Question 24 Deposition: Duke Energy and Gov. McCrory ignored cancer-risk estimat
ID: 87937 • Letter: Q
Question
Question 24
Deposition: Duke Energy and Gov. McCrory ignored cancer-risk estimate for polluted well water approved by CDC Winston Salem Journal - June 9, 2016 http://www.iournalnow.com/news/local/deposition-duke-energy-and-gov-mccrorv-ignored-cancer-risk-estimate/article 85fce9cb-22cl-538d-ab8d-2689942cd98f.html ... "The screening level must carry a lifetime cancer risk of 1 in 1 million. Ideally, water should contain no hexavalent chromium, environmental advocates say, but the level of 0.07 parts per billion is considered health-protective. Well owners such as Amy Brown in Belmont, near Duke Energy's Allen power plant, would face a lifetime cancer risk of 1 in 1 million if the concentration of hexavalent chromium met that level. The chances would be even slimmer if the concentration were smaller." To make the calculations, what two values are needed to calculate incremental risk? _________ You have to drink the water to get exposed. So, what is being assumed about that process, and for how long? _______________ You work in a building for 10 years and develop asthma. Is this a chronic or acute effect? 100 additional cancers of some type were observed over course of peoples' lifetime in a population of 5 million. Everyone had the same exposure to the causative chemical, in units of mg/kg-day. What is the ILCR for the chemical and that cancer? The NOAEL concentration for a chemical in air for chronic exposure for some endpoint is 0.1 mu g/m^3. What will be selected as the reference dose concentration for inhalation? For the same chemical in the preceding problem, the measured exposure concentration is 0.05 mu g/m^3. What is the Hazard Quotient?Explanation / Answer
21. Chronic Effect
Chronic Effect : Adverse effect on animal or human body with symptoms that develop slowly, due to long and continuous exposure to low concentrations of a hazardous substance. Such symptoms do not usually subside when the exposure stops. Opposite of acute effect.
In non-clinical assessment NOAEL (no-observed-adverse-effect level) plays a pivotal role. It is determined or proposed by qualified personnel (pharmacologist, toxicologist) depending on the study, drug indications and its pharmacological therapeutics side/adverse effects. NOAEL could be defined as "the highest experimental point that is without adverse effect". It either does not provide the effects of drug with respect to duration and dose, or it does not address the interpretation of risk based on toxicologically relevant effects. The no-observed-adverse-effect level (NOAEL) denotes the level of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant (e.g. alteration of morphology, functional capacity, growth, development or life span) increase in the frequency or severity of any adverse effects in the exposed population when compared to its appropriate control.
In toxicology it is specifically the highest tested dose or concentration of a substance (i.e. a drug or chemical) or agent (e.g. radiation), at which no such adverse effect is found in exposed test organisms where higher doses or concentrations resulted in an adverse effect.
This level may be used in the process of establishing a dose-response relationship, a fundamental step in most risk assessment methodologies.
In drug development, NOAEL of a new drug is assessed in laboratory animals drugs prior to initiation of clinical trials to establish a safe clinical starting dose in human trials.
The United States Environmental Protection Agency defines NOAEL as 'an exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered as adverse, or as precursors to adverse effects.In an experiment with several NOAELs, the regulatory focus is primarily on the highest one, leading to the common usage of the term NOAEL as the highest exposure without adverse effects.
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