Common plastics chemicals linked to ADHD symptoms

Philadelphia, PA, 19 November 2009 - 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.

The article is "Phthalates Exposure and Attention-Deficit/Hyperactivity Disorder in School-Age Children" by Bung-Nyun Kim, Soo-Churl Cho, Yeni Kim, Min-Sup Shin, Hee-Jeong Yoo, Jae-Won Kim, Young Hee Yang, Hyo-Won Kim, Soo-Young Bhang, and Yun-Chul Hong. B-N Kim, S-C Cho, Y Kim, M-S Shin, J-W Kim, Y H Yang, and H-W Kim are affiliated with the Division of Child & Adolescent Psychiatry, Department of Psychiatry and Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. H-J Yoo is from the Department of Psychiatry, Seoul National University Bundang Hospital, Seong-nam, Republic of Korea. Y-C Hong is with the Department of Preventive Medicine, Seoul National University College of Medicine and Institute of Environmental Medicine, SNUMRC, Seoul, Republic of Korea. S-Y Bhang is affiliated with the Department of Psychiatry, Ulsan University Hospital, Ulsan, Republic of Korea. The article appears in Biological Psychiatry, Volume 66, Issue 10 (November 15, 2009), published by Elsevier.

The authors' disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, M.D. is Chairman of the Department of Psychiatry at the Yale University School of Medicine and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available at http://journals.elsevierhealth.com/webfiles/images/journals/bps/Biological_Psychiatry_Editorial_Disclosures_08_01_09.pdf.

Full text of the article mentioned above is available upon request. Contact Jayne M. Dawkins at ja.dawkins@elsevier.com to obtain a copy or to schedule an interview.

This international rapid-publication journal is the official journal of the Society of Biological Psychiatry. It covers a broad range of topics in psychiatric neuroscience and therapeutics. Both basic and clinical contributions are encouraged from all disciplines and research areas relevant to the pathophysiology and treatment of major neuropsychiatric disorders. Full-length and Brief Reports of novel results, Commentaries, Case Studies of unusual significance, and Correspondence and Comments judged to be of high impact to the field are published, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Concise Reviews and Editorials that focus on topics of current research and interest are also published rapidly.

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