Agent Orange: linked to birth defects?In 1969, a scientific study showed that Agent Orange -- the herbicide herbicide (hr`bəsīd'), chemical compound that kills plants or inhibits their normal growth. A herbicide in a particular formulation and application can be described as selective or nonselective. used by U.S. military forces in Vietnam -- causes birth defects birth defects, abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs in approximately 3% of all births. in animals. Since then, the saga of Agent Orange and birth defects has continued to unfold. A study published this month offers mostly good news for veterans exposed to Agent Orange. Joel E. Michalek of the Armstrong Laboratory at Brooks Air Force Base in San Antonio and his colleagues studied whether paternal exposure to Agent Orange increased the risk of adverse effects in children. The researchers examined 872 veterans who had participated in Operation Ranch Hand Operation Ranch Hand was a U.S. Military operation during part of the Vietnam War, lasting from 1962 until 1971. It involved spraying an estimated 19 million US gallons of defoliants over rural areas of South Vietnam in an attempt to deprive the Viet Cong of , which sprayed defoliants over about 3.6 million acres in Vietnam. During the study, the team measured concentrations of Agent Orange's dioxin dioxin Aromatic compound, any of a group of contaminants produced in making herbicides (e.g., Agent Orange), disinfectants, and other agents. Their basic chemical structure consists of two benzene rings connected by a pair of oxygen atoms; when substituents on the rings are contaminant contaminant /con·tam·i·nant/ (kon-tam´in-int) something that causes contamination. contaminant something that causes contamination. in each veteran's blood. The team also assessed Vietnam veterans who did not spray herbicides. In addition, the researchers collected a complete reproductive history reproductive history Obstetrics A set of 4 numbers that may be used to define a woman's obstetric Hx–eg, 4-3-2-1, would mean 4 term infants delivered, 3 preterm infants, 2 abortions, 1 child currently living from each man and his wife or partner. The scientists found no evidence of reduced fertility among Ranch Hand veterans, compared to the control group. Furthermore, a father's dioxin exposure during the Vietnam War Vietnam War, conflict in Southeast Asia, primarily fought in South Vietnam between government forces aided by the United States and guerrilla forces aided by North Vietnam. didn't seem to increase his partner's risk of suffering a miscarriage, the team reports in the January Epidemiology. Michalek and his coworkers detected no consistent pattern of birth defects in children born to Ranch Hand veterans. However, they did uncover an increased incidence of nervous system defects in these offspring, compared to the children of the control group. Yet that finding was based on just a few children, Michalek cautions. "The strength of this study is its use of medically verified pregnancy data and biological measurements of dioxin exposure," says Marja-Liisa Lindbohm of the Finnish Institute of Occupational Health in Helsinki. "Nevertheless, the book is not yet closed on the question of whether paternal dioxin exposure harms offspring," Lindbohm writes in an editorial that accompanies the study. |
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