Unlike some states, South Carolina has no plan to issue statewide advisories against eating freshwater fish most likely to experience mercury pollution.
South Carolina already warns people against eating more than moderate amounts of certain fish in more than 60 lakes and rivers, such as the Congaree and Saluda. Tests have shown some fish in those waterways contain elevated amounts of mercury. The agency also urges pregnant women to limit fish consumption on waterways without advisories.
But the S.C. Department of Health and Environmental Control is reluctant to extend the advisories statewide without more data to verify a problem on many lakes and rivers, agency officials say.
It's now safe to eat "as much fish as you would like" from at least 34 waterways, including Lake Murray and the Catawba River, according to a DHEC fish advisory sheet.
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"The science doesn't support a blanket advisory," agency spokesman Thom Berry said. "If we were to go out with a blanket advisory, knowing that there are some bodies of water where no advisory is necessary, we would be opening ourselves up to criticism."
Berry's comments are in response to recent questions by a retired fisheries biologist who said South Carolina should consider blanket warnings on big largemouth bass.
Bass are among the fish of most concern in fresh water because they are large predators. These fish generally build up larger amounts of mercury in their tissue than smaller fish that don't live as long.
Scientists have enough data to conclude that mercury is a problem in the biggest and oldest largemouth bass in most any waterway, retired Department of Natural Resources biologist Charlie Moore told The State newspaper last month.
Dozens of other states have some form of statewide advisories on various species, including North Carolina, according to the U.S. Environmental Protection Agency. The EPA does not list South Carolina as having statewide advisories.
Mercury is a threat to people who regularly eat fish tainted by the metal because it can cause brain damage and kidney system disorders. High levels in the bloodstreams of unborn babies and young children may harm developing nervous systems, making it harder for exposed children to learn.
A statewide mercury advisory for bass or other species would affect some of the most popular lakes in South Carolina - including Lake Murray and Lake Wateree near Columbia. Both are recreation and fishing hot spots, and Lake Murray has been the venue for major national bass tournaments.
DHEC says tests at Lake Murray don't show mercury levels are consistently high enough in bass to warrant health advisories. But agency records show mercury has tainted some of the biggest and oldest predator fish.
About 40 percent of the bass tested this decade at the lake showed elevated amounts of mercury, according to DHEC data analyzed by The State. The newspaper examined the state data in response to recently released federal data showing elevated mercury levels in largemouth bass at Lake Murray. The U.S. Environmental Protection Agency's report found elevated mercury levels in fish at 49 percent of the lakes tested, including those at Lake Murray in 2000.
DHEC's decision not to issue statewide mercury advisories on such fish as largemouth bass is a departure from what some states are doing. The EPA says 38 states have some form of statewide advisory on fish consumption, although federal officials acknowledge those vary in what they say. Most of the states that have statewide advisories listed in the EPA's 2008 fish advisory report are in the Northeast, Midwest, and Pacific Northwest.
In Washington state and North Carolina, officials say they have enough data to justify a statewide advisory on largemouth bass.
North Carolina tells people not to eat more than one meal per week of largemouth bass from any lake or river in the state. For children and pregnant women, the state says not to eat any largemouth bass, according to a fact sheet from the North Carolina Division of Public Health. The statewide mercury advisory has been in effect several years, a top official said.
"Rather than testing every lake, enough (tests) were positive that we felt an advisory was in order for the state," said Douglas Campbell, branch chief of North Carolina's occupational and environmental epidemiology division.
Washington officials were seeing elevated mercury levels in largemouth bass earlier this decade. After launching a special study to verify high mercury levels in 20 waterways, the state in 2003 issued a blanket advisory on bass for every river and lake.
"We had to look at resources," said Dave McBride, Washington's lead toxicologist for fish advisories. "How many more water bodies do you need to (test) to put out a statewide advisory."
DHEC issues mercury advisories when tests show the mercury levels in fish exceed the state standard over a three-year period. Elevated levels in a single year don't prompt advisories. Agency officials say it is important to verify a problem before issuing an advisory.
The agency, however, does give general advice to pregnant women and young children to limit consumption.
Such at-risk groups should not eat more than one meal a week of freshwater fish from any waterway that does not have an advisory, the agency says. The advice also tells pregnant women and children not to eat any swordfish, king mackerel, shark or tilefish from saltwater. These species typically contain high mercury levels.