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BIOACCUMULATION / BIOMAGNIFICATION EFFECTS
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Persistent Organic Chemicals from landfills bioaccumulate, or build up in the tissue of the food we eat. This diagram shows the degree of concentration in each level of the Great Lakes aquatic food chain for PCBs (in parts per million, ppm). The highest levels are reached in the eggs of fish-eating birds such as herring gulls. |
Richmond Rivers And Streams Under Fishing Advisory
Do not eat certain species of 'bottom
feeders" due to PCB contamination! 
Must Read
The nutrients necessary for plant growth (e.g., nitrogen and phosphorus) are found at very low concentrations in most natural waters. In order to obtain sufficient quantities for growth, phytoplankton must collect these chemical elements from a relatively large volume of water.
In the process of collecting nutrients, phytoplankton also collect certain human-made chemicals, such as leachate from landfills, which may be present in the water at concentrations so low that they cannot be measured even by very sensitive instruments. The chemicals, however, biologically accumulate (bioaccumulate) in the organism and become concentrated at levels that are much higher in the living cells than in the open water. This is especially true for persistent chemicals - substances that do not break down readily in the environment - like DDT and PCBs that are stored in fatty tissues.
The small fish and zooplankton eat vast quantities of phytoplankton. In doing so, any toxic chemicals accumulated by the phytoplankton are further concentrated in the bodies of the animals that eat them. This is repeated at each step in the food chain. This process of increasing concentration through the food chain is known as biomagnification.
The top predators at the end of a long food chain, such as lake trout, large salmon and fish-eating gulls, may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low. The concentration of some chemicals in the fatty tissues of top predators can be millions of times higher than the concentration in the open water.
The Arctic Monitoring and Assessment Program said in a Sept. 24, 2002 report that mercury levels in some Arctic indigenous people are high enough to affect children's development, and PCBs build up in the food chain, especially in fatty tissue like blubber -- key nutrition for polar bears and the Inuit. As a result polar bears and Inuit suffer subtle effects on the immune system, brain development and reproduction.
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STATE HEALTH COMMISSIONER ISSUES FISH ADVISORY IN TWO SOUTHWEST RIVERS
(Richmond, Va.)
The Virginia Commission of Health has issued a fish consumption advisory for carp in certain parts of the New River and Bluestone River due to contamination with polychlorinated biphenyls (PCBs).
"The first part of the advisory recommends no consumption of carp in the New River beginning at the Route 114 bridge crossing (Peppers Ferry Blvd.) just north of Radford, Virginia. The advisory continues downstream to the Virginia-West Virginia state line near the town of Glen Lyn in Giles County, Virginia. Carp samples caught in the New River at Glen Lyn had PCB levels at 3,259 parts per billion (ppb). Carp samples caught in the New River at Whitethorne had PCB levels at 686 ppb. The health departments level of concern for PCBs is 600 ppb or higher," Dr. Peterson said.
The second part of the advisory recommends no consumption of carp caught in the Bluestone River beginning at the Route 460 bridge crossing just south of Bluefield, Virginia. The advisory continues downstream to the Virginia-West Virginia state line near the town of Yards in Tazewell County, Virginia. Carp samples caught in the Bluestone River at Falls Mills had PCB levels at 2,369 ppb.
"Fish is an important part of a balanced diet and is a good source of protein. People should continue to eat other kinds of fish caught in these areas. Other species of fish caught in the New River and the Bluestone River did not have high levels of PCBs and are safe to eat," Dr. Peterson said.
The fish consumption advisory was issued after data from the Virginia Department of Environmental Qualitys (DEQ) routine fish tissue sampling was evaluated by the Virginia Department of Health. "DEQ will be collecting additional fish samples from the affected segments of the Bluestone River and the New River to better define the extent of the advisory areas. In addition, DEQ will investigate possible sources of the PCBs, which apparently have entered the rivers over many years," said Khizar Wasti, Ph.D., Director of the state health department's Division of Health Hazards Control.
PCBs are a group of man-made industrial chemicals that exist as a mixture and may contain up to 209 individual compounds. Since 1977, PCBs have not been produced in the U.S., but they are still found in the environment. PCBs were once widely used as coolants and lubricants in transformers, capacitors and other electrical equipment.
(Follow These Steps In Cooking River and Stream Fish)
Long-term consumption of
fish contaminated with high levels of PCBs may
increase the risk of cancer. The Virginia
Department of Health recommends the following
preparation precautions to reduce any potential
harmful effects from PCBs:
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