"I hated the task because the [Agent Orange] barrel had to be tilted, a black rubber bucket filled and carried over to the main bladder -- one bucket per every 300 gallons.
"The spillage on to my boots and clothing was a constant aggravation," he says.
Santiago claims he was also exposed to the notorious herbicide when carrying out maintenance on the generator fuel filter when breakdowns occurred.
That was almost 45 years ago and Santiago is now 62, long retired from the military and living in Florida -- yet the spectre of Agent Orange still looms large over his life.
I am a wounded veteran and deserve the respect and same treatment provided to those veterans whose life-changing wounds merited compensation.
Santiago suffers from multiple myeloma, a type of cancer of the plasma cells, which he believes was primarily caused by his exposure to Agent Orange in Okinawa.
The link between Agent Orange and multiple myeloma is well established, so much so that even the US Department of Veteran Affairs (VA) states on its website: "Veterans who develop multiple myeloma and were exposed to Agent Orange and other herbicides during military service do not have to prove a connection between their disease and service to be eligible to receive VA health care and disability compensation."
Yet despite this official acknowledgement, Santiago, and many other veterans like him, have not received compensation from the US Government, even though the VA physician who discovered his cancer documented Agent Orange as the cause, a conclusion affirmed again at a later date by another independent doctor.
Santiago does receive government compensation for Post Traumatic Stress Disorder (PTSD) triggered by witnessing the death of two fellow marines, and also for a traumatic brain injury he suffered while on duty when a crane rolled over a ravine, but not for his cancer and other Agent Orange related ailments.
Santiago believes the Government's refusal to acknowledge the Agent Orange link is because he was based in Okinawa, rather than Vietnam, or one of the other areas where the military has formally admitted the herbicide was used.
He thinks the Pentagon's ongoing "denial of the existence of the substance on the island" is in part because it wants to avoid upsetting Okinawans by admitting activities occurred on the island that were not officially talked about or sanctioned.
He says he has suffered terribly from his Agent Orange-related illnesses and is seeking compensation, not just to pay his medical bills, but also to gain the recognition he feels he deserves.
"The impact of this terrible disease on me is a living horror -- knowing death can overtake me anytime.
"I am a wounded veteran and deserve the respect and same treatment provided to those veterans whose life-changing wounds merited compensation," he says.
Veteran Don Schneider also served on Okinawa during the Vietnam War and he, too, believes exposure to Agent Orange on the island has made him sick.
Schneider, who is now 70, worked from 1968 to 1969 as a veterinary technician preparing sentry dogs for duty in Vietnam and treating them on their return from the battle zone.
He says he came into direct contact with Agent Orange as vet technicians were the first people to handle the dogs when they returned from Vietnam.
According to Schneider, the clinic compound at Camp Mercy and the dog schools at Yomitan and Machinato were "often sprayed with Agent Orange to keep down the mosquito, tick and flea populations and kill off the tall elephant grass that was the favourite hiding place for [venomous] Habu snakes". He says that although the vet technicians and dog handlers didn't do any spraying themselves, they were exposed through working in the area and handling the dogs.
"Humans could walk through an area that had been sprayed with Agent Orange and be exposed by later handling clothing that had come in contact with the herbicide, but a dog had to walk through it daily on all four, unprotected paws, had to eat close to it, and had to sit and sleep on areas that had been sprayed with Agent Orange.
"Now picture the vet tech and handlers having to hold, pick up, and wrestle with their animals and you can get a better understanding of the degree of exposure each dog, dog handler, and vet tech dealt with," he says.
Schneider also says a mysterious blood disease was detected among some of the dogs that returned from Vietnam and he believes it was likely due to Agent Orange exposure.
"This handful of dogs were emaciated and had bad diarrhoea and a strange, funky smell to their fur and head -- a barnyard faeces smell mixed with oily burned plastic.
"They also had dried blood around their noses.
"In three days their Nasal bleeding spread to their gums and their mucous membranes were really strange-looking and they were all sent one at a time to the autopsy room," he says.
Schneider says the army sent experts to Okinawa to study the mysterious condition, which came to be called Idiopathic Hemorrhagic Syndrome (HIS), or bleeding disease of unknown origin, but, after six weeks of poring over blood and tissue samples and slides, they could find no known pathogen.
Similarly to Santiago, Schneider also suffers from a raft of serious medical conditions, including an enlarged spleen and liver, thrombocytopenia, type-2 diabetes and high blood pressure. He has also had to have a kidney removed because of the discovery of a large renal cell carcinoma on the organ.
Schneider has filed three claims for compensation for his exposure to Agent Orange in Okinawa, but to date all have been rejected.
Yet Schneider and Santiago are not alone and today there are more than 250 US veterans -- many of them sick -- who claim Agent Orange was stored on Okinawa.
Yet despite this, the US Government continues to claim the chemical was never on the island.
US Forces Japan said in a written statement that a team of researchers spent nine months conducting an in-depth records search at 16 locations in the US, and that no source documents were found that validate the claims that "Herbicide Orange was shipped to or through, unloaded, stored, used or buried on Okinawa".
"[The] Department of Defence's research has determined that the veterans who made claims about Herbicide Orange remembered actual events that happened including: a ship stranded on a reef; spraying pesticides in jungle operations; ships making port calls.
"However, the source documents showed that while these events took place, either the material involved was not Herbicide Orange or the location was not Okinawa," the statement says.
British investigative journalist and Agent Orange researcher Jon Mitchell says US military research into Agent Orange in Okinawa is limited to a report conducted by a former USAF colonel, Alvin Young, who has previously received research funding from the manufacturers of Agent Orange.
"During his nine months, he never visited Okinawa to take environmental tests. Nor did he talk to any veteran making these allegations," he says.
Mitchell adds that the US military's conclusions also directly contradict documentary evidence from their own records.
"There are US military reports which cite a herbicide stockpile at Kadena Air Base and the presence of 25,000 barrels of Agent Orange on Okinawa.
"Also there are photographs of these barrels on the island.
"For me, the smoking gun is the barrels -- some stamped Dow Chemical -- found in Okinawa City which contained traces of dioxins and herbicides," he says.
Between June last year and January this year, 83 buried barrels believed to have contained Agent Orange were found under a soccer field in Okinawa City on land that was formerly part of the Kadena Air Base, but was returned to Okinawa in 1987.
Samples from inside the barrels indicated the presence of dioxin -- one of the most toxic poisons known to man and the most infamous ingredient in Agent Orange. The field where the barrels were found was located next to, and used by, a number of schools in the area.
Mitchell says the US Government's refusal to acknowledge the presence of Agent Orange in Okinawa is likely to be more about politics than money.
"The American presence in Okinawa is so unpopular and it will be even more unpopular if the American Government admits to having used Agent Orange on the island.
"I think it is primarily a political issue, not a financial issue.
"America is the richest country in the world -- they can afford to pay off some veterans. The Pentagon is very worried about the PR fallout because it is Okinawa -- because they want to build a new base," he says.
