Growing scientific evidence shows that pathogens, antimicrobials and hormones are increasingly appearing in livestock and poultry manure across the United States, according to a literature review prepared by the U.S. Environmental Protection Agency (EPA).
Image courtesy USDAgov/Flickr
These “contaminants of emerging concern”—so named because their risks to human health and the environment may be unknown—could pose threats to plants, animals and people if rain, spills or storage failures push contaminated manure into rivers and streams.
The flow of manure into our waterways has long been linked to nutrient pollution. According to 2010 estimates, manure accounts for 19 percent of the nitrogen and 26 percent of the phosphorous entering the Chesapeake Bay, where it fuels the growth of algae blooms and creates dead zones that suffocate marine life. But research now shows that more of the nation’s manure could contain a new class of pollutants that could have serious implications for water quality.
Manure can contain pathogens, for instance, that could infect humans if allowed to contaminate our drinking water or food crops. It can contain antibiotics and vaccines that could facilitate the development of antimicrobial resistance. And it can contain natural and artificial hormones that, even in low concentrations, could affect the reproductive health and fitness of fish, frogs and other marine life.
Indeed, good manure management has become a key conservation practice in the watershed, where four states—Delaware, Pennsylvania, Maryland and Virginia—rank among the ten highest manure-generating states, according to the U.S. Department of Agriculture (USDA). As livestock and poultry production shift to larger, more concentrated operations, facilities produce more manure than can be used on the surrounding farmland. If this manure is properly applied, stored and transported, it can be kept out of rivers, streams and the Bay.
Learn more about contaminants in livestock and poultry manure.
For almost two decades, state and federal partners have worked to rebuild Poplar Island in the Maryland waters of the Chesapeake Bay. Once home to a sawmill, a general store and a schoolhouse, the island succumbed to sea level rise, shrinking to a fraction of its size by 1996. Rebuilt using sand and sediment dredged up from the bottom of the Bay and hand-planted with native marsh grass, the island has become a refuge for 175 species of shorebirds, songbirds, waterfowl and raptors.
Eastern bluebirds, black ducks and snowy egrets are among the birds that nest on Poplar Island, but it is the osprey whose presence stands out. Their sprawling nests can be found on wooden platforms, abandoned barges and Bay-side rip-rap. Plentiful food and nesting space mean Poplar’s osprey population is healthy, and can give researchers like Rebecca Lazarus an idea of what the birds should look like under the best environmental circumstances.
Working with the U.S. Geological Survey (USGS) and the U.S. Fish and Wildlife Service (USFWS), Lazarus is studying contaminant exposure in osprey around the Bay. Because the birds sit at the top of the food chain, their health is an indicator of environmental problems. Tracking the buildup of chemical compounds in the eggs and blood of birds that Lazarus calls a “sentinel species” can tell us what toxics are present in our rivers and streams.
Lazarus started her season of research when ospreys returned to the Bay in mid-March. The University of Maryland doctoral candidate and USGS employee visited nests, counted eggs and watched the ospreys grow.
Once the chicks hatched, Lazarus used motion-activated game cameras to monitor their diets. The birds on Poplar eat almost exclusively striped bass and menhaden, reminding us that the management of these two fisheries has a big impact on the balance of the Bay ecosystem.
As the chicks grew, Lazarus tagged each one of them with a metal band. She measured their weight and culmen length, and took samples of blood to test for chemical contaminants.
The last large-scale study of contaminant exposure in osprey was conducted close to a decade ago, and found elevated concentrations of polychlorinated biphenyls (or PCBs) and flame retardants in egg samples from the Anacostia and middle Potomac rivers. Lazarus hopes her updated research will show us what contaminants persist in the watershed, posing potential threats to wildlife and human health.
The birds on Poplar are healthy and serve as a benchmark against which Lazarus can compare those that nest in more polluted parts of the Bay. Ospreys experienced such a strong population boom after the United States banned the insecticide DDT and other contaminants that they are now nesting along urbanized waterways where dense development, wastewater treatment plants and the flow of pharmaceuticals and other new toxics into our water have concern about their potential to thrive.
By monitoring the link between clean water, contaminant-free fish and healthy osprey, Lazarus has taken a holistic approach to her research. Once published, her findings could help state and federal agencies develop plans to mitigate pollution or prioritize contaminants of concern. And they will help improve the environmental quality, ecosystem integrity and sustainability of the Bay.
To view more photos, visit the Chesapeake Bay Program Flickr page.
Images by Steve Droter and Olivier Giron.
Captions by Catherine Krikstan.
Tumor rates among catfish in the Anacostia River are down, according to a new report from the U.S. Fish and Wildlife Service (USFWS).
Biologists with the agency’s Chesapeake Bay Field Office have studied the brown bullhead catfish for decades as an indicator of habitat status and the success of cleanup efforts. The bottom-dwelling fish is sensitive to contaminants that accumulate in the mud in which it finds its food, often developing liver and skin tumors after exposure to cancer-causing chemicals.
Image courtesy USDA/Wikimedia Commons
Brown bullheads in the Anacostia River once had the highest rates of liver tumors in North America, but recent USFWS surveys show that tumors in the fish have dropped. While the rate is still higher than the Bay-wide average, this improvement could indicate that exposure to chemical contaminants is on the decline.
Liver tumors in fish are caused by exposure to sediment that is contaminated with polynuclear aromatic hydrocarbons, or PAHs. PAHs can be found in coal, oil and gasoline, and enter rivers and streams from stormwater runoff, waste sites and the atmosphere.
The U.S. Environmental Protection Agency (EPA) and the District Department of the Environment (DDOE) have coordinated a number of recent cleanup efforts to lower PAH contamination in the watershed, from improved stormwater management and more frequent street sweeping to the targeted inspection of local automobile repair shops to lower loadings of oil and grease.
Read more about Tumors in Brown Bullhead Catfish in the Anacostia and Potomac Rivers.
Chemical contaminants continue to afflict the Chesapeake Bay watershed, raising concern over water quality and the health of fish, wildlife and watershed residents.
Close to three-quarters of the Bay’s tidal waters are considered impaired by chemical contaminants, from the pesticides applied to farmland and lawns to repel weeds and insects to the household and personal-care products that enter the environment through our landfills and wastewater. But so-called “PCBs” and mercury are particularly problematic in the region, according to a report released last week by the U.S. Environmental Protection Agency (EPA), U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service (USFWS).
Both PCBs—short for “polychlorinated biphenyls”—and mercury are considered “widespread” in extent and severity, concentrating in sediment and in fish tissue and leading to fish-consumption advisories in a number of rivers and streams.
The District of Columbia, for instance, has issued such advisories for all of its water bodies, asking the public not to consume catfish, carp or eels, which are bottom-feeding fish that can accumulate chemicals in their bodies. While the District’s Anacostia and Potomac rivers raise the greatest concern in the watershed when it comes to fish tissue contamination, a November report confirmed that many Anacostia anglers are sharing and consuming potentially contaminated fish, sparking interest in reshaping public outreach to better address clean water, food security and human health in the area.
While PCBs have not been produced in the United States since a 1977 ban, the chemicals continue to enter the environment through accidental leaks, improper disposal and “legacy deposits”; mercury can find its way into the atmosphere through coal combustion, waste incineration and metal processing.
Exposure to both of these contaminants can affect the survival, growth and reproduction of fish and wildlife.
The Chesapeake Bay Program will use this report to consider whether reducing the input of toxic contaminants to the Bay should be one of its new goals.
A yearlong survey of anglers along the Anacostia River has confirmed that many fishermen are catching, sharing and consuming contaminated fish.
While fishing advisories in Maryland and Washington, D.C., have been in place for more than two decades, these warnings are often not seen, understood or listened to—and as many as 17,000 residents could be consuming fish caught in the Anacostia.
Image courtesy Len Matthews/Flickr
Located less than one mile from the nation’s capital, the Anacostia River has long suffered environmental degradation. Polluted runoff from urban streets and hazardous waste sites has caused toxic chemicals to build up in the water and in the bodies of fish, which could cause disease or development disorders in those who consume them.
According to the results of a survey that studied the social behavior of Anacostia anglers, a complex set of factors is driving the sharing and consuming of locally caught and potentially contaminated fish: past experience and present beliefs, a lack of awareness of the health risks involved and an overriding desire to share their catch with those who might otherwise go hungry.
Image courtesy LilySusie/Flickr
Research conducted through hundreds of interviews along fishing “hotspots” and a community survey that canvassed the lower Anacostia watershed found that 40 percent of fishermen had never heard that fish from the Anacostia could make them sick. Some anglers thought visual cues—like obvious lesions, cloudiness in the eyes or the color of a fish’s blood—would help them determine the health of a fish, or that related illnesses would soon be apparent rather than chronic or long-term. If a fisherman had not fallen ill from a meal of fish before, then he might perceive the fish to be healthy or think that his preparation methods made it clean.
Research also found that current advisories do not resonate among diverse anglers. Just 11 percent of fishermen had seen a sign or poster, and even fewer had received warning material with a fishing license or reviewed related information online. And English-only outreach is not effective among a population in which one-quarter speaks a language other than English at home.
Image courtesy 35millipead/Flickr
But how can Anacostia anglers be reached?
"The answer to this problem will be far more complex than simply telling anglers not to share their catch,” said Steve Raabe, principal of the Maryland-based research firm that conducted the survey.
The Anacostia Watershed Society, among the partners behind the survey, agrees. While the non-profit’s director of public policy acknowledged this study is not a “silver bullet solution,” he hopes it will bring about positive change.
“We are hoping [the study] will be the catalyst to engage all stakeholders—federal and local governments, food security and hunger organizations, environmental and health organizations, as well as residents—to come up with answers,” Brent Bolin said.
“Through this research effort, we have already begun identifying potential solutions,” Bolin continued, from directing better messaging to affected populations to expanding urban gardens, farmers markets and other programs that will address the long-term challenges of clean water, food security and human health.
The prevalence of intersex fish in the Potomac River basin has raised concerns about river health.
Intersex conditions, the presence of both male and female characteristics in an animal that should exhibit the characteristics of just one sex in its lifetime, occur when chemicals like pesticides, pharmaceuticals or personal care products enter the water and disturb the hormonal systems of fish and other species. Because the hormonal systems of fish are similar to those of humans, anomalies found in fish are an indication these chemicals may also pose a risk to people.
Image courtesy August Rode/Flickr.
According to a report released by the U.S. Geological Survey (USGS), intersex conditions in male smallmouth bass are widespread in the Potomac River basin: 50 to 75 percent of male smallmouth bass collected in the South Branch Potomac River exhibited signs of feminization, as did 100 percent of those collected at sites in the Shenandoah.
In the case of male smallmouth bass, the "intersex condition" reveals itself in the presence of immature eggs in the testes and of a certain protein--vitellogenin, normally found only in egg-laying females--in the circulating blood. Both conditions indicate exposure to chemical contaminants, and can result in reduced reproductive success or, in the case of a shorter-lived species like the fathead minnow, population collapse.
Intersex conditions have been linked to sewage flow from wastewater treatment plants and to runoff from farmland and animal feeding operations.
A popular sport fish, the smallmouth bass experienced spring kills in the Potomac and James rivers. A number of smallmouth bass collected during this survey were also observed with skin lesions, leading researchers to believe the fish may be a sensitive indicator of watershed health.
The USGS and Chesapeake Bay Program partners will use these findings to better identify chemical contaminants and their sources, planning to develop toxic contaminant reduction outcomes by 2013.
Learn more about the hormonal disruption of fish in the Chesapeake Bay watershed.
New tests by the Maryland Department of the Environment (MDE) show lower levels of contaminants in the Chesapeake Bay’s striped bass (rockfish), prompting the agency to increase its recommendation for the amount of the popular fish residents can safely eat.
Revised fish consumption advisories increase the recommended meal limits for striped bass caught in the Bay for nearly every population group.
The recommended meal limits for the general population for smaller striped bass increased by 50 percent, from two meals to three meals per month
The advisories no longer include the recommendation that had existed for women and children for certain striped bass
The new recommendations stem from recent test results that show a significant decline in PCB levels in striped bass from Maryland waters. Median PCB levels fell by more than half in fish analyzed between 2001-2005 versus in 2009-2010.
Data also suggest that contaminant levels are even lower in striped bass fillets prepared without fatty portions of the fish.
“Contamination has decreased in the striped bass we tested,” said MDE Acting Secretary Robert M. Summers. “Although we do not have the data to identify a specific explanation for the decline, PCBs have been banned in the United States since 1979, and we’re encouraged by this positive indication of the improving quality of our waters.”
MDE has also released new consumption advisories for bluefish caught in the Bay. Based on new data, MDE recommends a limit of two meals per month for bluefish less than 15 inches long. Residents should avoid eating bluefish larger than 15 inches.
Fish consumption advisories provide recommended limits on how often certain fish can be eaten and still enjoy health benefits while minimizing risks. For Maryland waters, fish consumption advisories are available on MDE’s website and posted at many public fishing areas.
For more information about the revised striped bass consumption advisory, including detailed consumption advisory charts, visit MDE’s website.
Many residents of the Chesapeake Bay region know that what they do on land has a direct effect on the Bay's health. But what lots of people don't know is that some of their everyday actions are actually major contributors of pollution.
The good news is that small changes in your daily activities can make a big difference. Consider the amount of people who live in our region. If each of the nearly 17 million Chesapeake Bay watershed residents changed one of the behaviors listed below, imagine how much it could help the Bay's health!
Here are five ways you may be hurting the Chesapeake Bay, and not even know it.
There is an unspoken competition in almost every neighborhood to have the best yard on the block. Everyone wants to hear their neighbors say, "Your flowers look so beautiful!" or ask, "How did your get your grass so green?" People often use large amounts of fertilizer and pest control products to get these results, ignoring the instructions provided on the packaging.
Excess fertilizer doesn't make your lawn extra green. It just gets washed off the grass during rain storms. This polluted runoff makes its way to the nearest storm drain, and then into your local creek or river, which eventually empties into the Bay. Fertilizer and pest control products contribute to "dead zones" that form in the Bay each summer: large areas of the Bay where fish, crabs and other life are unable to exist.
To reduce your yard's impact, limit fertilizing your yard to the fall months, when fewer rain storms allow fertilizer to stay on your lawn. Also, carefully follow product instructions so you don't apply more fertilizer than you need. Finally, pick plants that are native to your area; they require little to no fertilizer or pest control.
For more tips, check out the Plant More Plants campaign.
The one thing that most dog owners can agree on is how much they dislike picking up after their pets. Although most people hold their noses and pick up the waste, some give a few glances around them to see if anyone is watching and keep on walking. They may not know the harm they are doing to their local waterway and the Chesapeake Bay.
In addition to the risk of people stepping in the ignored waste (yuck!), another issue is that pet waste contains harmful nutrients, bacteria (like salmonella) and parasites (like roundworms). Just like fertilizer, runoff can pickup these harmful pollutants and send them straight into storm drains and local streams. Bacteria from pet waste can collect in water bodies, potentially causing infections and bacterial diseases in the people and animals that swim there. Who wants to eat a fish or crab that has been swimming in fecal matter?
Pet waste should be thrown away, flushed, or put in a pet waste composter. Do your part and pick up after your pet. It stinks, but we all need to do it for a clean Bay.
Spring is just around the corner, which means it is time to wash off all the salt and grime your car picked up during the harsh winter months. I bet many of you will think, "What a beautiful spring day. "I'm going to wash my car in the driveway." Think again! Washing your car the old-fashioned way, with a hose and bucket, can actually be very harmful to the environment.
Homeowners use an average of 116 gallons of water to clean their cars, while commercial carwashes use about 60 percent less. Additionally, you may think you are simply removing dirt and bird droppings, but motor oil, exhaust residue, heavy metals from rust and other possibly toxic substances will come off in your car wash. All of this, plus the soap you are using, will flow untreated down your street or driveway into the storm drain.
One way to reduce your impact and still have a clean car is to take it to a professional car wash. There, water is reused several times before it is sent to a treatment plant to be cleaned.
You can still wash you car at home, too. If you do, make sure to use a biodegradable, phosphate-free detergent. Also, wash your car on gravel or grass instead of on pavement. This gives water a chance to be absorbed and naturally filtered through the soil. And be sure to empty your wash bucket into a sink or toilet.
For more information on washing your car the Bay-friendly way, check out this pamphlet from the Environmental Protection Agency.
Remember when you used to be asked, "Paper or plastic?" at the grocery store? Well, we have a third option for you: reusable! Plastic bags are a huge source of trash pollution in the Chesapeake Bay's local rivers and streams. Most bags are used only once to carry purchases from one location to another, and then they are thrown away.
Not only is plastic bag trash unsightly, but the bags can harm animals who try to eat them or get trapped inside of them. And even if you throw them away, plastic bags can take 1,000 years to break down in the environment.
A number of cities and states have passed or are considering fees for plastic bag use. The most well-know is the District of Columbia, which launched its Skip the Bag, Save the River campaign to help clean up the Anacostia River. Maryland may create a similar law that would charge residents for each plastic bag they use.
So why not be ahead of the curve and start using reusable bags? They come in all sizes and colors. Many can even fold down to fit in a purse or glove compartment, making it easy for you to stash them away for your next trip to the store.
If you forget your reusable bags and have to use plastic, make sure you recycle your bags. Most local grocery stores have plastic bag recycling stations, as well as reusable bags for sale.
People have been told many reasons why they need to reduce the amount of time they spend behind the wheel. "You will get more exercise if you walk." "It will save you money on gas." But what about saving the Chesapeake Bay?
Pollution from air accounts for nearly one-third of the nitrogen pollution in the Bay, and vehicles are a large part of that. Like anything else released into the air, exhaust pollution will eventually come back down to the ground. Exhaust from cars also produces polycyclic aromatic hydrocarbons, or PAHs. When these toxic chemicals make their way into the water, they attach to sediment particles and can harm oysters, plankton and some species of fish. PAHs are thought cause cancerous tumors in catfish and other bottom-dwelling fish. Learn more about chemical contaminants here.
So help the health of animals and humans living in our region by driving less. Carpool to work, use public transportation or combine shopping trips.
For more ways to help, read our How To's and Tips page.
Welcome to the latest installment of the BayBlog Question of the Week. Each week, we take a question submitted on the Chesapeake Bay Program website or a frequently asked question and answer it here for all to read.
This week's question came from Mike, who asked, "Where can I find fish consumption advisories for the state of Maryland and other areas in the Bay watershed?"
We all love the fish and shellfish the Chesapeake Bay provides us with. But it's important to be mindful of the contaminants these species might be exposed to. If we eat fish and shellfish that have been exposed to toxic chemicals, it could harm our health.
Each of the Bay states and the District of Columbia post fish consumption advisories for specific species in certain bodies of water. Some are general advisories for everyone to abide by, while others are limited to sensitive populations, like children or pregnant and nursing women. These advisories are not necessarily meant to discourage you from eating fish and shellfish altogether, but rather to help you limit your consumption of contaminants that could be harmful to your health.
Check out your state's website for more information about fish consumption advisories in water bodies near you. Be sure to keep up with fish consumption advisories for your area if you fish the Bay or its rivers!
Do you have a question about the Chesapeake Bay? Ask us and we might choose your question for the next Question of the Week! You can also ask us a question via Twitter by sending a reply to @chesbayprogram! Be sure to follow us there for all the latest in Bay news and events.
“Intersex” fish – male fish with female traits – are showing up in more Chesapeake Bay region waterways. Government and university scientists have recently collected intersex smallmouth and largemouth bass from several waterways in Pennsylvania, Delaware and Maryland.
More than 90 percent of adult male smallmouth bass collected during studies on the Susquehanna River this year contained immature egg cells, according to a biologist with the U.S. Geological Survey.
The Susquehanna is the second major Chesapeake Bay river where scientists have found intersex fish. The Potomac River, as well as the Shenandoah and Monocacy rivers, have documented cases of intersex fish.
Intersex fish have recently been discovered in lakes and ponds on the Delmarva Peninsula as well. Researchers with the University of Maryland sampled six lakes and ponds in Maryland and Delaware and found intersex fish in all of the tested water bodies.
Scientists believe that male fish may develop these female trails through exposure to hormone-mimicking chemicals in the water. More research is needed, but these chemicals may come from agricultural pesticides, poultry waste, human personal care products or pharmaceuticals.
For more details about intersex fish in the Susquehanna River, read this Nov. 2 Baltimore Sun article. For more information about intersex fish found on Delmarva, read this Nov. 11 Baltimore Sun article.
A new report issued by the U.S. Geological Survey points to contaminated riverbank and floodplain soils as the main source of mercury found in fish in several Shenandoah Valley rivers.
The study found that 96 percent of the mercury loads to the South River – a tributary of the Shenandoah River’s South Fork – are from soil that was contaminated more than 50 years ago by a textile manufacturing plant in Waynesboro, Va.
Between 1929 and 1950, the textile plant discharged mercury waste that washed into the South River, eventually contaminating the South Fork of the Shenandoah River, the Shenandoah River and the floodplains along all three rivers.
“Currently, about 416 pounds of mercury get into the South River per year,” said Jack Eggleston, a USGS hydrologist and author of the report. “To meet safety standards in fish for human consumption, mercury loads to the South River cannot exceed 4 pounds per year. That’s a reduction of 99 percent.”
A health advisory on the consumption of fish from 128 miles of river downstream of the plant has been in place since 1977. The U.S. EPA sets mercury limits for fish at 0.3 parts per million, but fish and other wildlife can exceed this amount because they accumulate mercury in their bodies throughout their lifetime.
USGS scientists worked with partners from the Virginia Department of Environmental Quality (DEQ) and the U.S. EPA to collect and analyze hundreds of water and sediment samples. Computer models were used to simulate the movement of water, sediment and mercury in the South River watershed.
Based on the results of this study, Virginia DEQ will develop a plan for cleaning up the contaminated rivers.
Visit the USGS website for more information about the report.
Washington, D.C., has banned the use and sale of coal-tar pavement products to curb the flow of a toxic chemical contaminant called polycyclic aromatic hydrocarbons (PAHs) to the Anacostia River, Potomac River and Chesapeake Bay.
Coal-tar pavement sealers, which are commonly used to seal asphalt driveways and parking lots, are a major source of PAHs. The dust from parking lots sealed with coal tar has more than three times the concentration of PAHs as undiluted used motor oil, which is considered a leading source of PAHs. Other sources include auto exhaust, tire particles and broken-up asphalt.
A recent scientific study by the U.S. Geological Survey showed that PAH concentrations in dust from parking lots sealed with coal-tar products are about 80 times higher than in dust from unsealed parking lots. In D.C., rain washes these toxic PAHs from coal-tar sealant off paved surfaces and into the streams and creeks that flow to the Anacostia River, the Potomac River and the Chesapeake Bay. Research suggests that total PAH loads washed off parking lots could be reduced by as much as 90 percent if parking lots were left unsealed.
PAHs have been shown to cause cancerous tumors in animals, even in single doses. Non-cancerous health effects can include immune system suppression and red blood cell damage. In fish and invertebrates, adverse health effects have included cataracts, fin erosion, liver and reproductive abnormalities, and even death.
In the Anacostia River, scientists have discovered high rates of PAH-related lesions and tumors on bottom-dwelling fish. In one Fish and Wildlife Service study, 50 to 60 percent of collected fish had liver tumors. Tests suggested that PAH exposure was likely responsible for the tumors.
“It’s rare that we have a chance to knock out this kind of pollution in one fell swoop,” said George S. Hawkins, director of the D.C. Department of the Environment. “Now that we’ve discovered what’s in coal tar and what it does, we have a rare opportunity to protect our waterways relatively easily.”
The coal-tar pavement product ban took effect on July 1. Learn more about the ban at the District of Columbia’s website.
The Bay Program Toxics Subcommittee has updated its list of Toxics of Concern, ranking the toxic organic chemicals in the Chesapeake Bay with the most potential for harm. PCBs topped the list, followed by PAHs and organophosphate pesticides. Organochlorine pesticides and five other organic toxics are also included in the list.
The original Toxics of Concern list, which was completed in 1991, identified and documented chemicals that were adversely impacting or had the potential to impact the Bay. The list was subsequently refined in 1996 and 2000 prior to this latest update.
The 2006 Toxics of Concern list is based on the same chemical ranking system used for the 1996 list, incorporating chemicals' source, fate and effects of exposure. Also, like the 2000 list, fish consumption advisories and 303(d) impairments were considered for the 2006 revision.
The Toxics of Concern list is used by the Bay Program Toxics Subcommittee to help develop strategies to address the most problematic toxic organics in the Bay and its tributaries. It is not a complete list of all chemicals that may impact the Bay or its watershed. Some organics could not be included due to data gaps. Also, metals, such as mercury, are not included in the list because assessment guidelines comparable to those used for organics are not currently available.
Although PCB manufacturing was banned in 1977, PCBs can build up in bottom sediments and persist for many years; therefore, historic discharges of PCBs can still affect the Bay today. Also, when old PCB-containing equipment that is still in use fails, PCBs can flow into the nearest stream or river via stormwater.
PAHs are formed when coal, gasoline and fuel oil are burned and are a major component of tar and asphalt. The most rapid increases of PAHs in river bottom sediments are found in watersheds with increasing development and motor vehicle traffic.
Organophosphate pesticides are mostly herbicides and insecticides used in agriculture. Organochlorine pesticides, such as DDT, are no longer widely used but persist in the environment.
While they are relatively unknown to the public, PAHs—a class of chemical contaminants - have been shown to cause high rates of lesions and tumors on bottom-dwelling fish in at least two Bay tributaries: the Anacostia and Elizabeth rivers.
PAHs, or polynuclear aromatic hydrocarbons, are formed when coal, gasoline and fuel oil are burned. They are also a major component of tar and coal-tar based products. Specific sources of PAHs include:
In particular, coal-tar based driveway and parking lot sealants are a significant source of PAHs to the environment.
According to a study by the U.S. Geological Survey (USGS) in Austin, Texas, the average yield of PAHs from sealed parking lots was 50 times greater than that from unsealed lots. Estimates from this study indicate that total loads of PAHs coming from parking lots in the watersheds studied would be reduced to about one-tenth of their current loads if all of the parking lots were unsealed.
PAHs enter water bodies through run off from roads, driveways and parking lots into the closest storm water drain. Like PCBs, PAHs attach to sediment in water, where they are known to be toxic to plankton and bottom-dwelling organisms such as oysters and some fish.
Population growth and development are recognized as specific causes of PAH contamination of sediments. The USGS National Water Quality Assessment Program found that the most rapid increases of PAH collection in sediments were found in areas undergoing urban sprawl and increases in motor vehicle traffic.
Tumors and lesions found on fish in two Bay tributaries have been linked to high PAH concentrations.
In a study by the U.S. Fish and Wildlife Service (USFWS), between 50 and 60 percent of fish collected from the Anacostia River had liver tumors. These rates are alarming, as scientists consider an area with a liver tumor rate of more than 5 percent to be highly contaminated. Tests on fish tissues and bottom sediments suggest that exposure to PAHs is likely responsible for the tumors.
A related study examined the effects of PAH-contaminated sediments on mummichogs in Virginia's Elizabeth River. The study showed a strong correlation between tumors and liver lesions in mummichogs and PAH concentrations in the river.
Scientists are also taking a close look at the South River, located in Anne Arundel County, Maryland. In a 2005 study by the USFWS, 53 percent of brown bullheads had visible skin tumors and 20 percent had liver tumors. However, monitoring data for the South River do not show high PAH concentrations in bottom sediments.
Since the USGS study that found coal-tar sealants are a major source of PAHs, the city of Austin, Texas, has banned these sealants from use on parking lots. While there are no federal regulations against coal tar use in products, consumers can instead choose for their own driveways asphalt-based sealants, which contain significantly less PAHs.
In recent years, people have become increasingly concerned about the issue of toxic materials, like Polychlorinated Biphenyls (PCBs), contaminating fish and shellfish in water bodies around the world. In the Chesapeake Bay region, the Bay states have issued fish consumption advisories throughout the Bay and its rivers to protect the health of people who enjoy dining on the Bay's fish and shellfish.
One way that Bay scientists assess how toxic pollutants are affecting the animals and plants in the region, Bay Program partners have focused on PCB concentrations in local white perch. PCBs are persistent organic chemicals that were formerly used in industrial practices in the United States. They enter the environment and can impact the creatures living within it. Although PCBs are not the only contaminants in an area, PCB concentrations in white perch provide an indication whether other chemical contaminants are present in an area.
White perch are a good indicator of toxic contaminant concentrations in the Bay's waters because they are a resident species in the Bay; the majority of white perch remain in local waters throughout their lives. Considered an enjoyable fish to eat, white perch are a commercial and recreational fishery in the Bay. For scientists who are examining the effects of chemical contaminants on fish, as well as the impact on humans who eat PCB-contaminated fish, white perch are a logical species to study.
Data gathered from Maryland and Virginia suggests that PCB concentrations are higher among white perch in the upper Bay than they are in the lower Bay. Similarly, there is a trend in fish tissue where fish on the eastern shore have lower concentrations of PCBs than their counterparts on the western shore.
A common characteristic among the areas of the Bay where white perch have higher PCB concentrations is related to land development; the western shore of the Bay is more developed than the eastern shore of the Bay, and white perch from the Bay's western shore have higher PCB concentrations than their counterparts on the eastern shore. Additionally, white perch sampled from the Patapsco River had particularly high PCB concentrations, which can be attributed to the level and type of industrialization in the Baltimore area.
Many of the Bay's waters have active advisories for limiting the consumption of white perch. As is true with any fish, it is important for someone who plans to catch white perch in the Bay's waters to first check out the fish consumption advisories to see what the state recommends regarding consuming fish caught in the Bay and its rivers.
Without sufficient data to determine a trend in the PCB concentrations in white perch in the Bay, Bay scientists cannot say for sure what to expect regarding the future of those toxic contaminants in white perch in the Bay. However, PCBs were banned more than 25 years ago, so scientists expect to see a natural decrease in their concentration in white perch over time.
Chemical contaminants that get into the environment and harm the animals and plants around them are typically considered to be toxic pollution. Learn about toxic pollution in the Bay.