A Fish Story
BY TIM CONNOR
Thirty-nine years ago an accident occurred at the so-called "R" reactor at the Savannah River Site near Aiken. During a test in the reactor's water-filled fuel "disassembly" basin an experimental nuclear fuel rod failed, releasing its intensely radioactive contents.
The contaminated water was flushed to a second basin, which overflowed. As a result, highly radioactive water was diverted into one of the many streams near SRS that eventually drain into the Savannah River.
As accidents go, this was no Chernobyl. It was, however, the first of several large releases of a particularly nasty radioactive substance known as Cesium-137 into Savannah River tributaries. Before the releases were brought under control in the early 1970s, a reported 600 curies of Cs-137 were discharged into these streams.
Although significant releases of Cs-137 ended in 1972, the contamination resulting from earlier releases is considerable. A 1987 Department of Energy (DOE) environmental review found that one of the site streams, where it reaches the river, was so contaminated that by simply being present there year round a person would receive radiation exceeding DOE's guidelines for public exposures.
The fact that SRS' nuclear facilities released large amounts of Cs-137 and other radioactive materials during the bomb plant's Cold War heyday is by no means news. What is news is that on May 14 the state of South Carolina, backed by the U.S. Environmental Protection Agency (EPA), declared a fish consumption advisory for a stretch of the Savannah River from just above the site to the Webb Wildlife Center in Hampton County. The advisory was based on measured levels of Cs-137 and Strontium-90 (another radioactive substance largely attributable to SRS releases) in nine types of Savannah River fish.
Although the advisory issued by DHEC may have startled more than a few people who fish there, the reality is that fish in the Savannah River are actually less contaminated today than they were a quarter century ago. Therein lies a story that reveals as much about the spread of radioactive contamination from South Carolina's nuclear sacred cow as it does about the peculiar way government works when agencies with cross-purposes collide.
Cs-137 is created exclusively by splitting larger atoms in nuclear reactors or in nuclear explosions. In recent history it has been the main culprit in two nightmarish nuclear accidents. The first was in Chernobyl, where the nuclear inferno broadcast millions of curies of Cs-137 across Europe. The radioactive cesium in the fallout rendered livestock and foodstuffs from Scandinavia to Turkey unfit for human consumption for years following the 1986 accident.
The second was a bizarre episode in Goiania, Brazil, the following year in which scavengers removed a Cs-137-laden capsule from an abandoned cancer therapy machine. A scrapyard worker later opened the capsule. Fascinated by the glowing blue powder, he took it home and started giving it to friends as a novelty item. Before local physicians realized it, more than 240 people were seriously irradiated many severely and four were dying.
To be sure, the levels of Cs-137 near SRS are nowhere near those associated with Chernobyl or Goiania. Largemouth bass from the Savannah River do not glow blue, and the DHEC fish advisory says that you would have to have an extraordinary fondness for fish caught downstream of SRS to even slightly increase your chances of getting cancer.
Perhaps the most important public health message of the fish advisory is that it reminds us just how vulnerable the Savannah River is to radioactive and chemical releases at SRS. This is especially true for Cs-137. The reason radioactive cesium was in the capsule lifted from the cancer therapy machine in Goiania is that it is both fiercely radioactive and, with a half-life of 30 years, fairly long-lived relative to most other "fission" products created when heavy atoms like uranium and plutonium are split in reactors or bomb blasts.
It also turns out that water in the Savannah River and its tributaries are low in potassium content, which matters because cesium is chemically similar to potassium and tends to replace potassium in animal flesh. This phenomenon is especially important for predator fish like bass, which are at the top of the aquatic food chain. Bass in waters on and near SRS are so effective in absorbing Cs-137 that SRS scientists use measurements of Cs-137 in Savannah River bass to adjust their calculations of Cs-137 releases to the river.
Still, the timing of DHEC's fish advisory is baffling. Cesium discharges from SRS facilities are a mere fraction of what they were a quarter century ago and, overall, the measured levels of radiation in fish at and downstream from SRS have been gradually declining, not increasing. Moreover, the measurements of the relatively high radiation levels in Savannah River fish have been gathered and published for well over two decades.
So, what gives?
The official explanation from DHEC is that the fish data had, for the first time, been analyzed using "a more comprehensive data risk analysis." For one thing, in addition to Cs-137, DHEC and EPA addressed the elevated levels of strontium-90, another dangerous fission product chemically similar to calcium and thus concentrated in fish bones. Although doses from Cs-137 in fish flesh are greater than those from Sr-90 in fish bones, if the whole fish is used in a soup, for example, then the Sr-90 could be consumed along with the Cs-137 and add significantly to the dose.
But the real story is not the new analysis so much as who got to conduct it and interpret the results. Since SRS began operations in 1954, the safety of its releases has ultimately been determined by officials at the Atomic Energy Commission now DOE using standards that can generously be described as a compromise between public protection and what the emerging nuclear industry could afford to meet. Although these standards have gradually been tightened over the years, the essence of the compromise remains.
For more than a generation, SRS officials have told citizens of South Carolina and Georgia that the water, air, fish and anything else leaving the SRS boundary was certifiably safe defined by DOE standards.
The DHEC fish advisory is the most visible sign to date that state and EPA regulators have begun to hold the 42-year-old bomb plant to a different set of radiation protection standards. The main impetus for this change came in late 1989, when SRS was officially included on the priority list for the federal Superfund cleanup program. The designation required an agreement with EPA and DHEC laying out each agency's jurisdiction over both the rules and timeline for cleanup of chemical and radioactive wastes at SRS.
With the change in jurisdiction came the change in standards, particularly the human-risk-based standards that EPA promulgates under its Superfund jurisdiction. Whereas DOE radiation standards are based on allowable radiation doses, EPA looks at health risks. In this instance, the risk assessed was the increased lifetime cancer risk of people who rely heavily on Savannah River fish as a food source.
EPA and DHEC say that when the calculated lifetime cancer risks to individuals fall between a one-in-a-million to a one-in-10,000 chance of getting cancer as a direct result of exposure, the agency should consider advisories to alert those thought to be at risk.
The risk calculated by DHEC and EPA risk assessors for consumption of Savannah River fish was approximately one in 100,000. DHEC's Harry Mathis said, "It was a borderline call as to whether we advise the public or do nothing. We decided to err on the side of safety."
EPA's Camilla Bond Warren, who oversees SRS cleanup activities from the agency's regional office in Atlanta, characterized the action in broader terms. She said that by using EPA's health risk standards, they could account for an off-site risk that previously had not been acknowledged by DOE.
It is notable that even though there are important differences on the proper inputs to use in the EPA risk model, there appears to be agreement among EPA, DHEC and SRS technical staff on one key point. Using EPA's methodology, Tim Jannik of Westinghouse Savannah River Company said, "We cannot say that the [calculated] risk is wrong even within the differences of the input parameters."
More notable, however, is that SRS' view that the fish advisory overstates the current danger is shared by the two Georgia Department of Natural Resources (GDNR) officials who serve on the interagency team that examines radiation in Savannah River fish a team that exists largely because of long-standing concerns the Georgia agency has expressed about getting a better handle on the potential hazards of radiation in Savannah River fish.
Although GDNR officially supports the DHEC advisory, the agency's technical staff has misgivings about it. "By our methodology," said Jim Hardeman, manager of GDNR's environmental radiation program, "this just doesn't come up to the bar [for issuing an advisory]."
In addition to questioning the technical basis for the advisory, Hardeman poses an inescapable philosophical question. The conservative formula used by EPA and DHEC is geared toward the protection of "subsistence" fishermen whose catch of Savannah River fish is necessary for survival. Those relying on the fish are assumed to consume more than 100 pounds a year for 30 years. This consumption puts them into the one-in-100,000 lifetime cancer risk range.
The dilemma, Hardeman said, is whether to tell someone whose survival depends on eating these fish that they should consider changing their diet because of the extremely remote possibility they may contract cancer as a result of their eating habits. Surprisingly, none of the agencies has ever tried to determine if, or how many, subsistence fishermen actually live in the area covered by the fish advisory.
Moreover, it is by no means clear that eating Savannah River fish poses the greatest radiation hazard. For example, environmental monitoring results indicate that the cancer risks posed by eating deer in eastern South Carolina many of which have Cs-137 in their flesh from SRS and fallout from atmospheric nuclear weapons testing is potentially greater than that from eating Savannah River fish.
Another example is the risk from atmospheric and water-borne releases of radioactive tritium from SRS releases that SRS has long acknowledged to be responsible for the majority of the total population dose resulting from its operations.
In its press release announcing the fish advisory, DHEC stated that the safety of drinking water is not affected. Yet, as Mathis conceded, neither of the regulating agencies has actually performed the risk analysis to support that conclusion despite the fact that SRS tritium is readily measurable in downstream drinking water supplies and flows into the river from the same streams as the Cs-137.
Mathis said the fish advisory will be added to an existing health advisory about elevated mercury levels in Savannah River fish. The next step, he said, is to learn more about actual fish consumption patterns on the river and devise a plan for circulating the revised advisory to those most likely to be affected.
Tim Connor is associate director of the Energy Research Foundation.
The timing of DHEC's fish advisory last month is baffling. The measurements of the relatively high radiation levels in Savannah River fish have been gathered and published for well over two decades. So, what gives?