The 850,000 number was the original number the DVA originally used for the number of Blue Water Navy Vietnam Veterans to inflate the cost of a restoration of presumption and benefits due to Agent Orange exposure. They used the 850,000 number with 100% still alive, 100% submitting claims, 100% approved at a 100% rating and a 1st year cost of about $28 Billion and a 10 year cost of about $203 Trillion. The number was later dropped to 512,000 which was still too high. Last session the two restoration acts used the number of 253,000 and while still too high is an acceptable number as long as the VA accounts for the number of Veterans who became presumed due to being on a Blue Water Vessel that traveled into brown water and the death rate. Using that number of 253,000 and using the standard percentages of claimants, approvals and ratings as well as the death rate and those who are deemed exposed due to brown water service, the 1st year cost, including any Nehmer claims is under $2.75 Billion with a 10 year cost of about $940 Billion.
Here are the numbers from the DoD
TOTAL ARMY AIR FORCE MARINES NAVY
NUMBER SERVING SOUTHEAST ASIA** 3,403,000 2,276,000 385,000 513,000 229,000
NUMBER SERVING SOUTH VIETNAM** 2,594,000 1,736,000 293,000 391,000 174,000