Sub-module 2A, Page 1
| Sub-module 2A | Overview of laws and reg.'s, uses of risk assessment. |
Learning Goals:
Understand:
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.
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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 a little about the Toxic
Release Inventory. The "TRI Explorer" is a tool to sift the EPA database
regarding toxic chemicals released to the environment. Go to https://iaspub.epa.gov/triexplorer/tri_release.chemicall
then go to Release Reports at
https://iaspub.epa.gov/triexplorer/tri_release.chemical
. Use the menu box to choose
a state other than the state you live in, 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 compounds 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 cleaning store. Perhaps a notice that "this
is 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 described 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 is a brief explanation of CERCLA. https://www.epa.gov/superfund/superfund-cercla-overview, then at the bottom of that
page a link to SARA https://www.epa.gov/superfund/superfund-amendments-and-reauthorization-act-sara . Please read both those pages, then use your Back Button to 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 happened
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 https://www.epa.gov/superfund/introduction-hazard-ranking-system-hrs
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.
https://www.epa.gov/rcra/resource-conservation-and-recovery-act-rcra-overview.
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/oswer/riskassessment/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 (PA/SI). This step usually requires extensive sampling
of soils and materials and a thorough 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 pursuing.
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 to 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 thorough a risk assessment as is 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. In Course Documnets is a 20 meg pdf file of the Fox River RI. Just read the Executive Summary. Save the file.
During the RI, enough information becomes available to do a much more accurate
risk assessment, and this is called the Baseline Risk Assessment. It's
characterization of the risk is based on the information collected during the
RI. During the FS, different scenarios (by that I mean sets of design alternatives)
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.