From 1946 to 1970, federal records show, 55-gallon drums and other containers of nuclear waste were pitched into the Atlantic and Pacific at dozens of sites off California, Massachusetts and a handful of other states. Much of the trash came from government-related work, ranging from mildly contaminated lab coats to waste from the country’s effort to build nuclear weapons.

Federal officials have long maintained that, despite some leakage from containers, there isn’t evidence of damage to the wider ocean environment or threats to public health through contamination of seafood. But a Wall Street Journal review of decades of federal and other records found unanswered questions about a dumping program once labeled “seriously substandard” by a senior Environmental Protection Agency official:

• How many dump sites are there? Over the years, federal estimates have ranged from 29 to more than 60.

• How much of various types of radioisotopes are in the waste containers? While some isotopes are short-lived, others remain radioactive for hundreds or thousands of years.

• Has evidence of radioactive contamination in fish been adequately pursued? A 1983 California law calling for fish testing and annual reports on a major dump site off San Francisco produced just one state report, in 1991, even though that study found fish contamination and recommended follow-up research.

• Where are all the containers—whose numbers top 110,000, by one federal count—on the sea floor, even at known dump sites? For instance, an estimated 47,000 containers lie at the site near San Francisco. Though there were three designated dump areas for the containers, “many were not dropped on target,” according to a 2010 report from the National Oceanic and Atmospheric Administration, which called the waste site a “potentially significant resource threat.”

Much of the site—about 50 miles west of San Francisco, near the Farallon Islands—is within a national marine sanctuary that the federal government describes as “a globally significant” ecosystem “that supports abundant wildlife and valuable fisheries.” Only about 15% of an estimated 540 square miles of sea floor containing the barrels, at depths from 300 to over 6,000 feet, has been evaluated, the NOAA report said………http://online.wsj.com/news/articles/SB10001424052702304773104579268563658319196