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PUBLIC HEALTH ASSESSMENT

WESTERN PACIFIC RAILROAD, OROVILLE
OROVILLE, BUTTE COUNTY, CALIFORNIA


APPENDICES

APPENDIX A: EPA METHODS 3550/8015

EPA Method 3550 is reported to be a method for the preparation of the soil sample for analysis. It is an extraction by sonication which is conducted to make it easier to detect the heavier or diesel range hydrocarbons (>C24). However, this has the effect of lowering the sensitivity for the lighter semi-volatile C10-C20 hydrocarbons, and not detecting quantitatively the volatile, below C10, or short chained hydrocarbons. Method 8015 is the gas chromatographic method using a flame ionization detector (California Analytical Laboratories, personal communication, July, 1990, and California DHS Hazardous Material Laboratory, personal communication, April, 1991). This method more accurately quantifies total extractable hydrocarbons (TEH), rather than total petroleum hydrocarbons (TPH).


APPENDIX B: WELL INVENTORY FOR WESTERN PACIFIC RAILROAD SITE

Well Inventory for Western Pacific Railroad Site

Well Name Well Number Owner/Location Year Drilled Diameter Depth of Well Screened Interval Ground Surface Interval Water Level Data Pumping Capacity (gpm) Water/Quality Tested Well Use
MW-3 19N/4E-19 Olive Products Evaporation
SW of Plant
1986 Kleinfelder 2.5' 60' 45-60'   26.37'   No Monitor
Wyandotte 19N/4E-200 Wyandotte Olive Growers/NW. Corner of Idora/Truckee 1925 10' 334' Unknown 210'     No Unknown
Roco 19N/4E-29 Roco (Box 205)
.8 Miles off Marysville/Baggett
1979 6 5/8' 145'     120'   No Domestic
O.J. Sampson 19N/4E-29E O.J. Sampson
.25 Miles off West/Pac. Crossing
1956 10' 104' 56-86'   41'   No Domestic
Boyd 19N/4E-30 Boyd (Box 577)
300' from W. Line
1975 12' 140'     20'   No Industrial
Pruitt   Pruitt
2825 Marysville/Baggett Rd.
1950?   110'         Yes Domestic
Olive Products   Olive Products
1800 Idora St.
1960?   150'?         Yes  
Sewage Treatment Plt.   2880 55th St. 1978   150'       200 Yes  
Card 19N/4E-5E-19 Paul Card
5250 Olive Highway
1979   180'     110' 5.5 No Domestic
Carson 19N/4E-19 .25 Mile off Olive Hwy./ Miner's Ranch Road 1979 6' 120'     19' 6 No Domestic
C.P.I. 19N/4E-19 C.P.I. 1985 10' 90'     37'   No Domestic
Diamond Int. Corporation 19N/4E-19 Diamond Int.
2733-5th Ave.
Lumber Yard
1976 16' 240' 85-227'   12'   No Irrigation
Western Pacific 19N/4E-20N1 Western Pacific Unknown 1' 152' Unknown 195' 70' 575 Yes Municipal
CWS 2-01 19N/4E-18C1 CWS
7th/Montgomery
1928   186' 100'   38' 1050 Yes Municipal
CWS 15-01 19N/4E-20C1 CWS
Fort Wayne Rd./
W. of Truckee Rd.
1948   335' 60'   32' 150 Yes Municipal
CWS 10-01 19N/4E-7P1 CWS
Marysville Rd./
N. of Stafford St.
1956   150' 98'   43' 800 Yes Municipal
13 19N/4E-19 Groundwater Tech.
480 Oro Blvd.
1986 2' 22' 8-22'   17'   No Monitor
12 19N/4E-19 Groundwater Tech.
480 Oro Blvd.
1986 2' 22.5' 8-22'   17'   No Monitor
11 19N/4E-19 Groundwater Tech.
480 Oro Blvd.
1986 2' 22' 8-22'   17'   No Monitor
MW-1 19N/4E-19 Olive Products Evaporation Pond
SW of Plant
1986 Kleinfelder 2.5' 30' 10-30'   8.9'   No Monitor
MW-2 19N/4E-19 Olive Products Evaporation
SW of Plant
1986 Kleinfelder 2.5' 30' 10-30'   18.41'   No Monitor
* Approximately 0.35 Mile North of Marysville-Baggett Rd. on W.P. Access to Well is on the Southside of W.P. Office Building.


APPENDIX C

State of California—Health and Welfare Agency
Department of Health Services
2151 Berkley Way
Berkeley, CA 94704-1011
(415) 540-3657

May, 1991



Update on Oroville Health Studies
May, 1991

Dear Resident:

The California Department of Health Services (DHS) began its investigation in Oroville in 1985, when residents were concerned about pentachlorophenol (penta) contamination in their drinking water. After the Koppers fire in 1987, DHS became involved in investigating possible dioxin contamination in the surrounding community. This letter presents an update of the penta and dioxin studies.

UPDATE ON PENTACHLOROPHENOL STUDY

Study of Potential Community Exposure to Penta in the Drinking Water

Penta was detected in the groundwater near the Koppers facility. DHS interviewed residents who lived in that area and took tap water and urine samples. The interview included questions about health problems and other factors such as age and sex. DHS also chose a control neighborhood near Oroville. The control neighborhood was similar to Oroville in most ways, but there was no known penta contamination. Residents of the control neighborhood were also interviewed and tap water and urine samples were taken. At the present time, DHS is comparing the frequency of health problems among the people living near Koppers and the people in the control neighborhood. DHS is also determining if there is a relationship between the concentrations of penta in the well water, tap water and urine samples taken in Oroville.

UPDATE ON DIOXIN STUDIES

Investigation of Dioxin Contamination in Animal Produce

In 1988, DHS took a variety of samples from homes located near Koppers, including samples of soil and chicken eggs, and analyzed these samples for dioxins. This analysis showed that the eggs and meat from chickens that were allowed to peck in the soil contained high levels of dioxins. After more homes were identified with contaminated chicken eggs, DHS issued a Health Advisory in January, 1989 which recommended that people reduce their consumption of chicken eggs produced in the area. DHS also took blood samples from the people who lived at the two homes with the highest levels of dioxins in the eggs.

DHS is investigating the contamination in animal produce (which include eggs, meat and milk) because the main route of dioxin exposure for the people in Oroville seems to be eating home-produced chicken meat and eggs. DHS wants to answer the following questions in its Oroville investigation:

  1. In what parts of Oroville and South Oroville is animal produce contaminated with dioxins?


  2. In what way could animal produce become contaminated? Is it from the air, soil, or water?


  3. What is the source of the dioxin contamination?


  4. Besides chicken eggs and meat, is other animal produce (such as cow milk and beef) also contaminated?

In order to answer these questions, DHS has been involved in the studies which are described below.

Review of Land Use in South Oroville

DHS reviewed county documents to find out how the land around Oroville had been used in the past. DHS now has a listing of the potential sources of dioxins in South Oroville that existed after 1960. Besides Koppers, these sources include incinerators and areas where pesticides may have been used. DHS is currently evaluating this list of sources to determine if additional samples should be taken at each source.

Chicken Feeding Study

This study has three purposes:

  1. to determine whether the dioxin contamination found in the chicken eggs was the result of the chickens' exposure to soil, air or water.


  2. to determine how long it takes for a chicken to produce contaminated eggs once it has been exposed.


  3. to determine how the dioxins accumulate in a chicken's body.

In the first part of the study, chickens were raised in an enclosed area in a backyard in Oroville. The chickens were allowed to peck on the soil. In the same backyard, another group of chickens was raised in cages without being allowed to peck on the soil. Both groups of chickens had the same feed, air and water. Since the only difference between the two groups of chickens was the contact with soil, any differences in the amount of dioxins in the chicken eggs and meat would be the result of contamination in the soil.

In the second part of the study, three groups of chickens were raised in a laboratory at UC Davis. Scientists mixed soil into the chickens' feed. One group received soil that contained no dioxins; another group received soil from the Oroville backyard, and the third group also received soil from the backyard but with more dioxins added to it. This part of the experiment would help determine how quickly dioxins are picked up from the soil, and how different dioxins accumulate in the chicken eggs and meat.

Preliminary results of the analysis show that the chickens that were not exposed to contaminated soil did not have dioxins in their eggs or meat, while the chickens that were exposed to contaminated soil did have dioxins in their eggs and meat. This suggests that the dioxins found in the chicken eggs are the result of the chickens' exposure to soil. The levels of dioxins in the eggs and meat were higher than the levels of dioxins in the soil, which suggests that dioxins concentrate in the chickens' bodies. At the present time, DHS is continuing to analyze the samples that were collected to confirm these findings, and to determine how long it takes for the chicken to produce contaminated eggs once it has been exposed.

Breast Milk Analysis

Studies have found that women in the general population have very small amounts of dioxins in their breast milk. This is not surprising since dioxins are found in small amounts throughout the environment and it is known that dioxins accumulate in fat. In 1988, DHS took samples of breast milk from three Oroville women. These women did not eat home-produced eggs or meat, so they did not have any additional exposures to dioxins that were identified. Analysis of their breast milk showed that the levels of dioxins in the breast milk were very similar to the levels reported for women in the general population.

Analysis of Beef Samples

Cow Livers: DHS took samples of cow liver in 1988 and analyzed them for dioxins. In a previous fact sheet, DHS reported that liver samples from a cow that grazed at a home in South Oroville after the fire were contaminated with dioxins. DHS has also analyzed liver samples from cows that grazed at this home before the 1987 fire. These samples contained as much dioxins as the cow liver from the cow that had grazed after the fire. These results show that the fire is not the only source of dioxin contamination at this home.

DHS has advised the residents of this home to not eat home-produced cow meat. However, DHS cannot use one sample to give advisory guidelines for the entire Oroville area. DHS does not know if other cows were also contaminated before the fire or if they are contaminated now.

Cow Milk: In 1988, a sample of cow milk was collected from a cow that grazed in a backyard in Palermo. DHS had already analyzed the chicken eggs from this home and found that they only contained low levels of dioxins. The cow milk was found to contain levels of dioxins that were much higher than the levels typically found in grocery store milk. DHS advised the family to stop drinking the cow milk. As with the cow livers, DHS cannot use one sample to give advisory guidelines for the entire Oroville area.

Analysis of Soil in One Backyard

A limited amount of soil sampling was done in 1988 at several of the homes where chicken eggs with high levels of dioxins were produced. This soil sampling showed that the soil contained levels of dioxins ranging from about 20 to 50 parts per trillion (ppt). In soil, levels of dioxins below 1000 ppt are considered safe. The levels found in the homes were well below 1000 ppt. In order to see if there was a wide range of dioxins levels in soil, DHS took about 30 soil samples from one of the homes. The backyard was divided up so that DHS knew which soil samples had come from the cow pasture and which had come from the chicken yard. Preliminary results show that the levels of dioxins are all much less than 1000 ppt and that the dioxins are spread out evenly in all areas of the backyard.

Study of the Air Released from Stacks at Wastewood Burners

At the request of DHS, the California Air Resources Board tested the air released from the stacks of the wastewood burners at Pacific Oroville Power, Louisiana-Pacific, and Koppers. The air was tested for dioxins. The results were received by DHS in May, 1991 and they are currently being evaluated. Preliminary analysis shows that the levels of dioxins released by the stacks are very low.

If you have any questions about these studies, please call Michael Armstrong, Jennifer Flattery, or Suzanne Teran collect at 415/540-3657.


Environmental Epidemiology and Toxicology Branch
5900 Hollis Street, Suite E
Emeryville, CA 94608





State of California—Health and Welfare Agency
Department of Health Services
2151 Berkley Way
Berkeley, CA 94704-1011
(415) 540-3657

May, 1991



Dear Resident:

This letter contains answers to a series of questions posed by the residents of Oroville. If you have any questions about the information presented here, please call Michael Armstrong, Jennifer Flattery or Suzanne Teran collect at (415) 540-3657.

DIOXINS

  1. What are dioxins?
    The term "dioxin" refers to over 200 chemicals which are grouped together because they have a similar chemical structure. Dioxins are part of the waste that is produced by many different industrial processes, such as wood treatment, chemical manufacturing, waste incineration, and metal recovery.


  2. What does a "dioxin fingerprint" mean?
    Although there are various industries that produce dioxins, each industry produces a different combination of dioxins. For example, dioxins that are produced as a result of treating wood with pentachlorophenol (penta) are different from the dioxins that are produced from burning municipal waste. Each industry produces different types of dioxins in different amounts. Each of these combinations is called a fingerprint.
  3. Department of Health Services (DHS) compares the dioxin fingerprint found in a sample (for instance a sample of soil) to the known fingerprints of different industries. By making this comparison, DHS may be able to identify the industrial source of the dioxin contamination.

    Scientists do not know if there are also more specific differences between fingerprints that are produced by the same industry. For example, although all dioxin fingerprints produced by using penta are similar, scientists do not know if the fingerprint from penta used by Koppers is slightly different than the fingerprint from penta used by another facility. The process of identifying fingerprints is very difficult, and scientists may never be able to identify specific fingerprints for each facility.

HEALTH CONCERNS

  1. How might people be exposed to dioxins?
    It is believed that people everywhere have very small amounts of dioxins in their bodies. The people who are most likely to be further exposed to dioxins are the ones who work in industrial facilities that produce dioxins as waste. People who live near such facilities might be exposed if dioxins spread into the surrounding community. People can be exposed to dioxins by coming into contact with contaminated soil, inhaling contaminated dust or by eating foods that are contaminated with dioxins, such as eggs and meat that are home-produced on contaminated soil.


  2. How might residents of Oroville have been exposed to dioxins?
    The main route of dioxin exposure for people in Oroville seems to be eating home-produced chicken meat and eggs. DHS has recommended that people reduce their consumption of home-produced eggs because of the dioxin levels found in some eggs.


  3. What are the health effects of dioxins? What are the risks of cancer and birth defects in Oroville?
    Tests have shown that dioxins can cause a wide range of health effects in laboratory animals. These include cancer, birth defects, liver damage, digestive problems, weight loss and damage to the immune and reproductive systems.
  4. Human exposure to large amounts of dioxins has led to severe skin reactions and liver problems. There is now scientific evidence that dioxins can cause cancer in humans. This evidence is based on people who were exposed on the job to much larger amounts of dioxins than those found in Oroville.

  5. Will DHS do a cancer investigation in Oroville?
    In California, one in three people get cancer. Because cancer is so common, it is very difficult to do a cancer investigation to determine if a community has a higher rate of cancer than expected.
  6. In July, 1988 the Region VI Cancer Registry was set up to monitor cases of cancer in the northern region of California. DHS will monitor the cancer cases that are reported in Butte County. Unless the number or types of cancer that are reported are unusual, DHS does not plan to conduct a cancer investigation in Oroville.

  7. Is it safe to live in Oroville? If people moved now, would they decrease their risk of disease?
    Based on the environmental sampling conducted for dioxins in Oroville, DHS does not believe that dioxin levels in the environment are a threat to the health of people living in the area. DHS took soil samples at the homes where the contaminated eggs were produced and found that the dioxin levels in these samples were higher than those which might be expected for a rural community, but they were far below levels that have been shown to cause any health problems in humans.
  8. There is evidence that chickens and cows eat soil as they graze. If this soil is contaminated with dioxins, the dioxins can concentrate in the tissues of the chickens and cows. The consumption of contaminated eggs and meat is the main source of dioxin exposure to the people in Oroville. Eating contaminated eggs or meat increases people's exposure to dioxins, which increases their risk of long term health effects. Simply living in Oroville is not considered to be a health risk, so moving from Oroville would not decrease the risk of future health effects.

  9. Does the health advisory refer to all of Oroville or just South Oroville?
    In 1989, DHS issued a health advisory which recommended that people reduce their consumption of home-produced eggs. Contaminated eggs have also been found outside of South Oroville. Therefore, the health advisory refers to all of Oroville and the surrounding area because DHS does not know the geographical boundaries of the contamination. The surrounding area includes South Oroville, Palermo, Thermalito and East Biggs.


  10. What are the health effects of dioxins when they are combined with other chemicals?
    There are so many possible chemical combinations that toxicologists cannot predict the health effects of a combination of two chemicals, let alone three or more. Health effects of combinations of chemicals are a subject that scientists continue to study. When dioxins are present with other chemicals, the toxicity of any of the chemicals may increase, decrease or stay the same. At this time, scientists assume that chemicals which cause the same health effect do so with greater strength if they are combined.


  11. Oroville residents state that there is a high rate of respiratory problems and that the air still burns people's eyes and lungs. Are these problems caused by exposure to dioxins or other chemicals?
    Respiratory problems are not symptoms that have been observed as a result of exposure to dioxins. The respiratory system can be irritated when the air is dry or when the air contains pollen, smog, wood smoke, cigarette smoke or various other chemicals produced by industries. These contaminants may be the cause of the respiratory problems reported in Oroville. The local air pollution control district should be able to identify potential sources of contaminants which irritate the respiratory system. As a community grows, pollution usually increases. This could also lead to increased irritation of the eyes and respiratory systems.

ENVIRONMENTAL CONCERNS

  1. How long have people in Oroville been exposed to dioxins? What is the source of the contamination? Is the community still being contaminated?
    Since the source of the dioxins has not been determined, DHS does not know how long people have been exposed to them. Samples of cow livers from animals butchered before the 1987 fire show that the contamination existed before the fire. DHS is attempting to determine the source of the dioxins, but because of the limits in environmental science and the many potential sources of dioxins, a single source may never be identified.
  2. DHS has not yet determined whether the community is still being exposed to dioxins. As was mentioned earlier, the main route of exposure seems to be eating home-produced eggs and meat. DHS is currently involved in studies which say establish whether a source of exposure still exists. (Please see "Update on Oroville Health Studies, May 1991").

  3. Why can some people continue raising and selling their animal produce while others cannot?
    In January 1989, DHS advised the people who lived at the homes with the contaminated chicken eggs to stop eating and selling their eggs. Because DHS didn't know if untested chicken eggs were contaminated, DHS issued a Health Advisory which recommended that people from Oroville and the areas around Oroville reduce their consumption of eggs produced by chickens that are allowed to peck on soil.
  4. DHS has not tested home-produced animal produce at all Oroville homes. Since the extent of dioxin contamination in the soil is not known, DHS cannot predict whether animal produce will be contaminated. In some cases, samples that were taken from one property had low levels of dioxins, while samples taken at a neighboring property had very high levels of dioxins. DHS cannot assume that animal produce is contaminated if it hasn't been tested.

  5. Why aren't real estate agents forced to advise prospective buyers of the contamination?
    DHS does not have the legal authority to force real estate agents to advise prospective buyers of the contamination. The local government has this authority. DHS has the authority to declare an area a hazardous waste site and forbid its use for homes, day care centers, schools, health institutions, etc., but the levels of contamination in Oroville are well below hazardous waste site levels.


  6. Shouldn't the old Oroville-Wyandotte Irrigation District (OWID) well near Custer Lane be tested as a potential source of dioxin contamination? Would this help identify Koppers as the source?
    A small number of water samples from one well would not identify Koppers as the source of dioxins. DHS does not believe it is likely that dioxins would be found in the water because dioxins do not easily dissolve in water. Instead, dioxins remain attached to soil. If dioxins were to reach the groundwater, they would generally remain attached to the soil and not move with the flow of water.
  7. DHS did test the water at one of the homes near Custer Lane, and could not detect dioxins in the sample. Using current technology, however, scientists cannot detect extremely low levels of dioxins in water. Therefore, DHS does not know if there were no dioxins in the sample, or if the levels were too low to be detected. If samples were taken from the old OWID well, it is likely that the laboratory would not be able to detect dioxins.

  8. Are other places besides Oroville contaminated with dioxins?
    Industries that produce dioxins as waste are located throughout California. Some industries have made improvements that reduce the amounts of dioxins that are created. Scientists do not know to what extent dioxins spread from the facilities into the surrounding communities. DHS has detected dioxin contamination in another community in California and is continuing to study the spread of dioxins into communities.


  9. Has DHS done any testing in Palermo?
    DHS analyzed samples of chicken eggs, goat milk, cow liver, cow milk, soil and water from Palermo. All these samples were found to have very low levels of dioxins, below the levels of concern for people's health. Seven samples of chicken eggs were taken from six different homes. The dioxin levels in these eggs were less than 5 parts per trillion (5 ppt). DHS advises that people stop eating eggs if they contain levels of dioxins above 5 ppt, and that people reduce their consumption of eggs if they contain levels between 1 and 5 ppt. Some of the eggs tested in Palermo contained levels of dioxins above 1 ppt. Palermo is therefore included in the Health Advisory, and DHS has recommended that people reduce their consumption of chicken eggs produced in the area.
  10. The soil samples taken from a yard in Palermo showed very low levels of dioxins, comparable to those found in other rural areas. The laboratory was not able to detect dioxins in the water samples from this yard.

    The sample of cow liver and the sample of goat milk had levels of dioxins below 1 ppt, which are considered safe for people to eat. The sample of cow milk taken from a home in Palermo was found to have a level of dioxins that was much higher than the level typically found in grocery store milk. DHS advised the people at that home to not drink the cow milk. Since only one sample of cow milk was taken, DHS cannot give advisory guidelines about cow milk for the entire Oroville area.

  11. Are the dioxin fingerprints in the water the same as the fingerprints in the soil?
    DHS was not able to detect dioxins in the water samples taken from the homes with contaminated chicken eggs. Therefore, DHS was not able to identify the dioxin fingerprints in the water. Some of the soil samples appear to have the dioxin fingerprints that are produced by penta. Other fingerprints from soil samples taken by DHS are still being compared to the known fingerprints of industrial sources.

KOPPERS

  1. Based on the dioxin fingerprints, the State had made a statement identifying Koppers as the source of the contamination. Now they have backed off from that position. Is the State trying to cover up for Koppers?
    DHS never stated that Koppers was the known source of the dioxin contamination. DHS has stated that the dioxin fingerprints found in eggs and some of the soil samples look like the fingerprints produced by penta. DHS has also stated that Koppers is a large user of penta in the area. Although DHS has found that the dioxin fingerprints look like penta fingerprints, we have not been able to determine if the penta fingerprints are specifically from Koppers' penta.


  2. Why doesn't DHS look for other chemicals that Koppers uses and produces, in addition to dioxins, to establish the source of the contamination?
    It is just as difficult to trace other chemicals to their source as it is to trace dioxins. Koppers does not seem to be the only source of any one chemical. For example, there is arsenic contamination at Koppers, but there are also many other sources of arsenic in the community, including natural sources. If DHS found that there was arsenic contamination in the backyards where the dioxin contaminated chicken eggs were produced, DHS would not know whether the arsenic came from Koppers, a natural source or another industrial source.
  3. In addition, different chemicals spread in different manners throughout the environment. If DHS found the source of arsenic, it would not prove that dioxins also came from the same source.

  4. Who is monitoring Koppers' continued use of chemicals?
    Local fire, law enforcement and health officials are monitoring Koppers' use of chemicals. They are responsible for monitoring the use and storage of chemicals, as well as chemical transport in and through the community. The U.S. Environmental Protection Agency, the DHS Toxic Substances Control Program and the Regional Water Quality Control Board are responsible for monitoring the handling and storage of hazardous waste produced at Koppers. These agencies also monitor the ongoing Superfund clean-up at Koppers. The Superfund program is a federal program for investigating and cleaning up hazardous waste sites throughout the country. If a spill, fire or other accident should occur, these federal and state agencies could assist the local officials, as they did after the fire in April, 1987.
  5. Businesses that use chemicals are required by law to produce a plan for an emergency response to spills, fires or other accidents. Koppers' plan was updated in May, 1990. This plan includes an inventory of all hazardous materials used and/or stored at Koppers. Residents can request copies of the plan from local fire, law enforcement and health officials.

DHS STUDIES

  1. Will a study of how the land was used in the past help identify the source of dioxin contamination?
    A land use study will identify where incinerators and other potential sources of dioxins have been in the past. It will also identify where pesticides may have been used in Oroville. However, it will not identify a specific source of the dioxin contamination in Oroville.


  2. What were the results of the blood and urine samples tested for pentachlorophenol after the fire?
    In April 1987, DHS collected urine samples from 448 people at the Koppers' Fire Clinic. Samples were taken from residents and from people who worked during the fire (i.e. firefighters). The laboratory could not detect penta in the urine of 440 people. However, the laboratory could only detect levels of penta that were above 10 parts per billion (10 ppb). DHS does not know if these 440 people had 9 ppb of penta in their urine, or if they had none at all. The level of penta is reported by the laboratory as "less than 10 ppb." Studies of people with no known exposure to penta have found that levels of penta in the urine range from 1 to 17 ppb.
  3. The other eight people, who were all exposed to penta while on the job, had levels between 11 and 153 ppb of penta in their urine. These levels are well below the levels of penta that have been shown to cause health problems.

    DHS also collected blood samples from 224 adult people. The laboratory could not detect penta in the blood of 219 of these people. However, the lowest level that the laboratory could detect in blood was 50 ppb. DHS does not know if these people had 49 ppb of penta in their blood or if they had none at all. The level of penta is reported by the laboratory as "less than 50 ppb." Studies of people with no known exposure to penta have found that levels of penta in blood range from 15 to 75 ppb.

    The other five individuals, who were all exposed to penta while on the job, had levels between 60 and 355 ppb. These levels are well below the levels that have been shown to cause health problems.

  4. Why did DHS use Nevada County as the control site for the egg sampling and blood testing? Why didn't they choose a place where higher levels might be expected?
    Nevada County was chosen because it is similar to Oroville in many ways but it does not have industries which are known to produce dioxins. This allows DHS to use the measurements found in Nevada County as "control levels," that is, levels that may be expected in a community that has no known contamination. By comparing the levels found in Oroville to these background levels, DHS can determine if the levels in Oroville are elevated. If DHS had chosen an area where high levels of dioxins were expected, we would not be able to determine if the Oroville levels are high for a rural area.


  5. Why is the study so slow? Why did the lab results take so long?
    DHS is fortunate to have one of the few laboratories in the country that can analyze samples for dioxins. However, dioxin research can be frustrating because it is slow and tedious. The laboratory analysis involves many steps and it is time consuming. DHS has continued its dioxin research in Oroville, but the current phase of the research is less visible. (Please see "Update on Oroville Health Studies", May 1991.)


Environmental Epidemiology and Toxicology Branch
5900 Hollis Street, Suite E
Emeryville, CA 94608

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