<&ERA
United States
Environmental Protection
Agency
Need information?
Visit the site information
repository:
Cincinnati Public Library
Miami Township Branch
8 Miami Ave.. Clcvcs
Contact a member of the EPA site
team:
Chris Black
EPA Project Manager
(312) 886-1451
black, christophcru7jcpa.gov
Bri Bill
EPA Community Involvement
Coordinator
(312)353-6646
bill.brianau7jcpa.gov
EPA toll free:
(800)621-8431
weekdays 10 a.m. - 5:30 p.m.
Attend a CAP meeting:
Anyone can attend a Chevron
community advisory panel meeting.
The CAP typically meets the first
Wednesday of every month at the
Whitewater Senior Center and
Township Hall at 6125 Dry Fork
Road. You can ask questions at the
end of each meeting.
Contact meeting facilitator Monte
McKillip at (402) 327-9498 or
montc c/ nicki 11 ipassociates.com for
the meeting schedule or more
information.
EPA Answers Your Questions about
Health Risks from Polluted Ground Water
ChevronTexaco Cincinnati Facility
Hooven, Ohio	October 2004
U.S. Environmental Protection Agency continues to oversee ChevronTexaco
Environmental Management Co.'s environmental study and cleanup of the
former refinery and nearby property located in Hooven. Over the past year,
some of you as well as Chevron community advisory panel members have
asked EPA questions about health risks and the human health risk assessment
done in 2000. This assessment looked at the possibilities of people being
exposed to polluted vapors (gases) coming from water deep underground,
beneath Hooven homes. The assessment found health risks to people from
vapors to be at levels EPA considers safe. EPA provides more detail in
answers to frequently asked questions below. See the back page for a
summary of the refinery's history and environmental study.
Questions and answers
What's the problem with the old refinery? As a result of past refinery
operations, a large amount of petroleum products are floating in the water
deep underground. This water, called ground water, lies beneath the former
facility. It has flowed under portions of neighboring residential areas.
Chevron, under EPA supervision, is studying this pollution to identify the
best way to reduce harm to residents.
How can the polluted ground water cause harm to residents? Some of the
chemicals within the polluted area of water, called a plume, could pose a
health risk to people who are in contact with the chemicals over a long period
of time. EPA is most concerned about the risk from a process called vapor
intrusion. Vapor intrusion is a way that chemicals in soil or ground water can
get into indoor air. This happens because some chemicals can travel as
vapors (gases) through spaces and cracks between soil, gravel and rock.
These vapors can move up through the soil into outside air or basements.
Vapors venting directly to the outside are usually harmless because of the
low concentrations and dilution in air. Vapors can enter basements through
cracks in the foundation where residents can breath them in. Fortunately, at
most sites, risk posed by vapor intrusion is quite low. However, each site
needs to be evaluated when vapor intrusion is a possibility.
To better understand the possible risk to Hooven residents from vapors,
Chevron conducted a risk assessment in September 2000.
What is ground water?
Ground water is the water that collects deep
underground in the spaces between dirt, gravel
and rock.

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What is a human health risk assessment? A risk
assessment is the process of estimating how dangerous a
polluted site is - now and in the future - to people that live
and work nearby. The goal of a risk assessment is to
understand what levels of cleanup are necessary to protect
peoples' health. To understand the results, it is important
to know what a human health risk assessment is and what
it is not. Unlike health studies, risk assessments do not
show whether or not people have actually been exposed to
site contaminants or whether they have actually suffered
health effects from these exposures. Instead, scientists look
at the possibility of people coming in contact with
pollutants and being harmed by them. Three outcomes can
happen following the completion of a risk assessment:
risk is within levels EPA considers safe and no
further action is taken;
risk is higher than the levels EPA considers safe
and action needs to be taken to lower the risk to
exposed individuals;
risk is uncertain and more information needs to be
collected.
To determine the health risk, risk assessors need to have
information about how toxic specific chemicals are (the
hazard) and to what extent people are exposed to the
hazards (the exposure). See the figure below for more.
How was the Chevron risk assessment done and what did
it show? The Chevron risk assessment looked at the risk
posed by vapors moving up from the ground water plume.
To study the health risk, Chevron collected samples of
vapors from boreholes at the site and in residential areas.
Also, the company identified categories of people
(residents, school students, school employees) that could
potentially come in contact with these chemicals and
studied the ways this contact could occur. Along with this
information, they took what was known (in 2000) about
the toxicity (harmfiilness) of site chemicals and calculated
the human health risk.
The risk assessment found that health risks from the
ground water plume and vapors to Hooven residents is
low, well within EPA's guidelines for safety, with one
exception discussed below.
Here's what the risk assessment found:
The most direct way for people to be exposed to
vapors would be by breathing vapors entering the
home. The most likely place for vapors to enter the
home would be through the basement. People at
most risk are those living in basements. The risk
assessment showed that a basement dweller
(someone in the basement 16 hours each day for
30 years) had an 8 in 100,000 chance of getting
cancer from exposure to site contaminants.
Although this risk is higher than for residents that
don't live in the basement, the risk still falls within
the range EPA considers safe. It is important to
keep in mind that for the purposes of the study, it
was assumed that vapors entered the basement.
We don't really know if this is the case.
The assessment also showed that basement
dwellers are at higher risk for other health
problems, but the data was not reliable. Chevron
will have to explore this in more detail.
Residents do not ingest (drink) polluted ground
water. Water to Hooven residents is supplied by a
municipal water supply from Cleves, a
neighboring community. The wellfield supply
water to the Cleves municipal system is not
affected by the ground water plume.
Health Risk = Hazard x Exposure

Health Risk
Health risk is the
chance that exposure
to a hazard (such as a
hazardous substance)
will harm you. Typically, risk from
cancer is expressed as a probability, or
chance. For example, a 1 in 10,000
chance means that for every 10,000
people exposed, one extra cancer may
occur beyond what would be expected
from all other causes.
IT
Animal
Experiments Human Studies
Hazard
A hazard is a
potential source
of harm, from
contact with a
chemical, for example. Animal experiments
or human studies provide information about
how hazardous a chemical is. Scientists use
this research to estimate the likelihood of
illness at different levels of exposure or
contact with the chemical.
Exposure
Information on
the ways
(breathing,
touching,
drinking and
eating) people are exposed to site
chemicals comes from samples taken
from ground water, soil and air.
Mathematical models are then used to
estimate exposure based on the
amounts of chemicals in the ground
water, soil and air.
Residents are not in direct skin contact with polluted
soil and gravel because polluted materials are deep
2

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(35 - 65 feet below the surface).
•	Research of toxicity found that cancer-causing
chemicals exist in the vapors. Again, for people to
be harmed by the vapors, they would need to come
in contact with the vapors for a long period of time.
The chemical that causes the most concern is
benzene, a solvent found in gasoline and other
petroleum products.
•	Cancer risk posed by site pollutants to students and
employees at the Hooven Elementary School is low
and well within EPA's safety guidelines available in
2000.
If risk to health is low, why does the human health risk
assessment have to be redone?
EPA recently made changes to the national standards for
calculating hazards. Two of the changed standards were
for chemicals found in the Hooven ground water plume. In
addition, EPA wants Chevron to revise the assessment to
address concerns made by Hooven residents about some of
the assumptions used in the assessment, such as the
percentage of cracks in the typical Hooven crawl space or
basement floor. (Most of these areas have dirt floors.) In
light of these developments, EPA asked Chevron to update
the 2000 risk assessment, and Chevron has agreed to do
so. Chevron is evaluating the information collected about
crawl spaces and basements collected during a recent
door-to-door survey. They will factor information gained
into the revision. It may be necessary to collect crawl
space or basement air samples to learn more.
When will the revised risk assessment be done?
Chevron has agreed to submit a revised risk assessment to
EPA in the fall of 2004. EPA will review the assessment
and prepare comments requesting revisions or approve the
assessment as is.
How will the results be used?
Results will help determine the need to sample indoor air.
It will also be used in months to come to identify
additional cleanup options for polluted ground water and
vapors.
Why bother doing a risk assessment? Why not just
sample the air to see if vapors are entering basements?
A number of factors can greatly affect results of indoor air
sampling, making it difficult to determine if site-related
vapors are present or not. Indoor air quality changes a lot
from day to day. Also, chemicals in household products
such as paints, paint strippers and thinners, aerosol sprays,
moth balls, air fresheners, new carpeting or furniture,
hobby supplies (glue and solvents), stored fuels, dry
cleaned clothing and cigarette smoke can confuse the
results of indoor air sampling, particularly when
concentrations of site-related vapors are very low. In fact,
studies have found that the health risks from site-related
vapors is often lower than that posed by the chemicals
found in household products.
A contractor prepares a soil boring for
laboratory analysis.
A cleanup plan came out last summer for sludges and
polluted soil on the Chevron property. When will EPA
propose a final cleanup plan for polluted ground water?
EPA is reviewing a draft "corrective measures study"
prepared by Chevron. This study outlines various options
for addressing polluted ground water and vapors. EPA has
requested that Chevron make revisions to the document to
address EPA comments. Chevron will revise the study
based on these revisions. Then, EPA will propose a final
cleanup plan based on these findings and results from the
revised human health risk assessment. Before making a
decision on the cleanup plan, EPA will mail its proposal to
residents as well as make it available for review at the
library. EPA will also hold a public meeting to present the
proposal and hear residents' views.
3

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Cnvironm«mal Protection
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77 West Jdrkj>nn Bouevard
Chicago	60R04
Local Patron
Hooven, OH 45033
ChevronTexaco: EPA Answers Your Questions about
Health Risks from Polluted Ground Water

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