PUBLIC HEALTH ASSESSMENT
Elizabeth Copper Mine
(a/k/a Elizabeth Mine)
Strafford, Orange County, Vermont
CERCLIS NO. VTD988366621
August 23, 2004
|1793||Eliz. Mine||Elizabeth Mine opens (large sulfide ore deposit discovered nearby)|
|1810||Eliz. Mine||Large-scale production of copperas at Elizabeth Mine begins|
|1880s||Eliz. Mine||Large-scale production of copperas at Elizabeth Mine ends|
|1930||Eliz. Mine||Copper mining at Elizabeth Mine ends|
|1943||Eliz. Mine||On-site flotation mill at Elizabeth Mine site begins operation|
|Feb. 1958||Eliz. Mine||Elizabeth Mine closes permanently|
|Aug. 1991||VTANR||Sampled on-site surface soil at Elizabeth Mine|
|Mar. 2000||VTDEC||Drinking water sampled at residences|
|Apr. 2000||EPA||U.S. Army Corp of Engineers (ACOE) collected and analyzed drinking water samples from residences|
|May 2000||EPA||ACOE collected and analyzed drinking water samples from residences|
|Jul. 2000||EPA||Collected three surface soils samples from residential yards on Old Mine Road|
|Jul. 2000||USGS||Collected soil samples from Elizabeth Mine site|
|Oct. 2000||ATSDR||Issued document "Health Consultation: An Evaluation of Residential Drinking Water Wells Adjacent to the Elizabeth Copper Mine Site"|
|Nov. 2000||EPA||Collected surface soil, indoor dust and indoor wipe samples at three residences on Old Mine Road|
|Nov. 2000||ATSDR||Issued document "Health Consultation: Residential Soil and Mine Tailings. Elizabeth Mine, Strafford, Orange County, VT"|
|Oct. 2001||multiple||Site visit (by ATSDR, VTANR and VTDOH)|
|Dec. 2001||ATSDR||Issued document "Petitioned Health Consultation: Residential Soil, Indoor Dust, and Ambient Air. Elizabeth Mine, Strafford, Orange County, VT"|
| Key: |
ACOE = U.S. Army Corps of Engineers
ATSDR = Agency for Toxic Substances and Disease Registry
EPA = U.S. Environmental Protection Agency
VTANR = Vermont Agency of Natural Resources
VTDEC = Vermont Department of Environmental Conservation
VTDOH = Vermont Department of Health.Appendix E: ATSDR Public Health Assessment Methodology
The groundwater, private well, surface soil, surface water, dust, sediment, air and fish data presented in the Remedial Investigation (1) were validated to assure that samples were analyzed in accordance with quality control requirements stipulated by EPA for Superfund sites. No significant quality assurance/quality control problems were noted in file data.
Human Exposure Pathway Evaluation and the use of ATSDR Comparison Values
ATSDR assesses a site by evaluating the level of exposure in potential or completed exposure pathways. An exposure pathway is the way chemicals may enter a person's body to cause a health effect. It includes all the steps between the release of a chemical and the population exposed: (1) a chemical release source, (2) chemical movement, (3) a place where people can come into contact with the chemical, (4) a route of human exposure, and (5) a population that could be exposed. In this assessment, ATSDR evaluates contaminants found in different media that people living near the site may consume or come into contact with.
Data evaluators use comparison values (CVs), which are screening tools only used to evaluate environmental data that is relevant to the exposure pathways. CVs are levels of contaminants that are considered to be safe levels of exposure. CVs used in this document include ATSDR's environmental media evaluation guide (EMEG) and cancer risk evaluation guide (CREG), as well as the U.S. Environmental Protection Agency's (EPA) risk-based concentrations (RBCs). CVs are derived from available health guidelines, such as ATSDR's minimal risk levels (MRLs) and EPA's reference doses or cancer slope factors.
The derivation of a CV uses conservative exposure assumptions, resulting in values that are much lower than exposure levels observed to cause adverse health effects, thus, insuring the CVs are protective of public health in essentially all exposure situations. That is, if the levels in the exposure medium are less than the CV, the exposures are not of health concern and no further analysis of the pathway is required. However, while levels below the CV are not expected to lead to any observable health effect, it should not be inferred that a level greater than the CV will necessarily lead to adverse effects. Depending on site-specific environmental exposure factors (for example, duration of exposure) and activities of people that result in exposure (time spent inarea of contamination), exposure to levels above the CV may or may not lead to a health effect. Therefore, ATSDR's CVs cannot be used to predict the occurrence of adverse health effects.
The CVs used in this evaluation are defined as follows:
Cancer Risk Evaluation Guides (CREGs) are levels of a contaminant in air, water, or soil which, assuming default values for (adult) body weight and intake rates, would correspond to exposure doses estimated to produce no more than one excess cancer in a million persons exposed. CREGs are calculated from EPA's cancer slope factors and therefore reflect estimates of "risk" based on the assumption of zero threshold and lifetime exposure. It should be noted, however, that the true risk is unknown and could be as low as zero.
The CREG is used to evaluate potential cancer effects. The CREG is the most conservative of CVs because it assumes that no threshold exists for the effects of chemical carcinogens. The resulting CREG can therefore often be below typical background levels and common detection limits. CREGs do not define levels of actual hazard (e.g., a 1-in-a-million "risk" level) and cannot be used to predict actual cancer incidence under specified conditions of exposure. As stated in EPA's 1986 Cancer Risk Assessment Guidelines, "the true risk is unknown and may be as low as zero."
Environmental Media Evaluation Guides (EMEGs) are levels of a contaminant in air, water, or soil that are calculated from ATSDR's MRLs for acute, intermediate, or chronic exposure by factoring in default body weights and ingestion rates for adults and children (and, in the case of soil, pica children). The MRLs on which the EMEGs are based are ATSDR's estimates of daily human exposure doses of a contaminant (expressed in milligrams or contaminant per kilogram of body weight per day [mg/kg/day]) that ATSDR considers unlikely to be associated with any appreciable risk of harmful noncancer effects over a specified duration of exposure. MRLs are calculated using data from human and animal studies and, like the EMEGs derived from them, are reported for acute (< 14 days), intermediate (15-364 days), and chronic (> 365 days) exposures. MRLs are published in ATSDR Toxicological Profiles for specific chemicals, but the EMEGs are not.
Reference Media Evaluation Guides (RMEGs) are derived from EPA's oral reference doses (RfDs). The RMEG represents the level in water or soil at which daily human exposure is unlikely to result in adverse noncarcinogenic effects.
Lifetime Health Advisories for Drinking Water (LTHA) are derived by EPA based on information about the toxicity of a contaminant. LTHAs are considered the level of a contaminant in drinking water that is not expected to cause adverse noncancer health effects for a lifetime of exposure in drinking water.
Maximum Contaminant Levels (MCL) are drinking water standards established by EPA. They are the maximum permissible level of a contaminant in water that is delivered to the free-flowing outlet. MCLs are considered protective of public health over a lifetime (70 years) for people consuming 2 liters of water per day.
Risk-Based Concentrations (RBCs) were developed by EPA Region III. RBCs for tap water, air, and soil were derived by using EPA's reference doses and cancer slope factors combined with standard exposure scenarios, such as ingestion of 2 liters of water per day, over a 70-year life span. RBCs are contaminant levels that are not expected to cause adverse health effects over long-term exposures.
Soil Screening Levels (SSL) were derived by EPA for nation-wide application to sites used for residential areas. SSLs are estimates of contaminant levels that would be expected to be without noncancer health effects over a specified duration of exposure or to cause no more than one excess cancer in a million (10-6) persons exposed over a 70-year life span.
Selecting Contaminants for Further Evaluation Contaminants selected for further evaluation are the site-specific chemical substances that the health assessor identifies for further evaluation of potential health effects. Identifying these contaminants is a process that requires the assessor to examine contaminant levels at the site, the quality of environmental sampling data, and the potential for human exposure. A thorough review of each of these issues is required to accurately select contaminants in the site-specific human exposure pathway. The following text describes the selection process.
In the first step of the contaminant selection process, the maximum contaminant levels are compared directly to CVs. ATSDR considers site-specific exposure factors to ensure selection of appropriate CVs. If the maximum level reported for a contaminant was less than the CV, ATSDR concluded that exposure to that chemical was not of public health concern; therefore, no further data review was required for that contaminant. However, if the maximum level was greater than the CV, the contaminant was selected for additional data review. In addition, any contaminants detected that did not have relevant CVs were also selected for additional data review.
CVs have not been developed for some contaminants, and, according to new scientific information other CVs may be determined to be inappropriate for the specific type of exposure. In those cases, the contaminants are included as contaminants of concern if current scientific information indicates exposure to those contaminants may be of public health concern.
The next step of the process requires a more in-depth review of data for each of the contaminants selected. Factors used in the selection process included the number of samples with detections above the minimum detection limit, the number of samples with detections above an acute or chronic health comparison value, and the potential for exposure at the monitoring location.
A change in body function or the structures of cells that can lead to disease or health problems.
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 gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.
An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.
Used in public health, things that humans would eat – including animals, fish and plants.
A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control
Any substance shown to cause tumors or cancer in experimental studies.
See Comprehensive Environmental Response, Compensation, and Liability Act.
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.
Comparison Value: (CVs)
Levels 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 put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.
A belief or worry that chemicals in the environment might cause harm to people.
How much or the amount of a substance present in a certain amount of soil, water, air, or food.
See Environmental Contaminant.
A chemical getting onto your skin. (see Route of Exposure).
The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".
The amount of time (days, months, years) that a person is exposed to a chemical.
A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.
Usually refers to the air, water, and soil in which chemical 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 and enforces environmental laws to protect the environment and the public's health.
Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)
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 get exposed to) the chemical.
ATSDR defines an exposure pathway as having 5 parts:
- Source of Contamination,
- Environmental Media and Transport Mechanism,
- Point of Exposure,
- Route of Exposure, and
- Receptor Population.
How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.
Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.
ATSDR deals only with Adverse Health Effects (see definition in this Glossary).
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.
Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).
Breathing. It is a way a chemical can enter your body (See Route of Exposure).
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 needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.
No Apparent Public Health Hazard:
The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may 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.
Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.
Point of Exposure:
The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:
The area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.
A group of people living in a certain area; or the number of people in a certain area.
Public Health Assessment(s):
Public Health Hazard:
The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.
People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).
Route of Exposure:
The way a chemical can get into a person's body. There are three exposure routes: - breathing (also called inhalation), - eating or drinking (also called ingestion), and - or getting something on the skin (also called dermal contact).
The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.
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.
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.