Citation Nr: 20046813 Decision Date: 07/13/20 Archive Date: 07/13/20 DOCKET NO. 08-32 301 DATE: July 13, 2020 ORDER Service connection for hypertension as secondary to service-connected diabetes mellitus, type II (diabetes) is denied. REMANDED Entitlement to service connection for the cause of the Veteran’s death is remanded. Entitlement to service connection for hypertension as due to exposure to an herbicide agent is remanded. Entitlement to service connection for erectile dysfunction is remanded. Entitlement to dependency and indemnity compensation (DIC) under 38 U.S.C. § 1318 is remanded. FINDING OF FACT The Veteran’s hypertension was not caused or aggravated by his service-connected diabetes. CONCLUSION OF LAW The criteria for service connection for hypertension on a secondary basis have not been met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310. REASONS AND BASES FOR FINDING AND CONCLUSION The Veteran served on active duty from September 1963 to June 1969. The appellant is his surviving spouse, who has been substituted as the claimant with respect to the claims for hypertension and erectile dysfunction. See 38 C.F.R. § 3.1010. These matters come before the Board of Veterans’ Appeals (Board) on appeal from March 2007 and January 2018 rating decision of a Department of Veterans Affairs (VA) Regional Office (RO). The Board remanded the matters for further development in February 2020. The appellant testified at a hearing before the undersigned in June 2019; a transcript of the hearing is of record. The Board has bifurcated the claim for hypertension into two issues – service connection as secondary to diabetes, and service connection as due to herbicide exposure. The record is sufficiently developed to adjudicate the former issue, but not the latter issue. Moreover, further development of the herbicide theory will not affect the outcome of the secondary service connection issue. Therefore, bifurcation of the claim is appropriate. See Tyrues v. Shinseki, 23 Vet. App. 166, 176 (2009) (en banc), aff'd 631 F.3d 1380 (Fed. Cir. 2011). Service Connection for Hypertension on a Secondary Basis In this decision, the Board is only addressing the issue of whether the Veteran’s hypertension may be secondary to his service-connected diabetes, as explained above. The Board finds that service connection on a secondary basis is not established. Service connection may be granted on a secondary basis for a disability which is proximately due to, or the result of, a service-connected disease or injury. 38 C.F.R. § 3.310(a). Secondary service connection may also be granted for aggravation of a disease or injury by a service-connected disability. 38 C.F.R. § 3.310(b). Private treatment records show that the Veteran was first diagnosed with hypertensive vascular disease in October 1999, when his blood pressure was recorded as 158/94. See 38 C.F.R. § 4.104, Diagnostic Code 7101, Note (1) (providing, in pertinent part, that hypertension is established when diastolic blood pressure is predominately 90mm or higher; see also Duenas v. Principi, 18 Vet. App. 512, 519 (2004) (noting that the medical community has defined hypertension as high arterial blood pressure with a minimum threshold of 140mm for systolic blood pressure and 90mm for diastolic blood pressure). The Veteran was not diagnosed with diabetes until February 2002 based on the results of a blood glucose test, when he was seen as a new patient at a private facility. He was prescribed diabetic medication (Glucotrol) at this time. The February 2002 laboratory report reflects a blood glucose reading of 223, which is marked as “high,” with a normal reference range of 70-115. The sole fact that the Veteran’s diabetes was first diagnosed in 2002 does not rule out the possibility it was present before that time. However, the record does not establish that fact, and earlier records show blood glucose readings in the normal range. In this regard, a June 1998 VA treatment record shows a blood glucose reading of 99, and notes that the Veteran did not have a history of diabetes. A September 2000 VA laboratory report reflects a blood glucose reading of 113, with a normal reference range of 75-114. The April 2020 VA medical opinion, which is discussed below, confirms that these earlier readings were not diagnostic of diabetes. Thus, the preponderance of the evidence shows that the Veteran’s hypertension had its onset prior to the development of diabetes. In the April 2020 VA medical opinion, the examiner opined that the Veteran’s hypertension was less likely than not caused or aggravated by his diabetes. The examiner reviewed the Veteran’s medical records, including those discussed above, and found that the Veteran’s diabetes did not manifest until after the onset of his hypertension. Thus, based on this timeline, the examiner found that the Veteran’s hypertension could not have been caused by his diabetes, since his hypertension was present years before his diabetes. With respect to aggravation, the examiner stated that the Veteran’s hypertension was well-controlled so long as he took his antihypertensive medication, but that he also had a history of non-compliance with his medication regimen, as noted in July 2002 and February 2004 records, and that his blood pressure readings recorded after 2004 were not higher than those recorded prior to 2004. The examiner also noted that the Veteran’s renal function was normal until a few days before he died, when his liver failure caused hepatorenal syndrome. Thus, the examiner found that the Veteran’s diabetes less likely than not affected his renal function. In the opinion, the examiner observed that there appears to be a prescription for Ramipril, a medication for high blood pressure, back in 1996. This is because the header on the page with the prescription notes contains fax transmission data reflecting a date of January 1996. Why that is so is unclear, except that the Veteran was apparently re-using a page that had previously been sent as a fax. However, the prescription notes themselves bear a copyright notice of 2003, and the VA Form 21-4142 with which they were enclosed is dated in December 2003. Obviously, then, the prescription was not issued in 1996, but instead some time in 2003. Nevertheless, that error does not affect the probative value of the opinion, since the timeline still holds – the Veteran’s hypertension manifested in 1999, and his diabetes did not manifest until later, with an initial diagnosis in 2002. The April 2020 VA medical opinion is probative, as it is grounded in the Veteran’s medical history and supported by an explanation that enables the Board to make a fully informed decision. In essence, the examiner found that the Veteran’s diabetes could not have caused his hypertension, since the latter pre-existed the former, and did not aggravate his hypertension because his blood pressure was generally well-controlled except when he was noncompliant with taking antihypertensive medication, and that his blood pressure readings were not worse after 2004. The examiner also noted that the Veteran did not have impaired renal function due to his diabetes, which implies that if such were the case, that is, if his renal function was in fact impaired by diabetes, that would be a possible mechanism of aggravation of hypertension by diabetes. Thus, the absence of impairment of renal function by diabetes was another indication that the Veteran’s diabetes did not aggravate his hypertension, as suggested by the examiner’s opinion. There is no evidence in the record indicating that the Veteran’s diabetes may have aggravated his hypertension. Accordingly, the preponderance of the evidence shows that the Veteran’s diabetes did not cause or aggravate his hypertension. Consequently, the criteria for service connection on a secondary basis are not satisfied. 38 C.F.R. § 3.310. Because the preponderance of the evidence is against the claim, the benefit-of-the-doubt rule does not apply. See 38 U.S.C. § 5107; 38 C.F.R. § 3.102. REASONS FOR REMAND Service Connection for Cause of Death The Board finds that the April 2020 VA medical opinion cannot be relied on to make an informed decision regarding service connection for the cause of the Veteran’s death. The private hospitalization records dated in March 2010 indicate that the Veteran died of end-stage liver disease caused in part by his chronic hepatitis C. The Board therefore remanded this claim, in part, for a VA opinion addressing whether the Veteran’s hepatitis C may be related to his active service. See Hupp v. Nicholson, 21 Vet. App. 342, 352 (2007). Specifically, a September 2001 VA psychiatric treatment record reflects that the Veteran related a history of being exposed to blood during service when a soldier was shot in close proximity to him while in combat in Vietnam. He stated that the soldier’s blood squirted on to him. At this juncture, and for purposes of obtaining the opinion, the Board finds it credible that the Veteran had blood exposure in this manner. He served in a Beach Jumper Unit, had on-land service in Vietnam, and was authorized to wear the Fleet Marine Force Combat Insignia on the Vietnam Service Medal for duty with the 1st Battalion/3rd Marines in Operation Beaver Cage. His statement is plausible and not inconsistent with the circumstances of his combat service, even if not documented in the service treatment records. See 38 U.S.C. § 1154(b). In the April 2020 medical opinion, in concluding that the Veteran’s hepatitis C was less likely than not related to service, the examiner stated that there is no documentation in the service treatment records of the Veteran’s “story of blood exposure, which grew and became more elaborate over the years, and was not mentioned until decades after the alleged incident.” The examiner further stated that the Veteran’s records showed “many instance[s] of prevarication and medical non-compliance, including . . . non-disclosure of his HCV infection when [he underwent coronary bypass surgery in 2004].” The examiner also noted that the Veteran’s service personnel records showed disciplinary actions, and stated that “[t]hese facts do not support his probative value.” In the examiner’s review of the medical evidence, the examiner listed an instance of a nurse practitioner witnessing the Veteran drink from a large beer can in his car and then pull into traffic. The examiner’s opinion disregards the fact that the Board already found that the Veteran’s statement regarding in-service blood exposure sufficient to obtain a medical opinion on the matter. The Board does not find it implausible that his reported blood exposure would not have been documented in the service treatment records. The Veteran himself was not wounded. The examiner does not explain why such would ordinarily have been documented. The Board also does not find that the Veteran’s “story” became “more elaborate over the years.” He consistently described blood issuing on to him from the neck of a comrade who was shot and killed in close proximity. Further, the Board does not find the fact that the Veteran did not mention this experience (at least in the available records) until “decades” later has any bearing on its veracity. The Veteran may simply not have had a reason to report it earlier. Indeed, the nature of the experience is such that he generally may have not wished to mention it. When he did report it, it was in the context of seeking psychiatric treatment, where such a history becomes especially relevant. The record does not show psychiatric treatment prior to September 2001. Finally, and significantly, the examiner’s statements create a strong impression of lack of neutrality. For example, her observation that the Veteran did not disclose his hepatitis C status when he went in for surgery in 2004 has no relevancy to the issue of service connection, but instead is meant to impugn the Veteran’s character generally. The same is true with respect to the examiner’s listing in the review of medical evidence that someone observed the Veteran drinking and driving, or the examiner’s observation that disciplinary actions were instituted against the Veteran during service. These facts are irrelevant except insofar as they are meant to cast doubt on the Veteran’s reliability as a historian. The Board finds they do not. Instead, the Board is left with the strong impression that the examiner did not render a neutral opinion in this matter. Accordingly, a new opinion must be obtained that considers the Veteran’s in-service blood exposure as described above. In addition, VA treatment records dated in September 2001 reflect that the Veteran had a history of drug use, including cocaine. They state that he underwent drug rehabilitation in 1987 at Wichita. According to the April 2020 VA opinion, the Veteran’s history of drug use is a risk factor for hepatitis C. There are no VA treatment records in the file dated prior to 1998. It is not clear whether the Veteran’s treatment at Wichita was at a VA or non-VA facility. On remand, appropriate efforts must be made to obtain any VA treatment records dated prior to 1998 from the Wichita VA Medical Center (VAMC) and the Memphis VAMC.   Service Connection for Hypertension as Due to Herbicide Exposure For the reasons that follow, the Board finds that the April 2020 VA medical opinion is insufficient to render an informed decision on the issue of whether the Veteran’s hypertension may be related to his herbicide exposure, which is presumed based on his service in Vietnam. See 38 C.F.R. § 3.307. As instructed in the Board’s February 2020 remand, the opinion addresses the report by the National Academies of Sciences, Engineering, and Medicine (NASEM) (formerly NAS) titled Veterans and Orange: Update 11 (2018) (hereinafter Update 11). In that report, NASEM concluded that there is sufficient evidence of an association between hypertension and exposure to herbicide agents such as those used in Agent Orange. In the April 2020 opinion, the examiner notes that NASEM’s finding of sufficient evidence of an association between hypertension and Agent Orange exposure was based on a review of six studies, one of which NASEM considered a well-designed study with likely valid and scientifically reproducible conclusions. In that study, the authors found that having sprayed herbicides and having deployed to Vietnam were “both strongly associated with self-reported hypertension,” after adjusting for factors such as Vietnam service status, rank, age at the time of survey, tobacco use, alcohol use, race, and body mass index (BMI). The association was strongest when comparing veterans who had sprayed herbicides in Vietnam (“Vietnam-deployed sprayers”) and veterans who neither sprayed herbicides nor were deployed to Vietnam (“non-Vietnam-deployed non-sprayers”). In this regard, the “Odds Ratio (OR)” for developing hypertension in Vietnam-deployed sprayers was 2.21. Among Vietnam-deployed veterans, the authors found a significantly elevated association between the odds of hypertension for sprayers and non-sprayers remained after an adjustment was made for potential cofounders (OR = 1.77). For those veterans who did not deploy to Vietnam, self-reported hypertension was significantly elevated when sprayers were compared with non-sprayers (OR = 1.72). Reviewing the findings in the above study cited in the NASEM report, the examiner first noted that prior to the above findings, the authors had stated that “[t]o demonstrate a dose-response relationship”—meaning a relationship between degree of herbicide exposure and the development of hypertension—they showed that the mean serum TCDD levels (TCDD being one of the herbicide agents in Agent Orange) were significantly higher among Vietnam herbicide sprayers (mean = 3.5 ppt) than among Vietnam non-sprayers (mean = 2.5), but no differences in mean TCCD level were observed between non-Vietnam-deployed sprayers (2.4 ppt) and non-sprayers (2.2 ppt). The examiner stated that these findings mean that the effective levels of dioxins were the same in those deployed to Vietnam who did not spray herbicides as those not deployed to Vietnam, which “did not help [with determining] whether or not this toxin causes hypertension, or increases the risk.” The Board agrees that it is not clear why a higher level of TCDD exposure in Vietnam sprayers than in those deployed to Vietnam who did not spray herbicides, or the fact that there was no difference between those who sprayed herbicides outside Vietnam and those who neither sprayed herbicides nor served in Vietnam, would help demonstrate a positive relationship between TCDD exposure and the development of hypertension – i.e. a “dose-response relationship.” It would only seem to make a difference if those who had higher levels of TCDD exposure were more likely to develop hypertension. This is what the authors seem to suggest, but the Board is foggy as to how the above comparisons demonstrate that here. Indeed, as far as the Board can tell, apart from those who sprayed herbicides in Vietnam (3.5 ppt), all groups had about the same level of exposure, assuming the differences are not considered significant (2.5ppt for Vietnam-deployed veterans; 2.2ppt for non-Vietnam deployed veterans who did not otherwise spray herbicides; and 2.4ppt for those who sprayed herbicides but were not deployed to Vietnam). The Board is thus mystified as to how a higher level of TCDD exposure in those who sprayed herbicides in Vietnam compared with non-sprayers demonstrates a dose-response relationship if diagnoses of hypertension were elevated in both groups. Nevertheless, the study does conclude that having deployed to Vietnam and having sprayed herbicides were both strongly associated with hypertension. It also found that among veterans who did not deploy, hypertension was significantly elevated in sprayers compared to non-sprayers. The NASEM report found this study persuasive enough to conclude that there is sufficient evidence of an association between Agent Orange exposure (referred to in the report as “chemicals of interest” or COI) and hypertension. It states that the statistical analyses in the study are robust, used state-of-the-art methods, and adjusted for appropriate confounders. Update 11 at 497. The VA examiner also stated that an Odds Ratio (OR) greater than 2.0 means that there is a significantly increased risk of hypertension, and that all the OR’s listed for the categories studied are less than 2.0, even for the Vietnam-deployed sprayers, although it was higher than for the other three categories. The examiner stated that in order for hypertension to be “at least as likely as not” related to herbicide exposure, the OR must be greater than 2.0. The examiner stated that an OR of 1 shows an association, but not to the extent that there is an increased risk of developing the disease with exposure to the toxin. In other words, according to the examiner, it is not strong enough to show “etiology.” The examiner observed in this regard that the OR is a statistic that quantifies the strength of an association between two events, but noted that an association is not the same as an etiological relationship. The examiner stated that the NASEM report does not make this distinction in its interpretation of the study. Finally, with respect to how the findings in the study apply to the Veteran, the examiner stated that the Veteran was a non-sprayer who deployed to Vietnam from May 16, 1967 through May 20, 1967. The examiner stated that this four-day period in Vietnam significantly limited the dose-response relationship, thereby making the Veteran’s OR much lower than for those who spent multiple months in Vietnam, whether or not they sprayed herbicides. The examiner observed that even for those with a typical tour of one year in Vietnam, only the sprayers had a statistically significant mean serum TCDD level, and that the study stressed the importance of the amount of exposure or “dose.” The examiner further noted that the incidence of hypertension is so high in the general population that hypertension can be associated with many factors, and that the study had not accounted for the “significance of risk.” There are several issues with the examiner’s opinion. Most significantly, VA law does not differentiate between levels of herbicide exposure in veterans who served in the Republic of Vietnam during the Vietnam Era. See 38 C.F.R. §§ 3.307(a)(6), 3.309(e). Regardless of the length of time in Vietnam or the nature of the duties involved, a veteran who had such service is presumed to have been exposed to an herbicide agent and, at least implicitly, to have had sufficient exposure to result in potential adverse health outcomes that may be associated with such exposure. See id. The degree of exposure makes no difference whether the disease at issue is among those for which a presumption of service connection has been established based on such exposure, as set forth in 38 C.F.R. § 3.309(e), or is one that does not qualify for the presumption. Thus, the fact that the Veteran did not have a full tour of duty in Vietnam, or that he did not spray herbicides, makes no difference in terms of the degree of exposure; it is presumed sufficient to result in potential adverse health outcomes from such exposure for service connection purposes. The Board also notes that in the study itself, the authors’ conclusion does not state that the findings ultimately turn on degree of exposure, although that was a factor in terms of demonstrating the “dose-response relationship.” The fact that those with a known high level of exposure had an elevated incidence of hypertension supported the conclusion that there is a relationship between such exposure and hypertension, but the authors concluded that deployment to Vietnam or having sprayed herbicides were both strongly associated with hypertension. Further, with regard to the examiner’s statement that there must be an OR greater than 2 in order to establish an “at least as likely as not” relationship between hypertension and herbicide exposure, the study states that Vietnam veterans who sprayed herbicides there had an OR of 2.21. As just noted, VA law does not differentiate between degree of herbicide exposure among veterans who served in the Republic of Vietnam. It would thus appear that the OR of 2.21 would be applicable in this case. The examiner’s discussion does not account for the OR of 2.21. Moreover, the examiner states that an OR of 1 shows an association, but not to the extent that there is an increased risk of developing the disease with exposure to the toxin. However, the examiner does not address the fact that the OR for veterans who served in Vietnam but did not spray herbicides was 1.77, and the OR for veterans who sprayed herbicides but did not service in Vietnam was 1.72. These OR’s are higher than 1. The examiner also does not explain why there must be an OR of higher than 2.0 to rise to the level of a 50 percent probability (i.e. “at least as likely as not”) of an association between hypertension and herbicide exposure. With regard to the examiner’s observation that there is a difference between a statistical association and an etiological relationship, the Board realizes that the former does not necessarily equate to the latter. But statistical associations are one of the means by which, albeit indirectly, a cause-and-effect relationship can be established. That is why VA based its presumptions of service connection for certain diseases found in prior NAS studies to be associated with herbicide exposure. See Agent Orange Act of 1991, Public Law 102-4 (codified in part at 38 U.S.C. § 1116); 77 FR 47924 (August 10, 2012) (Determinations Concerning Illnesses Discussed in National Academy of Sciences Report: Veterans and Agent Orange: Update 2000); Euzebio v. Wilkie, 31 Vet. App. 394, 399 (2019); see also 38 C.F.R. § 3.309(e). Thus, the fact that only a statistical association may be shown rather than more direct evidence of a biological mechanism for the cause-and-effect relationship is not a basis in itself for concluding that there is insufficient evidence of such a relationship. Although not cited by the examiner, the NASEM report does find some “biologic plausibility” for a relationship between hypertension and dioxin exposure. See Update 11 at 495. The report states that dioxin’s impact on hypertension is being investigated in animal models and human cell cultures, and that studies have shown clear effects on gene expression, vascular function, and lipid glucose metabolism. Id. The report states that exposure of human endothelial cells to TCDD causes the down-regulation of genes involved in blood pressure regulation, suggesting a potential molecular mechanism for TCDD’s impact on hypertension. Id. It also found support for the hypothesis that TCDD activation of AHR increases the development of hypertension. Id. at 497. In short, there is some evidence of a “plausible” biological basis for a cause-and-effect relationship between herbicide exposure and hypertension, in addition to the statistical association. The examiner’s opinion does not account for these findings. Finally, the examiner’s statement that the incidence of hypertension is so high in the general population that hypertension can be associated with many factors, and that the study does not account for the “significance of risk” does not acknowledge the fact that the study did control for confounding factors such as age and BMI. If there were risk factors specific to the Veteran for developing hypertension that more likely caused it in his case, the examiner did not identify what these were. The Board appreciates the examiner’s detailed, exhaustive, and thoughtful review of the evidence in this and the other opinions she provided. These are complicated issues from both a medical and legal standpoint, and so it is not surprising that they require further consideration. On remand, a new VA medical opinion must be obtained that addresses the issues identified above. Service Connection for Erectile Dysfunction In the April 2020 VA medical opinion, the examiner opined that it was less likely than not that the Veteran’s service-connected diabetes caused his erectile dysfunction, as the evidence indicated that the latter was a long-term issue, while the diabetes was of more recent onset. The examiner further stated that there was insufficient information in the records, and that a VA genitourinary examination that went over the Veteran’s entire sexual history, surgical history, as well as a urological examination, would be necessary to provide an informed opinion in this matter. Presumably for the same reasons, the examiner found the record insufficient to render an opinion as to whether the Veteran’s diabetes aggravated his erectile dysfunction. The Board finds that a new medical opinion is warranted. The earliest diagnosis of diabetes in the medical records was in February 2002. The Veteran sought medication for erectile dysfunction in March 2004. The VA examiner noted that there is a diagnosis of “ED” in a problem list dated December 30, 2002, but that still post-dates the February 2002 diagnosis of diabetes. Thus, the examiner’s suggestion that the Veteran’s erectile dysfunction pre-existed his diabetes does not comport with the evidence of record. The Board realizes that genitourinary and urology examinations were not conducted during the Veteran’s lifetime, and the record does not otherwise reflect a review of the Veteran’s sexual history. Nevertheless, the Board finds that such evidence is not necessarily required, or that further explanation is needed as to why an opinion cannot be provided without such evidence. The Veteran’s history of diabetes and other medical conditions are well-documented. As just noted, the evidence indicates that his erectile dysfunction manifested after the diagnosis of diabetes. An April 2007 VA treatment record, in reference to the Veteran’s erectile dysfunction, notes that he had a testosterone level of 681. Based on the available evidence, the new opinion should consider the degree of severity of the Veteran’s diabetes and the fact that diabetes is a known potential cause of impotence, as well as any other factors in the Veteran’s medical history that may have caused his erectile dysfunction. If the examiner finds that the information is insufficient to render an opinion without resort to mere speculation, the examiner must provide a specific explanation as to what information, in particular, is missing that would enable a non-speculative opinion. (Continued on next page)   DIC Benefits Under 38 U.S.C. § 1318 The Board will defer a decision on the issue of entitlement to DIC benefits under 38 U.S.C. § 1318 at this time. The matters are REMANDED for the following action: 1. Request any VA treatment records dated prior to 1998 from the Memphis and Wichita VAMC’s. In particular, any records of drug rehab treatment in 1987 at the Wichita VAMC should be obtained, if such exist. 2. Obtain a new VA medical opinion as to whether it is at least as likely as not (50 percent probability or more) that the Veteran’s hepatitis C may have been linked to in-service blood exposure. The opinion should be provided by a medical professional who has not previously rendered an opinion in this matter. For purposes of rendering the opinion, the examiner must assume it is credible that the Veteran was exposed to blood during combat operations in 1967 when a nearby soldier was shot. The examiner should consider the potential for the Veteran to have contracted hepatitis C in this manner, and whether the initial diagnosis of hepatitis C in March 2002 would be consistent with that timeline. The examiner should also consider whether the Veteran had other risk factors for contracting hepatitis C, and the relative likelihood of contracting hepatitis C from those factors as opposed to the in-service blood exposure. 3. Obtain a new VA medical opinion as to whether it is at least as likely as not (50 percent probability or more) that the Veteran’s hypertension may have been linked to in-service herbicide exposure. The opinion should be provided by a medical professional who has not previously rendered an opinion in this matter. The examiner must review the April 2020 opinion and address the following issues. According to the study in the NASEM (formerly NAS) report (Veterans and Orange: Update 11 (2018)) discussed in that opinion, the authors found an Odds Ratio (OR) of 2.21 for developing hypertension in veterans who sprayed herbicides in Vietnam. According to the April 2020 opinion, an OR greater than 2 satisfied the “at least as likely as not” standard for a relationship between herbicide exposure and hypertension. While the Veteran did not spray herbicides in Vietnam, VA law makes no distinction in degree of exposure among veterans with service in the Republic of Vietnam during the Vietnam Era. In other words, for VA purposes, the exposure is deemed sufficient, and thus it cannot be found that a given health outcome is unrelated to herbicide exposure on the basis that a veteran who did not spray herbicides may have had less exposure. The examiner should consider the fact that the study concludes that having deployed to Vietnam and having sprayed herbicides were both strongly associated with hypertension, after adjusting for factors such as age at the time of survey, tobacco use, alcohol use, race, and BMI. NASEM determined that the study provided sufficient evidence of an association between herbicide exposure and hypertension, noting that the statistical analyses in the study are robust, used state-of-the-art methods, and adjusted for appropriate confounders. NASEM’s report also notes that studies lend support for a potential molecular mechanism for TCDD’s impact on hypertension. In other words, NASEM found some evidence supporting a plausible biological basis for a cause-and-effect relationship between herbicide exposure and hypertension. The examiner should also consider whether the Veteran’s medical history presented any other risk factors for developing hypertension, and discuss the relative likelihood that the Veteran’s hypertension resulted from such factor or factors (if found to present) as opposed to in-service herbicide exposure. 4. Obtain a new VA medical opinion as to whether it is at least as likely as not (50 percent probability or more) that the Veteran’s erectile dysfunction may have been secondary to his service-connected diabetes. The opinion should be provided by a medical professional who has not previously rendered an opinion in this matter. In rendering the opinion, the examiner should consider the fact that the Veteran’s diabetes was first diagnosed in February 2002. He sought treatment for erectile dysfunction in March 2004. Based on the available evidence, the examiner should consider the degree of severity of the Veteran’s diabetes, which is a known potential cause of impotence, as well as any other factors in the Veteran’s medical history that may have caused his erectile dysfunction. If the examiner finds that the information is insufficient to render an opinion without resort to mere speculation, the examiner must provide a specific explanation as to what information, in particular, is missing that would enable a non-speculative opinion. P.M. DILORENZO Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board J. Rutkin, Counsel The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.