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Exposure Investigation



The purpose of this health consultation is to respond to a request for assistance from the Palm Beach County Health Department (PBCHD) to the Florida Department of Health (DOH) to evaluate the results of indoor air collected by the Environmental Protection Agency (EPA). The Florida DOH, in cooperation with the U.S. Agency for Toxic Substances and Disease Registry (ATSDR), evaluated indoor air for mercury for two Lake Park, Florida residents.

Financial support for this consultation is provided entirely by the U.S. Agency for Toxic Substances and Disease Registry (ATSDR). The conclusions and recommendations of this consultation are only applicable to those who occupy the Lake Park residence.


On September 18, 2002 a Lake Park resident opened a box containing a leaking antique mercury barometer. The barometer was shipped from overseas. The cork plug on the barometer was loose, so mercury leaked in the box. The residents removed the barometer from the box, leaned the barometer against the sofa and then placed the barometer on the dining room table. In the process, the leaking barometer dripped on carpeting and furniture in the home. The couple collected as much mercury as possible with a spoon and returned the mercury to the mercury tube on the barometer. The couple also used a hand held vacuum to clean up mercury beads. The amount of spilled liquid mercury is unknown. No children, pets, or pregnant women live in the house.

On September 19, 2002, the couple contacted the PBCHD for assistance. Between September 19 and September 24, 2002, the PBCHD inspected the home and tested the air for mercury using a Jerome meter.

When the PBCHD first arrived on September 19, the air conditioning was off and the windows were open for ventilation. The PBCHD recapped the barometer and placed it in the garage until the mercury could be reclaimed. The PBCHD informed the couple anything in contact with the mercury needed to be disposed as a hazardous waste. The PBCHD advised the family to have their contractor remove the barometer, carpeting, contaminated vessels, collected mercury, vacuum cleaner, shipping box with materials, and other materials that may have contacted the liquid mercury. The residents informed the PBCHD they would take the barometer to the nearest recycling facility. The residents used their insurance company's contractor for cleanup and disposal of the mercury-contaminated items. The PBCHD gave directions on cleanup of counters and furniture. The PBCHD suggested the residents continue to keep the home well ventilated and keep the air conditioning off at least 24 hours after cleanup.

The wife began experiencing headaches and contacted her physician. Her physician tested her blood for heavy metals including mercury. The results were negative.

On September 20, 2002, the PBCHD requested the Florida DOH evaluate the air mercury levels in the residents' home. The Florida DOH recommended the EPA test the air using a Lumex meter. In October 2002, the EPA tested the air mercury levels in the residents' home using a Lumex meter.


Mercury Results

On September 19, 2002, the PBCHD detected air mercury levels ranging from 8-193 micrograms mercury per cubic meter (ug/m3). The barometer box had the highest levels of 193 (ug/m3). Once the barometer and box were removed from the home and after ventilation and mercury cleanup, the air mercury levels ranged from 0 - 103 (ug/m3)(table top mercury beads). The final air mercury results in the home were well below 25 (ug/m3). The PBCHD used Occupational Safety and Health (OSHA) guidance to determine if air levels were acceptable.

On October 10, 2002, the EPA tested the air mercury levels and detected 0.4 ug/m3 of mercury. In a letter dated November 5, 2002, the PBCHD informed the Lake Park residents the air mercury levels in their home were less than the EPA and ATSDR guidance levels (1.0 ug/m3) (EPA 2002) . The PBCHD stressed that, while this level is acceptable, it remains slightly elevated above the toddler breathing zone guidance level (one foot above the floor at 80 degrees) of 0.3 ug/ m3. EPA staff believes the 0.4 ug/m3 may have been from the mercury levels emitting from the barometer case (recorded at 5-7 ug/m3 approximately 1-3 inches above the case).

Mercury Interpretation

Using EPA and ATSDR's guidance level of 1.0 ug/m3, the Florida DOH determined no serious health effects were likely based on the 0.4 ug/m3 maximum mercury level found in the residence (EPA 2002).


Even though this health consultation does not involve children living in the Lake Park residents' home, exposure to mercury for visiting children are a concern. Pregnant women, nursing mothers and children can be affected by mercury in air. It is important to remember children are not small adults. Children are more sensitive to the effects of mercury than are adults. Also, a child's mercury exposure can differ substantially from an adult's exposure. Children drink more fluids, eat more food, and breathe more air per kilogram of body weight than do adults. A child's diet-that often differs from that of an adult's-and a child's behavior and lifestyle can also influence exposure (ATSDR 1999).

Thus DOH reviewed the results of the air mercury analysis, aware that sensitive populations such as pregnant women, nursing mothers and children are a particular concern. Still, we conclude that the mercury found in the Lake Park residence is not likely to cause illness in adults or children.


Based on the information evaluated in this report, the Lake Park Residential Mercury spill is categorized as a no apparent public health hazard. Because indoor air mercury levels were below health guidelines and one resident's blood mercury level was determined to be below average, the Lake Park couple is unlikely to suffer illness from this exposure.


The Florida DOH does not offer any recommendations for this site at this time.


[ATSDR] Agency for Toxic Substances and Disease Registry. 1999. Toxicological profile for mercury. Atlanta: US Department of Health and Human Services.

[EPA] Environmental Protection Agency. EPA/ATSDR OSC Training: Mercury cleanup guidelines, Tampa, Florida. April 2002.


Susan Bland
Biological Scientist IV
Florida Department of Health
Bureau of Environmental Epidemiology

Florida DOH Designated Reviewer

Randy Merchant
Program Administrator
Florida Department of Health
Bureau of Environmental Epidemiology

ATSDR Technical Project Officer

Debra Gable
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
Agency for Toxic Substances and Disease Registry


The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency with headquarters in Atlanta, Georgia, and 10 regional offices in the United States. ATSDR's mission is to serve the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harmful exposures and diseases related to toxic substances. ATSDR is not a regulatory agency, unlike the U.S. Environmental Protection Agency (EPA), which is the federal agency that develops and enforces environmental laws to protect the environment and human health.

This glossary defines words used by ATSDR in communications with the public. It is not a complete dictionary of environmental health terms. If you have questions or comments, call ATSDR's toll-free telephone number, 1-888-42-ATSDR (1-888-422-8737).

The process of taking in. For a person or animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs.

Occurring over a short time [compare with chronic].

Acute exposure:
Contact with a substance that occurs once or for only a short time (up to 14 days) [compare with intermediate duration exposure and chronic exposure].

Adverse health effect:
A change in body function or cell structure that might lead to disease or health problems.

Surrounding (for example, ambient air).

A substance measured in the laboratory. A chemical for which a sample (such as water, air, or blood) is tested in a laboratory. For example, if the analyte is mercury, the laboratory test will determine the amount of mercury in the sample.

Background level:
An average or expected amount of a substance or radioactive material in a specific environment, or typical amounts of substances that occur naturally in an environment.

Decomposition or breakdown of a substance through the action of microorganisms (such as bacteria or fungi) or other natural physical processes (such as sunlight).

Biologic indicators of exposure study:
A study that uses (a) biomedical testing or (b) the measurement of a substance [an analyte], its metabolite, or another marker of exposure in human body fluids or tissues to confirm human exposure to a hazardous substance [also see exposure investigation].

Biologic monitoring:
Measuring hazardous substances in biologic materials (such as blood, hair, urine, or breath) to determine whether exposure has occurred. A blood test for lead is an example of biologic monitoring.

Biologic uptake:
The transfer of substances from the environment to plants, animals, and humans.

Biomedical testing:
Testing of persons to find out whether a change in a body function might have occurred because of exposure to a hazardous substance.

Plants and animals in an environment. Some of these plants and animals might be sources of food, clothing, or medicines for people.

Body burden:
The total amount of a substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly.

Any one of a group of diseases that occurs when cells in the body become abnormal and grow or multiply out of control.

Cancer risk:
A theoretical risk of for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower.

A substance that causes cancer.

Central nervous system:
The part of the nervous system that consists of the brain and the spinal cord.

[see Comprehensive Environmental Response, Compensation, and Liability Act of 1980]

Occurring over a long time (more than 1 year) [compare with acute].

Chronic exposure:
Contact with a substance that occurs over a long time (more than 1 year) [compare with acute exposure and intermediate duration exposure].

Comparison value (CV):
Calculated concentration of a substance in air, water, food, or soil that is unlikely to cause harmful (adverse) health effects in exposed people. The CV is used as a screening level during the public health assessment process. Substances found in amounts greater than their CVs might be selected for further evaluation in the public health assessment process.

Completed exposure pathway:
[see exposure pathway].

Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA):
CERCLA, also known as Superfund, is the federal law that concerns the removal or cleanup of hazardous substances in the environment and at hazardous waste sites. ATSDR, which was created by CERCLA, is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances.

The amount of a substance present in a certain amount of soil, water, air, food, blood, hair, urine, breath, or any other media.

A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects.

Referring to the skin. For example, dermal absorption means passing through the skin.

Dermal contact:
Contact with (touching) the skin [see route of exposure].

Detection limit:
The lowest concentration of a chemical that can reliably be distinguished from a zero concentration.

Disease prevention:
Measures used to prevent a disease or reduce its severity.

Dose (for chemicals that are not radioactive):
The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs.

Environmental media:
Soil, water, air, biota (plants and animals), or any other parts of the environment that can contain contaminants.

Environmental media and transport mechanism:
Environmental media include water, air, soil, and biota (plants and animals). Transport mechanisms move contaminants from the source to points where human exposure can occur. The environmental media and transport mechanism is the second part of an exposure pathway.

United States Environmental Protection Agency.

Contact with a substance by swallowing, breathing, or touching the skin or eyes. Exposure may be short-term [acute exposure], of intermediate duration, or long-term [chronic exposure].

Exposure assessment:
The process of finding out how people come into contact with a hazardous substance, how often and for how long they are in contact with the substance, and how much of the substance they are in contact with.

Exposure investigation:
The collection and analysis of site-specific information and biologic tests (when appropriate) to determine whether people have been exposed to hazardous substances.

Exposure pathway:
The route a substance takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination (such as an abandoned business); an environmental media and transport mechanism (such as movement through groundwater); a point of exposure (such as a private well); a route of exposure (eating, drinking, breathing, or touching), and a receptor population (people potentially or actually exposed). When all five parts are present, the exposure pathway is termed a completed exposure pathway.

Feasibility study:
A study by EPA to determine the best way to clean up environmental contamination. A number of factors are considered, including health risk, costs, and what methods will work well.

Water beneath the earth's surface in the spaces between soil particles and between rock surfaces [compare with surface water].

A source of potential harm from past, current, or future exposures.

Hazardous Substance Release and Health Effects Database (HazDat):
The scientific and administrative database system developed by ATSDR to manage data collection, retrieval, and analysis of site-specific information on hazardous substances, community health concerns, and public health activities.

Hazardous waste:
Potentially harmful substances that have been released or discarded into the environment.

Health consultation:
A review of available information or collection of new data to respond to a specific health question or request for information about a potential environmental hazard. Health consultations are focused on a specific exposure issue. Health consultations are therefore more limited than a public health assessment, which reviews the exposure potential of each pathway and chemical [compare with public health assessment].

Health education:
Programs designed with a community to help it know about health risks and how to reduce these risks.

Health promotion:
The process of enabling people to increase control over, and to improve, their health.

Indeterminate public health hazard:
The category used in ATSDR's public health assessment documents when a professional judgment about the level of health hazard cannot be made because information critical to such a decision is lacking.

The act of swallowing something through eating, drinking, or mouthing objects. A hazardous substance can enter the body this way [see route of exposure].

The act of breathing. A hazardous substance can enter the body this way [see route of exposure].

Lowest-observed-adverse-effect level (LOAEL):
The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects in people or animals.

Medical monitoring:
A set of medical tests and physical exams specifically designed to evaluate whether an individual's exposure could negatively affect that person's health.

The conversion or breakdown of a substance from one form to another by a living organism.

Any product of metabolism.

Milligram per kilogram.

Milligram per square centimeter (of a surface).

Milligram per cubic meter; a measure of the concentration of a chemical in a known volume (a cubic meter) of air, soil, or water.

Moving from one location to another.

Minimal risk level (MRL):
An ATSDR estimate of daily human exposure to a hazardous substance at or below which that substance is unlikely to pose a measurable risk of harmful (adverse), noncancerous effects. MRLs are calculated for a route of exposure (inhalation or oral) over a specified time period (acute, intermediate, or chronic). MRLs should not be used as predictors of harmful (adverse) health effects [see reference dose].

National Priorities List for Uncontrolled Hazardous Waste Sites (National Priorities List or NPL):
EPA's list of the most serious uncontrolled or abandoned hazardous waste sites in the United States. The NPL is updated on a regular basis.

No apparent public health hazard:
A category used in ATSDR's public health assessments for sites where human exposure to contaminated media might be occurring, might have occurred in the past, or might occur in the future, but where the exposure is not expected to cause any harmful health effects.

No-observed-adverse-effect level (NOAEL):
The highest tested dose of a substance that has been reported to have no harmful (adverse) health effects on people or animals.

No public health hazard:
A category used in ATSDR's public health assessment documents for sites where people have never and will never come into contact with harmful amounts of site-related substances.

[see National Priorities List for Uncontrolled Hazardous Waste Sites]

A craving to eat nonfood items, such as dirt, paint chips, and clay. Some children exhibit pica-related behavior.

A volume of a substance that moves from its source to places farther away from the source. Plumes can be described by the volume of air or water they occupy and the direction they move. For example, a plume can be a column of smoke from a chimney or a substance moving with groundwater.

Point of exposure:
The place where someone can come into contact with a substance present in the environment [see exposure pathway].

A group or number of people living within a specified area or sharing similar characteristics (such as occupation or age).

Potentially responsible party (PRP):
A company, government, or person legally responsible for cleaning up the pollution at a hazardous waste site under Superfund. There may be more than one PRP for a particular site.

Parts per billion.

Parts per million.

Actions that reduce exposure or other risks, keep people from getting sick, or keep disease from getting worse.

Public availability session:
An informal, drop-by meeting at which community members can meet one-on-one with ATSDR staff members to discuss health and site-related concerns.

Public health action:
A list of steps to protect public health.

Public health assessment (PHA):
An ATSDR document that examines hazardous substances, health outcomes, and community concerns at a hazardous waste site to determine whether people could be harmed from coming into contact with those substances. The PHA also lists actions that need to be taken to protect public health [compare with health consultation].

Public health hazard:
A category used in ATSDR's public health assessments for sites that pose a public health hazard because of long-term exposures (greater than 1 year) to sufficiently high levels of hazardous substances or radionuclides that could result in harmful health effects.

Public health hazard categories:
Public health hazard categories are statements about whether people could be harmed by conditions present at the site in the past, present, or future. One or more hazard categories might be appropriate for each site. The five public health hazard categories are no public health hazard, no apparent public health hazard, indeterminate public health hazard, public health hazard, and urgent public health hazard.

Public health statement:
The first chapter of an ATSDR toxicological profile. The public health statement is a summary written in words that are easy to understand. The public health statement explains how people might be exposed to a specific substance and describes the known health effects of that substance.

Public meeting:
A public forum with community members for communication about a site.

[See Resource Conservation and Recovery Act (1976, 1984)]

Receptor population:
People who could come into contact with hazardous substances [see exposure pathway].

Reference dose (RfD):
An EPA estimate, with uncertainty or safety factors built in, of the daily lifetime dose of a substance that is unlikely to cause harm in humans.

A systematic collection of information on persons exposed to a specific substance or having specific diseases [see exposure registry and disease registry].

Remedial Investigation:
The CERCLA process of determining the type and extent of hazardous material contamination at a site.

Resource Conservation and Recovery Act (1976, 1984) (RCRA):
This Act regulates management and disposal of hazardous wastes currently generated, treated, stored, disposed of, or distributed.

RCRA Facility Assessment. An assessment required by RCRA to identify potential and actual releases of hazardous chemicals.

See reference dose.

The probability that something will cause injury or harm.

Risk reduction:
Actions that can decrease the likelihood that individuals, groups, or communities will experience disease or other health conditions.

Risk communication:
The exchange of information to increase understanding of health risks.

Route of exposure:
The way people come into contact with a hazardous substance. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact].

Safety factor:
[see uncertainty factor]

[see Superfund Amendments and Reauthorization Act]

A portion or piece of a whole. A selected subset of a population or subset of whatever is being studied. For example, in a study of people the sample is a number of people chosen from a larger population [see population]. An environmental sample (for example, a small amount of soil or water) might be collected to measure contamination in the environment at a specific location.

Sample size:
The number of units chosen from a population or environment.

A liquid capable of dissolving or dispersing another substance (for example, acetone or mineral spirits).

Source of contamination:
The place where a hazardous substance comes from, such as a landfill, waste pond, incinerator, storage tank, or drum. A source of contamination is the first part of an exposure pathway.

Special populations:
People who might be more sensitive or susceptible to exposure to hazardous substances because of factors such as age, occupation, sex, or behaviors (for example, cigarette smoking). Children, pregnant women, and older people are often considered special populations.

A person, group, or community who has an interest in activities at a hazardous waste site.

A branch of mathematics that deals with collecting, reviewing, summarizing, and interpreting data or information. Statistics are used to determine whether differences between study groups are meaningful.

A chemical.

Substance-specific applied research:
A program of research designed to fill important data needs for specific hazardous substances identified in ATSDR's toxicological profiles. Filling these data needs would allow more accurate assessment of human risks from specific substances contaminating the environment. This research might include human studies or laboratory experiments to determine health effects resulting from exposure to a given hazardous substance.

Superfund Amendments and Reauthorization Act (SARA):
In 1986, SARA amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from substance exposures at hazardous waste sites and to perform activities including health education, health studies, surveillance, health consultations, and toxicological profiles.

Surface water:
Water on the surface of the earth, such as in lakes, rivers, streams, ponds, and springs [compare with groundwater].

A systematic collection of information or data. A survey can be conducted to collect information from a group of people or from the environment. Surveys of a group of people can be conducted by telephone, by mail, or in person. Some surveys are done by interviewing a group of people.

A substance that causes defects in development between conception and birth. A teratogen is a substance that causes a structural or functional birth defect.

Toxic agent:
Chemical or physical (for example, radiation, heat, cold, microwaves) agents which, under certain circumstances of exposure, can cause harmful effects to living organisms.

Toxicological profile:
An ATSDR document that examines, summarizes, and interprets information about a hazardous substance to determine harmful levels of exposure and associated health effects. A toxicological profile also identifies significant gaps in knowledge on the substance and describes areas where further research is needed.

The study of the harmful effects of substances on humans or animals.

An abnormal mass of tissue that results from excessive cell division that is uncontrolled and progressive. Tumors perform no useful body function. Tumors can be either benign (not cancer) or malignant (cancer).

Uncertainty factor:
Mathematical adjustments for reasons of safety when knowledge is incomplete. For example, factors used in the calculation of doses that are not harmful (adverse) to people. These factors are applied to the lowest-observed-adverse-effect-level (LOAEL) or the no-observed-adverse-effect-level (NOAEL) to derive a minimal risk level (MRL). Uncertainty factors are used to account for variations in people's sensitivity, for differences between animals and humans, and for differences between a LOAEL and a NOAEL. Scientists use uncertainty factors when they have some, but not all, the information from animal or human studies to decide whether an exposure will cause harm to people [also sometimes called a safety factor].

Urgent public health hazard:
A category used in ATSDR's public health assessments for sites where short-term exposures (less than 1 year) to hazardous substances or conditions could result in harmful health effects that require rapid intervention.

Volatile organic compounds (VOCs):
Organic compounds that evaporate readily into the air. VOCs include substances such as benzene, toluene, methylene chloride, and methyl chloroform.

Other glossaries and dictionaries:
Environmental Protection Agency
National Center for Environmental Health (CDC)
National Library of Medicine


The Lake Park Residential Mercury Health Consultation was prepared by the Florida Department of Health, Bureau of Environmental Epidemiology, under a cooperative agreement with the Agency for Toxic Substances and Disease Registry. It is in accordance with approved methodology and procedures existing at the time the health consultation was begun.

Debra Gable
Technical Project Officer,

The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation, and concurs with its findings.

Roberta Erlwein
Section Chief,

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