Although dated June
1999 the Glynn Environmental Coalition (GEC) only recently received the
Final Baseline Risk Assessment for Human Health. This document contains
information on how dangerous the site is to people. The Environmental
Protection Agency (EPA) uses computer modeling to determine if chemicals at
the site are dangerous.
There are concerns that the
present site conditions may be very different than those described in this
document. Many of these studies remain incomplete. Very little can be
concluded from this Risk Assessment, except that a considerable amount of
work remains to be done before EPA can select a remedy.
The Human Baseline Risk Assessment
Risk assessments are used to
decide what chemicals need to be cleaned up, where the site needs treatment,
and the type of cleanup methods that will be used. There are two basic kinds
of assessments, the Human Health Assessment and the Ecological Assessment.
The Human Health Assessment looks only at the danger to people; the
Ecological Assessment considers the threat to plants, fish, insects, birds
and other wildlife.
The risk assessment study looks at
what kinds of chemicals are at the site, where they occur within the site,
how they occur—in topsoil, underground, in ponds or streams, or in
groundwater. The study also looks for “pathways”—for instance, if the
chemical is in groundwater, will anyone actually drink water from the site.
Finally, the study looks at the type of injury the chemical can cause.
Chemicals that cause cancer are studied differently than chemicals that are
Located in western Glynn County,
the Brunswick Wood Preserving Superfund Site treated wood products with oils
and minerals. Many of the chemicals used in the treatment processes
contained toxins or carcinogens (“cancer-causers”). When the company closed
down, these chemicals were left untreated. The company had very poor
containment practices and the chemicals can be found offsite as groundwater
plumes and in the sediments of nearby Burnett Creek.
The EPA Emergency Response Branch
did perform a partial removal of contaminated materials. Also, the State of
Georgia Environmental Protection Division (EPD) removed a considerable
amount of contamination. EPA documents designate the site area as 84 acres.
Because the site has never been fully stabilized, it continues to pollute
nearby streams and groundwater. The full extent of the waste and the exact
positions of offsite plumes are still not known.
Contaminants of Concern
The main toxins came from wood
treatment by combinations of pentachlorophenol, oil (creosote), or
copper-chromium-arsenate (CCA). This resulted in contamination from arsenic,
PCP, dioxins, PAH, and other chemicals. The toxic effects range from
long-term threat of cancer to short-term poisoning.
Areas of Concern
There are no safe areas on this
site. The levels of contaminates are high enough that safety is “relative”
to how long a person is exposed. A person visiting the site for a few hours
could be injured in some areas, but not in others. However, since all areas
have some amount of contamination there can be no long-term use of the site.
There may be offsite areas that are unsafe as well. Much of the information
in the Risk Assessment is based on early studies during the emergency
cleanup. The purpose of that work was to stabilize the site and remove the
most dangerous material. Offsite and perimeter areas were not well
All “media” show toxins on the
site, including topsoil, buried soil, groundwater, surface water and
sediments. There are at least two groundwater plumes that are carrying
toxins offsite. Plumes are high concentrations of chemicals that flow away
from a source. The toxins most likely to move in groundwater are carcinogens
(cancer-causing chemicals) such as PAH (aromatic hydrocarbons) and PCP
(chlorinated phenol). EPA says the chemicals are moving in groundwater to
Burnett Creek; however there has been no modeling study to prove this
theory. So far there is no study showing a hydraulic connection between the
groundwater and the creek.
There is a difference between risk
and threat of risk. It is generally accepted that, if there is no “pathway”
to exposure, then there is no risk. So if a chemical is completely bound up
and isolated away from people then the chemical has no actual risk. Risk
“threat” comes from concern that chemicals which are not stabilized or
protected in some way may move from the site into neighborhoods, or into
homes from contaminated tap water.
Each chemical also has unique
effects. Some dissolve in water, some will move in air. Each chemical
usually damages only one type of organ in the body—skin or liver for
example. Not only the proximity of the chemical to a person but the type of
exposure—skin, eating, drinking or breathing—is taken into consideration
when a risk assessment is done.
Risk for cancer is reported as
probability of cancer in a range of “one in one-million” to “one in
one-thousand” chance. These numbers are interpreted the same way as “lotto”
or other games of chance. If an average person is exposed to site chemicals
their “odds” of getting cancer sometime during their lifetime increase by
“one in one-million” to “one in-one-thousand” depending on the amount of
chemical. “One in one-million” is considered to be absolutely no chance of
getting cancer from this exposure. However, “one in one-thousand” is
considered very risky.
Toxicity—how poisonous a chemical
is—is calculated differently than cancer risk. Since toxicity is usually
short-term there is often information on the effects of a chemical on
animals that can be used to estimate danger to people. All of the toxic
effects are added up and a “Hazard Index” (or “HI”) calculated for all
non-cancer risk. If the HI is greater than 1 then site chemicals are
dangerous and the levels unacceptable. HI’s lower than 1 are acceptable.
EPA considered two risk models:
the Current Use model and the Future Use models. The Current Use model only
looked at “industrial” site use; however Future Use was further broken down
to future residential and future commercial/industrial use. When forming
the models EPA uses different exposure standards for residential or
commercial uses. For example, the number of days in a year a child would be
exposed under commercial standard is 250 days (about 8 months and 3 weeks),
while the same child would be exposed under a residential standard for 350
days/year (about l1 months and 2 weeks).
nder the Current Use model the EPA
claims there is no risk for cancer or toxicity. However, the cancer risk
model gave the value of “one in ten-thousand” chance, which is just barely
passing. If EPA’s guidelines are even slightly off there could be a high
cancer risk under the Current Use model. The site would not pass using
For the Future Use model the site
does fail under the residential standards. Cancer risk is within the level
of a “one in one-thousand” chance, which exceeds safety guidelines. Further,
the groundwater plumes fail under residential standards, and these plumes
may extend offsite. Also, the Hazard Index is higher than 1 for site
chemicals, and was especially high for children.
Actual Site Conditions May
Not Match Models
Risk models are only as good as
the numbers used in the math calculations. Poor or incomplete studies result
in models that have no usefulness.
The groundwater studies are incomplete. There is
no information provided on direction and rate of plume movement.
Subsurface soil data was not considered.
Sediments in impoundments and ditches were not considered, even though it is
known that some ponds dry out.
The soil data is based on grid sampling that is
very widely separated. According to Figure 2.1 in the Report some of the
more contaminated areas were sampled at 300-foot intervals, this can bias
the data into concluding that the site is safer than shown.
The EPA has modeled the Brunswick
Wood Preserving Site to show very little risk to the public. There were very
few samples taken during the Remedial Investigation. These were scattered
over a wide area. During the Risk Assessment modeling, some potential
pathways were not used.
models assume that no one can enter the site or stay for any length of time
without EPA’s permission.
The models assume that no fish are
contaminated from Burnett Creek and no one eats them if they are.
The studies assume that no one
drinks or uses groundwater from the site.
EPA assumes they have found the
highest chemical concentrations.
Further, the EPA assumes that all
chemicals occur within areas defined by fences and ditches, although
residents say that clouds of toxic fumes often covered the site.
Unfortunately, the public cannot
assume the site is safe based on this Risk Assessment.
by R. Kevin Pegg, Ph.D.; edited by Dr. Mary S. Saunders. Copies of the
newsletter are available from the GEC, at the Glynn County library, or at
www.NucleicAssays.com/tags on the Internet.
"This project has been funded wholly or partly by the U.S. Environmental
Protection Agency under Assistance Agreement Number 1984482-98-0 to The
Glynn Environmental Coalition, Inc. The contents of this document do not
necessarily reflect the views and policies of the U.S. Environmental
Protection agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use."