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RESEARCH HIGHLIGHTS
Pages 15-32

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From page 15... ... Other terms often used interchangeably with birth defects are "congenital anomalies" and "congenital malformations." Major birth defects are usually defined as those abnormalities that are present at birth and severe enough to interfere with viability or physical well-being. Major birth defects are seen in approximately 2 to 3 percent of live births (Kalter and Warkany, 1983~. Read the entire page →
From page 16... ... A major limitation of this study is its limited statistical power to detect an elevated odds ratio for specific defects. The authors noted that the study had 26 percent power to detect a doubling of risk due to exposure for a group of indicator malformations (anomalies thought to be easily recognized and reported by the mother, such as an oral cleft, spine bifida, and Down's syndrome) Read the entire page →
From page 17... ... Interpretation of the results of these environmental studies is difficult, because most of the studies were inconsistent, were based on ecologic correlations, had inadequate statistical power, did not validate birth defects recorded from vital statistics or self-reports, and included both male and female exposures. A recently published study from Vietnam evaluated the risk of birth defects among the offspring of mothers who resided in a village in the southern part of the country that had been sprayed during the conflict (Phuong et al., 1989~; 81 cases of birth defects (diagnosis not specified) Read the entire page →
From page 18... ... An analysis of Vietnam veterans' self-reported herbicide exposure found a dose-response gradient, with an adjusted odds ratio for birth defects of 1.7 (CI 1.2-2.4) at the highest level of exposure. Read the entire page →
From page 19... ... An analysis by race did indicate an elevated odds ratio (3.4, CI 1.5-7.6) for black Vietnam veterans. Read the entire page →
From page 20... ... No association was noted between Vietnam veteran status or self-reported Agent Orange exposure and risk of fathering a child with multiple birth defects (OR = 1.1, CI 0.7-1.7~. The odds ratios for Vietnam veteran status, self-reported Agent Orange exposure, and logistic regression coefficients for EOI based on self-report and military records for most of the 95 birth defect groups were not significantly elevated. Read the entire page →
From page 21... ... The analyses compared the risk of malformations among children of 107 Vietnam veterans to that for children of 1,432 men without known military service; the risk in 313 non-Vietnam veterans compared to the men without military service; and the risk in the Vietnam veterans compared with the non-Vietnam veterans. There was a slight, nonsignificant increase in the odds ratio for all congenital anomalies for Vietnam veterans compared to men without known military service (OR = 1.3, CI 0.9-1.9) Read the entire page →
From page 22... ... As part of the National Vietnam Veterans Birth Defects/Learning Disabilities Registry and database, a joint project of the Association of Birth Defect Children and the New Jersey Agent Orange Commission, a self-administered questionnaire was sent to Vietnam veterans to inquire about birth defects and a variety of conditions and disabilities in the children of Vietnam veterans and nonVietnam veterans (Lewis and Mekdeci, 1993~. A preliminary analysis indicated no differences in birth defects between the two groups; however, for a variety of conditions, including allergies, frequent infections, benign tumors, cysts, and chronic skin disorders, the veterans showed a higher frequency. Read the entire page →
From page 23... ... The Australian study of veterans living in Tasmania reported more congenital anomalies among the 357 Vietnam veterans than among the comparison families (Field and Kerr, 1988~. The authors suggested that the results indicated a pattern of association with congenital heart disease and anomalies of the central nervous system. Read the entire page →
From page 24... ... Although the etiology of most birth defects remains unknown, the study accounted for an array of factors controlled for in most previous studies of birth defects. Considering all birth defects combined, there was a slightly higher proportion of defects among Ranch Hand children than among comparison children (22.3 percent versus 20.8 percent) Read the entire page →
From page 25... ... These findings require a consideration of the current evidence for an association between herbicides and neural tube defects and an increased risk among Vietnam veterans exposed to herbicides. Table 2.1 includes a summary of the studies that have reported results specifically for neural tube defects (typically anencephaly and/or spine bifida) Read the entire page →
From page 26... ... However, the exposure opportunity index based on interview data was associated with an increased risk of spine bifida; for the highest estimated level of exposure (EOI-5) Read the entire page →
From page 27... ... Health Studies, 1983 Neural tube defects 16 0.9 AFHS, 1995 Follow-up of Air Force Ranch Hands Neural tube defects 4 among Ranch Handb 0 among comparison NOTE: N= number of exposed cases; OR/RR = Odds Ratio/Relative Risk; CI = Confidence Interval; SIR = Standardized Incidence Ratio. aNumber of Vietnam veterans fathering a child with a neural tube defect given any exposure opportunity index score. Read the entire page →
From page 28... ... , it therefore follows that there is limited/suggestive evidence for an increased risk in Vietnam veterans of spine bifida in offspring. PERIPHERAL NEUROPATHY Introduction This section taken from Chapter 10 of the full report summarizes published scientific literature on exposure to herbicides and acute and subacute transient peripheral neuropathy. Read the entire page →
From page 29... ... Review of the Scientific Literature on Acute and Subacute Transient Peripheral Neuropathy Occupational Studies A number of reports have suggested that acute or subacute peripheral neuropathies can be associated with occupational exposure to herbicides (Ashe and Suskind, 1950; Baader and Bauer, 1951; Goldstein et al., 1959; Todd, 1962; Berkley and Magee, 1963; Poland et al., 1971; Jirasek et al., 1974~. However, only a very limited number of studies on the PNS provide any control or comparison group data. Read the entire page →
From page 30... ... Vietnam Veterans Studies The committee has identified no data on acute or subacute neuropathies related to herbicide exposure in Vietnam. All published data concern chronic effects. Read the entire page →
From page 31... ... Increased Risk of Disease among Vietnam Veterans If TCDD is associated with the development of transient acute and subacute peripheral neuropathy, the disorder would become evident shortly after exposure; therefore, there is no evidence that new cases that develop long after service in Vietnam are associated with herbicide exposure that occurred there. Read the entire page →

From page 15...

... Other terms often used interchangeably with birth defects are "congenital anomalies" and "congenital malformations." Major birth defects are usually defined as those abnormalities that are present at birth and severe enough to interfere with viability or physical well-being. Major birth defects are seen in approximately 2 to 3 percent of live births (Kalter and Warkany, 1983~.

RESEARCH HIGHLIGHTS Pages 15-32

RESEARCH HIGHLIGHTS
Pages 15-32