CRS Report: 97-872 - Pfiesteria: Natural Resource and Human Health Concerns

Eugene H. Buck, Claudia Copeland, & Jeffrey Zimi
Senior Analysts, Environment and Natural Resources Policy Division

Congress, federal agencies, and affected mid-Atlantic states are seeking to better understand Pftesteria piscicida, a recently identified species of dinoflagellate algae that appears to have harmful effects on both fish and human health, and to determine how best to mitigate its impacts. While individual states seek to address concerns, Congress and federal agencies are considering how best to assist state efforts. Issues of likely interest to Congress include water quality management, agriculture and its possible role in the problem, human health effects, and impacts on fisheries.

Pfiesteria piscicida, a dinofiagellate algae first identified and named in 1988, appears to be able to exist in possibly more than 20 different physical forms, primarily in brackish water estuaries. At least some forms appear able to release toxins that have been blamed for fish kills and human illness along the mid-Atlantic coast.

Pfiesteria has been positively identified in several areas. While major fish kills have been reported in North Carolina (primarily in the Neuse and Pamlico River drainages) since the early 1990s and more recently in Maryland (primarily in the Pocomoke River drainage), Pfiesteria has reportedly been identified in Delaware, Virginia, South Carolina, and Florida. Fish with lesions or open sores have been noted in other regions, including India and Southeast Asia and Europe's North Sea, since the early 1970s, but whether Pfiesteria has caused these problems is unknown. Instances of "ulcerative mycosis" in mid-Atlantic menhaden during the mid-1980s may have been caused by Pfiesteria.

This organism exists over an extensive geographic range and in a range of environmental conditions. It has a wide salinity tolerance for both freshwater and seawater, as well as wide temperature tolerance. Optimum conditions for Pfiesteria are brackish, slow-moving waters, typically found in estuaries, and temperatures of about 75 degrees F.

Scientists believe that the organism is present at all times in estuarine waters where it has been found, but becomes active, and potentially toxic, under certain conditions. Nutrient (nitrogen and phosphorus) enrichment of the waters plays a role in at least two ways. First, when a waterway is over-enriched in nutrients from sources such as sediment and fertilizer runoff from farms, lawns, and city streets, algae in the water are stimulated to multiply, and Pfiesteria feast on these small algae. Bacteria in the water break down algae, which depletes the water of oxygen needed to sustain aquatic species; waters in which Pfiesteria are found also are characterized by low dissolved oxygen levels.

Second, Pfiesteria can also be stimulated by dissolved organic forms of nutrients which occur in human and animal wastes (sewage and manure). Pfiesteria has been found in higher abundance near sewage outfalls than in areas without wastewater outfalls. Given these characteristics about Pfiesteria, one possibility for its transformation from dormancy to an active state is that rainfall transports nutrient-rich livestock wastes, other farm pollutants, and urban runoff into waterways where algae are stimulated to grow.

Schools of fish that enter areas in which algae are abundant consume the algae. Scientists have postulated that a substance excreted or secreted by the feeding fish triggers Pfiesteria to become active and toxic. The toxins released by Pfiesteria cause fish to become less active, whereupon the Pfiesteria organism feeds upon the skin and external tissues of fish causing sores, lesions, or ulcers. In extreme cases, Pftesteria occurs in such abundance that the toxin released causes major fish kills. Menhaden, an industrial fish harvested primarily for its oil, is the fish species that has most often been affected. Other fish species inhabiting these waters are also affected and include flounder, croakers, spot, and gar. The fish kills in the Neuse and Pamlico River Basins, NC, during 1991-1993 were reported to have killed "billions" of fish, primarily menhaden.

During its complex life cycle, Pfiesteria apparently produces one or more toxins. The toxin is released into the water and appears to be in air close to the water. Apparently, it dissipates a few hours after release. The toxin has been blamed for causing adverse health effects in people who have come in close contact with infected water. Apparent victims include several watermen (commercial fishermen), a water skier, and two researchers working on Pfiesteria in their laboratory. Common complaints by these people include skin sores, such as rashes, blisters, and peeling skin. The toxin also appears to have neurotoxic effects causing memory loss, disorientation, mood changes, and learning difficulties. Other reported health effects include eye irritation, headache, sore throat, nausea, and weakness in hands, feet, and lips. Those symptoms have not followed a particular pattern and it is unclear if the health effects are acute or chronic.

Since the organism was first identified in 1988, very little research has been conducted on the human health effects of this organism's toxins. The strongest evidence of adverse human health effects so far comes from case studies of two laboratory researchers who were overcome in their laboratory in 993. They still complain of some impairment of their cognitive abilities, particularly after exercising. Duke University Medical Center researchers conducted experiments on rats, which showed that the toxin appeared to slow learning but did not affect the memory. Another study looked at whether Pfiesteria was causing greater illness among North Carolina crabbers. The study found that 11 crabbers, compared to individuals with little water exposure, suffered a higher rate of skin problems. However, the crabbers in areas subject to Pfiesteria did not suffer higher rates of illness when compared to crabbers in Pfiesterla-free areas.

Research, recently completed at the direction of the Governor of Maryland by Johns Hopkins School of Medicine and the University of Maryland, examined 22 people exposed to waters containing Pfiesteria. In a September 1997 preliminary report, the medical team reported that it was impressed with the collected medical histories from patient after patient of acute problems with memory loss. The researchers reached a preliminary conclusion that the presence of Pfiesteria toxin in water could pose a health risk.

Maryland officials have been in the forefront in focusing attention on the Pfiesteria problem. Using funds provided by NOAA and the EPA, Maryland is conducting two surveys to learn more about agricultural activities in the affected watersheds. The Maryland Department of Agriculture is evaluating Best Management Practices (BMPs), including a review of current activities and maintenance by producers. The University of Maryland is conducting a companion study of agricultural nutrient management plans. Both studies were started in late August 1997, and results are anticipated by the end of September 1997. In addition, Governor Glendening has announced three positions will be added in the Department of Agriculture to provide technical support to farmers and three positions will also be added in the Department of Environment to inspect farms and initiate any necessary regulatory enforcement to protect water quality in the affected watersheds. Both Maryland and Virginia officials have taken an active role in making a clear distinction that most Maryland seafood is harvested from areas unaffected by Pfiesteria and pose no concern for consumers. In addition, Maryland officials have made statements to the effect that certain commercial crabbers are likely to be reimbursed for losses directly related to the closing of Maryland estuaries to fishing

In North Carolina, both the General Assembly and state regulators have imposed new planning and management requirements on agricultural operators to address nutrient overload and Pfiesteria problems with fish kills in certain waters, particularly the Neuse River. The state's Environmental Management Commission is seeking agreement on measures to achieve a 30% reduction in nutrient loadings to that river.

On September 19, 1997, the Governors of Maryland, Virginia, Delaware, West Virginia, and representatives from North Carolina, Pennsylvania, and the Clinton Administration met and agreed to conduct joint research and to share data on future research on Pfiesteria. However, two of the major states with recent problems have taken different approaches to these outbreaks. While Governor Glendening of Maryland, citing human health risks, has closed almost all the estuaries where fish kills have been observed, Governor Allen of Virginia believes more evidence of human health risks is needed before closing segments of the Rappahannock River in which lesions have been found on menhaden. He has asked Virginian scientists to review the Maryland medical team findings. Meanwhile, Maryland officials advise against swimming in areas where researchers have found that Pfiesteria could have caused lesions in fish and against eating fish with open, red sores.

In response to concerns raised by the State of Maryland, several agencies, including the National Oceanic and Atmospheric Administration (NOAA), Environmental Protection Agency (EPA), U.S. Department of Agriculture (USDA), and U.S. Geological Survey have provided funding to investigate the problem. EPA is developing an action plan in response to the problem; details are not yet available. USDA research programs are also being conducted by the Agricultural Research Service Center on fish and fish health, and on changes in water quality that accompany nutrient management activities.

Agencies in the USDA are helping Maryland collect information, and assisting agricultural producers. Programs to assist producers in addressing agricultural waste and by-products center on installing BMPs. The Natural Resources Conservation Service reportedly will provide more funds, perhaps $300,000, under the new Environmental Quality Incentives Program for producers in the affected watersheds to develop and implement multi-year conservation plans to implement BMPs and other conservation practices. Also, the Farm Service Agency reportedly will make more funds available to increase the incentive for producers in these watersheds to enroll land in the Conservation Reserve Enhancement Program and retire it from production for 10 years or more. Participants install approved vegetation in return for annual payments.

From a water quality perspective, specific pollution problems such as Pfiesteria, where they occur, reflect a larger set of issues. If the scientific theories regarding the organism are correct, the water quality conditions associated with its emergence - nutrient enrichment, in particular - contribute to water pollution problems generally in the same areas and others nationwide. Nutrient over-enrichment of waters and algae blooms can depress oxygen levels and lead to fish kills, even where Pfiesteria is not present. From that perspective, Pfiesteria is not a singular problem. It is only one example of the challenge to improve quality in waters that experience nutrient enrichment, often from numerous sources.

Data reported by states to EPA indicate that nutrients and bacteria are the leading causes of pollution in estuaries, where Pfiesteria has primarily been found, and that the principal sources of that pollution are urban runoff (discharges from Storm sewers), municipal sewage treatment plants, and agriculture. It is difficult to determine which specific sources in an area may be contributing to the conditions where Pfiesteria apparently thrives. Thus, the first challenge for water utility managers is to assess point and nonpoint sources to quantify environmental effects of particular discharges, on a case-by-case basis. If sewage treatment plant discharges are implicated, officials may tighten existing permit limits and call for added technological controls. If runoff from farms or city streets is implicated, management is more complicated, because under current federal law (the Clean Water Act), these sources are not regulated by similar programs. Instead, they primarily are subject to state-run management programs that rely largely on voluntary efforts to minimize runoff. The effectiveness of voluntary programs may be an issue for policymakers in considering how to address Pfiesteria-related and similar water pollution problems in connection with Clean Water Act reauthorization.

Runoff or discharges from animal production facilities (both open and confined) have particularly been implicated in Pfiesteria problems in Maryland and North Carolina waters. Prior outbreaks in Florida and North Carolina have occurred in rural watersheds where agriculture is an intense activity, as it is in the three Maryland watersheds where Pfiesteria has been identified, leading to suspicion that the industry, and especially areas with high concentrations of poultry farms, may play an important role. The Maryland Department of Agriculture is gathering information to more precisely characterize agriculture in these watersheds. The survey of the 2,500 agricultural parcels encompassing 170,000 acres and managed by almost 550 operators in the Pocomoke drainage is further along. More than 100 million chickens reportedly are raised in the Pocomoke watershed each year, producing a very large volume of manure. The Department also has information on the number of facilities where it has provided cost-sharing or technical assistance, but not on their effectiveness.

Agricultural interests have generally held that no scientific evidence proves that their activities cause or even contribute to the Pfiesteria problem. They also state that most producers in these watersheds participate in voluntary programs to implement conservation plans and to install and maintain BMPs. But no data show either how many producers or what portion of the land have BMPs, or how the installation, maintenance, or operation of these practices have affected water quality. Because of the lack of information about the causes of these outbreaks, agricultural interests believe that they may be unfairly singled out before the full dimensions of the problem and the more effective solutions are known.

Critics believe that agricultural activities are either the primary source for conditions that have resulted in these problems or a major contributor. They believe that stronger management of manure could improve water quality, and that stricter pollution control rules combined with more aggressive enforcement is necessary. Given the severity of the problem, many advocate the need for action now, even though research to precisely define the causes of this problem has not been completed.

Large confined animal feeding operations (CAFOs, feedlots with more than 1,000 animal units) are subject to discharge permit requirements under the Clean Water Act. Other animal feeding operations may be designated as CAFOs if they pose a threat to water quality or use. The regulatory requirements for CAFOs generally prohibit discharge of waste water pollutants into navigable waters. Still, unpermitted waste discharges and spills from feedlots in a number of states, and the recent attention to Pfiesteria, have raised questions about the adequacy of regulation and enforcement and whether the size threshold for CAFOs should be lowered to bring more operations under regulation. Several states have enacted or are considering measures that would impose additional waste management controls on animal production facilities, beyond current federal rules.

Until scientists identify the active ingredient in Pfiesteria's toxin and the toxin's mode of action, and characterize the organism's life cycle, there remain many unanswered questions about its potency and how it could affect human health. For example, there have been no reported human illnesses from eating Pfiesteria-stricken fish, so it is unknown whether the toxin affects human internal organs, whether it is destroyed by cooking, or whether the toxin breaks down or is diluted in the air or water. If the toxin does dissipate in the environment in a few hours, only the freshest infected fish might be dangerous to consume, but even that is unclear.

It is also unclear if Pfiesteria produces toxins at different stages in its life cycle or whether there are different dinoflagellate or other organisms producing toxins. There could also be variations in the toxins. Until some of these questions are answered, it is difficult to assess the implications of these recent fish kills on human health.

State and federal managers have taken a generally conservative approach to questions of whether Pfiesteria may pose any concern for seafood safety. Maryland managers have prohibited all commercial and recreational fishing in affected waters, and have advised citizens to not consume fish with lesions or those that appear to be diseased. Although no instances of tainted seafood or human illness from eating fish exposed to Pfiesteria have been reported, health officials advise caution and avoidance of diseased fish or those with conspicuous sores since so little is known about Pfiesteria. Commercial and economic interests, however, remain concerned that the occurrence of Pfiesteria diminishes consumer confidence in seafood safety generally, and that consumers may make broad assumptions about seafood sanitation and quality leading them to reject safe seafood. The issues to be addressed are whether additional efforts may be necessary to promote seafood safety when Pfiesteria is present and to assist the seafood industry in addressing consumer confidence concerns with seafood.

Other links, added by the NCSE:

North Carolina State University Aquatic Botany Homepage: http://www2.ncsu.edu/unity/lockers/project/aquatic_botany/
The Harmful Algae Page [NSF, NOAA] http://www.redtide.whoi.edu/hab/
University of Maryland: Fish Health in the Chesapeake Bay: http://www.mdsg.umd.edu:80/fish-health/
The Hughes Report, State of Maryland on Pfiestieria: http://www.dnr.state.md.us/Hot/contents.html

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