How are Local People Exposed to PCBs?
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Everyone in Northeast Wisconsin and Michigan is contaminated with PCBs. It’s just a matter of degree. Each of us has a unique history of PCB exposures over time, and we continue to accumulate PCBs even now. Unfortunately, many of us have lived through an explosive time when PCBs were used heavily from 1940 to 1980; therefore, we carry a large PCB dose with us, even though PCBs have declined overall since then. (Fox River PCB discharges started in 1954.) We will continue to carry the sum of most of our PCB exposures over our entire lifetimes. Any PCBs we pick up now are adding to levels which are already too high in our bodies in many cases. This means we must work to clean up as many PCB sources as we can, including the Fox River and Green Bay.
| The major local route of human
PCB exposure is through eating PCB contaminated fish from the Fox River,
Green Bay, Lake Michigan and connected tributaries. (Fish upstream of dams
on tributaries are less likely to be contaminated.)
Fish spend their whole lives acting like vacuum cleaners, as they eat smaller fish or insects contaminated with PCBs. They can gather high concentrations of PCBs from very small amounts in the water, because the smaller fish and insects have also spent years gathering PCBs. This food chain "bioaccumulation" can magnify the PCBs from 100,000 to 1,000,000 times higher than background PCBs. Fattier fish --- such as salmon, carp or suckers --- accumulate more PCBs because PCBs are attracted to and accumulated along with fat. Larger older fish tend to have more PCBs, because they’ve had more time to accumulate. Fish which eat other fish manage to collect more PCBs than fish eating only insects or vegetation. |
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The Wisconsin Division of Health and Wisconsin Dept. of Natural Resources (DNR) publish a Fish Consumption Advisory to let the public know which species of fish are most contaminated and which are "safer". They also give advice on how to trim and cook the fish to minimize the PCBs and other chemicals. However, these advisories are political compromises which still allow a 1-in-10,000 cancer risk in order to maintain the $8 billion Wisconsin tourism industry, commercial fishing and sport fishing industries.
Certain kinds of PCBs (out of 209 types) are more likely to accumulate in fish, especially the higher-chlorinated PCBs. This selectivity may result in increased health risks, such as cancer, associated particularly with those types of PCBs. Once contained in fish (and humans), these PCBs tend to be preserved in fat and degrade only very slowly.
People who eat fish from contaminated waters, such as Lake Michigan, have mean serum PCB levels several times those found in other general population groups. Some of these Lake Michigan fish eaters had PCBs levels at high concentrations similar to industrial workers involved in PCB capacitor manufacturing. (Kreiss, 1985)
Warnings have also been issued to limit human consumption of ducks which have nested or fed on the Fox River and Green Bay (or Sheboygan River). Many of them have accumulated high levels of PCBs.
Turtle, Frog and Crayfish Consumption
Turtles are known to accumulate extremely high levels of PCBs on the Fox River and Green Bay, but no government standards have been issued to warn consumers who eat local turtle stew or soup. Frogs and crayfish are shorter lived and accumulate fewer PCBs, but they still have measurable PCBs in their bodies. People who eat river and bay wildlife will accumulate more PCBs in their bodies.
Approximately 4,000 pounds of PCBs rise off the surface of the river and bay each year and blow downwind, according to the Green Bay Mass Balance Study, a cooperative project of many government agencies and research institutions led by the U.S. EPA. The enormous surface area of the bay and river contribute to this movement.
Many of these PCBs fall back into the water with rain or dust, only to rise again later. The system is constantly recycling. When PCB contaminated sediments or soil are newly exposed and drying in the air, the rate of PCB volatilization (evaporation) increases. This is true also for low water periods, as we’ve seen recently on the bay, when beach sediments are more exposed than usual. (This means dredged sediment must be handled properly to minimize exposure to the air.)
The closer a person is to the source, the higher the concentration of PCBs they breathe. The concentrations may be low relative to a meal of fish, but we breathe constantly, day and night, all our lives, which may make inhalation a cumulative risk. It may be that inhalation is a more direct exposure route to certain sensitive tissues (such as the nasal passages) and the blood stream. Several occupational health studies have detected PCB health effects primarily through inhalation of PCB vapors.
Certain lighter kinds of PCBs are more likely to rise into the air. These PCBs are more mobile, with fewer chlorines attached around the edges. They’re associated with certain kinds of PCB health risks, such as nervous system damage. (Parkinson’s, mood disorders, memory problems, etc.) When higher-chlorinated PCBs are degraded by sunlight or microorganisms, this often involves the loss of chlorine attachments, creating the lighter forms of PCBs. Therefore, PCBs do break down, but often just from one form to another.
The federal occupational health limit for PCBs in the air of workplaces is 1 microgram/m3, based on an 8-hour day, 5-days a week, according to the National Institute of Occupational Safety and Health. (1 microgram = 1,000 nanograms) This would translate into .240 micrograms/m3, or 240 ng/m3 for constant air exposure 24 hours a day, 7 days a week. This standard is outdated however, given the wealth of new health information coming available on PCBs. The standard also assumes that the people being exposed have no other PCB exposures at home, or in their food, air or water, when we know this is not the case. (Remember, many of us have already had a lifetime-plus dose of PCBs.)
According to DNR reports, 1995-1996 levels of PCBs in Green Bay air ranged from 0.04 to 2.15 ng/m3, with an average of 0.47 ng/m3. During warmer weather, the averages are much higher than in the winter. Improvements in sampling and analytical protocols led to an increase in the rate of detection, with PCBs detected in 92.6% of samples submitted. (A number of other toxic chemicals were detected at the same time.) The air monitoring station was located on South Washington Street in downtown Green Bay, just east (downwind) of the Fox River.
A 1989 study was conducted by the EPA’s Great Lakes National Program Office at the pilot atmospheric monitoring network at the University of Wisconsin, Green Bay Campus. This study reported levels of PCBs ranging from 3 to 6.5 ng/m3, with a 77.5% detection rate. These rates can be compared to a range of 0.6 to 1.8 ng/m3 obtained from a study conducted along the shore of Lake Superior in northern Wisconsin and Upper Michigan in 1984.
Dioxins and furans were also detected in Green Bay air by DNR in the same period. Dioxin totals were 0.0017 pg/m3 mean levels (max of .0211 and min of -0.0125). Furan totals were 0.1096 pg/m3 mean levels (max of 0.2067 and min of 0.0560)
According to the DNR’s air management section, the overall cancer risk of several toxins studied in 1994-95 (including PCBs) in Green Bay’s air ranged from 1-in-1,000 to 1-in-10,000. Government programs usually try to address problems creating more than one-in-a-million risk, but this issue has been neglected in Green Bay.
| PCBs can be rapidly absorbed through
the skin. Experts with the National Institute of Health speculate that,
due to the transport of PCBs on dust particles, the current primary route
of exposure of most people (non-fish-eaters) to PCBs is through skin exposure.
(Source: Matthews H., NIOSH and NIH) PCBs can settle out of the air with
the dust in our homes and workplaces, the dirt on our cars and sidewalks,
the invisible dust on our grass and bushes, the top layer of soil in our
gardens ---
where our skin comes into contact with it day after day. Dogs and children track the dust into the house. |
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PCBs can even pass through materials like PVC (polyvinyl chloride) plastic gloves. (Perkins et al, 1989) . Occupational studies show that skin absorption of PCBs is generally the route of entry into the bodies of exposed workers. (Wolff, 1985)
Monkey studies showed that in 24 hours they absorbed between 15.2 and 33.9 percent of the PCBs spread on their skin. Guinea pigs absorbed between 33.2 and 55.6 percent. The researchers concluded that "PCBs can be rapidly and excessively absorbed through the skin." (Wester et al, 1983)
Of particular concern are people who have regular contact with the sediments, water and fish of the Fox River and Green Bay, because PCBs could be absorbed through their bare skin, and they may track dirt and PCB contamination back to their homes. Swimmers, boaters, anglers and even waders along the shore are absorbing PCBs. Workers involved in dredging, moving, treating or disposing of contaminated sediments need to take extra precautions to avoid skin contact.
The lower-chlorinated PCBs (the ones more likely to be airborne or dissolved in water) are also more easily absorbed through the skin. These are different types of PCBs than the higher-chlorinated ones that tend to stick to particles and accumulate in fish. These PCBs are linked to different types of human health effects.
PCBs are present in Fox River, Green Bay and Lake Michigan water at low concentrations. The City of Green Bay decided in the 1950s to build a pipeline 30 miles to get drinking water from Lake Michigan proper (offshore from Kewaunee County) because local groundwater supplies were dropping and the Fox River and Bay were too obviously polluted to use. Most other communities in Northeast Wisconsin continue to use groundwater supplies, though some in the Green Bay area are considering building more pipeline capacity, because the River and Bay are STILL too polluted. The Wisconsin DNR does not classify the Fox River as a drinking water source; therefore, the pollution control standards are much weaker and dischargers can still dump significant pollution in the river.
All this means that most residents in Northeast Wisconsin are using groundwater with little or no PCB contamination. The City of Green Bay pumps and treats Lake Michigan water, which removes most of the particles. This removes most PCBs from the water, because PCBs prefer to stick to particles. Therefore, drinking water from the faucet is not a primary route of exposure. As one expert explained, "You’d have to drink a swimming pool full of city water to equal the PCB dose you’d get in just one meal of PCB contaminated fish from Green Bay."
Nevertheless, people swimming, sailing, or skiing on the Fox River and Bay may swallow raw water, particles and all. This may add to their body’s level of PCBs.
Exposure
in the Womb and Breastfeeding
| Children of PCB exposed adults
can get their heaviest and most important dose of PCBs even before they
are born. Several studies have found that PCB levels in the blood and tissue
of the unborn child are often equal to the mother’s PCB levels, even though
she spent years accumulating her PCBs. The PCBs pass directly through the
placenta to the baby. Once the baby is born, it gets additional PCBs, sometimes
in heavy doses, with its breast milk.
This early exposure is dangerous, because it comes at a time when the child is undergoing rapid growth and changes. The wrong chemical signal at a critical time in the baby’s development in the womb or after birth could change the rest of its life. These changes could leave them vulnerable to a variety of health effects later. (See Should Mothers Breastfeed Their Children?) |
eating PCB-contaminated fish. |
PCBs were widely used in our society for purposes most people were unaware of, such as for additives in paints and sealants, in fluorescent ballasts, in pumps and motors, inks, and electrical equipment. People were exposed through occupational or residential exposures. The International Agency for Research on Cancer determined as early as 1974 that "sea food and food packaged in gray cardboard packaging [recycled paper produced in the Fox River Valley?] appear to be the two main sources of dietary PCBs. Small residues may also occur in milk and meat products since upright silos may be sealed with PCBs." (IARC, 1974) Most of these uses have been outlawed, but PCBs are still allowed in old contained electrical equipment, as long as it lasts, such as transformers or capacitors. New electrical equipment is not allowed to contain PCBs. Recycled paper products are also allowed to contain traces of PCBs.
Because PCBs were used for decades for so many purposes, studies around the world have discovered that all humans now carry measurable levels of PCBs in their bodies.
For example, a 1972-74 Japanese study of 158 human cadavers from the general population found PCBs in all 823 samples analyzed from the fat tissue, head skin, abdominal skin, pancreas, liver, nails, heart, muscles, lung, brain, bile, kidney, serum, and spleen. Only the urine was uncontaminated. The maximum PCB level found in these samples was 6.25 ppm in abdominal fat tissue. The PCB blood levels of unborn babies equaled those of the mothers, showing that PCBs transfer to the fetus through the placenta. (Yamada, 1979)
In the U.S. in the 1980s, researchers found that mean serum levels of polychlorinated biphenyls (PCBs) in people without occupational exposure to PCBs were usually between 4 and 8 ng/mL, with 95% of individuals having serum PCB measurements of less than 20. (Kreiss, 1985)
Grande, David. Green Bay Urban Air Toxics Monitoring. (2 reports: 1991-95 and 1995-96) Wisconsin Dept. of Natural Resources, PUBL-AM-218-97 and PUBL-AM-230-97. 1997.
IARC. Polychlorinated Biphenyls. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man: Some Anti-Thyroid and Related Substances, Nitrofurans and Industrial Chemicals, Vol. 7, pages 261-289, 104 references, 1974
Kreiss K. Studies on populations exposed to polychlorinated biphenyls. Environ Health Perspect 1985 May;60:193-9
MATTHEWS H. BIOAVAILABILITY OF POLYCHLORINATED BIPHENYLS FROM SOIL Crisp Data Base National Institutes of Health. Author Address: NIEHS, NIH
Perkins JL, Knight VB. Risk Assessment of Dermal Exposure to Polychlorinated Biphenyls Permeating a Polyvinyl Chloride Glove American Industrial Hygiene Association Journal, Vol. 50, No. 3, pages A171-A172, 6 references, 1989.
Wester RC, Bucks DAW, Maibach HI, Anderson J. Polychlorinated Biphenyls (PCBs): Dermal Absorption, Systemic Elimination, And Dermal Wash Efficiency. Journal of Toxicology and Environmental Health, Vol. 12, No. 4, pages 511-519, 17 ref,1983
Wolff MS. Occupational Exposure To Polychlorinated Biphenyls (PCBs). Environmental Health Perspectives, Vol. 60, pages 133-138, 16 references, 1985
YAMADA T. Studies on polychlorinated biphenyls in organs and tissues of Japanese in 1972-1974. J NARA MED ASSOC; 30 (6). 1979. 445-456.
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