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Environmental Indexes by Amit Joshi. Purpose. Assess the potential risks posed by releases from industrial sources Conduct preliminary impact assessment Tool for screening analysis. Classification. Abiotic Indexes Health-Related Indexes Ecotoxicity Indexes. Abiotic Indexes.
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Purpose • Assess the potential risks posed by releases from industrial sources • Conduct preliminary impact assessment • Tool for screening analysis
Classification • Abiotic Indexes • Health-Related Indexes • Ecotoxicity Indexes
Abiotic Indexes • Global Warming • Stratospheric Ozone Depletion • Acid Deposition • Smog Formation
Health-Related Indexes • Inhalation Toxicity • Ingestion Toxicity • Inhalation Carcinogen Toxicity • Ingestion Carcinogen Toxicity
Ecotoxicity Indexes • Fish Aquatic 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) 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) Nc is the number of carbon atoms in the chemical MWi is the molecular wt.
Global Warming Index (contd..) • Factors affecting GWP • Chemical’s tropospheric residence time • 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)
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 response • Dose: Depends on complex series of steps involving 1) manner of release 2) environmental fate and transport of chemicals 3) uptake mechanisms • Response: 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 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 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