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National Children's Study: Endocrine Disruption Research Needed
(Beyond Pesticides, October 29, 2003) In the October 2003 issue of Environmental Health Perspectives, the need for researching the health effects of endocrine disrupting (ED) chemicals on children is discussed in a series of three articles. The risk that EDs pose to children is an important issue that needs further scientific research, especially considering that children are at a unique risk to environmental contamination and pesticide exposure. They take in more pesticides relative to body weight than adults and have developing organ systems that are more vulnerable and less able to detoxify toxic chemicals.

EDs wreak havoc by interfering with the body's hormone signaling systems. Hormones are chemicals made by the body that help control the body's functions. They are present in minute quantities. EDs may be mistaken for hormones by the body, and disrupt the systems controlled by the hormones. They may alter feedback loops in the brain, pituitary, gonads, thyroid, and other components of the endocrine system. In particular, some EDs are mistaken for the female hormone estrogen. These estrogen mimics interfere with the reproductive system, causing infertility, malformed sexual organs, and cancer of sensitive organs. Disturbingly, there are many commonly used pesticides that are suspected endocrine disrupters, such as 2,4-D and permethrin.

Philip Landrigan, M.D., Anjali Garg, and Daniel B.J. Droller discuss the need for endocrine disrupting chemicals to be studied in the U.S. federal government's National Children's Study (NCS), which examines "the effects of environmental influences on the health and development of more than 100,000 children across the United States, following them from before birth until age 21." Landrigan et al, in the paper "Assessing the Effects of Endocrine Disruptors in the National Children's Study" hypothesize that "in utero and early childhood exposures to EDs may be responsible, at least in part, for decreases in semen quality; increasing incidence of congenital malformations of the reproductive organs, such as hypospadias; increasing incidence of testicular cancer; and acceleration of onset of puberty in females." They state the importance of the opportunity that the National Children's Study gives to test these hypotheses.

In the article "Exposure Assessment for Endocrine Disruptors: Some Considerations in the Design of Studies," researchers Carol Rice, Linda S. Birnbaum, James Cogliano, Kathryn Mahaffey, Larry Needham, Walter J. Rogan, and Frederick S. vom Saal examine the various factors that must be addressed in a study of childhood exposure to EDs in order to fully understand their effects. These factors include "multiple routes of exposure; the timing, frequency, and duration of exposure; need for qualitative and quantitative data; sample collection and storage protocols; and the selection and documentation of analytic methods."

Finally, in the article "An Approach to Assessment of Endocrine Disruption in the National Children's Study," researchers Matthew P. Longnecker, David C. Bellinger, David Crews, Brenda Eskenazi, Ellen K. Silbergeld, Tracey J. Woodruff, and Ezra S. Susser discuss why it is important for such human studies on EDs to take place, referring to previous similar studies as points of reference for an efficient design of the National Children's Study to look at EDs. They state, "if properly designed, the NCS could serve as an excellent resource for investigating future hypotheses regarding endocrine disruption."

A list of suspected endocrine disrupters from the National Institute of Health Sciences is available at http://www.nihs.go.jp/hse/endocrine-e/paradigm/pesticide/pest-list-e.html. For more information on pesticides and children, see Beyond Pesticides' Children and Schools Program Page.