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Regional Site Location
Figure 1. Regional Site Location

Omega Site Location Map
Figure 2. Omega Site Location Map

Figure Depicting Industries in the Vicinity of the Omega Site
Figure 3. Figure Depicting Industries in the Vicinity of the Omega Site

Soil Gas Sampling Locations
Figure 4. Soil Gas Sampling Locations

Subsurface Soil Boring Locations
Figure 5. Subsurface Soil Boring Locations

Groundwater Sampling Locations
Figure 6. Groundwater Sampling Locations


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.

Adverse Health Effect:
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.

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.

Cancer Risk:

The potential for exposure to a contaminant to cause cancer in an individual or population is evaluated by estimating the probability of an individual developing cancer over a lifetime as the result of the exposure. This approach is based on the assumption that there are no absolutely "safe" toxicity values for carcinogens. USEPA has developed cancer slope factors for many carcinogens. A slope factor is an estimate of a chemical's carcinogenic potency, or potential, for causing cancer.

If adequate information about the level of exposure, frequency of exposure, and length of exposure to a particular carcinogen is available, an estimate of excess cancer risk associated with the exposure can be calculated using the slope factor for that carcinogen. Specifically, to obtain risk estimates, the estimated, chronic exposure dose (which is averaged over a lifetime or 70 years) is multiplied by the slope factor for that carcinogen.

Cancer risk is the likelihood, or chance of getting cancer. We say "excess cancer risk" because we have a "background risk" of about one-in-four chances of getting cancer. In other words, in a million people, it is expected that 250,000 individuals would get cancer from a variety of causes. If we say that there is a "one-in-a-million" excess cancer risk from a given exposure to a contaminant, we mean that if one million people are exposed to a carcinogen at a certain level over their lifetime, then one cancer above the background chance, or the 250,000st cancer, may appear in those million persons from that particular exposure. In order to take into account the uncertainties in the science, the risk numbers used are plausible upper limits of the actual risk based on conservative assumptions. In actuality, the risk is probably somewhat lower than calculated, and, in fact, may be zero.

Cancer Risk Evaluation Guide (CREG):
Carcinogenic chemicals are selected for follow-up by comparing the concentrations to the CREG (8). CREGs are derived from USEPA cancer slope factors. Cancer slope factors give an indication of the relative carcinogenic potency of a particular chemical. CREG values represent media concentrations which are thought to be associated with an extra lifetime cancer risk of one-in-a-million.

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.

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.

Dermal Contact:
A chemical getting onto your skin. (seeRoute 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".

Dose / Response:
The relationship between the amount of exposure (dose) and the change in body function or health that result.

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 that 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.

Environmental Media Evaluation Guide (EMEG):
EMEGs are media specific values developed by ATSDR to serve as an aid in selecting environmental contaminants that need to be further evaluated for potential health impacts (8). EMEGs are based on non-carcinogenic end-points and do not consider carcinogenic effects. EMEGs are based on the MRLs.

Coming into contact with a chemical substance. (For the three ways people can come in contact with substances, seeRoute 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 get exposed to) the chemical.

ATSDR defines an exposure pathway as having 5 parts:

    1. Source of Contamination,
    2. Environmental Media and Transport Mechanism,
    3. Point of Exposure,
    4. Route of Exposure, and
    5. Receptor Population.

When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway.

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 thrown away into the environment 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).

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).

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 people or animals.

Maximum Contaminant Level (MCL):
The USEPA has issued drinking water standards, or MCLs for more than 80 contaminants in drinking water (24). The MCLs are set based on known or anticipated adverse human health effects (which also account for sensitive subgroups, such as, children, pregnant women, the elderly, etc.), the ability of various technologies to remove the contaminant, their effectiveness, and cost of treatment (24). For cancer risk, USEPA generally sets the MCLs at concentrations that will limit an individual risk of cancer from a contaminant to between 1 in 10,000 (low increased excess risk) to 1 in 1,000,000 (no apparent increased excess risk) over a lifetime (24). As for non-cancer effects, USEPA estimates an exposure level below which no adverse health effects are expected to occur.

Non-Cancer Evaluation = ATSDR's Minimal Risk Level (MRL) and USEPA's Reference Dose (RfD) and Reference Concentration (RfC):
The MRL, RfD and RfC are estimates of daily exposure to the human population (including sensitive subgroups), below which non-cancer adverse health effects are unlikely to occur. The MRL, RfD and RfC only consider non-cancer effects. Because they are based only on information currently available, some uncertainty is always associated with the MRL, RfD, and RfC. "Safety" factors are used to account for the uncertainty in our knowledge about their danger. The greater the uncertainty, the greater the "safety" factor and the lower the MRL, RfD, or RfC.

When there is adequate information from animal or human studies, MRLs and RfDs are developed for the ingestion exposure pathway, whereas, RfCs are developed for the inhalation exposure pathway. A MRL, RfD or RfC is an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse (non-carcinogenic) health effects over a specified duration of exposure. No toxicity values exist for exposure by skin contact. Separate non-cancer toxicity values are also developed for different durations of exposure. ATSDR develops MRLs for acute exposures (less than 14 days), intermediate exposures (from 15 to 364 days), and for chronic exposures (greater than one year). USEPA develops RfDs and RfCs for chronic exposures (greater than seven years). Both the MRL and RfD for ingestion are expressed in units of milligrams of contaminant per kilograms body weight per day (mg/kg/day). The RfC for inhalation is expressed in units of mg/m3.

Non-Cancer and Cancer Evaluations = USEPA's Preliminary Remediation Goals (PRGs):
PRGs are developed by the USEPA to estimate contaminant concentrations in the environmental media (soil, air, and water), both in residential and industrial settings, that are protective of humans, including sensitive groups, over a lifetime (6). PRGs were developed for both industrial and residential settings because of the different exposure parameters, such as, different exposure time frames (e.g., industrial setting: workers are exposed for 8 hours/day and 5 days/week vs. residential setting: families are exposed 24 hours/day and 7 days/week; and different "human" exposure points (e.g., industrial setting: healthy adult males vs. residential setting: males, females, young children, and infants), etc. Media concentrations less than the PRGs are unlikely to pose a health threat; whereas, concentrations exceeding a PRG do not automatically determine that a health threat exists, but suggest that further evaluation is necessary.

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 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 may have occurred in the past or is still occurring but the exposures are not at concentrations 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.

Permissible Exposure Limits (PEL):
PELs are established by the California Occupational Safety and Health Administration (CAL/OSHA) to ensure worker safety from exposure to potentially hazardous chemicals in occupational and industrial settings. PELs are enforceable legal limits that must not be exceed during any 8-hour work shift of a 40-hour work week (8). The PELs were set to ensure worker safety (i.e., healthy males) and may not be protective of sensitive groups, such as, pregnant women, children, the elderly, etc.

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.

A line or column of air or water containing chemicals moving from the source to areas further 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 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.

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 clean up of a site.

Public Health Assessment(s):
See PHA.

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.

Public Health Hazard Criteria:
PHA categories given to a site which 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

Receptor Population:
People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).

Reference Dose based Media Evaluation Guide (RMEG):
RMEGs are equivalent to EMEGs, but are derived from USEPA RfDs instead of ATSDR's MRLs (8).

An estimate of daily exposure of the human population to a potential hazard that is likely to be without risk of deleterious effects during a lifetime. The RfD is operationally derived from the NOAEL (from animal and human studies) by a consistent application of uncertainty factors that reflects various types of data used to estimate RfDs and an additional modifying factor, which is based on a professional judgement of the entire data base on the chemical. The RfDs are not applicable to non-threshold effects such as cancer.

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).

Safety Factor:
Also called Uncertainty Factor. When scientists don't 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.

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 may 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.

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.

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

Uncertainty Factor:
See Safety Factor.

Urgent Public Health Hazard:
This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or 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 1: Summary of the Omega site Shallow Soil Gas Investigation

Soil Gas Location and Depth Total Vapor Concentration (ppmv)
SG-1-6.0' 0
SG-1-12.0' 0
SG-2-6.0' 311
SG-2-12.0' 308
SG-3-6.0' 150
SG-3D-6.0 129
SG-3-12.0' 551
SG-4-6.0' 1,164
SG-4-12.0' 1,479
SG-4-16.7' 0
SG-5-6.0' 1,034
SG-5-12.0' 1,145
SG-6-6.0' 208
SG-6-12.0' 366
SG-7-6.0' 223
SG-7-12.0' 430
SG-8-6.0' 0
SG-8-12.0' 226
SG-9-6.0' 1,470
SG-9-12.0' 1,344
SG-9D-12.0' 1,470
SG-10R-6.0' 214,783
SG-10-6.0' 2,059
SG-11-6.0' 887
SG-11-12.0' 1,574
SG-11D-12.0' 1,463
SG-12-6.0' 3
SG-12-12.0' 270
SG-13-6.0' 1,162
SG-13-12.0' 529
SG-14-6.0' 9
SG-14-12.0' 1,106
SG-15-6.0' 0
SG-15-12.0' 0
SG-16-6.0' 1,464
SG-16-12.0' 1,202
SG-16-24.0' 94
SG-17-6.0' 1,266
SG-17-12.0' 1,110
SG-18-6.0' 1,462
SG-18-12.0' 465
SG-19-6.0' 925
SG-19-12.0' 2,158
SG-19-24.0' 46
SG-19-24.0' 46
SG-20-6.0' 602
SG-20-12.0' 3
SG-20D-12.0' 261
SG-21-6.0' 478
SG-21-12.0' 1,239
SG-22-6.0' 1,035
SG-22-12.0' 117
SG-23-6.0' 1,193
SG-23-12.0' 210
SG-24-6.0' 1,063
SG-24-12.0' 1,015
SG-25-6.0' 2
SG-25-12.0' 0
SG-26-6.0' 123
SG-26-12.0' 30
SG-26D-12.0' 28
SG-27-6.0' 6
SG-27-12.0' 19
SG-28-6.0' 233
SG-28-12.0' 44
SG-29-6.0' 115
SG-29-12.0' 99
SG-30-6.0' 334
SG-30-12.0' 2
SG-31-3.5' 0
SG-1-6.0' = Sample location number - Depth of sample; ppmv = parts per million by volume
Total Vapor = Freon-12; trichlorofluoromethane; dichloromethane; trans-1,2-DCE; 1,1-DCA; cis-1,2-DCE; chloroform; 1,1,1-TCA; 1,2-DCA; TCE; PCE; 1,1-DCE; Freon-113; benzene; toluene; ethyl benzene; m,p-xylenes; and o-xylene.

Table 2: Maximum Level of Contaminants Detected in the Subsurface Soil

ContaminantMaximum Level (mg/kg)Health Comparison Value (mg/kg)/Source
Antimony180.8 (ATSDR's RMEG for pica child)
Arsenic90.6 (ATSDR's chronic EMEG for pica child)
Barium230100 (ATSDR's RMEG for pica child)
Chromium2106 (ATSDR's RMEG for pica child)
Nickel5540 (ATSDR's RMEG for pica child)
PCE26020 (ATSDR's RMEG for pica child)
Vanadium676 (ATSDR's intermediate EMEG for pica child)

Table 3: Maximum Level of Contaminants Detected in the Groundwater

ContaminantMaximum Level (mg/kg)Health Comparison Value (mg/kg)/Source
Acetone3020 (ATSDR intermediate EMEG for child)
Benzene0.0750.001(ATSDR's CREG)
Chloroform230.006 (ATSDR's CREG)
1,1-DCE6.90.00006 (ATSDR's CREG)
1,2-DCA100.0004 (ATSDR's CREG)
Methylene chloride1500.005 (ATSDR's CREG)
PCE860.1(ATSDR RMEG for child)
Toluene2.90.2 (ATSDR intermediate EMEG for child)
TCE6.30.005 (USEPA's MCL)
1,1,1-TCA140.2 (USEPA's Lifetime Health Advisory fordrinking water)
Trichlorofluoromethane4.33 (ATSDR's RMEG for child)

Table 4: List of Metals Analytes


Table 5: List of Volatile Organic Compounds (VOCs) Analytes

Carbon disulfide
Carbon tetrachloride
Freon 113
Methyl ethyl ketone
Methyl isobutyl ketone
Methylene chloride
Vinyl acetate
Vinyl chloride

Table 6: List of Semivolatile Organic Compounds (SVOCs) Analytes

Benzoic acid
Benzyl alcohol
Chrysene 218-01-9

Table 7: List of Chlorinated Pesticides and Polychlorinated Biphenyls (PCBs) Analytes

Aroclor 1016
Aroclor 1221
Aroclor 1232
Aroclor 1242
Aroclor 1248
Aroclor 1254
Aroclor 1260
Benzene hexachloride (BHC)
BHC, alpha isomer
BHC, beta isomer
BHC, delta isomer
BHC, gamma isomer
Endosulfan I
Endosulfan II
Endosulfan sulfate
Endrin aldehyde
Heptachlor epoxide

Table 8: Elements of Potential Exposure Pathways

Source Environmental Medium Point of Exposure Route of Exposure Exposed Populations Time Frame
Omega Site Soil gas On-site workers in the warehouse or the office building located on the Omega site. And Off-site workers, recreational users of Skateland, and residents in the vicinity of the Omega site Inhalation On-site and Off-site Workers, Recreational Users of Skateland, and Residents Current and future
Omega Site Groundwater from the City of Santa Fe Springs municipal groundwater well Off-site workers and residents in the City of Santa Fe Springs Skin absorption, incidental ingestion, and inhalation Off-site Workers and Residents Future
Omega Site Groundwater from private groundwater well Off-site workers and residents in the City of Whittier. Skin absorption, incidental ingestion, and inhalation Off-site Workers and Residents Past, current, and future

Table 9: Elements of Eliminated Exposure Pathways

SourceEnvironmental MediumPoint of ExposureRoute of Exposure Route of ExposureTime Frame
GroundwaterGroundwaterOn-site workers in thewarehouse or the officebuilding located on theOmega site and off-siteworkers and residentsin the vicinity of theOmega site served bythe City of WhittierMunicipal water systemSkin absorption,incidental ingestion,and inhalationCity of WhittierMunicipal water usersPast, current, andfuture
Omega SiteSoilOn-site workers,especially maintenanceworkers, located on theOmega siteSkin absorption,incidental ingestion,and inhalationOn-site andMaintenance WorkersFuture


Volatile Organic Chemicals


  • Acetone is a chemical that is found naturally in the environment and is also produced by industries.
  • Low concentrations of acetone are normally present in the body from the breakdown offat; the body can use it in normal processes that make sugar and fat. People and animalsbreathe out acetone produced from the natural breakdown of body fat.
  • People may be exposed to small amounts of acetone by breathing air, drinking water, andeating food with acetone. Several consumer products, including certain nail polishremovers, particle board, some paint removers, many liquid or paste waxes or polishes,and certain detergents or cleansers, contain acetone. People who work in certainindustries that process and use acetone can be exposed to higher concentrations than thegeneral populace. These industries include certain paint, plastic, artificial fiber, and shoe factories.
  • In occupational settings, workers exposed to high concentrations, which are not normallyfound in the environment, of acetone experienced headaches, lightheadedness, dizziness,unsteadiness, and confusion depending on the length of time they were exposed.
  • EPA's chronic oral RfD is 0.1 mg/kg/day (critical endpoint: increased organ weights & nephrotoxicity in rats).
  • The Department of Health and Human Services (DHHS) and the International Agency forResearch on Cancer (IARC) has not classified acetone for carcinogenic effects. The EPAhas determined that acetone is not classifiable as to its human carcinogenicity.


  • Benzene is a colorless liquid with a sweet odor.
  • Benzene is commonly found in the environment. Industrial processes are the mainsources of benzene in the environment. Benzene concentrations in the air can increasefrom emissions from burning coal and oil, benzene waste and storage operations, motorvehicle exhaust, and evaporation from gasoline service stations. Since tobacco smokecontains high concentrations of benzene, tobacco smoke is another source of benzene inair.
  • Most people are exposed to a small amount of benzene on a daily basis. Exposure of thegeneral population to benzene is mainly through breathing air that contains benzene. Individuals employed in industries that make or use benzene may be exposed to thehighest concentrations of benzene. These industries include benzene production(petrochemicals, petroleum refining, and coke and coal chemical manufacturing), rubbertire manufacturing, and storage or transport of benzene and petroleum productscontaining benzene.
  • Workers in occupational settings are exposed to concentrations of benzene in air fargreater than the concentrations normally encountered by the general population. Veryhigh concentrations, which are not normally found in the environment, of benzene in aircan result in death. Lower concentrations can cause drowsiness, dizziness, rapid heartrate, headaches, tremors, confusion, and unconsciousness. In most cases, people will stopfeeling these effects when they stop being exposed and begin to breathe fresh air.
  • The DHHS, IARC and EPA have determined that benzene is carcinogenic to humans.


  • Chloroform is a colorless liquid with a pleasant, nonirritating odor and a slightly sweet taste. Most of the chloroform found in the environment comes from industry.
  • Chloroform enters the environment from chemical companies and paper mills. It is alsofound in waste water from sewage treatment plants and drinking water to which chlorinehas been added.
  • People may be exposed to small amounts of chloroform in drinking water and inbeverages (such as soft drinks) made using water that contains chloroform. You can alsoget small amounts of chloroform in your body by eating food, by breathing air, and byskin contact with water that contains it. People who work at or near chemical plants andfactories that make or use chloroform can be exposed to higher-than-normal amounts ofchloroform.
  • In humans, chloroform affects the central nervous system (brain), liver, and kidneys aftera person breathes air or drinks liquids that contain large amounts of chloroform. Breathing high concentrations of chloroform for a short time causes fatigue, dizziness,and headache. Long term exposure to high concentrations of chloroform may cause liverand kidney damage.
  • ATSDR's chronic oral MRL is 0.01 mg/kg/day (critical endpoint: hepatotoxicity inmice).
  • IARC has determined that chloroform is possibly carcinogenic to humans. EPA hasdetermine that chloroform is a probable human carcinogen.


  • Benzo(a)pyrene is one of the polycyclic aromatic hydrocarbon (PAH) compounds.
  • Because it is formed when gasoline, garbage, or any animal or plant material burns, it isusually found in smoke and soot. This chemical combines with dust particles in the airand is carried into water and soil and onto crops.
  • People may be exposed to benzo(a)pyrene from environmental sources such as air, water,and soil and from cigarette smoke and cooked food. Workers who handle or are involvedin the manufacture of PAH-containing materials may also be exposed to benzo(a)pyrene. Typically, exposure for workers and the general population is not to benzo(a)pyrene alonebut to a mixture of similar chemicals.
  • The most common way benzo(a)pyrene enters the body is through the lungs when aperson breathes in air or smoke containing it. It also enters the body through the digestive system when substances containing it are swallowed.
  • The DHHS has determined that benzo(a)pyrene may reasonably be anticipated to be acarcinogen.


  • 1,2-dichloroethane is a clear, manufactured liquid that is not found naturally in theenvironment. It evaporates quickly at room temperature and has a pleasant smell and asweet taste.
  • The most common use of 1,2-dichloroethane is to make vinyl chloride, which is used tomake a variety of plastic and vinyl products including polyvinyl chloride (PVC) pipes andother important construction materials, packaging materials, furniture and automobileupholstery, wall coverings, housewares, and automobile parts.
  • 1,2-dichloroethane can enter the environment when it is made, packaged, shipped, orused.
  • People are exposed to 1,2-dichloroethane mainly by breathing air or drinking water thatcontains 1,2-dichloroethane. Exposure usually happens where the chemical has beenimproperly disposed of, or spilled onto the ground. People can be exposed to lowconcentrations of 1,2-dichloroethane through the skin or air by contact with old productsmade with 1,2-dichloroethane, such as cleaning agents, pesticides, and adhesives used toglue wallpaper and carpets. Such exposure is probably not enough to cause harmfulhealth effects.
  • People who were accidently exposed to large amounts of 1,2-dichloroethane in the air orwho swallowed 1,2-dichloroethane by accident or on purpose often developed nervoussystem disorders and liver and kidney disease.
  • The DHHS has determined that 1,2-dichloroethane may reasonably be expected to causecancer. The IARC has determined that 1,2-dichloroethane can possibly cause cancer inhuman. And, EPA has determined that 1,2-dichloroethane is a probably humancarcinogen.


  • 1,1-Dichloroethene is a chemical used to make certain plastics (such as packagingmaterials, flexible films like SARAN) and flame-retardant coatings for fiber and carpetbacking. It is a colorless liquid that evaporated quickly at room temperature.
  • 1,1-Dichloroethene can enter the environment when it is released to the air during itsproduction or released to surface water or soil as a result of waste disposal.
  • 1,1-Dichloroethene is found at very low concentrations in indoor and outdoor air,therefore, the potential for exposure in the environment is extremely low. The amountsare somewhat higher near some factories that make or use 1,1-dichloroethene (those thatmake food-packaging films, adhesives, flame-retardant coatings for fiber and carpetbacking, piping, and coating for steel pipes).
  • Information on the health effects in humans after breathing 1,1-dichloroethene isinsufficient. People who breathed high amounts in a closed space lost their breath andfainted. Available information indicates that prolonged inhalation of 1,1-dichloroethenecan induce adverse neurological effects and is possibly associated with liver and kidneydamage in humans.
  • ATSDR's chronic oral MRL is 0.009 mg/kg/day (critical endpoint: hepatic effects inrats).
  • The DHHS has not classified 1,1-dichloroethene with respect to carcinogenicity. TheIARC has determined that 1,1-dichloroethene is not classifiable as to its carcinogenicityin humans. The EPA has determined that 1,1-dichloroethene is a possible humancarcinogen.

FREON-11, Trichlorofluoromethane

  • Trichlorofluoromethane is a colorless, volatile liquid or a gas at 75F.
  • It is used as a refrigerant, solvent, in foam production and in making fire extinguishers.
  • Trichlorofluoromethane can irritate the skin and eyes. Repeated exposure can causedryness and cracking of the skin. Breathing trichlorofluoromethane can irritate the lungscausing coughing and/or shortness of breath. Overexposure can make you feellightheaded and dizzy. High exposure can cause irregular heart beat, which can be fatal.
  • EPA's chronic oral RfD is 0.3 mg/kg/day.
  • The International Agency for Research on Cancer (IARC) has not classifiedtrichlorofluoromethane for carcinogenic effects. The EPA has not made a determinationas to the carcinogenicity of trichlorofluoromethane.

FREON-12, Dichlorodifluoromethane

  • Dichlorodifluoromethane is a colorless, volatile liquid or a gas at 75F.
  • It is used as a refrigerant, solvent, and in making fire extinguishers.
  • Dichlorodifluoromethane can irritate the skin and eyes. Repeated exposure can cause dryness and cracking of the skin. Breathing Dichlorodifluoromethane can irritate the lungs causing coughing and/or shortness of breath. Overexposure can make you feel lightheaded and dizzy. High exposure can cause irregular heart beat, which can be fatal.
  • EPA's chronic oral RfD is 0.2 mg/kg/day.
  • The International Agency for Research on Cancer (IARC) has not classifieddichlorodifluoromethane for carcinogenic effects. The EPA has not made adetermination as to the carcinogenicity of dichlorodifluoromethane.

FREON-113, 1,1,2-Trichlorotrifluoroethane

  • 1,1,2-Trichlorotrifluoroethane is a colorless, volatile liquid or a gas at 75F.
  • It is used as a refrigerant, dry cleaning solvent, foam blowing agent and in making fire extinguishers.
  • 1,1,2-Trichlorotrifluoroethane can irritate the skin and eyes. Repeated exposure cancause dryness and cracking of the skin. Breathing 1,1,2-trichlorotrifluoroethane canirritate the lungs causing coughing and/or shortness of breath. Overexposure can makeyou feel lightheaded and dizzy. High exposure can cause irregular heart beat, which canbe fatal.
  • 96-hour LC50 for fathead minnow = 1250 ppm.
  • EPA's chronic oral RfD is 30 mg/kg/day.
  • The International Agency for Research on Cancer (IARC) has not classified 1,1,2-trichlorotrifluoroethane for carcinogenic effects. The EPA has not made a determination as to the carcinogenicity of 1,1,2-trichlorotrifluoroethane.

Methlyene Chloride

  • Methlyene chloride is a colorless liquid that has a mild sweet odor, evaporates easily, anddoes not easily burn. It is widely used as an industrial solvent and as a paint stripper. Itcan be found in certain aerosol and pesticide products and is used in the manufacture ofphotographic film. The chemical may be found in some spray paints, automotivecleaners, and other household products.
  • People may be exposed to methylene chloride in air, water, food, or from consumerproducts. Because methylene chloride evaporates easily, the greatest potential forexposure is when you breathe vapors of contaminated air. Contact with consumerproducts such as paint strippers or aerosol cans that contain methylene chloride is anotherfrequent source of exposure. The highest and most frequent exposures to methylenechloride usually occur in workplaces where the chemical is used.
  • Breathing high concentrations of methylene chloride for long periods cause dizziness,nausea, tingling or numbness of the fingers and toes, and drunkenness. In most cases,effects disappear shortly after exposure ends.
  • ATSDR's chronic oral MRL is 0.2 mg/kg/day (critical endpoint: hepatotoxicity in rats).
  • The DHHS has determined that methylene chloride may reasonably be anticipated to be acarcinogen. The IARC has determined that methylene chloride is possibly carcinogenicto humans. The EPA has determined that methylene chloride is a probable humancarcinogen

Tetrachloroethylene (10-13)

  • Synthetic chemical used as a dry cleaning fluid, a degreaser, and as a starting material for other products
  • Evaporates quickly, but breaks down very slowly
  • Can travel easily through soils to reach groundwater
  • Inhalation most common way to enter body, also ingestion if drinking water iscontaminated
  • Adverse health effects due to chronic inhalation exposure possibly include reproductive effects in women
  • Higher concentrations of exposure in animals may cause liver, kidney damage
  • EPA's chronic oral RfD is 0.01 mg/kg/day (critical endpoints: hepatotoxicity in mice and weight gain in rats).
  • The IARC has determined that tetrachloroethylene is probably carcinogenic to human.


  • 1,1,1-Trichloroethaneis a synthetic chemical that does not occur naturally in theenvironment.It is used in commercial products, mostly to dissolve other chemicals, suchas glues and paints. In industry, it is widely used to remove oil or grease frommanufactured metal parts. In home, it may be an ingredient of products such as spotcleaners, glues, and aerosol sprays.
  • Because 1,1,1-trichloroethane is used so frequently in home and office products, muchmore is usually found in the air inside buildings. Also, common consumer products thatcontain 1,1,1-trichloroethane include glues, household cleaners, and aerosol sprays. Thus, people are likely to be exposed to 1,1,1-trichloroethane vapor at higherconcentrations indoors than outdoors or near hazardous waste sites. In the workplace,workers may be exposed to 1,1,1-trichloroethane while using some metal degreasingagents, paints, glues, and cleaning products.
  • Breathing high concentrations of 1,1,1-trichloroethane for a short time may causedizziness and lightheadedness, and the lost of coordination. Breathing very highconcentrations of 1,1,1-trichloroethane , either intentionally or accidentally, may result in unconsciousness, decrease in blood pressure and the stoppage of the heart.
  • The IARC has determined that 1,1,1-trichloroethane is not classifiable as to itscarcinogenicity in humans. The EPA has also determined that 1,1,1-trichloroethane is notclassifiable as to its human carcinogenicity.


  • Trichloroethylene is a nonflammable, colorless liquid at room temperature with asomewhat sweet odor and a sweet, burning taste. This manmade chemical does not occurnaturally in the environment.
  • Trichloroethylene is mainly used as a solvent to remove grease from metal parts. It canbe found in some household products, including typewriter correction fluid, paintremovers, adhesives, and spot removers.
  • People may be exposed to trichloroethylene by its evaporation from paints, glues, andother products or by release from factories where it is made. People living nearhazardous waste sites may be exposed to it in the air or in their drinking water used forbathing or cooking.
  • People who are exposed to large amounts of trichloroethylene can become dizzy or sleepyand may become unconscious when exposed to very high concentrations. Death mayoccur from inhalation of large amounts.
  • ATSDR's acute oral MRL is 0.2 mg/kg/day (critical endpoint: behavior changes in mice).
  • The IARC has determined that trichloroethylene is probably carcinogenic to humans.



  • A silvery-white metal that is found in the earth's crust. Antimony ores are mined andthen mixed with other metals to form antimony alloys or combined with oxygen to formantimony oxide.
  • Antimony is released to the environment from natural sources and from industry.
  • In the air, antimony is attached to very small particles that may stay in the air for many days. Most ends up in soil, where it attaches strongly to particles that contain iron, manganese, or aluminum.
  • Because antimony is found naturally in the environment, the general population isexposed to low concentrations of it every day, primarily in food, drinking water, and air. Workers in industries that process it or use antimony ore may be exposed to higherconcentrations.
  • Exposure to antimony at high concentrations can result in a variety of adverse healtheffects; breathing high concentrations for a long time can irritate your eyes and lungs and can cause heart and lung problems, stomach pains, diarrhea, vomiting, and stomachulcers.
  • EPA's chronic oral RfD = 0.0004 mg/kg/day (critical endpoints: longevity, changes inblood glucose and cholesterol concentrations in rats).
  • The DHHS, the International Agency for Research on Cancer (IARC) and the UnitedStates Environmental Protection Agency(USEPA) have not classified antimony as to itshuman carcinogenicity.


  • Arsenic is found in nature at low concentrations.
  • It's mostly in compounds with oxygen, chlorine, and sulfur; these are called inorganicarsenic compounds.
  • Arsenic in plants and animals combines with carbon and hydrogen; this is called organic arsenic. Organic arsenic is usually less harmful than inorganic arsenic.
  • In the environment, arsenic does not evaporate. Most arsenic compounds can dissolve inwater. It can get into air when contaminated materials are burned, however, it settlesfrom the air to the ground. In the ground, it does not break down, but it can change fromone form to another. Fish and shellfish build up organic arsenic in their tissues, but mostof the arsenic in fish is not toxic.
  • You can be exposed to arsenic by breathing sawdust or burning smoke from woodcontaining arsenic; breathing workplace air; ingesting contaminated water, soil, or air atwaste sites containing arsenic; or ingesting contaminated water, soil, or air near areasnaturally high in arsenic.
  • Lower concentrations of exposure to inorganic arsenic may cause: nausea, vomiting, anddiarrhea; decreased production of red and white blood cells; abnormal heart rhythm;blood vessel damage; and/or a "pins and needles" sensation in hands and feet.
  • High concentrations of inorganic arsenic in food or water can be fatal. A high level is 60parts of arsenic per million parts of food or water (60 ppm). Arsenic damages manytissues including nerves, stomach and intestines, and skin. Breathing high concentrationscan give you a sore throat and irritated lungs.
  • Long term exposure to inorganic arsenic may lead to a darkening of the skin and theappearance of small "corns" or "warts" on the palms, soles, and torso.
  • ATSDR's chronic oral MRL = 0.0003 mg/kg/day (critical endpoints: hyperpigmentation,keratosis & possible vascular complications in humans).
  • The DHHS has determined that arsenic is a known carcinogen. Breathing inorganicarsenic increases the risk of lung cancer. Ingesting inorganic arsenic increases the risk of skin cancer and tumors of the bladder, kidney, liver, and lung.


  • Barium is a silvery-white metal that occurs in nature in many different forms calledcompounds. Two forms of barium, barium sulfate and barium carbonate, are often foundin nature as underground ore deposits. Barium is sometimes found naturally in drinkingwater and food. Other forms of barium compounds such as barium chloride, bariumhydroxide, and barium nitrate are manufactured from barium sulfate.
  • People may be exposed to barium when barium waste is released to air, land, and waterduring industrial operations. Also, exposure near hazardous waste sites may occur bybreathing dust, eating soil or plants, or drinking water that is polluted with barium.
  • The health effects of the different barium compounds depend on how well the specificbarium compound dissolves in water. For example, barium sulfate does not dissolve wellin water and has few adverse health effects. On the other hand, barium compounds, suchas barium acetate, barium carbonate, and barium chloride, that dissolve in water cancause adverse health effects. Eating and drinking large amounts of barium compoundsthat dissolve in water may cause paralysis or death in a few individuals. Some peoplewho eat or drink somewhat smaller amounts of barium for a short period may potentiallyhave difficulties in breathing, increased blood pressure, changes in heart rhythm, stomachirritation, minor changes in blood, muscle weakness, changes in nerve reflexes, swellingof the brain, and damage to the liver, kidney, heart, and spleen.
  • EPA's chronic oral RfD = 0.07 mg/kg/day (critical endpoint: no adverse effect inhumans).
  • The DHHS, IARC, and USEPA has not classified barium as to its carcinogenicity.


  • Chromium is a naturally occurring element found in rocks, soil, plants, animals, and in volcanic dust and gases.
  • Chromium has three main forms: chromium (0), chromium (III), and chromium (VI). Chromium (III) compounds are stable and occur naturally in the environment. Chromium(0) does not occur naturally and chromium (VI) occurs only rarely. Chromiumcompounds have no taste or odor.
  • Chromium (III) is an essential nutrient in our diet, but we need only a very small amount. Other forms of chromium are not needed by our bodies.
  • Chromium can enter the environment by the manufacturing, disposal of products orchemical containing chromium, or burning of fossil fuels release chromium to the air,soil, and water. Chromium particles settle from air in less than 10 days. Chromiumsticks strongly to soil particles. Most chromium in water sticks to dirt particles that fall to the bottom; only a small amount dissolves. Small amounts move from soil togroundwater. Fish do not take up or store chromium in their bodies.
  • You may be exposed to chromium by breathing contaminated workplace air (e.g.,stainless steel welding, chromate or chrome pigment production, chrome plating, leathertanning, etc.). Handling or breathing sawdust from chromium treated wood. Breathingcontaminate air, or ingesting water, or food from soil near waste sites or industries thatuse chromium. Very small amounts of chromium (III) are in everyday foods.
  • All forms of chromium can be toxic at high concentrations, but chromium (VI) is moretoxic than chromium (III). Breathing very high concentrations of chromium (VI) in aircan damage and irritate your nose, lungs, stomach and intestines. People who are allergicto chromium may also have asthma attacks after breathing high concentrations of eitherchromium (VI) or (III).
  • Long term exposures to high or moderate concentrations of chromium (VI) cause damageto the nose (bleeding, itching, sores) and lungs, and can increase your risk of non-cancerlung diseases. Ingesting very large amounts of chromium can cause stomach upsets andulcers, convulsions, kidney and liver damage, and even death. Skin contact with liquidsor solids containing chromium (VI) may lead to skin ulcers. Some people have allergicreactions including severe redness and swelling.
  • EPA's chronic oral RfD = 0.005 mg/kg/day (critical endpoint: no adverse effects reported in rats).
  • The DHHS has determine that certain chromium (VI) compounds are known carcinogens.


  • Pure nickel is a hard, silvery-white metal, which has properties that make it very desirablefor combining with other metals to form mixtures called alloys. Nickel combined withother elements occurs naturally in the earth's crust. It is found in all soil and is alsoemitted from volcanos.
  • Nickel may be released to the environment from the stacks of large furnaces used to makealloys or form power plants and trash incinerators. The nickel that comes out of thestacks of power plants is attached to small particles of dust that settle to the ground or are taken out of the air in rain.
  • People may be exposed to nickel by breathing air, drinking water, eating food, or smokingtobacco containing nickel. Skin contact with soil, water, or metals containing nickel aswell as with nickel plated with nickel can also result in exposure.
  • The most common adverse health effect of nickel in humans is an allergic reaction tonickel. People can become sensitive to nickel when jewelry or other things containingnickel are in direct contact with the skin. Once a person is sensitized to nickel, furthercontact with the metal will produce a reaction. The most common reaction is a skin rashat the site of contact. People who are not sensitive to nickel must eat very large amounts of nickel to suffer adverse health effects.
  • The most serious effects of nickel, such as cancer of the lung and nasal sinus, haveoccurred in people who have breathed dust containing nickel compounds while workingin nickel refineries or in nickel processing plants. Other lung effects including chronicbronchitis and reduced lung function have been observed in workers breathing nickel. Current concentrations of nickel in workplace air are much lower than in the past, andfew workers have symptoms from nickel exposure.
  • EPA's chronic oral RfD = 0.02 mg/kg/day (critical endpoint: decreased body and organweights in rats).
  • The DHHS has determined that nickel and certain nickel compounds may reasonably beanticipated to be carcinogens. The IARC has determined that some nickel compounds arecarcinogenic to humans and that metallic nickel may possibly be carcinogenic to humans. The USEPA has determined that nickel refinery dust and nickel sulfide are humancarcinogens.


  • Vanadium is a natural element in the earth. It is a white to gray metal, often found as crystals. It has no particular odor. Vanadium occurs naturally in fuel oils and coal. In the environment it is usually combined with other elements such as oxygen, sodium, sulfur, or chloride.
  • Most people are exposed daily to very low concentrations of vanadium in food, drinkingwater, and air. Most of your intake is from food. The vanadium in these sources is atleast partially due to naturally occurring vanadium in rocks and soil.
  • People are exposed to vanadium by breathing it into your lungs and eating or drinkingsmall amounts in food and water.
  • ATSDR's intermediate oral MRL = 0.003 mg/kg/day (critical endpoints: mild histologicalchanges in kidneys, lungs, and the spleen in rats).
  • If you breathe large amounts of vanadium dusts for short or long periods, you will have lung irritation that can make you cough, and you can also develop a sore throat and red irritated eyes. No studies designed to look for cancer in laboratory animals exposed to vanadium were found.


The Karimi Model is a diffusion-based air screening model used to approximate the migration ofvapors from soil or groundwater into buildings above contamination sources. While the KarimiModel is rather simplistic, it is useful because it provides a rapid evaluation of a number ofelements that affect the concentration of soil gas contaminants. In addition, the elementsconsidered by the Karimi Model can be estimated or chosen with the intention of producing anestimate of a "worst case" exposure scenario.

The following assumptions were made pertaining to the Omega Chemical Site Karimi Model:

1. The distance between gas vapors and model buildings is 6 feet or 1.83 meters.

2. Assume that 100% of vapors that reach building foundations will enter the building.

3. The air exchange rate used for the Administration Building was 0.5/hour based on Mueller,, 1988. Due to the ventilated condition of the warehouse, the air exchange rate used forcalculations of the gases in the warehouse was 1.0/hour.

4. Air filled porosity was assumed to be 0.30 (maximum).

5. Total porosity was assumed to be 0.47, per Weiss Assoc., 1988.

6. The area of the warehouse crawl space was estimated to be 2.4 square meters.

7. The area of the Administration Building was estimated to be 0.85 square meters.

8. The volume of air in the warehouse was estimated to be 20400 cubic meters.

9. The volume of air in the Administration Building was estimated to be 612 cubic meters.

10. The universal gas constant utilized for this model was 0.000082 M3 atm mol-1 K-1

Additionally, it should be noted that a number of additional values are chemical specific values,such as Henry's Law Constant and the vapor phase diffuse coefficient in air.

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