Nestled in Orange County, among the Starbucks, strip malls and highways, there’s a tiny immigrant community with an enormous historical burden.

They come from the Marshall Islands, an archipelago in the South Pacific made up of 2,000 small tropical atolls. And they have the unfortunate distinction of having the lowest per capita income of any racial and ethnic group in the entire United States.

In Southern California, the Marshallese settled in Costa Mesa. Some of the adults work as baggage handlers at nearby airports. Others work at a medical device company, sewing pig valves onto heart stents. Although poor, they are knit together by their faith and their history.

Greta Briand is the pastor’s wife, a volunteer health educator and a respected elder among the Marshallese. The children call her “bubu" -- Marshallese for “grandmother."

Briand started training as a health educator 12 years ago. She wanted to help her community deal with alarming rates of cancer, heart disease and diabetes. Marshall Islanders have the second-highest rate of diabetes in the world, and they also suffer from thyroid cancer, breast cancer, and cancers of the blood, stomach and colon.

These illnesses, Briand says, can be traced back 70 years, to the immediate aftermath of  World War II, when the U.S. occupied the atolls of the Marshall Islands and used them as a nuclear proving ground.

Over the course of 12 years, the U.S. detonated 67 nuclear bombs there.

"I always call it nuke. They nuke us!" she says. "And we never had these kind of diseases before. And I do believe it was because we were exposed to radiation. It was too strong."

Briand’s own family has suffered. Her older and younger sisters are cancer survivors, of breast and thyroid, respectively. Both these cancers are on an official list from the Nuclear Claims Tribunal of 37 cancers and diseases linked to nuclear weapons testing.

Nuclear Refugees in California

Greta Briand, now almost 70, came to California when she was a teenager, to work and to go to college. She was among the first group who came to Costa Mesa, which became the first Marshallese community in the U.S. Over the years, thousands of Marshallese followed her to America, uprooted and displaced by the U.S. nuclear testing.

Today, there are more than 23,000 Marshallese living in the U.S., and about 2,000 in California. They were able to come because of an agreement made between the Marshall Islands and the U.S. -- the Compact of Free Association. The Compact allows Marshallese to work and live freely on U.S. soil for as long as they want, but does not convey citizenship.

Briand originally planned to return to the Marshall Islands after she got her degree. But one reason she stayed was the health issues in her community. She wanted to help.

"You go to everybody's home, every home has a person sick -- or two -- with diabetes, cancer, heart disease," she says.

But the effects of the radiation and fallout may extend even farther. According to researchers, it’s possible that the radiation from the nuclear weapons tests can cause genetic damage that can be inherited. The possibility haunts Greta.

“If I don’t have it, my grandkids ...,” she breaks off tearfully. “My grandkids -- or my great-grandkids -- might have cancer. And it just breaks my heart. But that's why we got to live each day, because you know we don't know what will happen tomorrow.”

One Voice for Many Needs

Jane Pang, an advocate at the Pacific Islander Health Partnership in Orange County, trained Briand to recognize and combat the barriers that prevent many Marshallese from getting treatment.

"They don't understand the medical challenges. They don't understand the symptoms,” Pang said of the Marshallese. “It’s difficult for them to understand, because they have very little education in terms of health. They personally will not know what to ask for, and that's why Greta was so valuable. She was such an excellent voice."

Greta holds health classes in women’s homes, or at the church, to teach women how to do breast self-exams. She also encourages them to go to the doctor regularly, because of the health risks posed by the nuclear tests.

"I was thinking about what happened to us, and I know if I don't say anything, nobody will."

Briand is the only Marshallese resident in Costa Mesa who is trying to help her peers navigate the U.S. health system. She’s up against a lot. Aside from severe poverty, there’s a language barrier. One in four Marshallese households don’t speak English.

Marshallese culture also stigmatizes illness. Briand says this applies to any sickness: “You don't tell anybody,” she says. “Whenever a person is sick, they always think that they did something wrong and God is punishing them."

A Childhood Among the Bombs

To understand the root of the Marshallese health problems today, it’s important to go back to the late 1940s, when the Cold War began. At that time, the nuclear arms race was heating up and the U.S. needed a place, far from the populated mainland, to test bigger and more destructive nuclear weapons. Some of the 67 nuclear weapons tested in the Marshall Islands were detonated underwater, and some were dropped from airplanes. Some of the islands were completely destroyed.

When Briand was 5, she witnessed the largest and most radioactive of these bombs from her home island of Likiep. It was called Castle Bravo and it had a nuclear force equivalent to 1,000 times the force of the bomb dropped on Hiroshima.

"It was like, the sky was beautiful with orange color," Briand says. “And we thought it was something beautiful. We didn't know it was poison!"

After the detonation, dangerous clouds of radioactive, pulverized coral dust drifted across her island, coating homes and people.

Briand isn’t alone. Castle Bravo remains the most remembered bomb test on the islands -- and everyone received documented levels of fallout from the blast.

Kon Kon Wasay, 82, was a teenager when she saw the bomb. She remembers that she was outside playing with six other girls and one boy. “All of a sudden, we hear this loud noise and it looked like something evaporating.”

Afterward, her friends all got sick. They have all passed away from thyroid cancers and other diseases.

'Something Good for Mankind'

The U.S. was able to conduct these nuclear tests because it had occupied the Marshall Islands since World War II. After defeating the Japanese, who had previously occupied the archipelago, the U.S. military moved in, permanently.

Before the tests began, military governor Commodore Ben H. Wyatt took a sea plane to Bikini Island to talk to the islanders. Footage from a Navy propaganda film shows Wyatt speaking to their leader, Chief Juda, through a translator named James.

“All right now, James, will you tell them that the United States government now wants to attempt to turn this great destructive force into something good for mankind, and that these experiments here at Bikini are the first step in that direction.”

The film then portrays the people leaving their islands willingly. But the Marshallese didn't have a choice. The U.S. moved them from island to island, using them as cheap laborers on the military bases.

“They never asked permission,” says Barbara Rose Johnston, an anthropologist in Santa Cruz who has studied the effects of the nuclear tests on Marshallese culture.

“They just dictated: We're taking over, we're doing our test here. And in the years since, they never did any full disclosure of the extent of what they were doing, how, and why," she says. "The culture of the time did not think of the Marshallese as equal people.”

Johnston has unearthed previously classified documents revealing an invasive medical program called Project 4.1 that the U.S. performed on some Marshallese to learn how radiation damages the human body.

Over the course of four decades and 72 research trips to the islands, U.S. medical teams examined the Marshallese using X-rays and photography, and took samples of blood, urine and tissue. Some Marshallese even received radioisotope injections and underwent experimental surgery.

Since that time, the U.S. government has formally recognized some of the harm caused by the bombings, and the U.S. government pays for health care and government assistance on the Marshall Islands. But those programs aren't available to the Marshallese who have migrated to California and other states, and many remain poor and isolated.

As the sole health educator in Costa Mesa, Greta Briand is the only one connecting the dots, explaining to her people how the nuclear history of the past created the medical problems of the present.

The 23,000 Marshallese who live in the United States have settled most heavily in Arkansas, California, Hawaii, Missouri, Washington and Oregon. In some of those states, the unique migration status of the Marshallese means they are ineligible for Medicaid. Sarah Craig has also reported on a  community in Enid, Oklahoma, where most of the Marshallese are uninsured. One Enid resident, Terry Mote, is fighting to improve health care for his people. The story won the Untold Story Award from Narrative.ly. You can see her photos and read the whole story here.