PFIESTERIA HEALTH CONCERNS REALIZED Federal and state agencies coordinate research on unusual toxic microorganism when human health problems arise

Bette Hileman C&EN Washington

P fiesteria piscicida has been kill­ing fish in East Coast estuaries and rivers for at least six years. But a

concerted and coordinated federal re­sponse to the problem did not begin until this September. Since then, eight federal agencies began collaborating to intensify research into these microbes and the eco­logical conditions underlying their out­breaks. Also, the Environmental Protection Agency started to plan steps to strengthen control over the nutrients that may be caus­ing Pfiesteria outbreaks. And on Sept. 25, Congress held a hearing to discuss the Pfies­teria problem (C&EN, Sept. 29, page 8).

The first fish kill in the wild attributed to Pfiesteria took place in North Caroli­na in May 1991. That was followed by massive outbreaks of the microbe in 1995 and 1997 that killed millions offish in North Carolina estuaries.

In Maryland, Pfiestena was first ob­served in October 1996, when menhaden, fish used for bait or converted to oil and fertilizer, were found with Ffiesteria-reht-ed lesions in the Pocomoke River. This spring and summer, Pfiesteria killed 10,000 to 15,000 fish in the Pocomoke, and fish with lesions also were found in two other rivers along the Eastern Shore of the Chesapeake Bay. Each time an out­break was discovered, Maryland Gov. Par­tis Ν. Glendening closed the affected wa­terways to fishing and recreation. Fish with Pfiesteria-rdated lesions also were found in some Virginia rivers, including the Rappahannock, this summer.

Even though Pfiesteria has killed far more fish in North Carolina than in Mary­land, Maryland has led the way in eliciting a coordinated response to the microbe. This is probably because strong evidence for Pfiestena-rdated human health prob­lems (other than lab workers) was first found in Maryland. This summer, Glenden­ing assembled a medical team that noted a

probable link between intensive exposure to Pocomoke River water at the time of Pfiesteria attacks and human symptoms such as short-term memory loss. Also, in September he asked President Clinton for federal help with the problem. "Maryland faces an unprecedented challenge to the health and vitality of our fragile water­ways," he said.

What makes Pfiesteria apparently able to harm humans as well as fish? Pfiesteria, a one-celled microscopic algae, has a com­plicated life cycle with at least two dozen flagellated, amoeboid, and encysted stag­es. Unlike most dinoflagellates, it can have a predator-prey relationship with fish.

For much of its life cycle, Pfiesteria hides out in a nontoxic cyst stage on the bottom of the river. "Pfiesteria are only known to become toxic when they detect substances excreted/secreted by live fish or leached from fish tissues," says JoAnn N. Burkholder, associate professor of aquat­ic biology at North Carolina State Universi­ty, Raleigh. This stimulates the Pfiesteria to assume a toxic amoeboid or dinoflagel-late form, which excretes a water-soluble neurotoxin into the water and incapaci­tates the fish. Pfiesteria then attach them­selves to the lethargic fish, excreting a lip-id-soluble toxin that destroys the epider­mal layer of the skin and causes lesions ranging from pinpoint sores to deep hem­orrhaging wounds.

About 2% of all dinoflagellates are tox­ic, but in most toxic species, the toxin is carried inside the organism and is released only when the cells break up. What is un­usual about Pfiesteria is that it excretes tox­ins while still alive.

Three of Pfiesteria's two dozen stages. The amoeboid stage (top)

is toxic; the cyst stage with nontubular

spines (bottom left) and the zoospore

stage are nontoxic.

The water-soluble Pfiesteria toxin be­haves like a nerve gas on fish, stunning them and incapacitating them so they cannot move away quickly, and it appar­ently acts the same way on humans. The toxin also can form an aerosol above the water. Thus, people merely need to be in contact with the water or in boats while a Pfiesteria incident is under way to be exposed to the toxin.

Recent cell culture tests show that the water-soluble toxin destroys cell mem­branes, allowing the contents of the cell to leak out, says Patricia D. McClellan-Green, assistant research professor of toxicology at Duke University. "My guess is that in the live animal it interrupts the signaling pro­cess so nerves can't fire," she says.

Excreta from a lone fish is not enough to trigger Pfiesteria to become toxic, so Pfies­teria usually attacks schools offish. Most of­ten it affects menhaden, but it has also harmed croakers, flounder, and rockfish, Burkholder says. Relatively quiescent water is required for Pfiesteria to detect fish ex­creta and for the neurotoxin to become concentrated enough to stun the fish.

Because of the extreme toxicity of the Pfiesteria toxins, toxic bioassays with test fish must be conducted in class ΙΠ biohaz-ard facilities. Before researchers became aware of this, 13 lab workers experiment­ing with Pfiesteria suffered severe memo­ry loss, sores that healed very slowly, and difficulty breathing. Their symptoms sub­sided over time, Burkholder says, but some may return after strenuous exercise.

Excreta from schools of fish provide a proximate trigger that signals Pfiesteria to assume a toxic form, but most researchers

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believe that some other substance or sub­stances must be present in the water to nourish the large numbers of toxic Pfies­teria required to harm fish. "There is strong evidence connecting these algal blooms with nutrient pollution—exces­sive nitrogen and phosphorus—in the wa­ter," says Robert Perciasepe, EPA assistant administrator for water.

Burkholder agrees: "We have estab­lished through field and lab research that [Pfiesteria] can be highly stimulated by both inorganic and organic nitrogen and phosphorus enrichments," she says, es­pecially the nutrients in human sewage and swine effluent spills.

This summer, a team of physicians ex­amined patients with health complaints who had been exposed to Pocomoke River water during Pfiesteria incidents. On standard tests, the physicians found a dose-response relationship between the degree of water exposure and memory loss. Seventy-five percent of people with a high level of exposure to the Poco­moke had severely impaired verbal learn­ing and memory, testing in the second percentile compared with the general population, says J. Glenn Morris, profes­sor of medicine at the University of Mary­land School of Medicine, Baltimore. Some found themselves driving toward a destination and then on arrival wonder­ing what they were supposed to do. "Taken together," Morris says, "our data indicate that persons exposed to the Po­comoke River [during Pfiesteria inci­dents] have a distinctive clinical syn­drome characterized by chronic difficul­ty with learning and memory."

Five Virginia residents have reported memory loss and confusion after expo­sure to Pfiestena-infested Virginia water­ways. However, Virginia Commissioner of Health Randolph L. Gordon says, "Sci­entists . . . remain encouraged that Pfies­teria may not be harmful to human health through normal recreational or oc­cupational exposure."

However, says Fred R. Shank, director of the Food & Drug Administration's Center for Food Safety & Applied Nutrition, "to date, no evidence has been identified to suggest a hazard from human consump­tion of seafood associated with Pfiesteria:' Nevertheless, state health departments warn people not to eat fish with sores.

In part because of Glendening's concern about the possible human health threats, a federal interagency group has been set up to deal with Pfiesteria. EPA and the Nation­al Oceanic & Atmospheric Administration (NOAA) will be supplying $500,000 in

emergency funding and federally supported teams of experts to help monitor water con­ditions, analyze data, and investigate con­cerns about health effects.

Also, EPA, NOAA, the Department of Agriculture, the Centers for Disease Con­trol & Prevention, the National Institute of Environmental Health Sciences, FDA, the U.S. Geological Survey, and the U.S. Fish & Wildlife Service are setting up a coordinat­ed research strategy to determine what triggers Pfiesteria outbreaks and how they affect human health and the environment.

In addition, EPA, USDA, NOAA, and the Department of the Interior are under­taking a serious effort to reduce nitrogen and phosphorus pollution to the Chesa­peake Bay by 40%.

North Carolina has taken some unilat­eral action to control the runoff of farm nutrients to coastal waters. In August, Gov. James B. Hunt Jr. signed a bill that puts a two-year moratorium on new hog farms in the state, reduces nutrient limits for wastewater discharges and nonpoint sources, and includes provisions for land use management.

Maryland, which has weaker laws on agricultural runoff than either Virginia or North Carolina, approved in September a $2 million emergency appropriation to help Maryland farmers plant cover crops to absorb unused crop nutrients resulting from this summer's drought. And Virginia Gov. George Allen authorized $600,000 to establish a Pfiesteria research unit within the Virginia Department of Health.

A fundamental problem hindering the federal response to Pfiesteria outbreaks, if nutrients are the cause, is that EPA has very little authority under the Clean Water Act to control agricultural runoff. So far, Congress has refused to expand that authority.

Also, for the past two years Congress has refused to provide funding for the law that could perhaps do most to solve the Pfiesteria problem, Section 6217 of the Coastal Zone Act Reauthorization Amend­ments of 1990. The provision requires 30 states to put programs into effect to pre­vent polluted runoff into coastal waters. "It is the only comprehensive regulatory method to deal with runoff into coastal waters," says Beth Millemann, executive director of the Coast Alliance, a Washing­ton, D.C.-based coalition of environmental groups and others concerned with the condition of the coasts. The House recent­ly passed an amendment to the Commerce, Justice, State, and Judiciary appropriations bill that would provide $1 million to fund the program, but the comparable Senate bill provides no funding.^

Federal Aler t -new legislation This C&EN listing highlights legisla­tion introduced between Sept 2 and Oct. 3. House and Senate bills are listed under subject area by bill num­ber, primary sponsor, and commit-tee(s) to which they were referred

• HOUSE

Environment. H.R. 2485—Stupak (D-Mich.). Provides relief from liability for Superfund cleanups for small parties, innocent landowners, and prospective purchasers. Commerce; Transportation & Infrastructure.

Technology. H.R. 2429—Sensenbren-ner (R-Wis.). Extends through fiscal 2000 program that requires federal agencies with extramural R&D bud­gets in excess of $1 billion to set aside 0.15% of budget for technology transfer from government to small businesses. Science; Small Business.

Workplaces. H.R. 2579—Talent (R-Mo.). Amends Occupational Safety & Health Act to allow employers to ob­tain compliance evaluations from qualified third-party consultants, ex­pands availability of voluntary and technical compliance initiatives. Ed­ucation & the Workforce.

• SENATE

Award. S. 1152—McCain (R-Ariz.). Es­tablishes National Environmental Achievement Award to be presented annually by EPA and Department of Commerce and funded by private sec­tor to recognize premier technology advancements. Environment & Public Works.

Environment. S. 1219—Faircloth (R-N.C.). Establishes two-year, $6.9 million research grant program aimed at find­ing ways to eradicate or control Pfies­teria piscicida and other aquatic tox­ins. Environment & Public Works.

S. 1224—Allard (R-Colo.). Clarifies that federal facilities are subject to same environmental cleanup laws that apply to private sector. Environ­ment & Public Works.

Research. S. 1140—D'Amato (R-N.Y.). Prohibits reactivation of High Flux Beam Reactor at Brookhaven Na­tional Laboratory. Energy & Natural Resources.

S. 1150—Lugar (R-Ind.). Ensures that federally funded agricultural research programs address high-priority con­cerns that have multistate significance; reforms and extends agricultural re­search programs, but eliminates oth­ers. Agriculture, Nutrition & Forestry.

OCTOBER 13, 1997 C&EN 15