Over the span of 35 years, between 500,000 and 1 million people were exposed to contaminated water at Camp Lejeune in North Carolina, one of the most storied Marine bases in the country. A group of men have banded together saying that their surprising breast cancer diagnoses are linked to Camp Lejeune's contaminated water. Dr. Nancy Snyderman reports.

Some of the wells that supplied drinking water to Camp Lejeune in North Carolina were contaminated by cancer-causing solvents for as long as 60 years, a new federal report shows.

Month-by-month calculations show that Marines and their families at the base drank and bathed in water that may have been tainted with trichloroethylene (TCE) from 1948 through 2008. Other water sources were contaminated with benzene from 1951 to 2008, the report shows.

Federal officials have known for years that the base’s water supply was badly contaminated, from fuel leaks and probably from a dry-cleaning plant as well.

The Centers for Disease Control and Prevention (CDC) has estimated that between 500,000 and 1 million people were exposed to the contaminated water from 1953 to 1987, when the last of several contaminated wells were closed. The new report takes the potential estimates back five years earlier.

"It is possible," Dr. Christopher Portier, director of the CDC's Agency for Toxic Substances and Disease Registry, told NBC News. But he says he believes it more likely the contamination began in 1953, as previously estimated.

"It is most likely that TCE first exceeded its current MCL (maximum contaminant level) during August 1953, but this exceedance could have been as early as November 1948 if releases of TCE to the subsurface began during or immediately following the onset of construction (1941/1942) of USMCB Camp Lejeune," the agency writes in a report to be published Friday.

The highest levels were not reached until decades later, however, depending on the chemical. The highest levels of TCE, for example, were reached in the late 1970s. To add to the complication, each housing and office area on the sprawling base was affected differently.

Marines have complained they and their children suffered cancer, including breast cancer and fatal leukemia, because of the contamination. NBC’s Rock Center reported on the cases in February.

The chemicals found in the water are linked not only with cancer, but with aplastic anemia, kidney disease, infertility, lupus, Parkinson’s disease and other conditions. The findings mean people who lived at the base during the affected times can seek compensation and medical care from the federal government.

"This release marks a major milestone towards the completion of scientific efforts pertaining to this issue and another step in ongoing efforts to provide comprehensive science-based answers to the health questions that have been raised," the Marine Corps said in a statement.

"ATSDR will use these results and the results of a similar water model developed for the Tarawa Terrace area in 2007 to estimate chemical exposures for several of their on-going health studies." The Marines has a website dedicated to the case here.

Portier says someone who lived or worked at the base for 20 years would be at higher risk than someone who was stationed there for only two years. But women who were pregnant while at the base and children have different risks.

The ATSDR came up with the projections after making measurements of known leakage rates and sources of the chemicals into wells that supplied the base’s Hadnot Point Water Treatment Plant. It opened in 1942.

“The ATSDR is conducting epidemiological studies to evaluate the potential for health effects from exposures to volatile organic compounds [tetrachloroethylene (PCE), trichloroethylene (TCE), trans-1,2-dichloroethylene (1,2-tDCE), vinyl chloride (VC), and benzene] in finished water at U.S. Marine Corps Base Camp Lejeune, North Carolina,” it said. Most of the chemicals are certain or probable cancer-causing agents.

Portier says it’s not an exact science, but extrapolations made by looking at known contamination levels, studying groundwater seepage rates and the rates that chemicals dissolve in water. “We try to go backwards from what we are seeing today to what happened in the past,” he said.

"Basically, it's vindication and confirmation for what I've been saying for nearly 16 years," retired Marine Staff Sgt. Jerry Ensminger told the Associated Press. Ensminger, who attended a briefing on the report on Thursday, believes the contamination cause the leukemia that killed his 9-year-old daughter Janey. "The truth is finally coming out."

Portier says investigators will use the data to help assess the health risks to people who lived at the base. Different water sources had differing levels of contamination over the years. One report, looking at cancer cases among 12,500 children born at the base, will come out soon, Portier said. Another looks at deaths among Marines who were stationed there and will also come out soon. A third report, looking at health overall, should be finished in two years, he says.

"For each of those people who identified themselves as having the diseases we are interested in, they have to go get their health records," Portier says. "For 70,000 people, that takes a very long time."

The United States Marine Corps started routinely testing tap water in 1980. Officials have said it took them four years to determine which wells were contaminated, and that once those wells were identified, they were shut down immediately

“The level [of contamination] in the drinking water was the highest that I've ever seen,” said Dr. Richard Clapp, an epidemiologist at the University of Massachusetts. “I've been working on this kind of thing for 30 years. I have never heard of a community that's had the levels of contaminants that they had at Camp Lejeune.”

He has examined the data from Camp Lejeune and says he believes the contamination and the cancers are related. “The cluster of disease-- for example, male breast cancer-- may also turn out to be the highest that's been seen anywhere,” Clapp told Rock Center in February.

The VA has a website for people who think they may have been affected.

Under a law signed Aug. 6, 2012 , veterans and family members who served on active duty or resided at Camp Lejeune for 30 days or more between Jan. 1, 1957 and Dec. 31, 1987 may be eligible for medical care through VA for 15 health conditions,” the site reads.

They include lung, breast and bladder cancer, leukemia, infertility, kidney damage and other conditions.

Related:

Marine Corps response to NBC Rock Center story

Contractor underreported levels of chemicals

Congress probes toxic water at Marine base