---
kind: "section"
citation: "38 U.S.C. § 1168"
title: "38"
title_heading: "Veterans’ Benefits"
number: "1168"
heading: "Medical nexus examinations for toxic exposure risk activities"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/38/1168"
units:
  - "Part II — General Benefits"
  - "Chapter 11 — Compensation for Service-Connected Disability or Death"
  - "Subchapter VI — General Compensation Provisions"
---

# §1168. Medical nexus examinations for toxic exposure risk activities

- (a) **Medical Examinations and Medical Opinions.—**
  - (1) Except as provided in [subsection (b)](#b), if a [veteran](/usc/38/1101.md?p=1) submits to the [Secretary](/usc/38/101.md?p=1) a claim for [compensation](/usc/38/101.md?p=13) for a [service-connected](/usc/38/101.md?p=16) [disability](/usc/38/1701.md?p=1) under [section 1110 of this title](/usc/38/1110.md) with evidence of a [disability](/usc/38/1701.md?p=1) and evidence of participation in a [toxic exposure](/usc/38/101.md?p=37) risk activity during [active military, naval, air, or space service](/usc/38/101.md?p=24), and such evidence is not sufficient to establish a service connection for the [disability](/usc/38/1701.md?p=1), the [Secretary](/usc/38/101.md?p=1) shall—
    - (A) provide the [veteran](/usc/38/1101.md?p=1) with a medical examination under [section 5103A(d) of this title](/usc/38/5103A.md?p=d); and
    - (B) obtain a medical opinion (to be requested by the [Secretary](/usc/38/101.md?p=1) in connection with the medical examination under [subparagraph (A)](#a-1-A)) as to whether it is at least as likely as not that there is a nexus between the [disability](/usc/38/1701.md?p=1) and the [toxic exposure](/usc/38/101.md?p=37) risk activity.
  - (2) When providing the [Secretary](/usc/38/101.md?p=1) with a medical opinion under [paragraph (1)(B)](#a-1-B) for a [veteran](/usc/38/1101.md?p=1), the health care provider shall consider—
    - (A) the total potential exposure through all applicable military deployments of the [veteran](/usc/38/1101.md?p=1); and
    - (B) the synergistic, combined effect of all [toxic exposure](/usc/38/101.md?p=37) risk activities of the [veteran](/usc/38/1101.md?p=1).
  - (3) The requirement under [paragraph (2)(B)](#a-2-B) shall not be construed as requiring a health care provider to consider the synergistic, combined effect of each of the substances, chemicals, and airborne hazards identified in the list under [section 1119(b)(2) of this title](/usc/38/1119.md?p=b-2).
- (b) **Exception.—** [Subsection (a)](#a) shall not apply if the [Secretary](/usc/38/101.md?p=1) determines there is no indication of an association between the [disability](/usc/38/1701.md?p=1) claimed by the [veteran](/usc/38/1101.md?p=1) and the [toxic exposure](/usc/38/101.md?p=37) risk activity for which the [veteran](/usc/38/1101.md?p=1) submitted evidence.
- (c) **Toxic Exposure Risk Activity Defined.—** In this section, the term “[toxic exposure](/usc/38/101.md?p=37) risk activity” has the meaning given that term in [section 1710(e)(4) of this title](/usc/38/1710.md?p=e-4).

## Source credit

(Added Pub. L. 117–168, title III, § 303, Aug. 10, 2022, 136 Stat. 1779.)