This study guide summarizes key points from chapter 4 on risk assessment. It covers the main topics of risk perspectives, risk perception, the four main steps of risk assessment (hazard identification, dose-response assessment, exposure assessment, and risk characterization), and some methods used in risk assessment like relative risk, attributable risk, odds ratio, and dose-response modeling. Specific assessment models like CDI are defined. The guide also touches on human exposure assessment, contaminant degradation kinetics, and EPA's priority research topics for comparative risk analysis.

1. Problem Statement: Determine the total net rate if waste heat emission in kj/sec
to the environment; then compute the rate of coal input in kg/day; find the fly ash
removalefficiency by the APC system; lastly determine the fly ash sent to the
landfill frombottom ash and fly ash removed from the APC system, of a 600 MW
coal-fired power plant that burns Illinois bituminous coal, an efficiency of 39% and
an air permit limit of 7000 kg/day.
Conclusion:
𝑒̇waste =9.38x105
kj/sec Thetotal net rate of waste heat produced by the coal-fired
power plant and sent into the environment.
𝑚̇ 1 = 4.587x106
kg/day Thetotal input rate of coal coming into the power plant
per day
E%= 97.4% Thefly ash removal efficiency need to fulfill the 7000 kg/day
requirement.
𝑚̇ ash, disposal =3.82x105
kg/day Thetotal ash per day sent to a landfill fromthe
power plant consisting of bottom ash and fly ash captured.

2. Problem Statement: Determine the volumetric flow rate of each of the three
exhaust stacks and combine the flow rates to a total flow rate; complete a mass
balance on two chemicals IPA and MeOH to establish the quantity of each solvent
lost by vaporization; find the concentration of IPA and MeOH in ppmv and g/m3
in the stack exhaust; finally compute the volumetric flow rate of IPA and MeOH
through each exhaust stack, of a local microchip manufacturer. All figures can be
seen on figure2.
Conclusion:
Q1 = 2.12x104
cfmThevolumetric flow rate from stack 1
Q2 = 1.44x104
cfmThevolumetric flow rate fromstack 2
Q3 = 323 cfmThe volumetric flow rate of stack 3
Qtotal =3.59x104
cfm Thetotal volumetric flow rate of the entire building
𝑚̇ IPA, total =7666.1 lb/yr Themass flow rate of substanceIPA outof all the stacks
𝑚̇ IPA, 1 = 4527.1 lb/yr Themass flow rate of substanceIPA out of the firststack
𝑚̇ IPA, 2 = 3074.9 lb/yr Themass flow rate of substanceIPA outof the second stack
𝑚̇ IPA, 3 = 68.9 lb/yr The mass flow rate of substanceIPA outof the third stack
𝑚̇ MeOH, total =13632.553 lb/yr Themass flow rate of substanceMeOH out of all the
stacks
𝑚̇ MeOH, 1 = 8050.42 lb/yr Themass flow rate of substanceMeOH out of the first
stack
𝑚̇ MeOH, 2 = 5468.21lb/yr Themass flow rate of substanceMeOH out of the second
stack
𝑚̇ MeOH, 3 = 122.66 lb/yr Themass flow rate of substanceMeOH out of the third
stack

3. CCH3OH,1,2,3 = 8.833 ppmv =11,571.2g/m3
Theconcentration of Menthol inside
the building and inside the stacks in ppmv and g/m3
CC3H7OH,1,2,3 = 2.66 ppmv = 6517 g/m3
Theconcentration of IPA insidethe
building and inside the stacks in ppmv and g/m3
QMeOH, 1= 0.187 ft3
/min The total flow rate of MeOH leaving fromstack 1
QMeOH, 2 = 0.127 ft3
/min The total flow rate of MeOH leaving fromstack 2
QMeOH, 3 = 2.85x10-3
ft3
/min The total flow rate of MeOH leaving fromstack 3
QIPA, 1= 5.64x10-2
ft3
/min The total flow rate of IPA leaving fromstack 1
QIPA, 2 = 3.84x10-2
ft3
/min The total flow rate of IPA leaving from stack 2
QIPA, 3 = 8.59x10-4
ft3
/min The total flow rate of IPA leaving fromstack 3
Itis confirmed that the volumetric flow rate of the of the vaporized are small
relative to the total flow rate, allowing people to work without fear of toxicant
poisoning.

4. TDS = 363.5 mg/lThe total dissolved solids in the water samplewith a pH of 7.0
Alkalinity= 127.54 mg/las CaCO3 = 2.705 meq/l The measureof the sample’s
capability to absorb hydrogen ions withoutsignificantpH change.
TH = 199.29 mg/l= 3.986 meq/l Total hardness of the water sample the sumof Ca
and Mg
CH = 127.54 mg/l= 2.705 meq/lThe hardness of the sample associated with the
carbonates
NCH = 71.75 mg/l = 1.281 meq/l The hardness of the sample not associated with
carbonates
The solution is electrically neutral because the sumof cations and anions are
nearly equal.

5. Problem Statement: Read chapter 4and create brief type-written study guide.
1. Introduction
a. Exposureto substances can cause risk
b. Risk assessmentand risk management are processes of deciding
what to do
2. Perspectives on Risk
a. Everything we do has risk (i.e. car trip, smoking living in a city,
eating food)
3. Perception of Risk
a. How risk are perceived depend benefit out weighing cost
i. Attributes that lower perception – Voluntary, Known,
Controlled by self
ii. Attributes that elevate perception – Involuntary, Controlled
by others, Exotic
4. Risk Assessment
a. Hazard identification – the process of determining whether or not
a particular chemical is causally linked to particular health effects,
such as cancer of birth defects.
b. Dose-responseassessment –the process of characterizing the
relationship between the dos of an agent administered or received
and the incidence of an adversehealth effect.
c. Exposureassessment –involves determining the size and nature of
the population that has been exposed to the toxicant under
consideration and length of time and toxicant concentration to which
they have been exposed.
d. Risk characterization the integration of the previous threesteps.
5. Hazard Identification
a. Toxins can be indentified in the body severalorgans are
vulnerable to toxicants like the liver.
b. Relative risk=
𝑎/(𝑎+𝑏)
𝑐/(𝑐+𝑑)
Attributable risk=
𝑎
𝑎+𝑏
-
𝑐
𝑐+𝑑

6. Odds ratio =
𝑎𝑑
𝑏𝑐
6. Dose-ResponseAssessment
a. CDI =
𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 (
𝑚𝑔
𝑚3
) x Intake rate (
m3
day
) x Exposure (
day
life
)
𝐵𝑜𝑑𝑦 𝑊𝑒𝑖𝑔ℎ𝑡 ( 𝑘𝑔) 𝑥 70 (
𝑦𝑟
𝑙𝑖𝑓𝑒
) 𝑥 365 (
𝑑𝑎𝑦𝑠
𝑦𝑟
)
7. Human ExposureAssessment
a. Bioconcentration
i. provides the key link measuring the tendency for a substance
to accumulate in fish tissue.
b. Contaminant Degradation
ii. Degradation may be the result of a number of process that
remove pollutants from the medium which they reside.
C(t)=C(0)e-kt
8. Comparative Risk Analysis
a. Based on thosestrategic principles, EPA has defined six highest
priority research topics:
i. Drinking water disinfection
ii. Particulate matter
iii. Endocrinedisruptors
iv. Improved ecosystemrisk assessment
v. Improved health risk assessment
vi. Pollution prevention and new technologies