Environmental Indexes by Amit Joshi. Purpose Assess the potential risks posed by releases from...
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Transcript of Environmental Indexes by Amit Joshi. Purpose Assess the potential risks posed by releases from...
Purpose
Assess the potential risks posed by releases from industrial sources
Conduct preliminary impact assessment
Tool for screening analysis
Health-Related Indexes
Inhalation ToxicityIngestion ToxicityInhalation Carcinogen Toxicity Ingestion Carcinogen Toxicity
Global Warming Index
Ratio of cumulative infrared energy capture from the release of 1 kg of a green-house gas relative to that from 1 kg of carbon dioxide (IPCC,1991)
n
0
dtCa
n
0
dtCa
GWPi
22 coco
ii
ai is the predicted radiative forcing of the gas i (Wm-2)
Ci is its predicted concentration in the atmosphere (ppm)
n is the number of years over which the integration is performed
Global Warming Index (contd..)
The product of GWP and the mass emission rate of the greenhouse chemical gives the emission in terms of CO2 (the benchmark compound)
IGW= (GWPi * mi) For the, organic compounds, with atmospheric reaction
residence time less than ½ a year, an indirect GWP is defined (Shonnard and Hiew, 2000)
i
2
MW
MW Nc ect)GWPi(indir
CO
Nc is the number of carbon atoms in the chemical
MWi is the molecular wt.
Global Warming Index (contd..)
Factors affecting GWP
1) Chemical’s tropospheric residence time
2) The strength of its infrared radiation absorbance
Ozone Depletion Index
Ratio of the predicted time- and height- integrated change
[O3] in stratospheric ozone caused by the release of a specific quantity of the chemical relative to that caused by the same quantity of a benchmark compound, tricholorofluoromethane (CFC-11,CCL3F) (Fisher et al., 1990)
113
3
][
][
CFC
i
O
O
Ozone Depletion Index (contd..)
The product of ODP and the mass emission rate of the greenhouse chemical gives the emission in terms of CFC-11, the benchmark compound.
IOD= (ODPi * mi)
Acid Rain Index
The number of H+ created per number of moles of the compound emitted as shown in the following equation
X + ------------- H+ + ----------- where, X is the emitted chemicals substance initiating
acidification and is a molar stoichiometric coefficient.H+ created per mass of substance emitted (i,H+moles/ kg i)
i= i__
MWi
MWi is the molecular weight of the emitted substance (moles i /kg i )
Acid Rain Index (contd..)
ARPi = __i__
SO2
expressed in terms of benchmark compound SO2
The product of ARP and the mass emission rate of the chemical gives the emission in terms of SO2 (the benchmark compound)
IAR= (ARPi * mi)
Smog Formation Index
Incremental reactivity (IR) for evaluation of SWP
Definition: The Change in moles of ozone formed as a result of emission into an air shed of one mole of the VOC (Carter and Atkinson,1989)
VOC IR is proportional to NOx level relative to reactive organic gases (ROG)
Smog Formation Index (contd..)
Maximum Incremental Reactivity (MIR)- Most relavent scale for comparing VOCs. MIR occurs under high NOx conditions when the highest ozone formation occurs (Carter,1994)
SFPi= __MIRi__
MIRROG
MIRROG is the average value for background organic gases, the benchmark compound for this index
Smog Formation Index (contd..)
The product of SFP and the mass emission rate of the chemical gives the emission in terms of background ROG, the benchmark compound
ISF= (SFPi * mi)
Toxicity Potentials
Toxicity : Complex function of dose and responseDose: Depends on complex series of steps involving
1) manner of release
2) environmental fate and transport of chemicals
3) uptake mechanismsResponse: Response by the target organ in the body is a complex
function of
1) chemical structure
2) modes of action
Toxicity Potentials (contd..)
Types of Toxicity
1) Carcinogenic Toxicity: defined in terms of Benzene
2) Non-Carcinogenic Toxicity : defined in terms of Toluene
Dominant exposure routes for human contact with toxic chemicals in the environment
1) Inhalation
2) Ingestion
Toxicity Potentials (contd..)
Non-Carcinogenic Toxicity controlled by threshold exposure i.e., doses below the
threshold value do not manifest a toxic response whereas the doses above this will do.
Key parameters for chemicals Ingestion : reference does (RfD(mg/kg/day))
: lethal dose (LD50) Inhalation: reference concentration (RfC(mg/m3))
: lethal concentration(LC50)
RfCs and RfDs are not available for all chemicals so LD50 and LC50 are used
Toxicity Potentials (contd..)
Non-Carcinogenic Ingestion Toxicity Potential
Ingestion Toxicity Potential
Inhalation Toxicity Potential
I*ING
CW ,i LD50, Toluene
CW ,Toluene LD50,i
I*INH
CA, i LC50,Toluene
CA, Toluene LC50,i
C w,i and C w,Toluene are the steady-state concentrations of the chemical and the benchmark compound in the water compartment
C a,i and C a,Toluene are the steady-state concentrations of the chemical and the benchmark compound in the air compartment
Toxicity Potentials (contd..)
Non-Carcinogenic Ingestion Toxicity Potential (contd..)
The product of I*INGi and the mass emission rate of the chemical
gives the emission in terms of Toluene, the benchmark compound
IING= (I*INGi * mi)
The product of I*INHYi and the mass emission rate of the chemical
gives the emission in terms of Toluene, the benchmark compound.
IINH= (I*INHi * mi)
Toxicity Potentials (contd..)
Carcinogenic Toxicity
Ingestion Toxicity Potential
Inhalation Toxicity Potential
I*CING
CW ,i HVi
CW ,Benzene HVBenzene
I*CINH
CA, i HVi
CA ,Benzene HVBenzene
HV is the hazard value for carcinogenic health effects
Toxicity Potentials (contd..)
Carcinogenic Toxicity(contd..)
The product of I*CINGi and the mass emission rate of the chemical
gives the emission in terms of Toluene (the benchmark compound)
ICINGi= (I*CINGi * mi)
The product of I*INHYi and the mass emission rate of the chemical
gives the emission in terms of Toluene (the benchmark compound)
ICINHi= (I*CINHi * mi)
Toxicity Potentials (contd..)
In non-carcinogenic toxicity indexes, RfDs and RfCs can also be used if available instead of LD50 and LC50 .
In carcinogenic toxicity indexes, Slope Factor (SF) can be used instead of hazard values for chemicals.
Slope Factor : Known as a cancer slope potency factor. It is obtained using the excess cancer versus administered dose data
Ecotoxicity Index
Fish Toxicity Index
LC50 - the 4-day rodent or fish lethal dose (mg/l) which causes 50%
mortality in a test population.
Benchmark compound: PCP - pentachlorophenol
I*FT
CW,i LC50 f ,PCP
CW,PCP LC50 f ,i
Summary
R ela tiv e R isk In d e x E q u a tio n
IG W , i* GWP i
G lo b a l W a r m in g
IG W , i* N C
MW C O2
MW i
O zo n e D ep le t io nIO D, i
* ODP i
S m o g F o rm a tio nI S F, i
* MIR i
MIR R O G
A cid R a inIA R, i
* ARP i
ARP S O2
GW P = g lo b a l w a rm in g p o ten tia l, N C = n u m b er o f c a rb o n s a to m s, O DP = o zo n ed e p le tio n p o te n ta l, M IR = m a x im u m in c re m e n ta l rea c tiv ity , A R P = a c id ra in p o ten tia l .
Summary (contd..)
Relative Risk Index Equation
Human Toxicity Ingestion Route I*
ING CW ,i LD50, Toluene
CW ,Toluene LD50,i
Human Toxicity Inhalation Route I*
INH CA, i LC50,Toluene
CA, Toluene LC50,i
Human Carcinogenicity Ingestion Route
I*CING
CW ,i HVi
CW ,Benzene HVBenzene
Human Carcinogenicity Inhalation Route
I*CINH
CA, i HVi
CA ,Benzene HVBenzene
Fish Toxicity
I*FT
CW,i LC50 f ,PCP
CW,PCP LC50 f ,i
LD50 = lethal dose 50% mortality, LC50 = lethal concentration 50% mortality, and HV = hazard value for carcinogenic health effects.