. The phthalates that we found most strongly related to neurodevelopment were those commonly found in cosmetics, perfumes, lotions and shampoos. Current US regulations do not address these kinds of phthalates.”

For the study, phthalate metabolite levels were analyzed in prenatal urine samples of a multiethnic group of 404 women who were pregnant for the first time. The women were invited to participate in follow-up interviews when their children were between the ages of 4 and 9. The mothers were not informed of their phthalate metabolite levels and the researchers were unaware of their exposures when testing the children.

Follow-up visits were completed by 188 of the women and their children. At each follow-up visit, the mothers completed validated questionnaires designed to assess their behavior and executive functions. The researchers found that mothers with higher concentrations of low molecular weight phthalates consistently reported poorer behavioral profiles in their children. The strongest trends were in the categories of conduct and externalizing problems, characteristics typically associated with Oppositional Defiant Disorder, Conduct Disorder and ADHD.

“These are high level, chronic exposures that start before the child is even born, but continue throughout their life. More research is needed to examine the effects of cumulative exposure to phthalates on child development. But what this study suggests is that it’s not enough to regulate childhood exposure to these chemicals. The regulations need to include products that moms use,” said Dr. Engel.

Reference: The Mount Sinai Hospital / Mount Sinai School of Medicine, Mount Sinai finds prenatal exposure to certain chemicals affects childhood neurodevelopment, Jan. 28, 2010

Common plastics chemicals linked to ADHD symptoms



Are phthalates really safe for children? 

Phthalates are important components of many consumer products, including toys, cleaning materials, plastics, and personal care items. Studies to date on phthalates have been inconsistent, with some linking exposure to these chemicals to hormone disruptions, birth defects, asthma, and reproductive problems, while others have found no significant association between exposure and adverse effects. 

A new report by Korean scientists, published by Elsevier in the November 15th issue of Biological Psychiatry, adds to the potentially alarming findings about phthalates. They measured urine phthalate concentrations and evaluated symptoms of attention-deficit/hyperactivity disorder (ADHD) using teacher-reported symptoms and computerized tests that measured attention and impulsivity. 

They found a significant positive association between phthalate exposure and ADHD, meaning that the higher the concentration of phthalate metabolites in the urine, the worse the ADHD symptoms and/or test scores. 

Senior author Yun-Chul Hong, MD, PhD, explained that “these data represent the first documented association between phthalate exposure and ADHD symptoms in school-aged children.” John Krystal, MD, the Editor of Biological Psychiatry, also commented: “This emerging link between phthalates and symptoms of ADHD raises the concern that accidental environmental exposure to phthalates may be contributing to behavioral and cognitive problems in children. This concern calls for more definitive research.” 

The U.S. Centers for Disease Control and Prevention, in the Summary of their 2005 Third National Report on Human Exposure to Environmental Chemicals, state that “very limited scientific information is available on potential human health effects of phthalates at levels” found in the U.S. population. Although this study was performed in a Korean population, their levels of exposure are likely comparable to a U.S. population.

The current findings do not prove that phthalate exposure caused ADHD symptoms. However, these initial findings provide a rationale for further research on this association. 

Reference: Elsevier, Common plastics chemicals linked to ADHD symptoms, November 19, 2009

Association to household gas appliances with cognition and attention behavior in children

Gas Stove is dangerous for the Health of Children

The authors investigated the association of early-life exposure to indoor air pollution with neuropsychological development in preschoolers and assessed whether this association differs by glutathione-S-transferase gene (GSTP1) polymorphisms. A prospective, population-based birth cohort was set up in Menorca, Spain, in 1997-1999 (n = 482).

Children were assessed for cognitive functioning (McCarthy Scales of Children’s Abilities) and attention-hyperactivity behaviors (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition) at age 4 years.

During the first 3 months of life, information about gas appliances at home and indoor nitrogen dioxide concentration was collected at each participant’s home (n = 398, 83%). Genotyping was conducted for the GSTP1 coding variant Ile105Val. Use of gas appliances was inversely associated with cognitive outcomes (beta coefficient for general cognition = -5.10, 95% confidence interval (CI): -9.92, -0.28; odds ratio for inattention symptoms = 3.59, 95% CI: 1.14, 11.33), independent of social class and other confounders.

Nitrogen dioxide concentrations were associated with cognitive function (a decrease of 0.27 point per 1 ppb, 95% CI: -0.48, -0.07) and inattention symptoms (odds ratio = 1.06, 95% CI: 1.01, 1.12).

The deleterious effect of indoor pollution from gas appliances on neuropsychological outcomes was stronger in children with the GSTP1 Val-105 allele. Early-life exposure to air pollution from indoor gas appliances may be negatively associated with neuropsychological development through the first 4 years of life, particularly among genetically susceptible children.

Reference: Morales E, Julvez J, Torrent M, de Cid R, Guxens M, Bustamante M, Künzli N, Sunyer J., Association of early-life exposure to household gas appliances and indoor nitrogen dioxide with cognition and attention behavior in preschoolers, Center for Research in Environmental Epidemiology, Barcelona, Catalonia, Spain, Am J Epidemiol. 2009 Jun 1;169(11):1327-36.