New York University Environmental Science Case Study

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Zbun20

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New York University

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I have a quiz and I am looking for some help the course is called Exposure Assessment (Environmental health major). For answer, you can use the book which I will send it to you and you can use Trusted sources websites.

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Exposure assessment Instructions: Please create a word document with the answers to this test and upload it here. Place your last name and the page number in the upper right corner of each page of your document. Your exam must be properly cited (APA style). There must be an explanation in the form of text that accompanies any table, graph, or image. Any table, graph, or image not accompanied by an explanation will not be given full credit. Page Limit: Submissions are limited to 12 point font, 12 pages. Any submissions over this guideline will have points deducted. please include them as an appendix in order to not have them included in the page count. A) Following quiz instructions. Word document & Last name and Page Number in the upper right corner of each page of your document. B) Proper citation of quiz/ low Turnitin percentage must be under 15% 1) Explain direct and indirect exposure measurements and the difference between the two. Using two different specific pollutants, explain how each might be measured by both direct and indirect exposure measurements. Answer requirements 1. Explain direct and indirect exposure 2. Explain the difference between the two 3. Specific pollutant 1: how it can be measured by direct and indirect exposure measurement. 4. Specific pollutant 1: how it can be measured by direct and indirect exposure measurement. 2) Define exposure, potential dose, and internal dose Using a specific pollutant for each exposure route (dermal, ingestion, inhalation), explain at least two different factors that may affect each dose as it sequentially moves through each exposure pathway. Answer requirements: 1. Define: potential dose, internal dose, exposure 2. Specific pollutant for ingestion 1. Factor 1 that affects potential dose, internal dose, exposure 2. Factor 2 that affects potential dose, internal dose, exposure 3. Specific pollutant for inhalation 1. Factor 1 that affects potential dose, internal dose, exposure 2. Factor 2 that affects potential dose, internal dose, exposure 4. Specific pollutant for dermal 1. Factor 1 that affects potential dose, internal dose, exposure 2. Factor 2 that affects potential dose, internal dose, exposure 3) Using a specific pollutant for inhalation exposure, explain how much of the potential dose would get into the alveolar region of the lung and why? Note: answers should be quantitative (e.g. 40%, half, etc. ) 4) At what diameter are particles inhalable? What happens to the other particles that are not inhalable? Of those inhalable particles, please describe how they are inhaled and deposited into the different parts of the lung. How does their size affect where they settle and explain how the different parts of the lung deal with the particles (include structural descriptions of the different parts of the lung)? 5) Compare the barriers of the lung with that of the skin and digestive tract. How do the structures differ? How are they the same? How do these differences affect the route of pollutant penetration? 6) Name two pollutants for each route that are very easily absorbed through each route of exposure (lung, skin, and digestive tract) and explain why they are easily absorbed. Describe how each of their chemical/ physical characteristics aids in their absorption. Clarification: There should be a total of six different pollutants: 2 unique pollutants for inhalation, 2 unique pollutants for skin, and 2 unique pollutants for the digestive tract. 7) You are tasked with taking soil samples from a potentially contaminated field with an area of 50 by 100 feet next to an abandoned chemical factory. There are suspected "hot spots” of chemical contamination within the field, especially around sheds where chemical drums were stored. You need to get a good survey of what chemicals are present, where they are, and their contamination levels. Name two potential probability-based sampling designs you might employ. Why would you consider these two sampling designs and how would they help you identify hot spots in the sample area? Assume that money is not a factor when conducting your study. 8) What is the difference between accuracy and precision? What factors would affect the accuracy and precision of your data from question 7? What might you do while analyzing the samples to improve accuracy? What might you do while collecting the samples to improve accuracy? 9) Explain what Fick's law calculates and why it is important in estimating dermal dose. What assumptions are made in Fick's first law? Name at least two specific assumptions. 10) How does an ADD calculation differ with carcinogenic vs. non-carcinogenic compounds? Please explain the rationale behind this. 11) Why is calculating a reference dose important? Name at least two UF (uncertainty factors) and two MF (modifying factors). 12) Why is calculating a margin of exposure (MOE) important? What would the MOE of dioxin be and why? Does this pose a concern and why?
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Explanation & Answer

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Running head: ENVIRONMENTAL SCIENCE

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Environmental Science

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ENVIRONMENTAL SCIENCE

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Environmental Science
Exposure measurement involves estimating the magnitude, frequency, and period an
agent is exposed, together with the number and features of the population in context. There are
two approaches in determining exposure assessment; direct and indirect exposure. Direct
exposure refers to measuring the agents or pollutants exposed to an organism directly by using
personal monitors. Conversely, the indirect method evaluates the exposures using an activity
arrangement model to merge the data from the activity model to microenvironmental
concentrations (Ott et al., 2006). The direct approach is simple but costly. Since the process
applies a considerable burden (the quantity of a pollutant present in an individual’s body) on the
respondents, the sample selection tends to be biased. Simultaneously, the indirect exposure
measurement is less costly and involves less respondent burden. It is easy to make a systematic
measurement error in the estimated exposures. This is due to the microenvironmental
concentration data being forged from other sources. Methods of direct exposure include blood
samples, hand rinses, and food samples. Indirect exposure approaches are such as air, soil, or
water sampling, together with information from activity patterns.
Both approaches can estimate dermal exposure. The indirect method estimates dermal
exposure by establishing a relationship between its causative agents such as splashing, smearing,
or spraying aerosols and the resulting exposures on the skin. Dermal exposure can be assessed by
the direct method by the wash and wipe technique (Ott et al., 2006). This involves washing the
affected areas on an individual's skin with water or appropriate solvents, making personal
observations on any changes, and analyzing the eventual results. Human air pollution exposure is
also an instance where both approaches can be applied. A dual sample that offers both direct and
indirect measurements is used. This is by personal monitoring of the exposures like asthma, lung

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cancer, and an activity model that indicates how the causative agents like pollen and pollutants
from fossil-fuel relate to the outcomes on the human respiratory system. The air pollutants can be
measured directly by using a personal portable pump and simultaneously by the indirect means,
which involves employing an activity model with measurements of small-scale pollutants
concentration in the air combined with large-scale assessments to predict the exposure analysis.
Potential dose is described as the total amount of chemical in a liquid or solid substance
that an individual has swallowed. Still, it the amount of an agent an individual has inhaled or
applied to the skin (Ott et al., 2006). Internal dose is the quantity of a compound that the body
absorbs by diffusing by an epithelial barrier such as the respiratory system, skin, or eyes.
Exposure can be defined as the process when a pollutant is in direct contact with a human being
through the air, food, water, and skin as carrier media. It involves what people eat, drink,
breathe, and get in contact with the skin. Generally, it is the contact between a target and an
agent.
An example of a pollutant that is inhaled is the carbon monoxide gas. Factors such as
exposure concentration, background levels, and time profile affect the potential dose, internal
dose, and carbon monoxide exposure (Ott et al., 2006). The concentration of exposure to the gas
is the average concentration of air at each point of an individual's exposed surface. The exposure
at each end is the limited amount of carbon monoxide concentration available to a target. The
background levels of carbon monoxide affect its exposure since it is the capacity of the gas in a
medium that is unaccounted for by the sources investigated in the assessment. The time profile is
basically when the carbon monoxide is exposed to an individual’s surface and inhaled into the
respiratory system.

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A case of a dermal pollutant is the pesticide dichlorodiphenyltrichloroethane (DDT).
Some surfaces are usually exposed to aerosol DDT, aqueous DDT, or DDT molecules in the soil.
Factors like the contact volume, presence of an absorption barrier, and uptake, a function of the
exposure concentration, affect the dosage and exposure of DDT (Ott et al., 2006). The thickness
of contact volume is the distance above the skin, which the DDT molecules have a high
probability of getting in contact with during an exposure period. Uptake involves the penetration
of the DDT molecules, especially in the aqueous state, into the body. This will depend on the
volume of the exposed area; the larger the exposed area, the faster the absorption rate of the
molecules into the body. The stratum corneum is the primary barrier of the absorption of the
DDT molecules into the skin. This will affect the amount of DDT dose that will enter the body.
Food and drinking water are the basic pollutants that are ingested. In this instance, let us
consider the manganese present in a vitamin pill. Factors affecting its dosage and exposure are
such as contact boundary and absorption barrier (Ott et al., 2006). Contact boundary involves
that instance when the oral exposure of the manganese will be zero until when the tablet will be
in contact with the exposure surface. The vitamin pill may fail to be completely ingested because
of an absorption barrier of the epithelial lining in the gastrointestinal gut.
Examples of pollutants for inhalation exposure are oxygen and carbon dioxide gases. In
this case, the focus is on the oxygen gas. For the gas to get to the alveolar region, it passes
through the surfactant layer in the lung, lung tissues, interstitial space at the bloodstream, and
blood vessel walls. The alveoli are composed of tiny sacs with a large surface area estimated to
be 100 square meters during the process of inhalation (Ott et al., 2006). The amount of the
potential dose of oxygen gas diffused into the alveolar region in the lungs is in half concentration
like that of the carbon dioxide gas. For inhalation to take place, exhalation also needs to occur.

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Therefore, when oxygen is diffused into the lungs, the carbon dioxide present needs to be
eliminated, and at the same time, oxygen will replace the amount earlier occupied. However, an
aspect such as an absorption barrier may prevent the supposed total inhalation of oxygen into the
alveolar region.
The suitable diameter of particles to be inhaled into the alveolar region of the lungs is 0.5
micrometers or even smaller, considering the air in this area is calm (Ott et al., 2006). Particles
as large as 2.5 micrometers may get into the airway tract, posing great danger (USEPA, 2017).
Fortunately, there are tiny hairs referred to as the cilia that protect the nasal inner parts and the
rest of the respiratory tract by filtering out harmful particles hence purifying the air breathed in.
There are four significant mechanisms in which the inhaled particles are deposited into various
parts of the lungs. They include impaction, gravitational settling, interception, and Brownian
diffusion.
For impaction to occur, a particle with too much inertia crosses the streamlines and
collides into the respiratory tract surface. Coarse particles have increased inertia compared to the
fine particles, so they are affected more by the inertia's impaction. Moreover, impaction removes
coarse particles in the nasal-pharyngeal region. Gravitational settling happens when the pull of
gravity causes a particle to cross the streamlines to settle on the respiratory surface. This
mechanism is essential when the speed of the air streamlines has decreased sufficiently to allow
the settlement of the particles. Interception is a process whereby a particle trailing in the air
streamline gets in contact with an obstacle and is removed. Interception can be vital when it
comes to the deposition of particles with elongated shapes like fiberglass fragments. Brownian
diffusion takes place when a particle in Brownian motion gets into the respiratory wall. The
random collisions of gas molecules against a particle usually cause the Brownian motion.

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The smaller the size of a particle, the greater the influence of the gas molecules on its
movement. The lungs are composed of tissues such as the alveolar epithelium and the epithelial
basement membrane. It also has an interstitial space that connects it to the bloodstream. The
alveolar epithelium is made up of thin, flattened cells that are surrounded by capillaries. These
epithelial tissues deal with the particles passing into the respiratory tract by filtering, diffusing,
and absorbing them. The interstitial space is a supporting framework for the alveoli sacs in which
particles are inhaled (Ott et al., 2006). These structures of the lung enable it to deal with particles
being inhaled.
The absorption barriers of the lungs differ from those of the skin and the digestive tract.
The barriers in the lungs include the surfactant, epithelial tissues, surface lining liquid,
endothelium, and interstitial membrane. The skin has the stratum corneum, epidermal and dermal
tissues as its barriers. The digestive tract has a barrier, which is the epithelium of the
gastrointestinal tract (Ott et al., 2006). The barriers of the lungs, skin, and digestive tract are
similar in that they all include the epithelial tissues.
On the other hand, there are several differences in the structures. The lung has the
surfactant, surface lining fluid, and endothelium for the filtration and purification of the air
inhaled. The skin contains the stratum corneum as the outermost layer, which protects the inner
tissues of the skin from mechanical damage, retains body fluids, and prevents the living cells
from being disrupted by harsh environmental chemicals (Ott et al., 2006). For penetration of a
pollutant on the skin, it gets in contact with the skin by the stratum corneum, then diffuses into
the epidermis and dermis, circulating in the entire body. When a pollutant is inhaled, it diffuses
through the surfactant layer of the lungs to the lung tissues. T...


Anonymous
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