Risk Assessment - Chapter 14-1, LaGreca (et all)
By Peter Lembessis
Risks! We are taking them every day and some times we don't even know. Since the Industrial Revolution, humans realized that certain areas of their every day living, work, environment, food, health involves some type of risk that needs a more precise assessment and calculation. Some might say the science of risk was developed to protect life, injuries to the public and to save money for the businesses. Not everything can be measured. Risk is based in the probability theory. Based on the risk assessment, business make important decisions with the outcome being profit or saving money where Governments look out for the good of the people. The need for risk-based standards was developed.
LaGreca uses the term quantitative to describe the process of using scientific principles to calculate quantitative estimates of risk. His four stages varies very little from other scientist based on the risk calculated. For examples William C. Blackman. Jr in his book "Basic Hazardous Waste Management" defines the four steps of risk assessment as; Toxicology Evaluation, Dose-response evaluation, Exposure assessment and risk characterization. There is no real difference between the two authors other than the Dose-response evaluation.
Where mostly scientists involved with Risk assessment agree generally on the principles, there are also some critics.
From the Internet site of Wikipedia on the article of Risk assessment I noticed some of the critics comments. " Barry Commoner and Brian Wynne as well as other critics have expressed concerns that risk assessment tends to be overly quantitative and reductive. They argue that risk assessments ignore qualitative differences among risks. Some charge that assessments may drop out important and non-quantifiable or inaccessible information, such as variations among the classes of people exposed to hazards. Furthermore , Commoner and O'Brien claim that quantitative approaches divert attention from precautionary measures. Others, like Nassim Nicholas Taleb consider risk managers little more that "blind users" of statistical tools and methods" The arguments on risk calculation and risk assessment exist since their inception and set the stage for government involvement. EPA and other regulatory agencies have , as it should , set risk -based standards based on legislature Acts. The standards are needed and used because of the court-imposed need to "show harm" when a standard is challenged and works as a referee between conflicting opinions on the subject.
Professor Blacman writes that "the courts can be expected to lend a sympathetic ear to pleas for rationality in standards, and risk-based standards, and some of the verdicts will be with us for years to come"
I agree
Peter Lembessis
References
LaGreca, MichaleD, Buckinham, Philip L., Evans, Jeffrey C. 2001. Hazardous Waste Management. chapter 14-1 Quantitative Risk Assesment
William C. Blackman. Jr. Basic Hazardous waste management, Second Edition, chapter 4, toxicology and the Standard -Setting Processes
Internet, Web site, Wikipedia, calculating risk
Commoner, Barry. O"Brien, Mary. Shrader-Frechette and Westra 1997
The Fourth Quadrant: Amap of the limits of Statistics (9.15.08) Nassim Taleb , an Edge Original Essay
Saturday, September 11, 2010
Wednesday, September 8, 2010
RISK COMMUNICATION – UNDERSTANDING THE SCIENCE OR THE AFFECTED POPULATION?
The challenge that affects those who utilize risk communication is the ability to take technical information and present it to the non-technical public. While data that is wholly and completely objective would make sense to people that are scientifically incline, the public perceives it as information that is too complex for them to understand and comprehend. According to LaGrega, “[risk communication] enters the area of perception, and while not leaving the world of science, it is a much different world and one not relished by many scientists and engineers.”
“In the mid-1980’s, [risk communication] became recognized as a necessary component in risk management and community decision-making in environmental and occupational health issues” (US Public Health Service, 1995, p. 2). Many experts recognized that involving the public with technical papers and data can make the public comment process slow and cumbersome. However, the benefits of effective risk communication include a holistic approach of reaching a consensus among the stakeholders that includes solicitation of input from the public. In 1983, the Nuclear Regulatory Commission “provided the framework for improving risk assessment” (US Public Health Service, 1995, p. 2). The framework described the “methods for estimating risk to humans exposed to toxicants and in research directed to how individuals perceive risk” (US Public Health Service, 1995, p. 2).
In 2001, the Environmental Protection Agency published Stakeholder Involvement & Public Participation at the U.S. EPA. The document outlines various lessons and innovative methods to involve stakeholders and the public with decision and rule making. The process lists several lessons that were learned throughout the 1990’s which helped stakeholders and the public interject valuable input. The result was rules that were developed through consensus and more importantly decision ownership. Three lessons that were utilized and further refined were:
“In the mid-1980’s, [risk communication] became recognized as a necessary component in risk management and community decision-making in environmental and occupational health issues” (US Public Health Service, 1995, p. 2). Many experts recognized that involving the public with technical papers and data can make the public comment process slow and cumbersome. However, the benefits of effective risk communication include a holistic approach of reaching a consensus among the stakeholders that includes solicitation of input from the public. In 1983, the Nuclear Regulatory Commission “provided the framework for improving risk assessment” (US Public Health Service, 1995, p. 2). The framework described the “methods for estimating risk to humans exposed to toxicants and in research directed to how individuals perceive risk” (US Public Health Service, 1995, p. 2).
In 2001, the Environmental Protection Agency published Stakeholder Involvement & Public Participation at the U.S. EPA. The document outlines various lessons and innovative methods to involve stakeholders and the public with decision and rule making. The process lists several lessons that were learned throughout the 1990’s which helped stakeholders and the public interject valuable input. The result was rules that were developed through consensus and more importantly decision ownership. Three lessons that were utilized and further refined were:
References
LaGrega, Michael D., Buckingham, Phillip L., Evans, Jeffrey C. 2001. Hazardous Waste Management. Chapter 14: Quantitative Risk Assessment.
US EPA. 2001. Stakeholder Involvement & Public Participation at the U.S. EPA. Retrieved September 7, 2010 from www.epa.gov/stakeholders
US Public Health Service. 1995. Risk Communication: Working with Individuals and Communities to Weigh the Odds. Retrieved September 7, 2010 from http://odphp.osophs.dhhs.gov/pubs/prevrpt/archives/95fm1.htm
Tuesday, September 7, 2010
Risk Communication
Risk Communication
BY
Robin Walker
All Humans have the ability to communicate either through speech or through gestures. Language is the system in which we communicate information and the inability of effective communication causes confusion and delay. (Havland, 1996)
The need to communicate effectively in order to use risk assessment results to educate the nontechnical audiences. This includes the general public, legislators, environmental groups and other risk managers. The ineffectiveness of communication can lead to bad policy decisions and regulatory decisions. (Wiliams, James, & Roberts, 2000) In general people have limited exposure to scientific communication which includes lectures, papers, language and culture of the scientific community. (Moriarty, 1997) When communicating to different groups of people the risk manager needs to tailor his statements to knowledge level of his group. (Rodricks, 2007) Everyone who listens or reads makes up his or her own personal audience and hears and reads everything based on their own personal experience. But every person can be categorized into groups based upon their familiar they are with the subject.
The lay audience’s expertise falls into the realm of general knowledge. They have no specialty knowledge on the subject. It would not be appropriate in a community meeting of laypeople to use specialized acronyms and phrases. Use examples, photographs, diagrams and straights forward graphs. (Moriarty, 1997) In short keep it simple.
An operator is a person who can ‘operate’ or has a very basic understanding about the subject an example of this is a driver’s license which is an operator’s license. Operators only need to know basic maintenance and the rules of the road, but lack more in depth knowledge of the subject. Some technical information can be given. (Moriarty, 1997)
The technician possesses more indebt theoretical knowledge than the operator and can understand a greater level of complexity. A mechanic knows how to work on your vehicle but would not design a computer exponent for the braking system. (Moriarty, 1997)
The expert has an extensive knowledge in the theoretical aspects as well as the ramifications of the subject. Has knowledge of the sophisticated language, culture and is able to decode complicated graphs and charts. (Moriarty, 1997)
The ability of communication effectively to the understanding of your audience is an important tool in Risk communication if you are talking over their heads it can lead to misunderstanding. Which misunderstanding can lead to bad policy decisions and regulatory decisions (Wiliams, James, & Roberts, 2000)
Bibilogerphy
Havland, W. A. (1996). Cultural Anthropopogy (8th edition ed.). Fort Worth: Harcourt Brace College Publishers.
Moriarty, M. F. (1997). Writing Science through Critical Thinking. Boston: jones and Bartlett Publishers.
Rodricks, J. V. (2007). Calculated Risks The toxicity and Human Health Risks of Chemicals in our Environment (2nd Edition ed.). Cambridge: Cambridge university Press.
Wiliams, P. L., James, R. C., & Roberts, S. M. (Eds.). (2000). Principles of Toxicology (2nd Edition ed.). New York: John Wileey & Sons, Inc.
BY
Robin Walker
All Humans have the ability to communicate either through speech or through gestures. Language is the system in which we communicate information and the inability of effective communication causes confusion and delay. (Havland, 1996)
The need to communicate effectively in order to use risk assessment results to educate the nontechnical audiences. This includes the general public, legislators, environmental groups and other risk managers. The ineffectiveness of communication can lead to bad policy decisions and regulatory decisions. (Wiliams, James, & Roberts, 2000) In general people have limited exposure to scientific communication which includes lectures, papers, language and culture of the scientific community. (Moriarty, 1997) When communicating to different groups of people the risk manager needs to tailor his statements to knowledge level of his group. (Rodricks, 2007) Everyone who listens or reads makes up his or her own personal audience and hears and reads everything based on their own personal experience. But every person can be categorized into groups based upon their familiar they are with the subject.
The lay audience’s expertise falls into the realm of general knowledge. They have no specialty knowledge on the subject. It would not be appropriate in a community meeting of laypeople to use specialized acronyms and phrases. Use examples, photographs, diagrams and straights forward graphs. (Moriarty, 1997) In short keep it simple.
An operator is a person who can ‘operate’ or has a very basic understanding about the subject an example of this is a driver’s license which is an operator’s license. Operators only need to know basic maintenance and the rules of the road, but lack more in depth knowledge of the subject. Some technical information can be given. (Moriarty, 1997)
The technician possesses more indebt theoretical knowledge than the operator and can understand a greater level of complexity. A mechanic knows how to work on your vehicle but would not design a computer exponent for the braking system. (Moriarty, 1997)
The expert has an extensive knowledge in the theoretical aspects as well as the ramifications of the subject. Has knowledge of the sophisticated language, culture and is able to decode complicated graphs and charts. (Moriarty, 1997)
The ability of communication effectively to the understanding of your audience is an important tool in Risk communication if you are talking over their heads it can lead to misunderstanding. Which misunderstanding can lead to bad policy decisions and regulatory decisions (Wiliams, James, & Roberts, 2000)
Bibilogerphy
Havland, W. A. (1996). Cultural Anthropopogy (8th edition ed.). Fort Worth: Harcourt Brace College Publishers.
Moriarty, M. F. (1997). Writing Science through Critical Thinking. Boston: jones and Bartlett Publishers.
Rodricks, J. V. (2007). Calculated Risks The toxicity and Human Health Risks of Chemicals in our Environment (2nd Edition ed.). Cambridge: Cambridge university Press.
Wiliams, P. L., James, R. C., & Roberts, S. M. (Eds.). (2000). Principles of Toxicology (2nd Edition ed.). New York: John Wileey & Sons, Inc.
Monday, September 6, 2010
Risk in the workplace- Safety
When you think of risk assesment, it is common to think of the actual job at hand and how the environment can be affected such as a landfill that leaches to the groundwater, chemiclas from a wastepile that volatize into the atmosphere or soil that becomes contaminated from a spill. All of these things affect the environemnt and they are usually the focal point when doing an ESA (Environmetnal Site Assessment). But something commonly overlooked is worker safety. This could be from becoming complacent in your duties, improper training, lack of knowledge or simply thinking "nothing will happen". Often, when tasked with the cleanup of a spill or a sampling procedure, the focus shifts to the job at hand and away from worker protection. For instance, if you were to visit a site and assess it for hazards are you prepared for what you may find? For example, do you have the proper PPE, respirator if needed, etc. Are you practicing the "buddy system"? Would you know what to do in the event of an accident? These are all questions to ask prior to beginnig a project.
The nature of environmental work can often include personal safety hazards. While intentions are good, sometimes people tend to "jump in" without first assessing all hazards and ultimately leading to delays in completing the task at hand or worse, someone getting hurt. A good practice is to perform a job safety analysis and risk assessment prior to each job being performed. All personnel should be aware of applicable OSHA standards as no job has a safety guarantee of 100%.
Risk Assessment involves several steps including identifying the hazard(s), assessing the toxicity and exposure levels, characterization and communication of the risk(s) and often an ecological assessment. Each step is equally important and must be given careful consideration.
Some common workplace hazards (defined as something that can cause harm) that need careful risk assesment (which is the combination of probablilty & severity of the hazards) are chemical and biological hazards, physical hazards and emotional hazards (stress, harrassment, ect.).
If you think about it, there is risk to basically everything you do, not just pertaining to the environment, site remediation and waste disposal. It is up to the worker to weigh the risks and arrive at a decision that is effective without compromising safety.
The nature of environmental work can often include personal safety hazards. While intentions are good, sometimes people tend to "jump in" without first assessing all hazards and ultimately leading to delays in completing the task at hand or worse, someone getting hurt. A good practice is to perform a job safety analysis and risk assessment prior to each job being performed. All personnel should be aware of applicable OSHA standards as no job has a safety guarantee of 100%.
Risk Assessment involves several steps including identifying the hazard(s), assessing the toxicity and exposure levels, characterization and communication of the risk(s) and often an ecological assessment. Each step is equally important and must be given careful consideration.
Some common workplace hazards (defined as something that can cause harm) that need careful risk assesment (which is the combination of probablilty & severity of the hazards) are chemical and biological hazards, physical hazards and emotional hazards (stress, harrassment, ect.).
If you think about it, there is risk to basically everything you do, not just pertaining to the environment, site remediation and waste disposal. It is up to the worker to weigh the risks and arrive at a decision that is effective without compromising safety.
Saturday, September 4, 2010
14.2 Hazard Identification
Hazard identification is the first step in risk assessment for waste regulatory. Hazard identification isn't confined to only waste regulatory, it is used in a whole variety of programs, but the purpose of this blog entry is to discuss its use in hazardous waste. Hazard identification is used to analyze whether there are foreign contaminants in a specific site. Investors need to know whether a plot of land is suitable for use.
So how is hazard identification used? A piece of land is surveyed, the soil, air, and water are measured to see what they are comprised of. Any containmanents identified will be noted, the most toxic or highest concentration elements usually presents the most risk. While many containminants maybe present, not all are hazardous due to their concentration or they do
not pose an imminent risk.
What do we do after we find unwanted stuff in the land? Many possibilities exist, but the most common solutions are to either treat it or leave it alone. Treatment is used to lessen the extent of the threat posed by the containment. A popular method is to use combustion or incineration to burn organic waste. Using treatment can be very expensive depending on the characteristic of the waste. Leaving it alone is not ideal but it is an option. Sometimes it is not worth the cost of removing the containment, it is easier to find another site to invest in.
References:
Superfund Risk Assessment
http://www.epa.gov/oswer/riskassessment/superfund_toxicity.htm
EPA Treatment and Disposal
http://www.epa.gov/osw/hazard/tsd/td/index.htm
FEMA Disposing Waste
http://www.fema.gov/plan/ehp/regioniii/debris.shtm
Arizona Department of Environmental Quality
http://www.azdeq.gov/environ/waste/hazwaste/index.html
So how is hazard identification used? A piece of land is surveyed, the soil, air, and water are measured to see what they are comprised of. Any containmanents identified will be noted, the most toxic or highest concentration elements usually presents the most risk. While many containminants maybe present, not all are hazardous due to their concentration or they do
not pose an imminent risk.
What do we do after we find unwanted stuff in the land? Many possibilities exist, but the most common solutions are to either treat it or leave it alone. Treatment is used to lessen the extent of the threat posed by the containment. A popular method is to use combustion or incineration to burn organic waste. Using treatment can be very expensive depending on the characteristic of the waste. Leaving it alone is not ideal but it is an option. Sometimes it is not worth the cost of removing the containment, it is easier to find another site to invest in.
References:
Superfund Risk Assessment
http://www.epa.gov/oswer/riskassessment/superfund_toxicity.htm
EPA Treatment and Disposal
http://www.epa.gov/osw/hazard/tsd/td/index.htm
FEMA Disposing Waste
http://www.fema.gov/plan/ehp/regioniii/debris.shtm
Arizona Department of Environmental Quality
http://www.azdeq.gov/environ/waste/hazwaste/index.html
14 - 1 Risk
The understanding of risk is a valuable asset for any environmental manager. In order to understand risk it must be defined and measured. The measurement of risk is used to obtain accurate information that will allow environmental manager to make decisions. The decisions that environmental managers make affect many entities which includes the environment, the health and safety of the general population, and even the business community.
The defenition of risk is the probability of encounteringharm or loss. Another approach to the defenition of risk would be the weighing of costs and benifits of an action. Risk is all about tradeoffs. A decision that benefits one party may come as a cost to another. An example would be the opening of a new facility. The facility would bring newjobs to the community but at the cost of pollution to the environment. Risk can be measured by taking the product of the probaility of harm and the severity of harm. This formula can calculatethe quantifiable assets that can be lost. An example includes a company assets. There are other forms of risks that are not quantifiablesuch as death and illness. Risks that are not quantifiable can be measure by other methods such as population samples and surveys. This measurement of risk is known as the liklihood of harm occurring. If the benefits of harm occurring are acceptable then the risk is taken but if the costs are great then it will not be taken. There are two different kinds of risks. The first kind of risk is background risk. Background risk is defined as a nonspecific source of risk. Incremental risk is defined as risk that result from a specific source of risk. The total risk is known as the sum of the two kinds of risks and is necessary to calculate risk.
In order to understand the concept of risk it is necessary to distinguish it from a hazard. A hazard is a source of risk that is used to desecribe how harmful a risk can be based upon its charecteristics. Variables that describe risk are indicators of danger. An example would be the four charecteristics that classifyhazardous waste which includes toxicity, ignitability, corrositivity, and reactivity.
Once risk is defined and measured, it can be managed and controlled. The management of risk depends upon types of risk and what is being protected from these risks. The determination of the presence of risk can differ from protecting the health and safety of a poulation or ecosystem to protecting business assets that may result from a disaster. The basic steps for any risk assessment include:
1) Hazard or threat identification: Determination of what poses the greatest threat.
2) Asset identification: This step determines what is at risk. This includes ecosystems, populations, and company assets.
3) Vulnerabilities Assessment: This includes identifying who is at risk how they will be exposed and to what.
4) Risk Charecterization: This includes a determination of the magnitude of risk and gathering information to develop a solution. This is also the stage that risk is prioritized. Some risk poses a greater risk than othersa and some assets are more valuable than others.
5) Risk Management: Implementing a solution that will control risk.
References
1) Chater, Ian(2007). Risk Evaluation and control: practical guidelines for risk assessmentin The Defenitive Handbook of Business Continuity Management. Hiles, Andrew pp 137 - 145
2) Milton, Quantitaive Risk Assessment, Chp 14 pp 865 - 906
3) Suter, Glen. Ecological Risk Assessment 2nd Edition., Boca Raton, FL, CRC Press (2007), Print
The defenition of risk is the probability of encounteringharm or loss. Another approach to the defenition of risk would be the weighing of costs and benifits of an action. Risk is all about tradeoffs. A decision that benefits one party may come as a cost to another. An example would be the opening of a new facility. The facility would bring newjobs to the community but at the cost of pollution to the environment. Risk can be measured by taking the product of the probaility of harm and the severity of harm. This formula can calculatethe quantifiable assets that can be lost. An example includes a company assets. There are other forms of risks that are not quantifiablesuch as death and illness. Risks that are not quantifiable can be measure by other methods such as population samples and surveys. This measurement of risk is known as the liklihood of harm occurring. If the benefits of harm occurring are acceptable then the risk is taken but if the costs are great then it will not be taken. There are two different kinds of risks. The first kind of risk is background risk. Background risk is defined as a nonspecific source of risk. Incremental risk is defined as risk that result from a specific source of risk. The total risk is known as the sum of the two kinds of risks and is necessary to calculate risk.
In order to understand the concept of risk it is necessary to distinguish it from a hazard. A hazard is a source of risk that is used to desecribe how harmful a risk can be based upon its charecteristics. Variables that describe risk are indicators of danger. An example would be the four charecteristics that classifyhazardous waste which includes toxicity, ignitability, corrositivity, and reactivity.
Once risk is defined and measured, it can be managed and controlled. The management of risk depends upon types of risk and what is being protected from these risks. The determination of the presence of risk can differ from protecting the health and safety of a poulation or ecosystem to protecting business assets that may result from a disaster. The basic steps for any risk assessment include:
1) Hazard or threat identification: Determination of what poses the greatest threat.
2) Asset identification: This step determines what is at risk. This includes ecosystems, populations, and company assets.
3) Vulnerabilities Assessment: This includes identifying who is at risk how they will be exposed and to what.
4) Risk Charecterization: This includes a determination of the magnitude of risk and gathering information to develop a solution. This is also the stage that risk is prioritized. Some risk poses a greater risk than othersa and some assets are more valuable than others.
5) Risk Management: Implementing a solution that will control risk.
References
1) Chater, Ian(2007). Risk Evaluation and control: practical guidelines for risk assessmentin The Defenitive Handbook of Business Continuity Management. Hiles, Andrew pp 137 - 145
2) Milton, Quantitaive Risk Assessment, Chp 14 pp 865 - 906
3) Suter, Glen. Ecological Risk Assessment 2nd Edition., Boca Raton, FL, CRC Press (2007), Print
ETM525 Ch14. New dose response paradigm needed
By Lesley Evans:
Subsection 4, Toxicity Assessments (Chapter 14 of this week’s reading) describes the risk assessment stage whereby toxicities are defined for chemicals of concern. This subsection discusses the mathematical relationship between a particular dose of a chemical and the extent of the human response. Early Roman physician, Paracelsus first coined the phrase: “the dose makes the poison,” which was intended to show that all things can be poison and what distinguishes therapeutic use of a compound from a toxic effect depends upon dose strength. Until recently, the slope of this relationship was determined to be a positive slope—the more you ingest, the greater the effect. When human responses to a toxic chemical are uncertain, government risk assessors rely on findings from animal studies and build in safety factors to account for more vulnerable human populations, uncertainties inherent in extrapolating human effects from animal studies, and/or reliance on in vitro studies. For non-carcinogens, the protective factor is often two factors of ten. For carcinogens, models assume the studies apply at the 95% confidence level. Using these models, toxicologists set exposure limits often starting at the highest dose and then progressively retest at lower doses until reaching the point at which the effects are no longer seen. The endpoint of no effects is termed the “no observed adverse effect level” or NOAEL. Combining the use of safety factors and NOAEL, scientists determine the Reference Dose to determine the safety of human exposure to toxic chemicals. Besides ISIS databases, the Agency for Toxic Substances and Disease Registry (ASTDR) also lists handy toxicological profile readily available on their website.
There are several problems in this approach, but Chapter 14 discusses only one—synergistic chemical interactions. Synergistic effects occur when the effects of substances A and B taken together are higher than simply adding the effects together—implying that somehow calculation of risk needs to consider combinations of chemicals. Determining synergistic effects is often difficult to accomplish because of many unknowns, multiple different combinations of synergistic chemicals, and the time/expense of conducting dose-response experiments. One complication that Chapter 4 fails to mention is extensive research in recent years challenges the assumption of positive slope dose-response curves for all chemicals. Positive slope curves are monotonic curves and can either be linear or non-linear. For human exposure to chemicals that contain hormonally active compounds, a very different dose-response curve has been discovered to hold true in recent years. It is a non-monotonic curve that has both positive and negative slopes and can either be a U-shaped curve or an inverted U-shaped curve (see Figure 1).
(Figure 1.) Source: (Myers & Hessler, 2007)
As discussed by Myers, Zoeller & von Saal (2007), the use of high dose level testing to predict low dose human responses is not valid for endocrine disrupting chemicals (EDCs). Examples of EDCs include the plastic monomer bisphenol A (BPA), dioxins, PCBs, DDT/DDE, phthalates, alkylphenols and phytoestrogens. If effect, the low dose hormonally active compounds have their most powerful effects at dose levels far below the NOAEL. For example, the prescription drug Tamoxifen, used to treat women with breast cancer, stimulates breast cancer at low doses but inhibits the disease at higher doses. These authors also state that research conducted in the past two decades has revealed that many of the EDCs are widespread in the environment and commonly found in people. Yet the toxicology studies have missed effects that happen at extremely low doses (i.e. picomolar parts per trillion). Moreover, not only are higher impacts seen at ultra low doses, but the effects may be entirely different. For example, high exposures to phthalate diethylhexylphthalate (DEHP) can result in liver failure, while exposures to DEPH that are 1/1000th of the current safety standard results in allergic reactions.
The consequences of missing non-monotonic effects are not insignificant. For EDCs commonly found in the ambient environment (phthalates, for example) evidence demonstrates that prenatal exposure of males in utero can now be seen as they become infants and children. These effects include reproductive malformations (smaller penises, undescended testicles), smaller gestational age at birth (both genders), premature menarche, and respiratory symptoms in both genders (rhinitis, eczema, asthma) (Swan, 2008). Swan also states that animal testing of phthalates used much higher doses than those seen in ambient human populations. Moreover, phthalates have traditionally been tested as singular insults when in reality, humans are exposed to multiple phthalates simultaneously. However, in experiments with rats, exposure to multiple phthalates was shown to have additive synergistic effects.
In a review of the many health risks incurred from exposure to a variety of EDC chemicals, Yang, Park, & Lee (2006) discussed many human effects of EDCs, specifically: immune and hormonal disorders (i.e., compromised immune function, higher rates of Type-2 diabetes), reproductive disorders (i.e., precocious puberty, polycystic ovary disorder, low sperm counts and qualities, male reproductive tract abnormalities, altered birth sex ratios), and neurobehavioral disorders (such as lower IQ, memory changes, motor impairments, and thyroid disorders).
In light of findings of non-monotonic effects of EDCs, one might wonder whether EPA’s protective nature of calculations used in evaluating toxicity assessment is truly sufficient. For example, Soto, Vandenbert, Marrini & Sonnenschein (2007) discuss how rat studies demonstrated that fetal exposure to BPA resulted in higher incidences of breast cancer when such rats reached adulthood. Epidemiological studies based on the toxicological assumption that the dose makes the poison will not find these effects. A whole new paradigm of assumptions must be incorporated to shift toward greater acceptance of non-monotonic dose-response curves to more effectively protect human health from these ubiquitous EDCs. Moreover, tests need to be conducted on synergistic effects from combinations of EDCs commonly seen among human populations to increase the validity and applicability of study findings.
In recent testimony before Congress, Dr. Linda Birnbaum, Director, National Toxicology Program and Director, The National Institute of Environmental Health Science, both at HHS (2010) elucidated on the urgent need for additional research to incorporate new tools from biomedical science (i.e. genomics, proteomics, metabolomics, informatics, and computational biology) to establish a new framework for toxicity testing for chemicals that will improve risk assessment and management for EDCs, such as BPA. So I am hoping that incorporating these new tools will result in improved paradigms for toxicity testing that are cheaper/quicker, more effective, and more closely identify appropriate dose-response effects.
References:
Burnbaum, L.S. (2010). Testimony before the US House of Representatives, Committee on Energy and Commerce, Subcommittee on Health, April 22, 2010. The environment and human health: The role of HHS. Accessed on September 4, 2010 from http://www.hhs.gov/asl/testify/2010/04/t20100422a.html
Myers, P., Hessler, W. (2007). Does the ‘dose make the poison.’ Environmental Health News. April 30. 1-6.
Peterson, J, Zoeller, R.T., Von Saal, F.S. (2009). A clash of old and new scientific concepts in toxicity, with important implications for public health. Environmental Health Perspectives. 117(11). Retrieved on September 4, 2010 at http://ehsehplp03.niehs.nih.gov/article/fetchArticle.action;jsessionid=3ACF3993995ED5BBD7879F4F3A5CA7D8?articleURI=info%3Adoi%2F10.1289%2Fehp.0900887
Soto, A.M., Vandenbert, L.N., Marrini, M.V., Sonnenschein, C. (2007). Does breast cancer start in the womb? Basic & Clinical Pharmacology & Toxicology. 102:125-133.
Swan, S.H. (2008). Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans. Environmental Research. 108:177-184.
Yang, M, Park, M.S., Lee, H.S. (2006). Endocrine disrupting chemicals: human exposure and health risks. Journal of Environmental Science and Human Health, Part C. 24: 183-224.
Subsection 4, Toxicity Assessments (Chapter 14 of this week’s reading) describes the risk assessment stage whereby toxicities are defined for chemicals of concern. This subsection discusses the mathematical relationship between a particular dose of a chemical and the extent of the human response. Early Roman physician, Paracelsus first coined the phrase: “the dose makes the poison,” which was intended to show that all things can be poison and what distinguishes therapeutic use of a compound from a toxic effect depends upon dose strength. Until recently, the slope of this relationship was determined to be a positive slope—the more you ingest, the greater the effect. When human responses to a toxic chemical are uncertain, government risk assessors rely on findings from animal studies and build in safety factors to account for more vulnerable human populations, uncertainties inherent in extrapolating human effects from animal studies, and/or reliance on in vitro studies. For non-carcinogens, the protective factor is often two factors of ten. For carcinogens, models assume the studies apply at the 95% confidence level. Using these models, toxicologists set exposure limits often starting at the highest dose and then progressively retest at lower doses until reaching the point at which the effects are no longer seen. The endpoint of no effects is termed the “no observed adverse effect level” or NOAEL. Combining the use of safety factors and NOAEL, scientists determine the Reference Dose to determine the safety of human exposure to toxic chemicals. Besides ISIS databases, the Agency for Toxic Substances and Disease Registry (ASTDR) also lists handy toxicological profile readily available on their website.
There are several problems in this approach, but Chapter 14 discusses only one—synergistic chemical interactions. Synergistic effects occur when the effects of substances A and B taken together are higher than simply adding the effects together—implying that somehow calculation of risk needs to consider combinations of chemicals. Determining synergistic effects is often difficult to accomplish because of many unknowns, multiple different combinations of synergistic chemicals, and the time/expense of conducting dose-response experiments. One complication that Chapter 4 fails to mention is extensive research in recent years challenges the assumption of positive slope dose-response curves for all chemicals. Positive slope curves are monotonic curves and can either be linear or non-linear. For human exposure to chemicals that contain hormonally active compounds, a very different dose-response curve has been discovered to hold true in recent years. It is a non-monotonic curve that has both positive and negative slopes and can either be a U-shaped curve or an inverted U-shaped curve (see Figure 1).
(Figure 1.) Source: (Myers & Hessler, 2007)
As discussed by Myers, Zoeller & von Saal (2007), the use of high dose level testing to predict low dose human responses is not valid for endocrine disrupting chemicals (EDCs). Examples of EDCs include the plastic monomer bisphenol A (BPA), dioxins, PCBs, DDT/DDE, phthalates, alkylphenols and phytoestrogens. If effect, the low dose hormonally active compounds have their most powerful effects at dose levels far below the NOAEL. For example, the prescription drug Tamoxifen, used to treat women with breast cancer, stimulates breast cancer at low doses but inhibits the disease at higher doses. These authors also state that research conducted in the past two decades has revealed that many of the EDCs are widespread in the environment and commonly found in people. Yet the toxicology studies have missed effects that happen at extremely low doses (i.e. picomolar parts per trillion). Moreover, not only are higher impacts seen at ultra low doses, but the effects may be entirely different. For example, high exposures to phthalate diethylhexylphthalate (DEHP) can result in liver failure, while exposures to DEPH that are 1/1000th of the current safety standard results in allergic reactions.
The consequences of missing non-monotonic effects are not insignificant. For EDCs commonly found in the ambient environment (phthalates, for example) evidence demonstrates that prenatal exposure of males in utero can now be seen as they become infants and children. These effects include reproductive malformations (smaller penises, undescended testicles), smaller gestational age at birth (both genders), premature menarche, and respiratory symptoms in both genders (rhinitis, eczema, asthma) (Swan, 2008). Swan also states that animal testing of phthalates used much higher doses than those seen in ambient human populations. Moreover, phthalates have traditionally been tested as singular insults when in reality, humans are exposed to multiple phthalates simultaneously. However, in experiments with rats, exposure to multiple phthalates was shown to have additive synergistic effects.
In a review of the many health risks incurred from exposure to a variety of EDC chemicals, Yang, Park, & Lee (2006) discussed many human effects of EDCs, specifically: immune and hormonal disorders (i.e., compromised immune function, higher rates of Type-2 diabetes), reproductive disorders (i.e., precocious puberty, polycystic ovary disorder, low sperm counts and qualities, male reproductive tract abnormalities, altered birth sex ratios), and neurobehavioral disorders (such as lower IQ, memory changes, motor impairments, and thyroid disorders).
In light of findings of non-monotonic effects of EDCs, one might wonder whether EPA’s protective nature of calculations used in evaluating toxicity assessment is truly sufficient. For example, Soto, Vandenbert, Marrini & Sonnenschein (2007) discuss how rat studies demonstrated that fetal exposure to BPA resulted in higher incidences of breast cancer when such rats reached adulthood. Epidemiological studies based on the toxicological assumption that the dose makes the poison will not find these effects. A whole new paradigm of assumptions must be incorporated to shift toward greater acceptance of non-monotonic dose-response curves to more effectively protect human health from these ubiquitous EDCs. Moreover, tests need to be conducted on synergistic effects from combinations of EDCs commonly seen among human populations to increase the validity and applicability of study findings.
In recent testimony before Congress, Dr. Linda Birnbaum, Director, National Toxicology Program and Director, The National Institute of Environmental Health Science, both at HHS (2010) elucidated on the urgent need for additional research to incorporate new tools from biomedical science (i.e. genomics, proteomics, metabolomics, informatics, and computational biology) to establish a new framework for toxicity testing for chemicals that will improve risk assessment and management for EDCs, such as BPA. So I am hoping that incorporating these new tools will result in improved paradigms for toxicity testing that are cheaper/quicker, more effective, and more closely identify appropriate dose-response effects.
References:
Burnbaum, L.S. (2010). Testimony before the US House of Representatives, Committee on Energy and Commerce, Subcommittee on Health, April 22, 2010. The environment and human health: The role of HHS. Accessed on September 4, 2010 from http://www.hhs.gov/asl/testify/2010/04/t20100422a.html
Myers, P., Hessler, W. (2007). Does the ‘dose make the poison.’ Environmental Health News. April 30. 1-6.
Peterson, J, Zoeller, R.T., Von Saal, F.S. (2009). A clash of old and new scientific concepts in toxicity, with important implications for public health. Environmental Health Perspectives. 117(11). Retrieved on September 4, 2010 at http://ehsehplp03.niehs.nih.gov/article/fetchArticle.action;jsessionid=3ACF3993995ED5BBD7879F4F3A5CA7D8?articleURI=info%3Adoi%2F10.1289%2Fehp.0900887
Soto, A.M., Vandenbert, L.N., Marrini, M.V., Sonnenschein, C. (2007). Does breast cancer start in the womb? Basic & Clinical Pharmacology & Toxicology. 102:125-133.
Swan, S.H. (2008). Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans. Environmental Research. 108:177-184.
Yang, M, Park, M.S., Lee, H.S. (2006). Endocrine disrupting chemicals: human exposure and health risks. Journal of Environmental Science and Human Health, Part C. 24: 183-224.
Ecological Risk Assessment
Ecological Risk Assessment
By Mary Steffen-Deaton
What is Ecological Risk Assessment? Ecological Risk Assessment is a tool used in policy analysis. An Ecological Risk Assessment (ERA) may be performed to determine or estimate the possibility that potentially harmful effects could occur if exposed to a particular chemical or contaminant.
Similar to a risk assessment performed for human health, an ecological risk assessment determines or estimates potential risk to the environment if exposed to a chemical or contaminant through a qualitative (scientific judgment) and quantitative (scientific methods) process. The EPA has published documents that provide a list of guidelines for the risk assessment process. Framework for Ecological Risk Assessment (EPA/63-R-92/001) and Guidelines for Ecological Risk Assessment (EPA/630/R-95-002F) are the two documents that provide a description of the process of risk evaluation and EPA approved analytical methods. LaGrega discusses, in 14-7, four phases of Ecological Risk Assessment.
The Ecological Risk Assessment begins with the general and moves to the specific. The process starts with a screening process that gives a description of the setting, what chemicals exists already on site, are there known endangered or threatened species on site, and possible routes of environmental fate. This phase of the process provides a characterization of the initial site. This gives a description of what is already there before the introduction, (or possible introduction) of a contaminant or chemical.
The next phase is to determine the Ecological toxicity of the environment. Scientific information is used to make assessments based on known responses to particular chemicals. Modeling is a tool that can be utilized. Analytical methodology is used to determine toxicity. Scientific testing specific to the type of ecosystem media (terrestrial vs. aquatic) are performed to determine lethality.
Next the Potential Exposures routes are identified. This phase identifies all the possible potential exposure methods as well as intensity, frequency, and duration of exposure.
Finally, the risk characterization is the phase that combines all the information learned in the previous phases to pose an estimation of the risk and risk description. All the analytical testing are analyzed and then grouped with scientific judgment to create a characterization of the risk.
References:
Lackey, Robert T. Challenges to Using Ecological Risk Assessment to Implement Ecosystem Management, Environmental Effects Research Laboratory, Corvallis, Oregon
LaGrega et al. Hazardous Waste Management, 2nd ed., p. 865-906.
U.S. EPA. ECO-Update, Catalogue of Standard Toxicity Tests for Ecological Risk Assessment, Publication 9345.0-05l, March 1994.
U.S. EPA. Framework For Ecological Risk Assessment. http://www.epa.gov/raf/publications/pdfs/FRMWRK_ERA.PDF
U.S. EPA. Guidelines for Ecological Risk Assessment, U.S. Environmental Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/R095/002F, 1998. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12460
By Mary Steffen-Deaton
What is Ecological Risk Assessment? Ecological Risk Assessment is a tool used in policy analysis. An Ecological Risk Assessment (ERA) may be performed to determine or estimate the possibility that potentially harmful effects could occur if exposed to a particular chemical or contaminant.
Similar to a risk assessment performed for human health, an ecological risk assessment determines or estimates potential risk to the environment if exposed to a chemical or contaminant through a qualitative (scientific judgment) and quantitative (scientific methods) process. The EPA has published documents that provide a list of guidelines for the risk assessment process. Framework for Ecological Risk Assessment (EPA/63-R-92/001) and Guidelines for Ecological Risk Assessment (EPA/630/R-95-002F) are the two documents that provide a description of the process of risk evaluation and EPA approved analytical methods. LaGrega discusses, in 14-7, four phases of Ecological Risk Assessment.
The Ecological Risk Assessment begins with the general and moves to the specific. The process starts with a screening process that gives a description of the setting, what chemicals exists already on site, are there known endangered or threatened species on site, and possible routes of environmental fate. This phase of the process provides a characterization of the initial site. This gives a description of what is already there before the introduction, (or possible introduction) of a contaminant or chemical.
The next phase is to determine the Ecological toxicity of the environment. Scientific information is used to make assessments based on known responses to particular chemicals. Modeling is a tool that can be utilized. Analytical methodology is used to determine toxicity. Scientific testing specific to the type of ecosystem media (terrestrial vs. aquatic) are performed to determine lethality.
Next the Potential Exposures routes are identified. This phase identifies all the possible potential exposure methods as well as intensity, frequency, and duration of exposure.
Finally, the risk characterization is the phase that combines all the information learned in the previous phases to pose an estimation of the risk and risk description. All the analytical testing are analyzed and then grouped with scientific judgment to create a characterization of the risk.
References:
Lackey, Robert T. Challenges to Using Ecological Risk Assessment to Implement Ecosystem Management, Environmental Effects Research Laboratory, Corvallis, Oregon
LaGrega et al. Hazardous Waste Management, 2nd ed., p. 865-906.
U.S. EPA. ECO-Update, Catalogue of Standard Toxicity Tests for Ecological Risk Assessment, Publication 9345.0-05l, March 1994.
U.S. EPA. Framework For Ecological Risk Assessment. http://www.epa.gov/raf/publications/pdfs/FRMWRK_ERA.PDF
U.S. EPA. Guidelines for Ecological Risk Assessment, U.S. Environmental Protection Agency, Risk Assessment Forum, Washington, DC, EPA/630/R095/002F, 1998. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12460
14.3 Exposure Assessment
The exposure assessment requires an understanding of fate and transport of the substance of concern among others. This type of analysis will involve the specific environment in which the spill occurs such as soil, water, air or a combination of the three. The spill must be characterized to identify its specific constituents and the potential for any of them to undergo either biodegrading or chemical reaction hence potential derivatives. The effects of advection, diffusion and dispersion of the spill is important in trying to answer to question of the form: where is it going? to what extend, What direction? and to what degree or concentration.
A good understanding of the spill is critical because it lays the basis for exposure assessment. For instance non-aqueous phase liquid (LNAPL) will behave in a certain way in containing medium compare to a Dense non-aqueous phase liquid (DNAPL) due to distinct physical and chemical properties. LNAPL tends to remain on upper layer of water while DNAPL tends to sink to bottom of water table.
Also the toxicity level will be different containing short and long chain-organic compounds, and possibly aromatics hydrocarbon compounds.
The geographical area is important factor as well for considering the population proximity and obtaining a time frame before reaching potential receptors. Through the investigation a monitoring plan is essential to understand the transport patterns taking place and also to obtain initial and changing measurements in concentration in air, water and soil. Once enough data has been collected to provide enough resolution modeling tools become useful in predicting movement of the spill and constituent concentrations at receptors of concern.
The main routes of exposure for a given population are; ingestion, inhalation and skin absorption. if the contaminant is to reach the population it's important to determine the thresholds at which the contaminants adversely effect the human health.
References:
Transport Phenomena by R. Byron Bird
Fate of Spill Oil in Marina Waters by The American Petroleum Institute
http://www.epa.gov/region4/sesd/reports/1999-0219/nbsect5.pdf
http://www.clu-in.org/conf/itrc/dnaplpa/dnapl_handbook_final.pdf
A good understanding of the spill is critical because it lays the basis for exposure assessment. For instance non-aqueous phase liquid (LNAPL) will behave in a certain way in containing medium compare to a Dense non-aqueous phase liquid (DNAPL) due to distinct physical and chemical properties. LNAPL tends to remain on upper layer of water while DNAPL tends to sink to bottom of water table.
Also the toxicity level will be different containing short and long chain-organic compounds, and possibly aromatics hydrocarbon compounds.
The geographical area is important factor as well for considering the population proximity and obtaining a time frame before reaching potential receptors. Through the investigation a monitoring plan is essential to understand the transport patterns taking place and also to obtain initial and changing measurements in concentration in air, water and soil. Once enough data has been collected to provide enough resolution modeling tools become useful in predicting movement of the spill and constituent concentrations at receptors of concern.
The main routes of exposure for a given population are; ingestion, inhalation and skin absorption. if the contaminant is to reach the population it's important to determine the thresholds at which the contaminants adversely effect the human health.
References:
Transport Phenomena by R. Byron Bird
Fate of Spill Oil in Marina Waters by The American Petroleum Institute
http://www.epa.gov/region4/sesd/reports/1999-0219/nbsect5.pdf
http://www.clu-in.org/conf/itrc/dnaplpa/dnapl_handbook_final.pdf
Risk Communication vs Fear Mongering
After reading Milton’s Chapter 14, I found Section 14-6 (Risk Communication) to be interesting, particularly when appling it to today's media. In this age of media inundation, and sometimes overload, it is easy to feel like everything you do, eat, drink, breath, or touch can be hazardous. After listening to the nightly news (or even taking some of these ETM classes), it makes it easier to understand why some people might want to live in a cabin in the middle of nowhere, grow their own food, drink from a private well, and just steer clear of humanity in general. But how do we know when to ignore the risk depicted in these frightening newscasts, and when to prepare? Like section 14-7 reads, “…the public will often express more concern with the possible magnitude of the worst case scenario, either not understanding or electing to ignore how unlikely if not incredible it may be” (Milton, 894). Remember in 2009 when we all waited to come down with the H1N1 flu? If you watched the news or read a newspaper, it felt like there was no way to escape that risk. We heard stories every night about how many people were infected, and how many more died. As that flu season came and went an interesting trend started to emerge: it turned out H1N1’s bark may have been worse for Americans that its bite. According to the Center for Disease Control (CDC) the reported number of deaths attributed to H1N1 from April 2009 to January 2010 was 2,498 (http://www.cdc.gov/H1Nflu/hosp_deaths_ahdra.htm#5). If you’re one of the nearly 2,500 families that dealt with one of these deaths, the statistics become unimportant. If you’re the average American not personally affected though, they matter. According to the Flu.gov website, which receives its information from a variety of government sources included the CDC, the estimated number of US deaths from the seasonal influenza virus averages at about 36,000 deaths per year (http://pandemicflu.gov/individualfamily/about/seasonalflu/). Interestingly, further research found that the 36,000 deaths per year is the average for the over 30 years the numbers were being compiled by the CDC. In other words, it is not that an average of 36,000 people die from the flu each year, rather, that between 1971 and 2007 the number of deaths ranged from about 4000 deaths per year to 49,000 deaths per year, resulting in the 36,000 average that is often cited (http://www.cdc.gov/flu/about/disease/us_flu-related_deaths.htm). Granted, the comparison I’m making here is exactly apples to apples, the H1N1 number doesn’t account for a 12-month average, rather only from April to January. Considering even the lowest number of deaths per year from the seasonal flu virus (4000 in the early 1970s), that number is still nearly twice what H1N1 accounted for during the 2009 flu season. That’s a lot of wasted airtime from news agencies. Or is it?
Hindsight is 20/20, so they say. Perhaps all the media attention and information made widely available to the public made the effects of H1N1 less detrimental than they would have been otherwise. After all, as of December 2009, an estimated 43 million people had received the H1N1 vaccine in the US (http://www.cdc.gov/h1n1flu/in_the_news/influenza_vaccination.htm). Or, maybe the media hyped the CDC’s concerns to the point of paranoia. By August of 2010, the World Health Organization (WHO) had already declared an end to the H1N1 pandemic. Margaret Chan, WHO director general stated, “We expect the H1N1 virus to take on the behaviour of a seasonal influenza virus and continue to circulate for some years to come” (http://www.cbc.ca/health/story/2010/08/10/who-h1n1-swine-flu-pandemic.html#ixzz0ybG6R1mj). A statement that seems fairly unthreatening compared to the news accounts in the Spring of 2009.
The effectiveness of risk communication is a fine line to walk. The public must be made aware of hazards, and how to prevent encountering these risks, but without unnecessary fear and panic.
Hindsight is 20/20, so they say. Perhaps all the media attention and information made widely available to the public made the effects of H1N1 less detrimental than they would have been otherwise. After all, as of December 2009, an estimated 43 million people had received the H1N1 vaccine in the US (http://www.cdc.gov/h1n1flu/in_the_news/influenza_vaccination.htm). Or, maybe the media hyped the CDC’s concerns to the point of paranoia. By August of 2010, the World Health Organization (WHO) had already declared an end to the H1N1 pandemic. Margaret Chan, WHO director general stated, “We expect the H1N1 virus to take on the behaviour of a seasonal influenza virus and continue to circulate for some years to come” (http://www.cbc.ca/health/story/2010/08/10/who-h1n1-swine-flu-pandemic.html#ixzz0ybG6R1mj). A statement that seems fairly unthreatening compared to the news accounts in the Spring of 2009.
The effectiveness of risk communication is a fine line to walk. The public must be made aware of hazards, and how to prevent encountering these risks, but without unnecessary fear and panic.
Uncertainty Factors Used to Ensure Protection of Public Health. Based on Chapter 14-4: Toxicity Assessment
Chapter 14 of LaGrega et.al.’s Hazardous Waste Management pointed out that various approaches to dose-response assessments and hazard characterizations are utilized for threshold versus non-threshold endpoints. Carcinogens exhibit a non-threshold effect where the carcinogenic potency is determined by the slope factor, defined as the 95% upper bound confidence limit of the dose-response curve from a lifetime exposure to a chemical. Non-carcinogens exhibit a threshold effect, whereby Reference Doses (RfDs) or concentrations (RfCs) are used as estimates of a daily exposure to an agent that fails to induce any adverse health impact in humans. Unfortunately, the majority of chemicals of concern do not have human toxicological indices and thus, surrogate data or rodent NOAELS (No Observable Adverse Effect Levels) are used to determine these important RfC’s by dividing the NOAEL by uncertainty or safety factors.
The EPA adopted the term “uncertainty factor” to reflect true scientific uncertainties in the establishment of acceptable intakes. In principle, dividing by the uncertainty factors allows for interspecies variability (such as using mice data for human extrapolation) and intraspecies variability (such as different genetic predispositions or chemical sensitivities among human populations). Additional uncertainty factors may be required if there are experimental inadequacies (such as inadequate numbers of study animals), or an LOAEL (Lowest Observable Adverse Effect Levels) is used instead of an NOAEL. Each factor is normally assigned a default value of 10.
In today’s world, decisions and actions are often demanded or required even when there is a high level of uncertainty in the available toxicological data. As a result, most risk assessments are actually scientific hypotheses that are not testable with any practical epidemiological study. To account for these uncertainties, The EPA has taken a protective approach to ensure all uncertainty factors are considered when calculating the toxicological indices so risks are overestimated rather than underestimated.
Though the public may be skeptical in accepting these estimated values instead of absolute, proven values, the policy decision to act before science is certain is the right approach and the only way to adequately protect the public until more advanced models are available. From my readings, there definitely appears to be an increasing need to integrate biologically and mechanistically based data (such as that derived by physiologically based pharmacokinetic (PB-PK) modeling) to refine this risk-assessment process. Though this modeling started to be used in risk assessments in the mid 1980’s, the complexity seems to have limited the use to chemicals of very high concern such as polychlorinated biphenyls and other persistent molecules. I hope we start to see more widespread use of this, and other advanced modeling techniques, to more accurately predict dose responses and relieve public fears of “uncertain” estimates.
References:
Anderson, M.E. (1999). Physiologically based pharmacokinetic (PB-PK) models in the study of the disposition and biological effects of xenobiotics and drugs. Toxicology Letters, 82, 341-348. doi:10.1016/0378-4274(95)03487-0.
Dorne, J.L.C.M. & Renwick,A.G. (2005). The Refinement of Uncertainty/Safety Factors in Risk Assessment by the Incorporation of Data on Toxicokinetic Variability in Humans. Toxicological Sciences, 86(1), 20–26. doi:10.1093/toxsci/kfi160.
Greim, H. & Snyder R. (2008). Toxicology and Risk Assessment: A Comprehensive Introduction. West Sussex, England: John Wiley & Sons Ltd. Pages 5-6.
Klassen, C.D. (2008). Casarett and Doull’s Toxicology: The Basic Science of Poisons. McGraw-Hill eBook. DOI: 10.1036/0071470514.
LaGrega et al (2001). Hazardous Waste Management, 2nd edition. Pages 884-887.
Rodricks, J.V. (2007). Calculated Risks: The Toxicity and Human Health Risks of Chemicals in our Environment. Cambridge, UK: Cambridge University Press. Pages 231-249.
Blog from 14-7 Ecological Risk Assessment
The blog assignment for this week was to read Chapter 14-Quantitative Risk Assessment. Out of this chapter there were seven subsections to read on. I decided to blog about the 14-7 Ecological Risk Assessment. I chose this section because I do not know very much information on this topic, until the oil spill that occurred from BP Corporation. There seems to be more focus on reacting to human exposure and risk assessment then ecological. But when the oil spill happened all the focus was geared towards the ecosystem and how the affects lead to food supply, jobs, cultural aspects, and endangered species hazard. So when I read this section of Chapter 14 it got me thinking about the process and procedures that needed to be outline and wondered if BP had a plan to use as a guideline for cleanup and response. Since most of the reporting through the media about BP was that there was nothing being done or any type of reaction for cleanup. Now, when you turn on the TV or listen to the radio every morning, I notice that there are some commercials of representative speaking on behalf of BP on the cleanup and that they are concern and will not stop until all ways of life are restored back to it’s natural habitant and ecosystem.
Within Chapter 14 it covers information and guidelines that should be address at the time of an assessment is thought through. This section defines the four tasks that need to be overview and highlighted before the assessment is carried out. The importance of identifying and making a list of different types of species around the affected area or location is needed. This helps to distinguish what species plant or animal are threatened or endangered. The toxicity assessment is based on the amount and type of chemical exposure that might or has already affected the ecological area. Chapter 14 describes the affects correlated to the potential of how or what species it might affect. End points are needed to be determined based on the species or ecological role of reproduction process and the well being of future affects will not be affected. I found the table used in this chapter the correlation between mammalian toxicology and ecotoxicology, and realize that was probably what BP had a difficult time with outlining. The ecotoxicology that is based on the aquatic and avian toxicology assessment is more difficult to assess and determine within an affected area, since there are just so many species to list and to determine there route of exposures.
Having to understand the process in identifying what the guidelines are in determining if a site or ecosystem is at risk I found this website at USEPA : http://www.epa.gov/raf/publications/pdfs/ECOTXTBX.PDF. This document details and breaks up the sections about how to outline and process an ecological risk assessment for a majority of cleanups. Also it states that the understanding of the assessment can affect environmental decision makers who think more about legal issues that might lead to law suit, increase in money for environmental program, or political standpoint and how it could affect congress. After reviewing this document it made me think that’s why USEPA got involved in the process of the cleanup and made statements that BP will be affected by the consequences of the spill.
This website that I found, http://www.earthportal.org/news/ , is very interesting website. It has most of all environmental news related to any type of earth news updated. But the one website that got my attention about PB was the, “Deepwater Horizon oil spill”, at this website: http://www.eoearth.org/article/Deepwater_Horizon_oil_spill. This article states some facts about the spill and the amount of oil that was leaking on a daily base. Also this article has a section that discusses the assessment process that was done and what other companies were involve for example NASA had got involve with it’s technology program called NASA’s Airborne Visible InfraRed Imaging Spectrometer (AVIRIS), which helped determine the amount of barrels leaked, burned, or evaporated. This article has a section towards the end discussing the cleanup activities that have been taken place and who the other governmental agencies that are involve, for example USEPA, US Geological Survey, CDC, and OSHA. Just like what Chapter 14 stated that it’s difficult to determine the affects of ecotoxiclogical assessment due to the type of species that are in the area. This stated as well in this article that there are no data determining the actual affects of the ecosystem and its habitants. Not only are birds, fish eggs, swampland, shrimp are affected, the concern of seep communities are stated in this article as well. The type of ecosystem that are within this community are corals, clams, mussels, tube worms.
Another article I came across not as detrimental as the BP oil spill is one that occurred in Greenpoint, NY, with the company called Greenpoint Oil Company at this website: http://www.eoearth.org/article/Greenpoint_Oil_Spill. The ecological risk assessment had to be based on the leaking tanks and pipelines affected the ecosystem. Soil and ground water testing was part of the assessment, since the affected areas seeped into Newton Creek. This affected the ecosystems wildlife that caused toxic vapors and chemicals from the oil to cause hazard over a long period of time.
Aside from the ecological risk assessment I came across this article about some “Tribes fights for survival as BP oil spill ravages Gulf Coast, http://www.fsrn.org/audio/tribe-fights-survival-bp-oil-spill-ravages-gulf-coast/7197. I am part of the Navajo Nation reservation and thought this article was interesting and how the affects within the ecosystem has made difficulties for this tribe. Since majority of all tribal culture are mostly dependable on the livelihood of the ecological contributions. For example, in my culture (Navajo) we depend on the corn for corn pollen that is used in ceremonies for praying. Also the way of life of eating sheep is part of my culture. The Houma tribe depends on the fishing and hunting aspect for there cultural identification for survival within the wetlands and off the coast of Louisiana. Also this article states that the oil has cause harm towards there fishing beds and hunting grounds for food supply. The plant species that they depend on has been affected as well. The United Houma Nation Council states that plant remedies that the tribe used for many generations are at risk, as well as the indigenous crafts that are use from the plants like traditional baskets.
Overall, I hope I have collected enough information from these four reference website that focused on the affects from the BP oil spill. Also that the importance of the ecological risks assessment is a vital concept that should not be taken lightly. Every since the oil spill it made me think what are companies putting in place in case of a spill? I hope now they use this spill as a learning experience for future spills and to have plans in place, so the community and media will have a sense of positive comfort that plans will be carried out.
Within Chapter 14 it covers information and guidelines that should be address at the time of an assessment is thought through. This section defines the four tasks that need to be overview and highlighted before the assessment is carried out. The importance of identifying and making a list of different types of species around the affected area or location is needed. This helps to distinguish what species plant or animal are threatened or endangered. The toxicity assessment is based on the amount and type of chemical exposure that might or has already affected the ecological area. Chapter 14 describes the affects correlated to the potential of how or what species it might affect. End points are needed to be determined based on the species or ecological role of reproduction process and the well being of future affects will not be affected. I found the table used in this chapter the correlation between mammalian toxicology and ecotoxicology, and realize that was probably what BP had a difficult time with outlining. The ecotoxicology that is based on the aquatic and avian toxicology assessment is more difficult to assess and determine within an affected area, since there are just so many species to list and to determine there route of exposures.
Having to understand the process in identifying what the guidelines are in determining if a site or ecosystem is at risk I found this website at USEPA : http://www.epa.gov/raf/publications/pdfs/ECOTXTBX.PDF. This document details and breaks up the sections about how to outline and process an ecological risk assessment for a majority of cleanups. Also it states that the understanding of the assessment can affect environmental decision makers who think more about legal issues that might lead to law suit, increase in money for environmental program, or political standpoint and how it could affect congress. After reviewing this document it made me think that’s why USEPA got involved in the process of the cleanup and made statements that BP will be affected by the consequences of the spill.
This website that I found, http://www.earthportal.org/news/ , is very interesting website. It has most of all environmental news related to any type of earth news updated. But the one website that got my attention about PB was the, “Deepwater Horizon oil spill”, at this website: http://www.eoearth.org/article/Deepwater_Horizon_oil_spill. This article states some facts about the spill and the amount of oil that was leaking on a daily base. Also this article has a section that discusses the assessment process that was done and what other companies were involve for example NASA had got involve with it’s technology program called NASA’s Airborne Visible InfraRed Imaging Spectrometer (AVIRIS), which helped determine the amount of barrels leaked, burned, or evaporated. This article has a section towards the end discussing the cleanup activities that have been taken place and who the other governmental agencies that are involve, for example USEPA, US Geological Survey, CDC, and OSHA. Just like what Chapter 14 stated that it’s difficult to determine the affects of ecotoxiclogical assessment due to the type of species that are in the area. This stated as well in this article that there are no data determining the actual affects of the ecosystem and its habitants. Not only are birds, fish eggs, swampland, shrimp are affected, the concern of seep communities are stated in this article as well. The type of ecosystem that are within this community are corals, clams, mussels, tube worms.
Another article I came across not as detrimental as the BP oil spill is one that occurred in Greenpoint, NY, with the company called Greenpoint Oil Company at this website: http://www.eoearth.org/article/Greenpoint_Oil_Spill. The ecological risk assessment had to be based on the leaking tanks and pipelines affected the ecosystem. Soil and ground water testing was part of the assessment, since the affected areas seeped into Newton Creek. This affected the ecosystems wildlife that caused toxic vapors and chemicals from the oil to cause hazard over a long period of time.
Aside from the ecological risk assessment I came across this article about some “Tribes fights for survival as BP oil spill ravages Gulf Coast, http://www.fsrn.org/audio/tribe-fights-survival-bp-oil-spill-ravages-gulf-coast/7197. I am part of the Navajo Nation reservation and thought this article was interesting and how the affects within the ecosystem has made difficulties for this tribe. Since majority of all tribal culture are mostly dependable on the livelihood of the ecological contributions. For example, in my culture (Navajo) we depend on the corn for corn pollen that is used in ceremonies for praying. Also the way of life of eating sheep is part of my culture. The Houma tribe depends on the fishing and hunting aspect for there cultural identification for survival within the wetlands and off the coast of Louisiana. Also this article states that the oil has cause harm towards there fishing beds and hunting grounds for food supply. The plant species that they depend on has been affected as well. The United Houma Nation Council states that plant remedies that the tribe used for many generations are at risk, as well as the indigenous crafts that are use from the plants like traditional baskets.
Overall, I hope I have collected enough information from these four reference website that focused on the affects from the BP oil spill. Also that the importance of the ecological risks assessment is a vital concept that should not be taken lightly. Every since the oil spill it made me think what are companies putting in place in case of a spill? I hope now they use this spill as a learning experience for future spills and to have plans in place, so the community and media will have a sense of positive comfort that plans will be carried out.
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