AN OVERVIEW OF THE RISK ASSESSMENT PROCESS AND LIMITATIONS OF AIR STUDIES
| Jurisdiction | United States |
(Feb 2013)
AN OVERVIEW OF THE RISK ASSESSMENT PROCESS AND LIMITATIONS OF AIR STUDIES
Quality Environmental Professional Associates
Thornton, Colorado
DOLLIS WRIGHT is the president and founder of Quality Environmental Professional Associates, Inc. (QEPA), an environmental health risk communication firm in Thornton, Colorado. She has worked in the government and private sector for over twenty-five years in the fields of Epidemiology and Toxicology. She started her career working for the Centers for Disease Control collecting epidemiological data for the Metropolitan Atlanta Congenital Birth Defects and Very Low Birth Weight Program. She has conducted research in male and female reproductive potential for the National Institute for Occupational Safety and Health (NIOSH). Dollis served as the Staff Toxicologist and Director of Environmental Epidemiology for the Indiana State Department of Health, where she was responsible for reducing and preventing human exposure to chemicals spilled or released throughout the State. She is the author of many Health Assessments and Consultations for Superfund Hazardous Wastes Sites. Other activities from her professional experience include exposure investigations, cancer cluster investigations, community health, and Health Professional Education. In the 11 years since she started QEPA, her clients have ranged from industry to the U.S. EPA. The QEPA team of associates performs various aspects of risk communication and assessments including: critical reviews of documents for scientific soundness, guidance in study development, OSHA Hazardous Materials and Site Investigation training, public meeting presentations, and consultation in risk communication for communities with chemical exposure concerns. Dollis' passion is bringing clarity to issues that lead to decisions and actions based on facts not perceptions.
Dollis M. Wright
Managing Principle & CEO
Quality Environmental Professional Associates, Inc.
Thornton Colorado
February 28, 2013
This general overview presentation addresses the limitations of the risk assessment process as well as current air studies that have been done in and around oil and gas activities. A brief description of risk assessment is included in an effort to assist the reader in understanding the limitations of the studies. The paper is supplemented by a PowerPoint presentation that is available.
ABSTRACT
The determination of the likelihood and severity of chemical harm to individuals living in communities where oil and gas activities are occurring has many limitations. These limitations are compounded by authors drawing conclusions about health risk that are not based on risk assessment principles. The impacts of chemicals are often presented by authors as a list of all their possible health effects with no regard or mention of dose-response relationship, exposure analyses, or risk characterization. This sensationalizing of data may be diverting individuals from addressing identified and controllable health risk that are not chemically induced. The precautionary principle is commonly suggested by special interest groups when there are data gaps in environmental data. The limitations of this principle are presented. There is a need for scientific accountability and integrity when reporting risk to communities.
WHAT IS RISK?
We all face risk throughout our daily lives. So much so, that we make decisions about what is safe and what is risky without seemingly much effort.1 One definition of risk is: exposure to possible loss or injury.2 Another definition is: exposure to the possibility of loss, injury or other adverse or unwelcome circumstance. In many ways risk is closely related to trust. We are accepting of something if we have some familiarity with it. In other words, what we don't know takes us out of our comfort zone which heightens our awareness and concern for our safety. Often times something is perceived as a risk because it is new to us. Unfortunately, human tendency also lends to the unbalanced, sometimes irrational focusing on an unfamiliar small risk over a known larger risk.3 These risks are sensationalized in the media and by interest groups and end up diverting human and economic resources from real known and preventable risk.
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RISK GUIDELINES
Despite the fact that perceptions of the degree of risk of exposure to possible loss or injury may vary in the general population, there are established guidelines to help place some reality around health concerns.4 These guidelines are based on a review of scientific data and an understanding of the frequency of occurrence of cancer or disease in a population. Federal agencies and other organizations conduct animal and human research in an effort to gain information to protect human health from chemical exposure. They also use data from accidental and occupational releases of chemicals to determine safe levels for human exposure. The recommendations of various federal agencies may differ because they use different exposure times, different studies, different exposure populations or other study parameters.
Cancer Risk (1x10-4 -1 x10-6) Environmental Protection Agency Guideline
The American Cancer Society has concluded that one in every three individuals (0.33 x100) will get cancer in some form5 The current acceptable cancer risk range is one in 10,000 (1x10-4) to one in a million cancer (1 x10-6).
Minimal Risk Level (MRL) Agency for Toxic Substances and Disease Registry Guideline
The MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse, non-cancer health effects over a specified duration of exposure. They are designed to protect sensitive populations. For Chronic MRLs, it is generally presumed that exposure is 24 hours a day over a lifetime and has several safety and uncertainty factors used to select the number.
Permissible Exposure Limit (PEL) Occupational Safety and Health Administration Guideline
They are based on an 8 hour time weighted average exposure for 40 - 45 years. Enforceable limits provided by OSHA to protect workers against the health effects of exposure to hazardous substances
Recommended Exposure Limit (REL) National Institute for Occupational Safety and Health Guideline
It is an occupational exposure limit that is believed to be protective of worker safety and health over a working lifetime if used in combination with engineering and work practice controls, exposure and medical monitoring, posting and labeling of hazards, worker training and personal protective equipment. Estimate exposure can be 8 or 10 hours per day for a corresponding 5 or 4 day work week.
Reference Concentration (RfC) US Environmental Protection Agency
An estimate of a continuous inhalation exposure concentration to people (including sensitive subgroups) that is likely to be without risk of deleterious effects during a lifetime. An RfC is reported in milligrams of pollutant per cubic meter of air (mg/m 3). Based on a predicted exposure of 24 hrs/day for 70 years. It is not a direct estimator of risk but rather a reference point to gauge the potential effects and has several safety and uncertainty factors used to select the number. At exposures increasingly greater than the RfC, the potential for adverse health effects increases.
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PLANNING A HUMAN HEALTH RISK ASSESSMENT
6 According to the EPA, the following are typical questions that should be asked prior to starting a risk assessment.
1. Target for the risk (Who, What, Where)
An individual, general population, subgroup of the population (highly susceptible, highly exposed), life stages (children, teenagers, pregnant/nursing women)
2. What is the Environmental hazard of concern?
Chemical, physical, nutritional, socio-economic, biological
3. What is the source of the environmental hazard?
Point, nonpoint, and natural sources
4. How does exposure occur?
Pathways
• Air
• Surface water
• Groundwater
• Soil
• Solid Waste,
• Food,
• Non-food consumer products, pharmaceuticals
Routes
• Ingestion
• Dermal contact
• Inhalation
• Non-dietary ingestion (hand to mouth activity)
5. How does the body handle the contaminant
a. Absorption- does the body take it up or store it
b. Distribution - does it travel throughout the body or stay in one place
c. Metabolism - does the body break it down
d. Excretion - how does the body get rid of it
6. What are the health effects
Examples include: Cancer, liver disease, nerve disease
7. Latency period from exposure to potential health impact
a. Acute - right away or within a few hours to a day
b. Sub-chronic - weeks or months (for humans generally less than 10% of lifespan)
c. Chronic - at least seven years.
d. Is there a critical time that the chemical is most toxic (e.g., fetal development, aging)
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OVERVIEW OF RISK ASSESSMENT
7 EPA defines a human risk assessment as the qualitative or quantitative evaluation of the risk posed to human health and or the environment by the actual or potential presence or release of hazardous substances, pollutants or contaminants.8 A more concise definition is a computation and communication of risk uncertainty. The following is a summary of EPA guidelines for risk assessment taken from the EPA Risk Assessment Portal. Provided here for the convenience of the reader.9 There are four steps in any risk assessment as stated by the National Research Council and defined in the EPA Risk Assessment Glossary:
1. Hazard Identification
Examines whether a stressor has the potential to cause harm to humans and/or ecological systems, and if so, under what circumstances.
Sources of data
...a.
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