RALEIGH, N.C. (AP) — Tens of thousands more Marines and their relatives could be eligible for government health care for their illnesses now that a federal agency determined that the water at North Carolina’s Camp Lejeune was contaminated four years earlier than previously thought.

In a letter to the Department of Veterans Affairs, the Agency for Toxic Substances and Disease Registry said computer modeling shows that drinking water in the residential Hadnot Point area was unsafe for human consumption as far back as 1953. President Barack Obama signed a law last year granting health care and screening to Marines and their dependents on the base between 1957 and 1987.