PANNA: Making the Link Between Chemicals and Learning Disabilities ~ Pesticide Action Network North America: http://www.panna.org/legacy/gpc/gpc_200308.13.2.09.dv.html
The Collaborative on Health and the Environment (CHE) a new and important U.S. network working on environmental health issues, recently launched a nationwide Learning and Developmental Disabilities Initiative to raise awareness about the role of neuro-toxicants in the sharp increase in learning and developmental disabilities (LDDs) in children in the U.S. An estimated 12 million U.S. children (17% of youth under 18) are now affected by deafness, blindness, epilepsy, speech deficits, cerebral palsy, delays in growth and development, emotional or behavioral problems, or learning disabilities.(1)
Learning disabilities alone affect 5-10% of children in public schools.(1) Attention deficit hyperactivity disorder (ADHD) conservatively affects 3-6% of all U.S. school children.(2) Within the state of California, the number of children entered into the autism registry increased by 210% between 1987 and 1998. A few studies have suggested that the increase in autism over the past 10-12 years may be as much as tenfold.(3)
Some argue these increases reflect improved diagnostic techniques for conditions which scientists are still attempting to understand. For example, Asperger's Syndrome, one of the conditions considered an "autism spectrum disorder," was added to the Diagnostic Statistical Manual as recently as the early 1990s. In addition, LDDs and autism often manifest as complex sets of behaviors and symptoms, adding to difficulty of their diagnoses and the clinical response.
Research has shown that exposures to certain neurotoxicants such as pesticides (particularly organophosphates and pyrethroids), lead, mercury, polychlorinated biphenyls (PCBs) and solvents can disrupt neurological development and can lead to learning disabilities. Even a relatively small exposure to a toxic chemical during a window of vulnerability can have a permanent impact, one that might not occur if the same exposure happened at another time.(4)
The vast majority of chemicals in use today have never been examined for their impacts on the developing brain. Given the vulnerability of the developing brain to chemical exposures, scientists have raised concerns that this lack of information may be affecting many children and preventing us from recognizing the true magnitude of the public health threat.(5)
For example, despite the fact that organophosphate and pyrethoid pesticides are common and 90% of U.S. children have detectable residues of at least one organophosphate pesticide in their bodies,(6) little is known about their effects on the developing brain. In the laboratory, a single low-level exposure to an organophosphate pesticide or a pyrethroid at day 10 of life causes permanent changes in the brain and hyperactivity of rodents.(7) The effects of combined multiple and cumulative exposures experienced by children in the course of their daily lives remains virtually unstudied.
Neuro-developmental toxicants that have been studied, including lead, mercury, polychlorinated biphenyls, alcohol, and nicotine, have demonstrated the vulnerability of the developing brain to environmental agents at exposure levels much lower than those having a similar affect on an adult. Scientific understanding of the effects of these toxicants has emerged slowly, and the regulatory response has lagged even further. Meanwhile generations of children have been exposed to these chemicals at levels that may have caused irreversible damage. Evidence of this is the U.S. Centers for Disease Control (CDC) recent consideration of lowering even further the screening threshold of lead, from 10 microgm/dl blood to 5 microgm/dl blood, since impacts have now been documented at these lower levels.(8)
Most support groups for learning and developmental disabilities focus on filling the need for diagnosis and services. The Learning and Developmental Disabilities Initiative (LDDI ) bring a coordinated focus on preventing exposure to neurotoxicants to the ongoing work of national learning and disabilities groups. Together with scientists and health groups, LDDI works to raise public awareness, inform lawmakers and support specific legislation to eliminate dangerous neurotoxicants from our environment.
The American Association of Mental Retardation, the Arc of the United States, the Autism Society, Developmental Delay Resources, the National Institute for Literacy, the Epilepsy Foundation, the Asperger Syndrome Coaltion, Pesticide Action Network North America (PANNA), and U.S. Public Interest Research Groups (PIRGs), along with almost forty other groups and individuals have already joined LDDI.
LDDI has also formed a small group to focus on Criminal Justice, and will examine the role of environmental contaminants-recognized as risk factors for learning and developmental disabilities-found in disproportionate number in those in the juvenile and criminal justice system. This subgroup has been joined by Communities Against Violence Network, the National Association of Women Judges, and others.
Individuals and groups can sign on to the LDDI Resolution on Environmental Contributors to LDDs and read a summary of the neurotoxicants highlighted in the recent biomonitoring reports released by the CDC and the Environmental Working Group, on the CHE website, http://www.cheforhealth.org.
For more information, please contact Elise Miller at the Institute for Children's Environmental Health, 1646 Dow Road, Freeland, WA 98249, email firstname.lastname@example.org, phone (360) 331 77904, fax (360) 331-7908, or Frieda Nixdorf at the Collaborative on Health and the Environment, CHE, c/o Commonweal, PO Box 316, Bolinas, CA 94924, website http://www.cheforhealth.org, email email@example.com.
Parrill M. 1996. Research implications for health and human services. In: Learning Disabilities, Lifelong Issues (Cramer S, Ellis W, eds). Baltimore, MD: Paul W. Brookes Publishing.
Goldman L, Genel M, Bezman R, Slanetz P. 1998. Diagnosis and treatment of attention deficit hyperactivity disorder in children and adolescents. J Am Med Assoc 279(14):1100-1107.
Schettler, T, J Stein, F Reich, and M Valenti. 2000. In Harm--s Way: Toxic threats to child development, Greater Boston Physicians for Social Responsibility.
CHE Partnership Call Notes, Autism, April 23, 2003, http://www.cheforhealth.org/update/Apr2303Notes.html.
Schettler, Ted, Developmental disabilities--impairment of children--s brain development and function: the role of environmental factors, on CHE science website http://www.protectingourhealth.org/newscience/learning/2003-02peerreviewlearningbehavior.htm, adapted from Schettler T. Toxic threats to neurologic development of children. Environ Health Perspectives, 2001 Dec; 109 Suppl 6:813-6.
Ahlbom J, Fredriksson A, Eriksson P. 1995. Exposure to an organophosphate (DFP) during a defined period in neonatal life indusces permanent changes in brain muscarinic receptors and behaviour in adult mice. Brain Res 677:13-19.
Lanphear BP, Dietrich K, Auinger P, Cox C. 2000. Cognitive deficits associated with blood lead concentrations <10 microg/dL in U.S. children and adolescents. Public Health Reports 115(6):521-9.
Herbicides Implicated in Birth Defects
A study published in July 2003 in Environmental Health Perspectives connects herbicides with a variety of birth defects and corroborates earlier findings that the chlorophenoxy herbicides widely used in grain farming are a significant health risk.
The July study found that babies born in high wheat-producing counties were twice as likely to have circulatory/respiratory and musculoskeletal birth defects than babies born to parents in farming counties where little wheat was produced. Even more significant, baby boys born in high-wheat counties and conceived during April or June -- when herbicide applications peak -- were nearly five times as likely to have birth defects than boys conceived during other times of the year in counties with low wheat production.
The epidemiologic study, performed by Dr. Dina Schreinemachers, a researcher with the Environmental Protection Agency in North Carolina, examined records of more than 43,000 births from 1995 to 1997 in 147 rural counties in Montana, North Dakota, South Dakota and Minnesota. Researchers compared rural counties in these states where most U.S. spring and durum wheat is produced, with farming areas in the same states that did not produce wheat. In the four wheat-producing states, more than 85% of the wheat acreage was treated with chlorophenoxy herbicides such as 2,4-D and 4-chloro-2-methylphenoxyacetic acid, or MCPA. Other crops in the area were treated with herbicides other than chlorophenoxy compounds.
In 1996, an earlier study also found birth defects higher in western Minnesota, where chlorophenoxy herbicides are applied to wheat. That study, however, also implicated certain fungicides as a possible cause. A number of studies have connected chlorophenoxy herbicides and cancer, including one done in 2002 by Dr. Schreinemachers that observed increasing cancer mortality from several types of cancers in areas with increased in wheat acreage. Just last year in 2002, a study by Dr. Warren Porter connected chlorophenoxy herbicides with reduced fertility and miscarriages in laboratory mice. In that widely publicized study, researchers spiked the drinking water of laboratory mice with a common household lawn and garden weed killer, and discovered a 20% increase in failed pregnancies in mice, at doses seven times lower than the maximum allowable rate for U.S. drinking water.
The National Cancer Institute, National Institute of Environmental Health and the U.S. Environmental Protection Agency have funded an ongoing study to track 90,000 herbicide applicators and their spouses to look for possible health effects of pesticides.
Sources: Dina M. Schreinemachers, Birth Malformations and Other Adverse Perinatal Outcomes in Four U.S. Wheat-Producing States, Environmental Health Perspectives Volume 111 Number 9, July, 2003 abstract on line: http://ehpnet1.niehs.nih.gov/docs/2003/5830/abstract.html; Garry, V.F., D. Schreinemachers, M.E. Harkins and J. Griffith, 1996, "Pesticide Appliers, Biocides, and Birth Defects in Rural Minnesota," Environmental Health Perspectives, 104: 394-399; Maria Fernanda Cavieres, James Jaeger and Warren Porter, "Development Toxicity of a Commercial Herbicide Mixture in Mice: I. Effects on Embryo Implantation and Litter Size," Environmental Health Perspectives, Volume 110, Number 11, page 1081, November 2002; Pesticides and Birth Defects: A Minnesota Study, Global Pesticide Campaigner, Volume 6, Number 2, June 1996, Low Doses of Common Weedkiller Damage Fertility, PANNA, October 11, 2002, http://www.panna.org/resources/panups/panup_20021011.dv.html.
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