POTENTIAL HEALTH RISK ASSESSMENT FOR SOIL AND AIR HEAVY METAL CONTAMINATION IN BAGHDAD CITY

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    International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 2, February 2017, pp. 236251 Article ID: IJCIET_08_02_026 Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=2 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 IAEME Publication Scopus Indexed

    POTENTIAL HEALTH RISK ASSESSMENT FOR SOIL AND AIR HEAVY METAL CONTAMINATION

    IN BAGHDAD CITY Dr. Nabaa Shakir Hadi

    Assistant Professor, Environmental Engineering Department, Engineering College, Babylon University, Iraq

    ABSTRACT This paper was submitted an Environmental Risk Assessment process which is based on

    four steps defined by both National Academy of Science and the EPA. These are: Hazard Identification, Exposure Assessment, Toxicity Assessment, and Risk Characterization. It was taken into account two environmental media (Soil and Air). At first the concentration of some heavy metal (Cd, Cr, Zn, Ni and Pb) was collected from previous studied conducted in soil media at three locations (Residential area, Industrial area and Commercial area)in Urban Soil within Baghdad City. For air media the lead concentration was taken from previous studied conducted at two locations (Residential area, Industrial area) in Baghdad city. Also It was taken into account one environmental soil media. The average concentration of heavy metal (Cd, Ni and Pb) was collected from previous studied conducted in Baghdad soil media and different towns samples of environmental soil media. Based on these test results and data gathered, the potential human health risk assessment based on EPA model was used to calculate different types of Intake through (ingestion, dermal) for soil media and (ingestion, dermal and inhalation) for air media, noncarcinogen Hazard Index (HI) and carcinogen Risk (R) resulted from these exposure routes was also calculated.

    The results of the risk assessment indicated that the highest risks for individual element for both adults and children. Cumulative hazard quotient index (THI) for the study area showed that the adults and children population were seriously at the risk of chronic non-carcinogenic health problem. Key words: Risk-based assessment, Heavy metal, Soil & Air remediation techniques, Baghdad City. Cite this Article: Dr. Nabaa Shakir Hadi, Potential Health Risk Assessment for Soil and Air Heavy Metal Contamination in Baghdad City. International Journal of Civil Engineering and Technology, 8(2), 2017, pp. 236251. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=2

    1. INTRODUCTION The importance of environmental realities of the Baghdad city a vital fact because this city is the capital and occupy a large area of Iraq as well as a population of over five million, and most industrial and commercial activities stationed as well as agricultural activity. the pollution rates increased in the

  • Dr. Nabaa Shakir Hadi

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    soil of the Baghdad city because of overlapping set of factors increase the population of the city and the consequent environmental problems resulting from the depletion of natural resources and increasing waste of factories, landfills and increase the number of vehicles and other factors that lead to the introduction of many pollutants into the soil. These problems have increased the risks of environmental balance and ecosystem constituted a breach of the city [4].

    Environmental Risk Assessment (ERA) which defined as a tool used to evaluate the risks due to fate and transport of chemical in an environment which leads to harmful effects of receptors. ERA includes examinations of risk caused by natural events (flooding, extreme, weather events, etc.), technology, practice, processes, products, agents (chemical, biological, radiological, etc.) and adversely affect posed by industrial activities [5]. In this thesis risk assessment concerns with human health which defined as the process to estimate the nature and probability of adverse health effects in humans, who may be exposed to chemicals in contaminated environmental media, exist or potential[6].

    Environmental Risk Assessments typically fall into one of two areas: Human health risk assessment

    Ecological risk assessment Risk assessment addresses human health concerns and ecological risk assessment addresses

    environmental media and organisms. This study deals with human health risk assessment.

    2. AIM OF THE STUDY Create a database for including heavy metals concentration in environmental soil and Air media at

    contaminated sites in Baghdad City.

    Create a database for including heavy metals concentration in environmental Iraq soil(Baghdad City) with other data from different towns, (mean)

    Calculate and assess human health risks associated with these contaminants from three exposure routes(ingestion, dermal contact and inhalation) by using (ERA) tool.

    Comprise between Environmental Risk Assessments for heavy metals in Iraq (Baghdad city) soil with world soil.

    3. HEALTH RISK ASSESSMENT

    3.1. Hazard Identification Hazard identification includes identifying those sources that cause damage to receptors, especially human, living organisms, and ecosystem. This stage usually focuses on the most dangerous chemicals (which are classified as hazardous chemicals on humans and sorted according to toxicity carcinogenic or non-carcinogenic) [9].

    3.2. Exposure Assessment Exposure assessment defined as the estimation of the magnitude, frequency, duration, and route of exposure. The purpose of exposure assessment is the estimation of the contaminant concentrations and dosages to the populations at risk. More specifically, the primary tasks in exposure assessments include:

    Identifying potentially exposed populations,

    Identifying potential exposure pathways,

    Estimating exposure concentrations, and

  • Potential Health Risk Assessment for Soil and Air Heavy Metal Contamination in Baghdad City

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    Estimating chemical intakes [7]. For estimation of Intake, EPA recommends the use of exposure data normalizedfortime andbody

    weight, which is formulated into an equation for intake (I), the general equation for chemical in take is:

    =( )( )( )

    ( )( ) (1)

    Where: I = intake (the amount of chemical at the exchange boundary) (mg/kg-day). C = the average exposure concentration over the period (e.g., mg/L for water or mg/m3for air and mg/kg for soil).| CR= contact rate, the amount of contaminated medium contacted per unit time (L/day or m3/day or mg/day). EFD = exposure frequency and duration, a variable that describes how long and how often exposure occurs. The EFD is usually divided into two terms: EF - exposure frequency (days/year). ED = exposure duration (years). BW = the average body mass over the exposure period (kg). AT = averaging time; the period over which the exposure is averaged (days).

    Basic formulas and values used for the calculation of ingestion and dermal of soil and ingestion, dermal and inhalation of air are presented in Table (1&2).

    Table 1 Contaminated media and corresponding routes of exposure [10].

    Routes of exposure

    Media

    Ingestion, Dermal contact Soil Ingestion, Dermal contact, Inhalation of airborne chemicals Air

    Table 2 Basic formulas used for calculation of intake for environmental media and exposure route [10].

    Equation Exposure route

    Environmental media

    =( )( )( )( )( )( )

    ( )( ) Ingestion

    Soil =

    ( )( )( )( )( )( )( )( )( )( )

    dermal

    =( )( )( )( )

    ( )( ) Ingestion Air

    =( )( )( )( )( )( )( )

    ( )( ) dermal

    =( )( )( )( )( )

    ( )( ) inhalation

    Where: ABS= absorption factor for soil contaminant, unit less AD= absorbed dose, mg/kg.d AF= soil-to-skin Adherence Factor, mg/c m2 .event.

  • Dr. Nabaa Shakir Hadi

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    AT= averaging time, d BW= body weight, kg CA= contaminant concentration in air, mgm3 CDI= chronic daily intake, mg/kg.d CF= volumetric conversion factor for water= 1L/1.000 cm3 = conversion factor for soil = 10-6 kg/mg CR= contact rate, L/h CS= chemical concentration in soil, mg/kg CW= chemical concentration in water, mg/L ED= exposure duration, y EF= exposure frequency, d/y or events/y ET= exposure time, h/d or h/event EV = Event Frequency (events/day). FI= fraction ingested, unit less IR= ingestion rate, L/d or mg soil/d or kg/meal = inhalation rate, m3/h PC= chemical-specific dermal permeability constant, cm/h SA= skin surface area, cm2.

    4. EXPOSURE PARAMETERS

    4.1. Soil Media IR=200mg/day (child) and 100mg/day (adult) [7] CF=0.000001kg/mg FI=1[8]. EF=350 days/year [Residential], 250 days/year [Industrial, Commercial][7] ED=30 years (adult)[Residential], 25 years (adult)[Industrial, Commercial]and 6 years (child) [7] BW= (70kg for adult) and (15 kg for child) [10] AT= (365*30) for adult and (365*6) for child. [7] SA=5700 cm2 (adult) [Residential], 3300(adult) [Industrial, Commercial][11,12]. SA=2800 cm2 (child) [Residential], NA cm2(child) [Industrial, Commercial][11,12]. AF=0.07mg/cm2(adult)[Residential],0.2mg/cm2(adult)[Industrial,Commercial][11,12] AF=0.2mg/cm2(child)[Residential],NAmg/cm2(child)[Industrial,Commercial][11,12]. EV=1 event/d [3] ABS = 0.001(adult), 0.03(child) [12,13].

    4.2. Air Media IR=20m3/day (adult) and 5m3/day (child) [7]. ET=24 hour/day [7]. ED=70 year (carcinogen) [7]. AT=70*365[7].

    The other parameter is the same used in previous items.

  • Potential Health Risk Assessment for Soil and Air Heavy Metal Contamination in Baghdad City

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    4.3. Toxicity Assessment Toxicity assessment expresses the acquisition and evaluation of Toxicity data for each contaminant and then evaluated. This evaluation includes toxic carcinogenic and non-carcinogenic substances, In this method, (RfDs) and (SFs) used for determining non-carcinogenic and carcinogenic toxicity respectively. Almost all toxicity assessments make use of available data such as the list of reference doses and slope factors; therefore, toxicity assessment often includes obtaining tabular RfDs and SF information related chemicals to which receptors are exposed as shown in Table3.From this quantitative dose response relationship, toxicity values (e.g., reference doses and slope factors) are derived that can be used to estimate the incidence or potential for adverse effects as a function of human exposure to the agent. These toxicity values are used in the risk characterization step to estimate the likelihood of adverse effects occurring in humans at different exposure levels [14].

    Table 3 Oral and Inhalation Slope Factors and RfDs[7].

    Inhalation SF (kg.day/mg)

    Inhalation RfD (mg/kg.day)

    Oral SF (kg.day/mg)

    Oral RfD (mg/kg.day)

    Compound

    6.1 0.0005 Cadmium 41 0.005 Chromium 0.3 Zinc 0.02 Nickle

    0.085 0.006 Lead For evaluating Dermal Exposure, Oral RfDs converted to Dermal RfDs By multiplying with

    gastrointestinal absorption fraction (ABSGI), Oral SF can be converted to Dermal SF by dividing the Oral SF by the ABSGI.

    When ABSGI values are not available, USEPA recommends the following defaults for ABSGI: 80% for volatile organics; 50% for semi-volatile organics and nonvolatile organics; and 20% for inorganic [8].

    4.4. Risk Characterization Risk characterization defined as the calculation of riskforbothnoncarcinogens and carcinogens for allreceptors that maybeexposed to hazardouswastes. Some of the general requirements include calculating risk for all of the exposure routes to hazardous chemicals (ingestion and inhalation and dermal) for both noncarcinogens and carcinogens. Thel non-carcinogenicriskl is calculatedl as Hazard Index (HI), which is thel ratio of the daily intake to the referenceldosel (RfDl)[7].

    = (2)

    Where: HI = hazard index (dimensionless). I = intake (mg/kg.day). RfD = reference dose (mg/kg.day).

    Hazard Index

  • Dr. Nabaa Shakir Hadi

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    EPA sums the hazard indexes for each constituent as follow:

    Hazard Index T = HI For multiple pathways:

    Hazard Index T = HI

    Where: i=the compound and j= pathways [13]. The carcinogenic risk may be defined as the chronic daily intake dose (developed in the exposure

    assessment) multiplied by the carcinogenic slope factor (selected by the toxicity assessment).The product is a real term: the probability of excess lifetime cancer from exposure to this chemical. The computation is as follows:

    Risk = CDI SF (3) Where: Risk = the probability of carcinogenic risk (dimensionless). CDI = chronic daily intake (mg/kg.day). SF = carcinogen slope factor (kg.day/mg)[14]. In a like manner, the risk for multiple substances and pathways is estimated as:

    Risk = risk

    Where: i=the compound and j= pathways [14].

    5. MATERIALS AND METHODS

    5.1. Soil Media Samples Were collected environmental data and information on soil contaminants in the city of Baghdad from the previous studies. Selected stations located on different parts of the city of Baghdad for the purpose of collecting samples of soil, plants have been distributed on a regular basis so as to cover most areas of the city, with a focus on the type of each area as commercial, industrial or residential, as shown in Table4.

    Table 4 Samples of heavy metal in the soil of Baghdadcity[ 1].

    Contaminants Concentration(mg/kg) Mean

    Locations of samples

    Environmen-tal media Pb Ni Zn Cr Cd

    87.06 86.76 51.24 23.09 0.29 Roadside soil Residential area

    Soil

    94.90 80.42 46.51 26.46 0.23 Open area soil 90.98 83.59 48.88 24.77 0.26 All soils 156.14 80.82 94.92 32.69 0.94 Roadside soil Industrial

    area

    131.68 88.63 86.72 35.24 0.93 Open area soil 143.91 84.73 90.82 33.96 0.93 All soils 110.30 72.76 68.88 24.21 0.45 Roadside soil Commercial

    area 103.81 76.85 60.09 28.27 0.40 Open area soil 107.06 74.81 64.49 26.24 0.43 All soils

  • Potential Health Risk Assessment for Soil and Air Heavy Metal Contamination in Baghdad City

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    5.2. Air Media Samples Table (5 & 6) shows the concentration of lead in air was taken from previous studies conducted in Baghdad city as a trial for evaluation of lead in air from variable source at different type of stations as follow:

    A study evaluated air lead concentration in air-borne dust samples in Baghdad city as a result of the industrial expansion and population increase and increasing number of cars at different locations in industrial, residential region. Also study taken into account on the concentration of lead in streets-dust samples in Baghdad city air.

    5.3. Concentration of Lead in Baghdad City Air

    Tabl...

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