Gulf War and Health Volume 11: Generational Health Effects of Serving in the Gulf War (2018) / Chapter Skim
Currently Skimming:
2 Committee's Approach
2 Committee's Approach
Pages 25-40
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 25... ...
; and 1 The committee considered "reproductive effects" to include changes in reproductive function that may affect fertility and the ability to carry a healthy child through to a term birth. "Developmental effects" is used to represent any outcomes in offspring observed at birth and across the lifecourse.
|
From page 26... ...
The committee's approach to Task 2 was also driven by the literature as well as by the committee's expertise. Both the committee's framework for monitoring veteran and descendant populations for health effects and its guidance on conducting epidemiologic studies that might help link deployment exposures to health outcomes in descendants relied on literature describing studies that are gathering information on veterans' exposures (deployed and nondeployed)
|
From page 27... ...
Assessing Deployment Exposures Several important issues must be considered when evaluating the health impacts of stressors and toxicants in veteran populations. These issues include the route of exposure; the magnitude, duration, and frequency of the exposure; possible interactions between multiple single exposures; exposure to mixtures; and the time in the lifecourse at which the exposure occurs.
|
From page 28... ...
The number and combination of toxicants to which a veteran might be exposed make it difficult to determine whether any specific agent or combination of agents is likely to result in reproductive effects in the veterans or developmental effects in their descendants. Adding to the complexity of assessing multiple exposures is that although Gulf War veterans for the most part experienced single deployments to the Persian Gulf area during the war, many Post-9/11 veterans have been deployed more than once and to different areas of southwest Asia, for instance, Iraq and Afghanistan.
|
From page 29... ...
The 2011 IOM report Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan reviewed the air sampling done by the DoD and found numerous flaws in the sampling methodology that made it difficult to determine if military personnel stationed at bases with burn pits were likely to have an increased risk of health problems. The Volume 11 committee notes that burn pit emissions were only one poorly defined mixture to which service members might be exposed during their deployment.
|
From page 30... ...
. This is not to say that a female veteran's military occupational specialty or other duties after she returns from deployment will not expose her to toxicants, but it might be difficult to determine whether any adverse pregnancy outcomes in a veteran or developmental effects in her children could be attributed specifically to her deployment exposures.
|
From page 31... ...
Because few studies on reproductive or developmental effects were specific to veterans' exposures during deployment, the committee decided to approach its review of the health effects by identifying populations that had exposures to the same toxicants as Gulf War and Post-9/11 veterans. For the studies of occupational and environmental cohorts, it is difficult to ascertain how comparable the deployment exposures are to those of the study cohorts in terms of exposure magnitude, duration, frequency, mixtures, and co-exposures and also in terms of population characteristics such as gender, age, ethnicity, and lifestyle.
|
From page 32... ...
Epigenetic and genetic effects, including • Markers of DNA oxidative stress; • DNA methylation in maternal blood, umbilical cord blood, placenta, or peripheral blood lymphocytes, sperm; • mRNA expression; • Histone modifications; and • Mitochondrial DNA content in umbilical cord blood. and abstracts in that area and identified papers for full text retrieval; titles and abstracts of more than 4,000 publications were reviewed.
|
From page 33... ...
The information presented for each exposure included a review of the relevant prior Gulf War and Health volumes and their studies and conclusions, the populations used in any new studies, the methods for selecting and evaluating the populations, the study results, and the committee members' assessments of the strengths and limitations of the study. Because of the variability in the description of the reproductive and developmental effects considered in this report it was impossible for the committee to make a priori assumptions about the usefulness of any study.
|
From page 34... ...
Rather, the committee's review consisted of a thoughtful, nuanced, and qualitative consideration of all of the studies as well as expert judgment, and this could not be accomplished by adherence to a narrowly prescribed formula of what data would be required for each category of association or for a particular health outcome. In its evaluation of the evidence, the committee considered a set of overarching concerns -- specifically, statistical considerations, the availability of animal and mechanistic studies, the consistency of association, and biologic plausibility -- when assigning a category of association to a particular exposure and adverse reproductive or developmental effect.
|
From page 35... ...
Animal, Cellular, and Mechanistic Studies Animal, cellular, and mechanistic studies were included in the committee's considerations because they provide valuable information on reproductive and developmental effects that may not be evident in human populations or that cannot ethically be studied, such as spontaneous abortion. Furthermore, in animal studies the route, dose, timing of exposure, and mixture or co-exposure composition may be controlled.
|
From page 36... ...
Well-established experimental animal protocols exist that minimize the potential influence of coexposures, control for background responses, and more clearly characterize dose–response relationships.
|
From page 37... ...
Some mechanistic studies also provided evidence of epigenetic changes that may have effects on cellular processes that might affect reproduction or produce developmental effects. Consistency of Association To conclude that an association is consistent requires that the exposure–effect relationship be found regularly in a variety of studies -- for example, in more than one study population and with different study methods.
|
From page 38... ...
The evidence in experimental animal or cellular models was used to strengthen or weaken the associations between exposure and effect. Inadequate/Insufficient Evidence to Determine Whether an Association Exists The available studies are of insufficient quantity, quality, validity, consistency, or statistical power to permit a conclusion regarding the presence or absence of an association between an exposure and a reproductive or developmental effect in humans.
|
From page 39... ...
Experimental animal studies were examined to support such findings. REFERENCES Abdel-Rahman, A., S
|
From page 40... ...
2011. Long-term health consequences of exposure to burn pits in Iraq and Afghanistan.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.