Skip directly to search Skip directly to A to Z list Skip directly to site content

 PUBLIC HEALTH ASSESSMENT

ROYAL OAKS COMMUNITY
EDGEWATER, VOLUSIA COUNTY, FLORIDA
EPA ID No. FLN000407257
October 5, 2004




Appendix C. Tables

Table 1.

Highest Detected Chemical Concentrations in Onsite Groundwater
Chemicals of Concern Highest Groundwater Concentration Comparison Values
Toluene nd 0.2B
Ethylbenzene 30,250 1.0*
Total Xylenes 16,000 2.0
1,2,4-TMB 23,500 0.01
1,3,5-TMB 7,500 0.01
Samples collected 21DEC00, 24OCT01
All units in ppm = parts per million (mg/kg)
TMB = Trimethylbenzene
nd = Not Detected
* - ATSDR Hierarchy II (Intermediate) RMEG for Child
- ATSDR Hierarchy II (Intermediate) EMEG for Child
- FDEP Groundwater Criteria (Minimum Criteria Organoleptic)


Table 2.

Highest Detected Chemical Concentrations in Onsite Soil
Chemicals of Concern Highest Soil Concentration Comparison Values
Toluene nd 1,000
Ethylbenzene 11 5,000*
Total Xylenes 9.75 10,000
1,2,4 - TMB na 13
1,3,5 - TMB na 11
Samples collected 21DEC00, 24OCT01
All units in ppm = parts per million (mg/kg)
TMB = Trimethylbenzene
nd = Not Detected
na = not analyzed
* - ATSDR Hierarchy II (intermediate) RMEG for Child
- ATSDR Hierarchy II (Intermediate) EMEG for Child
- FDEP Direct Exposure (Residential)


Table 3.

Highest Detected Chemical Concentrations in Onsite Sediment
Chemicals of Concern Highest Sediment Concentrations Comparison Values
Toluene 5,400 1,000
Ethylbenzene 3,085 5,000*
Total Xylenes 4,950 10,000
1,2,4-TMB 1,050 13
1,3,5-TMB 300 11
Samples collected 21DEC00, 24OCT01
All units in ppm = parts per million (mg/kg)
TMB = Trimethylbenzene
* - ATSDR Hierarchy II (Intermediate) RMEG for Child
- ATSDR Hierarchy II (Intermediate) EMEG for Child
- FDEP Direct Exposure (Residential)


Table 4.

Highest Detected Chemical Concentrations in Onsite Air
Chemicals of Concern Highest Ambient Air Concentrations Comparison Values
Toluene 1.4 1.0**
Ethylbenzene 2.4 1.0
Total Xylenes nd 0.7**
1,2,4-TMB na na
1,3,5-TMB na na
Samples collected 24OCT01
All units in ppm = parts per million (mg/kg)
TMB = Trimethylbenzene
na = Not Analyzed
nd = Not Detected
NA = Not Applicable
** - ATSDR Hierarchy II (Intermediate) EMEG / MRL
- Additional Health Guidelines (Acute) EMEG / MRL


Table 5.

Potential Exposure Pathways
Pathway Name Potential Exposure Pathway Elements Time
Source Media Point of Exposure Route Of Exposure Exposed Population
Airborne Vapors Excavation Air Breathing Zone Inhalation About 31 residents December 2000 to July 2001
Airborne Dust Excavation Air Breathing Zone Inhalation About 31 residents December 2000 to July 2001


Table 6.

Calculated Average Daily Dose (ADD)
Contaminant of Concern Air (mg/cu m) Groundwater (mg/kg/day) Sediment (mg/kg/day)
Child Adult Child Adult Child Adult
Ethylbenzene 10.42 10.42 2000 857 0.021 0.004
Toluene 5.28 5.28 ND ND 0.036 0.008
Xylenes (mixed) ND ND 1067 457 0.033 0.007
1,2,4-Trimethylbenzene NA NA 1600 686 0.007 0.002
These doses were calculated using Risk Assistant software and accepted exposure parameters (EPA, 1991).
N.D.- Not detected
N.A.- Not analyzed
mg/kg/day = milligrams per kilogram per day
mg/cu m = milligrams per cubic meter

Appendix D. Risk of Illness, Dose Response/Threshold, and Uncertainty in Public Health Assessments

Risk of Illness
In this health assessment, the risk of illness is the chance that exposure to a hazardous contaminant is associated with a harmful health effect or illness. The risk of illness is not a measure of cause and effect-only an in-depth health study can identify a cause and effect relationship. Instead, Florida DOH uses the risk of illness to decide if the site needs a follow-up health study and to identify possible associations.
The greater the exposure to a hazardous contaminant (dose), the greater the risk of illness. The amount of a substance required to harm a person's health (toxicity) also determines the risk of illness. Exposure to a hazardous contaminant above a minimum level increases everyone's risk of illness. Only in unusual circumstances, however, do many persons become ill.

Information from human studies provides the strongest evidence that exposure to a hazardous contaminant is related to a particular illness. Some of this evidence comes from doctors reporting an unusual incidence of a specific illness in exposed individuals. More formal studies compare illnesses in people with different levels of exposure. Nevertheless, human information is very limited for most hazardous contaminants, and scientists must frequently depend upon data from animal studies. Hazardous contaminants associated with harmful health effects in humans are often associated with harmful health effects in other animal species. There are limits, however, to relying only on animal studies. For example, scientists have found some hazardous contaminants are associated with cancer in animals but lack evidence of a similar association in humans. In addition, humans and animals have differing abilities to protect themselves against low levels of contaminants, and most animal studies test only the possible health effects of high exposure levels. Consequently, the possible effects on humans of low-level exposure to hazardous contaminants are uncertain when information is derived solely from animal experiments.
Dose Response/Thresholds
The focus of toxicological studies in humans or animals is identification of the relationship between exposure to different doses of a specific contaminant and the chance of having a health effect from each exposure level. This dose-response relationship provides a mathematical formula or graph that is used to estimate a person's risk of illness. The actual shape of the dose-response curve requires scientific knowledge of how a hazardous substance affects different cells in the human body. One important difference exists between the dose-response curves used to estimate the risk of noncancer illnesses and those curves used to estimate the risk of cancer: threshold dose. A threshold dose is the highest exposure dose at which there is no risk of illness. The dose-response curves for noncancer illnesses include a threshold dose that is greater than zero. Scientists include a threshold dose in these models because the human body can adjust to varying amounts of cell damage without illness. The threshold dose differs for different contaminants and different exposure routes. It is estimated from information gathered in human and animal studies. By contrast, the dose-response curves used to estimate the risk of cancer assume no threshold dose (or, in other words, the cancer threshold dose is zero). This assumes a single contaminant molecule could be sufficient to cause a clinical case of cancer. Such an assumption is very conservative; indeed, many scientists also believe a threshold dose greater than zero exists for the development of cancer.
Uncertainty
All risk assessments, to varying degrees, require the use of assumptions, judgments, and incomplete data. These contribute to the uncertainty of the final risk estimates. Some more important sources of uncertainty in this public health assessment include environmental sampling and analysis, exposure parameter estimates, use of modeled data, and present toxicological knowledge. These uncertainties can cause risk to be overestimated or underestimated. And because of the uncertainties described below, this public health assessment does not represent an absolute estimate of risk to persons exposed to chemicals at or near the Royal Oaks community site.
Environmental chemistry analysis errors can arise from random errors in the sampling and analytical processes, resulting in either an over- or under-estimation of risk. These errors can be controlled to some extent by increasing the number of samples collected and analyzed and by sampling the same locations over several different periods. These actions tend to minimize any uncertainty caused by random sampling errors.
Two areas of uncertainty affect exposure parameter estimates. The first is the exposure-point concentration estimate. The second is the estimate of the total chemical exposures. In this assessment maximum detected concentrations were used as the exposure point concentration. Using the maximum measured value is considered appropriate because one cannot be certain of the peak contaminant concentrations and cannot statistically predict peak values. Nevertheless, this assumption introduces uncertainty into the risk assessment that could over- or underestimate the actual risk of illness. When one DOH selects parameter values to estimate exposure dose, default assumptions and values are used within the ranges recommended by the ATSDR or the EPA.These default assumptions and values are conservative (health protective) and can contribute to the overestimation of risk of illness. Similarly, the maximum exposure period are assumed to have occurred regularly for each selected pathway. Both assumptions are likely to contribute to the overestimation of risk of illness.
Also, data gaps and uncertainties exist in the design, extrapolation, and interpretation of toxicological experimental studies. Data gaps contribute uncertainty because information is either not available or is addressed qualitatively. Moreover, the available information on the interaction among chemicals found at the site, when present, is qualitative (that is, a description instead of a number). A mathematical formula cannot be applied to estimate the dose. These data gaps can tend to underestimate the actual risk of illness. In addition, great uncertainties exist in extrapolating from high to low doses and from animal to human populations. Extrapolating from animals to humans is uncertain because of the differences in the uptake, metabolism, distribution, and body organ susceptibility between different species. Human populations are also variable because of differences in genetic constitution, diet, home and occupational environment, activity patterns, and other factors. These uncertainties can result in an over- or underestimation of risk of illness. Finally, great uncertainties exist in extrapolating from high doses to low doses and controversy in interpreting these results. Because the models used to estimate dose-response relationships in experimental studies are conservative, they tend to overestimate the risk. Techniques used to derive acceptable exposure levels account for such variables by using safety factors. Currently, there is much debate in the scientific community about the extent to which the actual risks are overestimated and what the resultant risk estimates really mean.

Appendix E. Florida Dep No Further Action Letter

Department of Environmental Protection letter
Blood lead test results of children born 1994-1997 residing within 1 mile of NL Industries

Glossary of Environmental Health Terms


Absorption: How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.
Acute Exposure: Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.
Additive Effect: A response to a chemical mixture, or combination of substances, that might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
Adverse Health Effect: A change in body function or the structures of cells that can lead to disease or health problems.
Antagonistic Effect: A response to a mixture of chemicals or combination of substances that is less than might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
ATSDR: The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia, that deals with hazardous substance and waste site issues. ATSDR provides information about harmful chemicals in the environment and how people can protect themselves from contact with chemicals.
Background Level: An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.
Biota: As used in public health, things that humans would eat-including animals, fish and plants.
CAP: See Community Assistance Panel.
Cancer: A group of diseases that occur when cells in the body become abnormal and grow, or multiply, out of control.
Carcinogen: Any substance shown to cause tumors or cancer in experimental studies.
CERCLA: See Comprehensive Environmental Response, Compensation, and Liability Act.
Chronic Exposure: A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.
Completed Exposure Pathway: See Exposure Pathway.
Community Assistance Panel (CAP): Persons from community and health and environmental agencies who work together on issues and problems at hazardous waste sites.
Comparison Value: (CVs) Concentrations or the amount of substances in air, water, food, and soil that are unlikely, upon exposure, to cause adverse health effects. Comparison values are used by health assessors to select which substances and environmental media (air, water, food and soil) need additional evaluation while health concerns or effects are investigated.
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA): CERCLA was enacted in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, the cleanup of these substances, and the health issues related to hazardous waste sites. ATSDR was created by this act.
Concern: A belief or worry that chemicals in the environment might cause harm to people.
Concentration: How much or the amount of a substance present in a certain amount of soil, water, air, or food.
Contaminant: See Environmental Contaminant.
Delayed Health Effect: A disease or injury that happens as a result of exposures that might have occurred far in the past.
Dermal Contact: A chemical getting onto one's skin. (see Route of Exposure).
Dose: The amount of a substance to which a person might be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day."
Dose / Response: The relationship between the amount of exposure (dose) and the change in body function or health that results.
Duration: The amount of time (days, months, years) that a person is exposed to a chemical.
Environmental Contaminant: A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than those found in Background Level, or what would be expected.
Environmental Media: Usually refers to the air, water, and soil in which chemicals of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.
U.S. Environmental Protection Agency (EPA): The federal agency that develops regulations and enforces environmental laws to protect the environment and public health.
Epidemiology: The study of the factors that determine how often, in how many people, and in which people disease will occur.
Exposure: Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)
Exposure Assessment: The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.
Exposure Pathway: A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or become exposed to) the chemical.
ATSDR defines an exposure pathway as having five parts:
  • Source of Contamination,
  • Environmental Media and Transport Mechanism,
  • Point of Exposure,
  • Route of Exposure, and
  • Receptor Population.
When all five parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these five terms is defined in this Glossary.

Finished Water: This is a term used to refer to water that has been chlorinated, aerated and is ready for use by the public. "Finished Water" is usually filtered through air-stripping towers to remove chlorinated solvents and their breakdown products.

Frequency: How often a person is exposed to a chemical over time-for example, every day, once a week, twice a month.

Hazardous Waste: Substances that have been released or disposed of and, under certain conditions, could be harmful to people who come into contact with them.

Health Effect: ATSDR deals only with Adverse Health Effects (see definition in this Glossary).

Intermediate Exposure: Any chemical exposure that has occurred for more 14 days but less than one year (365 days).

Indeterminate Public Health Hazard: The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.

Ingestion: Swallowing something, as in eating or drinking. It is a way a chemical can enter the body (See Route of Exposure).

Inhalation: Breathing: It is a way a chemical can enter the body (See Route of Exposure).

LOAEL: Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in humans or animals.

Malignancy: See Cancer.

MRL: Minimal Risk Level: An estimate of daily human exposure-by a specified route and length of time-to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.

NPL: The National Priorities List: (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site requires investigation or clean up, or both, to determine whether people can be exposed to chemicals from the site.

NOAEL: No Observed Adverse Effect Level: The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.

No Apparent Public Health Hazard: The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals might have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.

No Public Health Hazard: The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.

PHA: Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and determines whether people could be harmed from coming into contact with those chemicals. The PHA also determines whether possible further public health actions are needed.

Plume: A line or column of air or water containing chemicals moving from the source to areas farther away. A plume can be a column or clouds of smoke from a chimney or contaminated underground water sources or contaminated surface water (such as lakes, ponds and streams).

Point of Exposure: The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For example, the area of a playground containing contaminated dirt, a contaminated spring used for drinking water, a location where fruits or vegetables are grown in contaminated soil, or a backyard area where someone might breathe contaminated air.

Population: A group of people living in a certain area, or the number of people in a certain area.

PRP: Potentially Responsible Party: A company, government or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the cleanup of a site.

Public Health Assessment(s): See PHA.

Public Health Hazard: The category is used in PHAs for sites that show credible evidence of chronic, site-related chemical exposure that could result in adverse health effects.

Public Health Hazard Criteria: PHA categories given to a site that tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:
  1. Urgent Public Health Hazard
  2. Public Health Hazard
  3. Indeterminate Public Health Hazard
  4. No Apparent Public Health Hazard
  5. No Public Health Hazard
Reference Dose (RfD): An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.

Route of Exposure: The way a chemical can get into a person's body. There are three exposure routes:
  1. breathing (also called inhalation),
  2. eating or drinking (also called ingestion), and
  3. or getting something on the skin (also called dermal contact).
Safety Factor: Also Uncertainty Factor: When scientists do not have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.

SARA: The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. Among other things, CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.

Sample: A small number of people chosen from a larger population (See Population).

Source (of Contamination): The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.

Special Populations: People who could be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.

Superfund Site: See NPL.

Survey: A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.

Synergistic Effect: A health effect from an exposure to more than one chemical, where one of the chemicals worsens the effect of another chemical. The combined effect of the chemicals acting together is greater than the effects of the chemicals acting by themselves.

Toxic: Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.

Toxicology: The study of the harmful effects of chemicals on humans or animals.

Tumor: Abnormal growth of tissue or cells that have formed a lump or mass.

Uncertainty Factor: See Safety Factor.

Urgent Public Health Hazard: This category is used in ATSDR's Public Health Assessment documents for sites that show credible evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.

Table of Contents

  
 
USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

A-Z Index

  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #