October 18, 2008

"Pesticides and Childhood Cancer"

"A pernicious, spreading evil (1)."

Children living on or near treated croplands can be exposed (to pesticides) through agricultural application drift, overspray, or off-gassing. Young children, who are likely to spend a large proportion of their time on the floor or ground and who frequently put hands and objects in their mouths, may be at particularly high risk of exposure . Addressing the conspicuous absence of information on chemical exposures and toxicity relating to children has become a priority at the EPA (2). Evidence that pesticide exposure may be associated with childhood cancer comes from case reports and several types of epidemiologic studies. Evidence from epidemiological studies suggests that environmental contaminants such as pesticides and certain chemicals, in addition to radiation, may contribute to an increased frequency of some childhood cancers. Some studies have found that children born to parents who work with or use such chemicals are more likely to have cancer in childhood (3). Malignancies linked to pesticides in studies include leukemia, neuroblastoma, Wilms' tumor, soft-tissue sarcoma, Ewing's sarcoma, non-Hodgkin's lymphoma, and cancers of the brain, colorectum, and testes. Many of the cancers associated with pesticides among children are the same cancers that are repeatedly associated with pesticide exposure among adults. There is a need to study and better quantify these exposures (4). Regulatory toxicology can no longer safely assume that "the dose makes the poison". Standard approaches used to develop estimates of safe exposure levels, by basing their design on a false assumption, are likely to have set safety standards that are not strong enough to protect public health (5). Although research is underway to characterize the risks of childhood cancer associated with pesticides and identify the specific pesticides responsible, it is prudent to reduce or, where possible, eliminate pesticide exposure to children, given their increased vulnerability and susceptibility. There is potential to prevent at least some childhood cancer by reducing or eliminating pesticide exposure (2,3,4).

American Heritage® Dictionary of the English Language: definition of "Cancer"
2. "Childhood Cancer: A Growing Problem", Environmental Health Perspectives Volume 106, Number1, January 1998
3. "Cancer Incidence and Mortality," U.S. Environmental Protection Agency.
4. "Pesticides and Childhood Cancer" by Shelia Hoar Zahm and Mary H. Ward. Environmental Health Perspectives Supplements Volume 106, Number S3, June 1998. Occupational Epidemiology Branch, Division of Cancer Etiology, National Cancer Institute, Rockville, Maryland, http://www.ehponline.org/members/1998/Suppl-3/893-908zahm/zahm-full.html
5. "Does 'the dose make the poison?" Extensive results challenge a core assumption in toxicology, by Pete Myers, Ph.D. and Wendy Hessler
Waimea Canyon Middle School and adjacent neighborhood shadowed by Field #809: Photo by Denis Fujimoto

1 comment:

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