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Mercury Rising

July 16, 2001

Heather Heilman
hheilman@tulane.edu
Michael DeMocker

Bluegill, sunfish, white crappie, largemouth bass, red-ear sunfish, redfish, speckled trout, flounder, white trout, red snapper, crab, shrimp, oysters and crawfish. Those are the kinds of seafood April and Damien Foret eat, although April can't identify all of those fish by name. "Whatever he catches, I eat," she says. "He brings it home and he cleans it. I don't know what kind of fish it is."

The Forets are a young couple from around Bayou LaFourche. They're sitting in the public health clinic in Cut Off, La., answering questions about what kinds of fish they eat and where it comes from. Damien wears a camouflage T-shirt with a picture of a deer on the front. He works on an oil rig, but lives to fish and hunt. The couple eats seafood at least twice a week, and except for an occasional can of tuna, Damien and his friends catch all of it in the waters of south Louisiana.

That's why they're here in Cut Off, getting ready to give a blood sample. They're concerned about the harmful effects of mercury, and they know that eating fish is the most significant source of exposure to the heavy metal for most people. The Forets have volunteered to participate in the Mercury Project, a study directed by William Hartley, associate professor and co-director of the Environmental Diseases Prevention Research Center at Tulane's School of Public Health and Tropical Medicine.

The Mercury Project is being conducted under the auspices of the Environmental Diseases Prevention Research Center, which is affiliated with the Centers for Disease Control. Funding for the project comes from the Louisiana Department of Health and Hospitals and the Louisiana Department of Environmental Quality.

The study is in part the result of lobbying by organizations and individuals in the community who became concerned about the levels of mercury that were appearing in Louisiana fish and convinced the state legislature to appropriate some money to look into the issue. 

Something Fishy

While Hartley directs the project, Angela Machen and Tonya Shropshire are the ones who load up the car and travel around southeast Louisiana to talk to study participants and take their blood samples. Machen is a doctoral student at the School of Public Health, and Shropshire is a registered nurse who received her master's degree in public health last fall. Their goal is to find 150 families from a five-parish area around New Orleans who eat locally caught fish at least once a week, in order to test the level of mercury in their blood.

"Fish are great food, but they accumulate all kinds of chemicals," Hartley says.

One of those chemicals is mercury, which gets into the environment mostly through the burning of fossil fuels. Medical- and hazardous-waste incinerators can also be a significant source of mercury contamination. Chlorine plants release some mercury into the air, and strip mines expose mercury buried in the earth. Mercury in the air is washed out when it rains and gets into the water and soil. Mercury exposed by strip mining will run off into the water.

Some industries, like paper mills, release relatively low amounts of mercury directly into the water. Across the country, about 2,000 mercury advisories have been issued on particular lakes and rivers in more than 40 different states. The problem in Louisiana does not seem to be as severe as in some other states, particularly in the Great Lakes region.

Nevertheless, Louisiana has a lot of fishermen and a lot of water--and it's just the kind of acidic, highly organic water that contributes to the rapid conversion of inorganic mercury into organic methyl mercury, which accumulates in fish. "Methyl mercury is the most dangerous kind of mercury because it crosses into the brain and nervous system," Hartley explains. The state of Louisiana has been testing levels of mercury in fish for a decade.

At this writing, the state has 20 mercury advisories on Louisiana lakes and rivers and the Gulf of Mexico. In most cases, the advisories only apply to particular species of fish, and only to the consumption of the fish by children under 7 and women who are pregnant, breastfeeding, or planning on becoming pregnant. The main concern with mercury is that it may damage the developing nervous systems of babies and small children, although it is toxic to the kidneys of both adults and children.

In adults, low to moderate mercury exposure will usually have no permanent adverse effects and any symptoms will disappear once exposure is stopped. It's a problem that is receiving a growing amount of national attention. The Food and Drug Administration recently issued a warning that pregnant women, or women who plan on becoming pregnant, should not eat shark, swordfish or king mackerel at all because of mercury accumulation in those fish.

The National Academy of Sciences estimates that as many as 60,000 mothers and children might be affected by mercury contamination, which could have a significant impact on the numbers of children who struggle in school.

Hartley endorses the mercury advisories that are issued by the state. The first one was issued a decade ago on the Ouachita River in north Louisiana. Both pregnant and nursing women, as well as children under 7, are advised to forgo eating bass from the river and to eat other fish from the river no more than twice a month.

Others are advised to limit bass consumption to no more than two meals per month. Hartley says the people who live around the Ouachita are very much aware of the advisory. When an advisory is issued, the Office of Public Health works to make sure the information gets out in the local media. Town meetings are sometimes conducted, and information about advisories is supposed to be distributed with fishing licenses. Even so, the information doesn't always get to the people who need it.

Researchers on the Mercury Project have found that many people they've talked to are not aware of the advisories in their area. Damien Foret, for example, said that nothing was mentioned or handed out when he got his fishing license at his local Wal-Mart. In southeast Louisiana, there are advisories on the Pearl River, the Bogue Chitto, Bayou Liberty, the Blind River, and the Gulf of Mexico.

"One of the important parts of this study is to find out how good communication is on the issue," Hartley says. "We need to know if there are things that need to be done to modify how we communicate this information."

Public awareness is crucial when it comes to mercury, because once it's in the environment there's no way to get rid of it. So it's up to individuals to be knowledgeable.

"Overt mercury poisoning is not the issue," Hartley explains. "To my knowledge, there has never been an actual case of outright mercury poisoning in the state. However, mercury, like lead, can act in very subtle ways. There can be subtle effects on learning and neurological development that can occur and manifest later in life."

But despite the testing and the nationwide advisories, it isn't clear whether the public is aware of the advisories, whether they are adhering to them, and what kind of impact, if any, mercury is having on the public health. So far there have not been widespread efforts to test mercury levels in people in order to get an understanding of the degree to which the public is being exposed to mercury. The Mercury Project puts Louisiana ahead of the curve.

The Louisiana Office of Public Health first tested mercury blood levels in a walk-in study conducted in the mid 1990s.

"That study showed that there were very few people with elevated levels of mercury," Hartley says. "What we're trying to do in this study is look at the worse-case situation--people who eat large amounts of locally caught fish. So we have an inclusion criteria where people have to have at least one meal per week of locally caught fish to be included in the study. We want to know what the magnitude of risk is."

Fishing for Answers

Globally, there have been occasional incidences of severe mercury poisonings that have shown the worst that mercury can do. In the 1960s there were two episodes in Japan in which several people died and more than a hundred became very ill after eating severely contaminated fish. And in the early 1970s, hundreds of Iraqis died and thousands were hospitalized after eating bread mistakenly prepared with seed that had been treated with a mercury fungicide.

In those cases, the symptoms of the poisoning seemed to progress long after exposure stopped, and there did appear to be a negative effect on infant development. But the impact of lower levels of exposure is not clear, in part because of the subtlety of the effect and in part because other environmental toxins can create the same symptoms.

The Mercury Project should show whether or not those who probably have the highest exposure to mercury are actually exposed to enough of it to cause health problems, yielding some much-needed information that will be of use to both public health workers and the individuals being tested.

Pregnant women who participate in the study can also agree to donate a blood sample taken at the time of delivery, which will give an idea of what levels the child was exposed to in the womb. Study participants are also asked about how many home-grown vegetables they eat.

Although fish are the primary source of exposure to mercury, the metal also can accumulate in plants. Some exposure also comes from inhaling it in the air. The blood sample can tell what the individual's total mercury exposure is, but not specifically how much came from fish. "We get information about how severe the problem of exposure is and what the potential health risks are at this time," Hartley says.

"The families get advice about what their levels mean with regard to health, and specific advice about how to bring levels down if they are too high. And the questionnaire tells us about where they're fishing, what they're eating, their socio-economic status, and about communication issues that need to be addressed."

Hartley and his team have disseminated the news about the Mercury Project through public service announcements on radio and television. WWL-TV, the New Orleans CBS affiliate, did a feature on the project, and there have been several articles in area papers. It even got some national television exposure through Ivanhoe Broadcast News, which produces syndicated programming on medical topics. But most people who have volunteered for the study already had concerns about mercury before they heard about the project, according to Machen.

The Forets signed up because of Damien's 7-year-old son, Troy, who is autistic. The Forets and their pediatrician believe his autism was induced by exposure to an organic form of mercury used in tiny amounts as a preservative in vaccines. The link between autism and the mercury in vaccines has not been proven, and the issue is extremely controversial among the medical community. But to the Forets the evidence is conclusive. Troy was developing normally until he was around 1-and-one-half or 2 years old.

"He was beginning to speak," April says. "He's completely nonverbal now."

According to the Forets, the trouble began when Troy began his vaccination series. He had a seizure after every vaccination, and by the time the series of shots was finished, he was diagnosed with autism. When their doctor suggested he be tested for mercury, the results showed his body was saturated in it. Since then, the couple has become increasingly aware of the mercury issue and called to volunteer to be tested for the Mercury Project after reading about it in their local paper.

"I don't know what the cause of autism is," Hartley says. "Regarding the vaccine, it's true there's a type of organic mercury in there, but the amount is so small, my feeling is that it's not a major source in lieu of these other sources." But whether or not mercury is linked to autism, it can cause developmental problems in children.

"Mercury is a neurotoxin," says Machen. "The particular concern with children is that the nervous system is still in development, so the adverse effects could possibly be permanent, depending on the timing of the mercury exposure. There could be learning disabilities or developmental delay. But we can't say for sure these problems are caused by mercury."

Fish Pondering

If mercury does present a serious problem, it's one that could cut across a wide segment of the community. People from all races and all incomes have qualified to be a part of the Mercury Project. Some live in the middle of the city and others live on rural backroads. One segment of the population that the project hasn't reached yet is the large Vietnamese community in the New Orleans area. Hartley wants to make sure that this population, which consumes a great deal of fish, gets included in the study.

While people at all income levels eat a lot of fish, Hartley is particularly concerned about poor people who depend on the fish they catch as a protein source, and for that reason sees mercury as an environmental justice issue.

"A lot of poor people in Louisiana get their primary source of protein from local fishing," he says. "Typically, that's a good source of protein. That's why it's important for us to have a risk-management system that protects the public but doesn't unnecessarily restrict fish consumption."

Let Them Eat Fish

The Forets look over a brochure that shows which species of fish are more likely to accumulate mercury and which are less likely to do so. Largemouth bass is one of the fish they eat which tends to build up mercury. But Machen reminds them that just because bass from a particular lake may be contaminated, doesn't mean that all bass are. Shrimp and crawfish are generally safe because they have a shorter life span in which to collect toxins.

"Keep in mind that fish is an excellent source of protein," Shropshire tells the couple. "Don't worry, you're not discouraging us from eating fish!" April says. "We'll probably have some tonight."

Heather Heilman is an editor at Tulane. If you live in southeast Louisiana and eat locally caught fish at least once a week, you can participate in the Mercury Project by calling (504) 988-1270 or toll free 1-866-443-4745. This article originally appeared in the Spring 2001 issue of Tulanian.

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