Risk Characterization

In the overall scope of the reading I found the overall process by which risk is characterized to be the most fascinating. Although the Exposure Assessment is very useful it can at times be a little much due to the fact that it investigates every facet of possible exposure. This includes routes where there might be little to no risk whatsoever. The Risk Characterization looks at the big picture and illustrates where the highest risks are and the exposure channel that it follows.

According to Dow Chemical, “Risk characterization combines the results of hazard identification and exposure assessments to describe the probability and severity of adverse health or environmental effects.” (http://www.dow.com/productsafety/assess/risk_char.htm) In a sense it integrates the other three levels of the human health risk assessment, it brings all the pieces of the puzzle together.

http://www.erg.com/portfolio/elearn/ecorisk/html/mod4/m4s13.html

Steps of Risk Characterization

1) The first step within a risk characterization is to estimate the overall risk level from both carcinogenic and non-carcinogenic materials. Carcinogenic risks are defined by LaGrega as, “the chronic daily intake dose (developed in the exposure assessment) multiplied by the carcinogenic slope factor (selected from the toxicity assessment). The result from this computation is the estimated risk for developing cancer from the chemical in question. In regards to non-carcinogenic materials there is a utilization of the hazard index which is the ratio of the estimated intake dose over the reference concentration which is measured on site. There is also an addition of a measurement of background risk which is the risk that would be left over even after remediation.

2) The second step of risk characterization, according to the EPA, is to describe the risk and in a sense provide a discussion that would logically support the estimated numbers. Numbers do not mean a whole lot on their own and as a result they need to be explained. In describing the risks it is necessary to either support or refute the quantitative evidence, very similar to a discussion on a scientific experiment. By discussing he evidence it presents a level of subjective certainty in an otherwise uncertain realm. According to the EPA there are three criteria that need to be accounted for when discussing the changes that need to be made. The first is how might the risk impact nature and what would be the intensity of the post effects. The next criteria is to view the area from a spatial point of view, as such how much area is going to be affected? The last criteria is what is the potential for an area to recover? This is extremely important in regards to remediation methods and whether or not there will be a lasting impact.

From the reading that was assigned, the first thought that came to mind was analyzing the debate over nuclear power and how to proceed with our country's energy needs. The most intriguing thing we can relate from this section of reading would be the idea of frequency times severity or impact to calculate risk. The real question is which direction should the country head in order to meet it's energy needs. On one hand we have coal power, relatively safe when it is used to make electricity, but mining however can be dangerous. The impact of coal fired plants is undeniable, the pollution impact is costly and the the health of the citizens can not be measured. I thought the cartoon pictured below is an accurate representation of our mindset when we think of nuclear power but yet fail to consider the risks of coal power.
-http://current.com/items/88942402/is_nuclear_energy_a_clean_solution_for_global_warming.htm

As we examine nuclear power and the "dangers and risks" associated with it, most people fail to take in to account the extreme dangers in coal mining. If we are examining risk assessment, we have to examine all variables to understand the risk associated with the idea. I truly believe there is no complete way to have risk assessment because of the extreme amount of variables involved with every equation. Frequency * Impact = Risk is simply the best option we have at this point and provides a notion to what we are looking at. With nuclear power, we would have to examine the ease at which radioactive material is mined, the dangers of handling, transporting, and storing it. What is the potential for disaster occurring, how often could it occur and what would be the impact of this event are all important questions that need to be assessed. With coal, we have to examine health hazards, mining issues, and environmental impacts. There are so many more options that need to be taken into account as well. There is simply no true way to account for a viable option one way or another and that is why is continues to be such a highly debated topic around the world today. Unfortunately, every option we have contain certain risks that need to be considered. Some have more costly impact, some have more common frequency. In order to have a successful plan, it needs to be balanced and since there is no true answer out there for us, having a balanced energy portfolio is essential to ensuring the meeting of our energy needs in this country.

Risk Assessment and the Yucca Mountain Geologic Repository

The Quantitative Risk Assessment model has been defined in Chapter 14 of the required reading as a four-stage process: Hazard identification; Exposure assessment; Toxicity assessment; and Risk characterization. What I found interesting was the application of the four-stages of quantitative risk assessment has been adopted by the Environmental Protection Agency (EPA). Researching further, I discovered that the EPA formalized their Human Health Risk Assessment beyond their planning and scoping process as: Hazard identification; Dose-Response assessment; Exposure assessment; and Risk characterization. Yet, the most interesting topic that I found in my initial research of the EPA and their process of risk assessment was the issue of Yucca Mountain, Nevada. This blog is simply an overview of the Yucca Mountain Geologic Repository.

Yucca Mountain is the proposed disposal facility for spent nuclear fuel and high-level radioactive waste (EPA, 2005). The EPA has revised the radioactive waste standards for storage in their final rule as documented in 40 CFR Part 197 (EPA, 2008). The EPA revised the radioactive waste standards in regards to the risk assessment and approval process for construction of a disposal facility at Yucca Mountain.

Background information on radioactive waste brings to light the Nuclear Waste Policy Act of 1982. The amended Act of 1982 highlights the fact that high-level radioactive waste shall be disposed of in a deep geologic repository and that Yucca Mountain will be the candidate site as a potential underground repository. The final rule of 40 CFR Part 197, titled Public Health and Environmental Radiation Protection Standards for Yucca Mountain, Nevada, states that even though Public Law 107-200 approved Yucca Mountain as a radioactive waste repository, the licensing approval has not been granted regarding the acceptability of the proposed Yucca Mountain site.

The Yucca Mountain Geologic Repository is a hot topic in the nation’s capitol as Nevada Senator Harry Reid fights over the proposal to store radioactive waste in his State. The following website provides detailed information on the issues of Yucca Mountain: http://reid.senate.gov/issues/yucca.cfm . Most interesting of the information on this website is the recent discussion of the Yucca Mountain debate and the support Senator Reid has from President Obama. Especially, the announcement made by Senator Reid on Thursday January 29, 2009, to work on cutting $100 million from the budget of the Yucca Mountain project.

The risk assessment and pertinent data revolving around the Yucca Mountain Geologic Repository is a topic that I will continue to monitor and research. In growing concerns of finding alternative energy sources such as wind, solar and, more relevant, nuclear energy the risk assessment of Yucca Mountain as a radioactive waste repository will be extremely interesting to research throughout this course. Most importantly, the Nation’s economic concerns will have an impact on the construction of the Yucca Mountain repository. The Yucca Mountain project is a hot topic and three federal agencies are responsible for the approving data and assessment. The Environmental Protection Agency, the Nuclear Regulatory Commission, and the Department of Energy all have responsibilities to the Nation and its citizens, so the question remains: Will the Yucca Mountain Geologic Repository continue to be built?

References: EPA (2008) 40 CFR Part 197-Public Health and Environmental Radiation Protection Standards & EPA (2005) Agency Roles in the Approval, Monitoring and Operation of a Potential Yucca Mountain Repository may be found at: http://www.epa.gov/radiation/yucca/

Photo 1 downloaded from: http://www.inyoyucca.org/

Photo 2 donloaded from: http://www.seismo.unr.edu/htdocs/yucca_map.jpg

Photo 3 downloaded from: http://www-esd.lbl.gov/NW/ymp.html

Hazard Anaysis of Critical Control Points

Reading this material on hazard analysis reminded me of when I worked in the food production industry. I had to have special training from the Food Processors Institute (FPI) on Hazard Analysis and Critical Control Points (HACCP) the tenets and process of HACCP and those we are learning here on risk assessment are quite similar.
HACCP process has several steps. The seven principles are: (1) hazard analysis, (2) critical control point identification, (3) establishment of critical limits, (4) monitoring procedures, (5) corrective actions, (6) record keeping, and (7) verification procedures. From http://www.fsis.usda.gov/OA/background/keyhaccp.htm more on these points in a bit.
While HACCP is primarily concerned with human health and not so much the environment, I thought the two approaches were quite similar. I worked in both the fruit juice concentrate plants and also in sun dried foods, each had its own complications but the HACCP teams I put together were made up of the same types of individuals. Just as we are learing, I had a representative from every aspect of production, even those who were not directly involved in production. HACCP is not a worker safety program, but one to protect the public from hazards in your product.

As such I had mechanics, secretaries, managers, fork lift drivers, cookers, and farmers on my teams.
HACCP is relatively new to the food industry, you think we have food scares and recalls now, you should look back in history. A forerunner to HACCP was developed in the form of production process monitoring during World War II because traditional "end of the pipe" testing wasn't an efficient way to ferret out artillery shells that would not explode. Sound familiar? That same thing could be said about any industrial pollution, not just in food.

Let me tell you a bit more about HACCP-
from http://en.wikipedia.org/wiki/Hazard_Analysis_and_Critical_Control_Points

Hazard Analysis and Critical Control Points (HACCP) is a systematic preventive approach to food and pharmaceutical safety that addresses physical,chemical, and biological hazards so that key actions, known as Critical Control Points (CCP's) can be taken to reduce or eliminate the risk of the hazards being realized.
Based on risk-assessment, HACCP plans allow both industry and government to allocate their resources efficiently
In the US, HACCP compliance is regulated by 21 CFR part 120 and 123. instaid of 40 CFR which contains RCRA, 29 CFR which regulates HAZWOPER remediation workers. Or 49 CFR which contains rules for transporting hazardous materials

As I said before there are seven principles in the HACCP process:
Principle 1: Conduct a hazard analysis. Determine hazards and identify the preventive measures that can be applied to control these hazards. For HACCP purposes a hazard is any biological, chemical, or physical property that could endanger human life or health.
Principle 2: Identify critical control points. A Critical Control Point (CCP) is a point, step, or procedure at which control can be applied and, as a result, hazard can be prevented, eliminated, or reduced to an acceptable level.
Principle 3: Establish critical limits for each critical control point. A critical limit is the maximum or minimum value to which a physical, biological, or chemical hazard must be controlled at a critical control point to prevent, eliminate, or reduce to an acceptable level.
Principle 4: Establish critical control point monitoring requirements. Monitoring activities are necessary to ensure that the process is under control at each critical control point.
Principle 5: Establish corrective actions. These are actions to be taken when monitoring indicates a deviation from an established critical limit. The final rule requires a plant's HACCP plan to identify the corrective actions to be taken if a critical limit is not met.
Principle 6: Establish record keeping procedures. The HACCP regulation requires that all plants maintain certain documents, including its hazard analysis and written HACCP plan, and records documenting the monitoring of critical control points, critical limits, verification activities, and the handling of processing deviations.
Principle 7: Establish procedures for ensuring the HACCP system is working as intended. Validation ensures that the plants do what they were designed to do; that is, they are successful in ensuring the production of safe product. Plants will be required to validate their own HACCP plans
Taken from http://www.cfsan.fda.gov/~lrd/bghaccp.html

Exposure Assessment: Definition and Models - According to the EPA

To me, the most interesting of the four stages of quantitative risk assessment is Exposure Assessment. This is the one area that would be of most importance to the general public. The common citizen is curious to know how an assessment and especially a risk assessment will effect either themselves or their families. Human exposure assessment is another area under the general term of 'Exposure Assessment' of which I find intriguing. This may be useful for upcoming posts!!

Upon further investigation on Exposure Assessment, I found some useful information from the United States Environmental Protection Agency (EPA).

ELEMENTARY DEFINITION:

First, for a baseline lets find an easy to understand definition of Exposure Assessment: "Exposure Assessment is the process of estimating or measuring the magnitude, frequency and duration of exposure to an agent, along with the number and characteristics of the population exposed. Ideally, it describes the sources, pathways, routes, and the uncertainties in the assessment." (Wikipedia, 2009) I understand that alot of the academic population frowns upon using Wikipedia, however I find that the definitions on Wikipedia are easy to understand.

Exposure Assessments are also used for determination of...

- what happens to chemicals when they are used and released to the environment

-how workers, the general public, consumers and the aquatic ecosystems may be exposed to chemicals.

MODELS:
The EPA Center for Exposure Assessment Modeling (CEAM) was established to meet the scientific and technical exposure assessment needs of the EPA as well as state environmental and resource management agencies. CEAM provides proven predictive exposure assessment techniques for aquatic, terrestrial, and multimedia pathways for organic chemicals and metals.

The four assessment models that the CEAM uses are found below...

Groundwater Models:

Groundwater models quantify the movement of subsurface water and provide inputs to subsurface contaminant transport models. Simulation provides insight into groundwater and contaminant behavior and quantitative assessments for environmental decision making.

Surface Water Models:

By modeling contaminant movement and concentration in lakes, streams, estuaries, and marine environments, researchers can better understand how exposure to contaminants affects aquatic environments.

Food Chain Models:

Contaminated aquatic and terrestrial environments typically result in the bioaccumulation of chemicals within all trophic levels of an ecosystem. Software models provide tools for tracking the movement of contaminants through food chains and for estimating chemical impacts on exposed biota.

Multimedia Models:

Contaminants may travel through the atmosphere, soil, surface water, and the organisms that inhabit these media. The multimedia approach to exposure modeling quantifies the impacts of contaminants as they travel through more than one of these environments.

Source:

(U.S. Environmental Protection Agency, Exposure Assessment Models, http://www.epa.gov/ceampubl/)

Hazard Identification and the Rocky Mountain Arsenal

Of the four stages of the quantatative risk assessment process (hazard identification, exposure assessment, toxicity assessment, and risk characterization), I am most familiar with the hazard identification stage. I've worked for seventeen years for an environmental consultant, and I performed a lot of investigations at a nearby Superfund site known as the Rocky Mountain Arsenal (RMA). RMA is a large (27 square mile) area northeast of Denver that was considered one of the most contaminated places in the United States. To the right you can see that the location was close to metro Denver.

Source:http://www.aaccessmaps.com/show/map/denver_metro

I wish to use RMA as an example to discuss Hazard Identification from our handout. The primary goal for hazard identification at a hazardous waste site is to find out what contaminants are there, and where are they. This can be much more difficult than it sounds and can end up costing a lot of money.

Taking RMA for our example, we will look at how they came to know what they had to clean up. When the government began to suspect that there was a problem at RMA they went back over the history of the site. RMA was founded in 1942 at the start of World War II. Its purpose was to manufacture, and when necessary, demilitarize, blister chemical agents and incendiary weapons. It made mustard gas bombs and phosphorus munitions in case Germany or Japan used them on us. They were manufactured in the southern section of the facility known as South Plants.

source: http://www.fws.gov/rockymountainarsenal/Cultural/CR.htm

In the 1950’s it began production of Sarin nerve agent, while parts of the facility were leased to Shell Oil Company to produce pesticides. A new facility called North Plants was built and the older section was turned over to Shell. The picture on the right shows North Plants. Source: http://www.globalsecurity.org/wmd/facility/rocky.htm

Wastes were dumped into unlined pits or buried. Below you can see the pits (known as Basin F) two blocks north of the large lake in the picture below.

Source: http://www.globalsecurity.org/wmd/facility/rocky.htm

In 1975, the government began to investigate the site, but where would you even start? As Table 14-2 from the handout shows us, once you have the site history and land use, you need to collect samples from the various media. The investigation included several rounds of surface, subsurface, and surface water investigations. The site, being so large, had to be divided into smaller operable units based on location, media, types of contaminants, and similar type variables. My office was involved in much of the investigation, and I installed many groundwater monitoring wells there. I participated in some of the sample collection efforts including surface soil, subsurface soil, surface water and the massive groundwater sampling programs. Some wells were so contaminated that they required us to be in full level B protection (supplied air with full suit on).

To gather the correct information you have to plan your sampling well. At RMA, soil and water samples were analyzed for a wide range of analytes including chemical agents, volatile organic compounds, metals, pesticides and associated breakdown products. It was an iterative process and sometimes analytes would be added or dropped as necessary. There were very specific protocols to follow so that your information would stand up in court. Well over a hundred groundwater monitoring wells were installed and soil samples filled a warehouse on RMA.

By the time the government signed a Record of Decision (ROD), there were more than 65 analytes that were contaminants of concern including nerve agents, blister agents (mustard gas and Lewisite), metals, volatile organic compounds including chlorinated solvents like tetrachloroethene (PCE), arsenic, pesticides, and associated breakdown products of these compounds. The contaminants were found in all media including air, soil, sediment, ground water and surface waters, as well as free products in waste liquids and solids. The ROD has a detailed risk assessment which could be very informative for someone wanting more detail. It can be found at http://www.epa.gov/superfund/sites/rods/fulltext/r0896128.pdf
Risk assessment pages 16-26 of 179.

Finally for this portion of the investigation you have to understand the geologic, hydrogeologic, atmospheric and topographic components of the site. Data obtained from the drilling and monitoring of the groundwater wells provides much of this information. Key information would be items such as the following:

Where does the water flow? How fast does it flow? What types of soil or rock is present? Is there any barrier, such as a thick claystone, to prevent the contaminants from migrating offsite or to other aquifers? Which way does the wind blow and how often? How far are you from population centers?

How do you conduct a site investigation to identify hazards? As this example shows, the process can be costly and time consuming. It took close to twenty years from the start of investigations to the final signing of the ROD in 1995 at the cost of millions of dollars. Luckily, there are many resources to find out the needed information. EPA has many guidance documents including:

The Remedial Investigation: Site Characterization and Treatability Studies (EPA, 1989) http://www.epa.gov/superfund/policy/remedy/pdfs/93-55301fs2-s.pdf

Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites (EPA, 2002) http://www.epa.gov/superfund/policy/remedy/pdfs/92-85608-s.pdf

Preparation of Soil Sampling Protocols: Sampling Techniques and Strategies (EPA, 1992)

http://www.epa.gov/swerust1/cat/mason.pdf

Furthermore, there is a large list of EPA documents covering risk assessment at : http://www.epa.gov/oswer/riskassessment/superfund_toxicity.htm

I have one last word on RMA. Okay, two. The site has figured prominently in environmental history and law as several major issues concerning Superfund were settled due to lawsuits concerning RMA (Army v. Shell and Colorado v. Army). Secondly, the site has been greatly cleaned up and is now a national wildlife refuge. Both North Plants and South Plants have been removed and either sent offsite or buried in the massive special landfills just north of the former North Plants area. The area is full of wildlife including bison, deer, and eagles. There is still some contamination in the groundwater, so some risk is present, but nothing like it was.

Hazard Identification

Voda Petroleum, Inc., Clarksville City, Texas
Photo from website: http://www.tceq.state.tx.us/assets/public/remediation/superfund/vodaoptim/pages/voda07_jpg.htm


Chemicals present at a hazardous waste or a contaminated site can number in the tens or hundreds depending on historical activities at the location. Risk assessment at the site involves identifying the chemicals, what levels of concentration are present, and how the chemicals are being distributed through the soil, water, and/ or air.

Early investigation requires data to be collected to best help identify the chemicals and severity of contamination of the site. Data Table 14-2 on page 869 of Chapter 14 from "Hazardous Waste Management" 2nd Edition by LaGrega et al. (2001), lists some of the questions that should be answered to assist in determining the type and possibly the quantity of chemicals present on a particular site. In addition, ASTM (American Society for Testing and Materials) E 1527 and E 1903 are standards for conducting Phase I and Phase II environmental site assessments. Covered in ASTM E 1527 for Phase I investigations are:

Scope of Phase I Environmental Assessments
Speaking the Language- Terminology
Application and use of E 1527
Responsibilities
Records Review
Site Reconnaissance
Safety and Health
Interviews
Report Preparation
Dealing with the Non-Scope Issues

Copies of ASTM E 1527 can be purchased through the ASTM website at: http://www.astm.org/Standards/E1527.htm

Once the chemical of concern or most hazardous chemicals are identified, these chemicals can be used as a subset or the surrogates for the other, less harmful chemicals at the site. Doing so limits the number of chemicals that would need to be modeled in fate and transport analyses. The risk posed by the contaminated site is represented by the surrogate chemicals and are classified by:

• The most toxic, persistent, and mobile
• The most prevalent in terms of spatial distribution (the distribution of a population within an area) and concentration
• Those involved in the more significant exposures
  

An initial screening of data from all detected chemicals at a site will assist in determining the subset or surrogate chemicals. The screening process includes:

• Sorting the contamination data by medium (groundwater, soil, etc.) for both carcinogens and noncarcinogens
• Tabulate for each detected chemical the mean and range of concentration values observed at the site
• Identify the reference concentrations for noncarcinogens and slope factors for carcinogens for each potential exposure route
• Determine the toxicity score for each chemical in each medium

Here is an example of how to calculate a toxicity score for a noncarcinogen:



TS=Cmax /RfC
Where: TS= Toxicity score
CMax = Maximum Concentration
RfC= Chronic reference concentration (i.e an estimate of acceptable daily intake) RfC data can be found at: www.epa.gov/iris/

Carcinogens use a slope factors to calculate the Toxicity score, and that information can be found at www.epa.gov/iris/ as well.




Examples of how a selection of both carcinogenic and non-carcinogenic chemicals are ranked can be found on page 871 of Chapter 14 from "Hazardous Waste Management" 2nd Edition by LaGrega et al. (2001). Assigning a Toxicity Score to certain chemicals helps prioritize and rate the chemicals into subset and/ or surrogate groups.

LaGrega also lists additional considerations, should further screenings be necessary. They include:

Mean concentration
Frequency of detection Mobility
Persistence in the environment
Chemicals associated with site operation
Treatability

This is just a brief look at hazard identification of contaminated sites. One day, there may be a cure-all technology to clean up contaminated sites in place. Researchers at Carnegie Mellon University are using nano-particles to clean up contaminated sites. In addition, I believe that contaminated site hazard identification will become somewhat less burdensome than in previous decades because of the development of satellite accessible images such as the one included below. These types of photographs were rare in the late 20th century, but now they allow the public to peer onto sites almost anywhere in the world with use of a personal computer. Locations of barrel yards and sludge ponds can easily be identified.

Southern Maryland Wood Treatment Plant- Taken from the EPA website on 1/29/2009

How to Post a Blog

Yikes!

How do you post to a blog?

Well, you must first be recognized as a contributor to the blog. If you've completed all of the necessary steps, your name will be listed under contributors on the left-hand side of the blog.

After you do the next part once or twice, posting to a blog will become very easy. It looks more complicated than it is when you read the instructions below.

If you want to create a new post, you click on "New Post". You can do this in either the intial window that opens when you log in, or in the blog, which you can access via "View Blog". In the blog window, click on "New Post" in the upper right hand corner. Then click the "Posting" tab. Click the "Create" button. You will be in the "Compose" window. Add a title. Type in your text. Click the "Add Image" button (looks like a mountain with a tree and blue sky) and follow instructions to add an image. To add the image, you browse to your image file and select it, choose whether you'd like the blog image to be on the left, middle or right, accept terms of service, and then click "Upload Image".

You can do something similar if you wish with video.

Once you're done, click the "Publish Post" button. You can then click on "View Blog" in the new window to see your new posting. You will be taken to the blog. Your new posting will appear separately from my old posting and from all others'.

If you wish to edit or modify your post, you can click back on "New Posting" in the upper right hand corner, and then click on "Edit Posts" in the new window that appears. You will be taken to a window where you can view, edit or delete your post. If you choose edit, then you get to edit your post and republish it.- Dr. Edwards

ETM 525 Risk Assessment: Assignment 2

Hi. I'm Dr. David Edwards. Welcome to the ETM 525 Risk Assessment blog site. The URL or address for this blog site is ETM525.blogspot.com. You are currently looking at the first posting (at the bottom of this blog site page) associated with the second assignment of this course. You will be creating a blog posting here for this assignment, too.

I will tell you how to do it in the next post.

By way of reminder, your second assignment is to (1) watch the narrated PowerPoint slide presentation for this assignment found in Blackboard, (2) read the assigned Chapter 14 from LaGrega et al. on risk assessment for hazardous waste sites, (3) choose a topic from this chapter to blog about, and (4) create a blog on this site on your chosen topic. The next blog entry will tell you how to do this.

A blog consists of text and pictures that perhaps anyone can access on the Internet. Typically, blogs contain random, periodic commentary from individuals. But, why limit it to that? In this case, we will be doing a blog as a class exercise, discussing elements of risk assessment for hazardous waste sites with each other in this class. Each of you will describe one facet or aspect of risk assessment for hazardous waste sites. You can include your own photos, or photos from the Internet in your assignment.

Later, we may add additional information to this blog on another topic. Each of you will be responsible on the final exam for all information posted here.