1,2,3,4,7,8 HXCDF. (vi) 1,2,3,6,7,8 HXCDD. (vii) 1,2,3,6,7,8 HXCDF. (viii) 1,2,3,7,8,9 HXCDD. (ix) 1,2,3,7,8,9 HXCDF. (x) 1,2,3,7,8 PECDD. (xi) 1,2,3,7,8 PECDF. (xii) 2,3,4,6,7,8 HXCDF. (xiii) 2,3,4,7,8 PECDF. (xiv) 2,3,7,8 TCDD. (xv) 2,3,7,8 TCDF. (xvi) octachlorodibenzodioxin. (xvii) octachlorodibenzofuran. (E) Such other toxins, chemicals, and airborne hazards as the Secretary, in collaboration with the Secretary of Defense, may add under paragraph (2). (2) The Secretary may add to or remove from the list under paragraph (1) as the Secretary determines appropriate in a report the Secretary shall submit to Congress not later than two years after the date of the enactment of the Veterans Burn Pits Exposure Recognition Act of 2019 , and not less frequently than once every two years thereafter. (d) Medical examinations and medical opinions (1) If a veteran described in subsection (a) submits to the Secretary a claim for compensation for a service-connected disability with evidence of a disability and service in a covered location and corresponding period set forth under subsection (b) and such evidence is not sufficient to establish a service connection for the disability, the Secretary shall provide the veteran with a medical examination and the Secretary shall request a medical opinion as to any causal link between the disability and a toxin, chemical, or hazard set listed in subsection (c). (2) When providing the Secretary with a medical opinion requested under paragraph (1), the provider shall consider the total potential exposure through all applicable military deployments, and the synergistic effect of all combined toxins through inhalation, dermal exposure, and ingestion. (e) Definition of burn pit In this section, the term burn pit means an area of land that is used for disposal of solid waste by burning in the outdoor air. . (b) Clerical amendment The table of sections at the beginning of chapter 11 of such title is amended by inserting after the item relating to section 1118 the following new item: