Sub-module 2A, Page 1
Sub-module 2A |
Overview of laws
and reg.'s, uses of risk assessment. |
Learning Goals:
Understand:
- The Hazard Identification of many contaminated
sites actually occurs in phases.
- Many details of the Hazard Identification
depend on the regulatory matrix of the particular situation.
- The relationship of risk assessments to
the common phases of a contaminated site evaluation.
While the risk assessment process outlined
in module 1 is quite general, in this sub-module we will spend
some time with environmental contaminants in the mode where most
of us deal with them. Let's start with some philosophy. Most health
risks from chemicals in the environment stem from releases. Releases
might be intentional (or permitted, accent on the first syllable)
or unintentional. The risks we are calculating might be due to
future releases or past releases.
Intentional, past |
Unintentional,
past |
Intentional, future |
Unintentional,
future. |
Examples:
1.) Insecticides such as DDT were released into the environment
in large quantities. (Intentional, Past)
2.) A local electroplating operation asks the city's wastewater
treatment facility for permission to discharge water containing
cadmium into the city's sewers. (Intentional, Future)
3.) An inspection reveals that a gasoline service station's tanks
have been leaking for several years (Unintentional, Past)
4.) A manufacturing company wants to set up chemical storage tanks
on a hill overlooking a school. (Unintentional, Future)
Risk assessments are required in all four cases. For the unintentional
future release, the probability of the harm is related to the
probably of the release. Will the tank burst? These are chiefly
engineering decisions relating to the design of the tank. Once
the engineers have analyzed the probability of a release, a human
health risk assessment is needed in a "what-if" analysis
of the consequences of possible future failure. In performing
the human health risk assessment, the risk analyst would be given
exact quantities of chemicals that would be released in order
to perform the risk analysis, but the quantities would be hypothetical.
For the intentional future releases, we have a similar situation.
Here the analyst would be given an exact number for the release,
or the party that plans to release the chemical would be given
an upper limit on the quantity that will be permitted. Perhaps
some of you did not realize that the release of toxic chemicals
is permitted (again, I mean a permit is given by the government(s))
to release the toxic chemicals into the environment. We should
digress from philosophy to reality. Go to this site TRI and read
the first few paragraphs about the Toxic Release Inventory, the
"TRI Explorer" is tool to sift the EPA data base regarding
toxic chemicals released to the environment. Go to http://www.epa.gov/triexplorer/
then go to Release
Reports at http://www.epa.gov/triexplorer/chemical.htm
. Use the menu
box to choose a state other than Alaska, then use the other menu
box to choose an industry. After you click on the "generate
report" button, you should get a matrix of toxic compound
by the media they were released to (air, water, land). Most of
these releases were quite legal. Bookmark the TRI site.
For all the past releases, both intentional and unintentional,
Hazard Identification is much more difficult. We generally do
not know the amounts of chemical released, and often we do not
even know the chemical. Often there are several chemicals. We
receive notice of them through a phone call (worse, a phone call
from a reporter) or a worker/neighbor/ member of the public shows
up with a Ziploc bag filled with something, or a well water sample
that smells like a dry clearing store. Perhaps a notice that "this
if from the area behind the storage shed," or "this
is from the place where all the vegetation is dead." What
next?
Following some type of initial notice, often times as informal
as note above, a chain of events will follow. Illogical as it
sounds to the uninitiated, the details of what follows will depend
on the regulatory matrix: what the substance is, the location
where it was found, and the nature of the party who likely put
it there. 100 kg of benzene from a chemical plant is different
than 100 kg of benzene from an oil spill. 100 kg of fresh benzene
on its way to factory is different from 100 kg of contaminated
benzene on its way to a recycler. We will try to avoid those details,
but two Federal laws for which you need to know their relations
to risk assessment are CERCLA and RCRA.
CERCLA is the "superfund law." That's pronounced "cerk
lah" and stands for the Comprehensive Environmental Response,
Compensation, and Liability Act, which was enacted in 1980. It
was overhauled in 1986 by SARA (pronounced like the female name,
Sarah), which stands for the Superfund Amendments and Reauthorization
Act. (I won't say much about SARA as separate from CERCLA, unless
some distinction is necessary) Here a brief explanation of CERCLA.
http://www.epa.gov/superfund/action/law/cercla.htm
then at the
bottom of that page a link to SARA http://www.epa.gov/superfund/action/law/sara.htm Please read both those pages, then use your Back
Button come back here.
When congress passed superfund in 1980, the original law had a
provision for a risk assessment, called a Hazard Ranking Score
(HRS). The idea was simple, since there were many sites competing
for superfund money, proponents of cleaning a particular site
would fill out a simple form. The form had a numbering system,
the higher numbers indicating increased risk to human receptors.
The EPA (who might also be a proponent) would arrange these into
a priorities list, with the highest score funded first. (I worked
with a HRS in the early 1980's and I remember it was 3 or 4 pages
long, the instructions were about 10 pages.) What happed was thousands
of contaminated sites were discovered, the cognoscenti realized
that the system could easily result in errors. Today the HRS regulations
are almost 200 pages long. Here's a little about it http://www.epa.gov/superfund/programs/npl_hrs/hrsint.htm
RCRA (pronounced "reck rah") stands for the Resource
Conservation and Recovery Act. This 1976 law was modified in 1984
by the Hazardous and Solid Waste Amendments (HSWA) again, no need
for me to talk about HSWA as distinct from RCRA. RCRA is the "hazardous
waste law." It provides cradle to grave control of hazardous
waste. You don't need to know any details about RCRA for this
course, but you should know that RCRA deals with producers of
hazardous waste and transporters and treatment facilities that
handle hazardous wastes and finally store it. You should also
know that RCRA has its own set of regulations that deal with clean
up of chemical spills and their associated risk assessments. But
on the whole, the procedure is similar to what we learn about
CERCLA below. Here's a capsule on RCRA you should look at the
first 3 FAQs:
http://www.epa.gov/epaoswer/osw/basifact.htm#RCRA
The key difference between
RCRA and CERCLA is that RCRA usually deals with current or ongoing
pollution events and usually there is some sort of viable economic
entity that is responsible and heavily involved. CERCLA usually
deals with past events, sometimes long ago, and either there is
not an economically viable entity available, or finding that entity,
and making them pay, is part of the process.
Back to your friend/client/public with the Ziploc bag. Clearly
you want to investigate the situation some more. In most situations,
the next thing you need to do is find the money and time to do
an investigation. You certainly want the substance in the bag
analyzed to determine what it is, and probably go out to the site
and observe the situation. When you have done these things, you
are in the middle of the Hazard Identification part
of a risk assessment. Let's assume the soil in the bag was saturated
with a chemical and your quick review of the site indicates there
may be a lot of soil so contaminated. Let's ignore issues of budget
and regulatory matrix, but we'll use the nomenclature from the
superfund process. What happens next?
You can find a more detailed discussion of the process in Chapter
1 of RAGS
http://www.epa.gov/superfund/programs/risk/ragsa/index.htm
1.) You need to "scope" the situation. Your analysis
of the gunk in the Ziploc bag and tour of the site is the start
of a scoping. Depending on what you find, the next step would
be,
2.) A more formal approach follows and is called a Preliminary
Assessment and Site Investigation. This step usually requires
extensive sampling of soils and materials and a through investigation
of the situation. Elaborate preparations and chemical analysis
procedures and quality control are required. This step would determine
if a significant release of contaminant occurred. If it did, the
next step is called,
3.) Remedial Investigation. This step is often combined with a
feasibility study and the acronym RI/FS is commonly used for this
process (pronounced "riff is") The RI is now done in
great detail, but the nature of the investigation is keyed to
the expected cleanup alternatives. For example if the PA/SI indicated
extensive groundwater contamination, the RI/FS would involve many
test wells to sample the groundwater. If the PA/SI indicted the
contaminants were bound up in the surface soil, the RI/FS would
not drill many wells. The feasibly study is the first step in
designing the remediation.
4.) Following the RI/FS, if this were a superfund site (and there
is usually an analogous procedure for non-superfund clean ups)
a Record of Decision is issued by the EPA. The record of decision
or ROD follows public comment and deliberation by the EPA and
firms up what will be done with the site.
5.) The next steps are called Remedial Design and Remedial Action,
the later is when the site actually gets cleaned up, or monitored
or whatever. The key acronyms in order are:
Initial scope > PA/SI >RI/FS > ROD > RD and RA
Back to the Ziploc bag and its chemical(s) and your evaluation
of the situation. Here you do a risk assessment to determine if
the matter is even worth perusing. Your report will mention the
chemicals that were in the bag. Are these chemicals toxic in the
doses people are likely to be exposed to? Is the site a playground
or an industrial storage yard? Based on this preliminary risk
assessment, you will try to get your boss to budget the money
to go to a PA/SI or try to get your friend agree and leave the
office. You might call this a back-of-the-envelope risk assessment.
Following the PA/SI a preliminary screening risk assessment is
done, if the PA/SI indicates that there is significant contamination
at the site. This will be a formal document that is as through
a risk assessment as practical, given the preliminary nature of
the information the PA/SI produces. This preliminary screening
risk assessment will identify the Chemicals of Potential Concern
(COPCs), that is the chemicals we are interested in. Here is a
neat site; it concerns the PCB contamination of the Fox River
in Wisconsin. http://www.dnr.state.wi.us/org/water/wm/lowerfox/rifs/rifs3.pdf
Bookmark this
site.
(You learn more about Fox River via http://www.dnr.state.wi.us/org/water/wm/lowerfox/index.html
if you are curious,
but you don't need this now.)
During the RI, enough information becomes available to do a much
more accurate risk assessment, and this is called the Baseline
Risk Assessment. Its characterization of the risk is based on
the information collected by the RI. During the FS, difference
scenarios (by that I mean sets of design alternative) of cleanup
are considered. For each of these, there is a risk assessment
of the alternatives, based on the likely effect of the cleanup
alternative considered.
As part of the ROD, the risk assessments of all the various options
studied are presented to the public. Note that the baseline risk
assessment is now the risk assessment for the "do-nothing"
alternative.
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