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Health Risks of Metals in Soil, Water, andMajor Food Crops in Hamedan Province,Iran

Moj gan Yeganeh a , Maj id Afyuni a , Amir-Hosein Khoshgoftarmanesha

, Ali-Reza Soff ianianb

& Rainer Schulinc

aDepartment of Soil Science, Facult y of Agriculture, Isfahan

Universit y of Technology, Isfahan, Iranb

Department of Environmental Science, Isfahan University ofTechnology, Isfahan, Iranc

ETHZ Inst itute of Terrestrial Ecosystems (ITES), Soil Prot ect ionGroup, Zurich, Swit zerland

Available online: 21 Mar 2012

To cite this art icle: Mojgan Yeganeh, Maj id Afyuni , Amir-Hosein Khoshgoft armanesh, Ali-RezaSoff ianian & Rainer Schulin (2012): Healt h Risks of Metals in Soil , Water, and Major Food Crops inHamedan Province, Iran, Human and Ecological Risk Assessment: An International Journal, 18:3,547-568

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Human and Ecological Risk Assessment, 18: 547568, 2012Copyright C Taylor & Francis Group, LLCISSN: 1080-7039 print / 1549-7860 onlineDOI: 10.1080/10807039.2012.672886

Health Risks of Metals in Soil, Water, and Major Food

Crops in Hamedan Province, Iran

Mojgan Yeganeh,1 Majid Afyuni,1 Amir-Hosein Khoshgoftarmanesh,1

Ali-Reza Soffianian,2 and Rainer Schulin3

1Department of Soil Science, Faculty of Agriculture, Isfahan University ofTechnology, Isfahan, Iran; 2Department of Environmental Science, IsfahanUniversity of Technology, Isfahan, Iran; 3ETHZ Institute of Terrestrial Ecosystems

(ITES), Soil Protection Group, Zurich, Switzerland

ABSTRACTFood, drinking water, soil, and air are the main routes of exposure to trace

metals, thus the assessment of the risks posed to humans by these elements isimportant. Wheat, potatoes, and maize are very important parts of the Iranian diet.The objectives of this study were to estimate the non-carcinogenic and carcinogenichealth risks of Hg, Pb, Cd, Cr, Se, As, and Ni to adults and children via soil, water,and major food crops consumed in Hamedan Province, northwest Iran, using thetotal non-cancer hazard quotient (THQ) and cancer risk assessment estimates. Total

non-cancer hazard of Ni and Hg, were greater than 1, and total cancer risk of As andPb was greater than 1 106. Food consumption was identified as the major routeof human exposure to metals, and consuming foodstuff threatens the health of thestudied population. In Hamedan Province, consumption of wheat is the main sourceof intake of metals from foodstuff for adults, and in children, the soil ingestion routeis also important.

Key Words: metals, risk assessment, non-cancer risk, cancer risk, Iran, HamedanProvince.

INTRODUCTION

Increasing metal concentrations in the environment have caused great concernworldwide. Metals in the environment may arise from natural and anthropogenicroutes and their concentrations are elevated due to solid-waste disposal, atmosphericdeposition, fertilizer and pesticide use, and the application of sewage sludge and

wastewater irrigation on land (Khan et al. 2008; Zheng et al. 2007).

Received 11 September 2010; revised manuscript accepted 17 April 2011.Address correspondence to Mojgan Yeganeh, Department of Soil Science, Faculty ofAgriculture, Isfahan University of Technology, Isfahan, 84156, Iran. E-mail: yeganehmoj-

[email protected]

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M. Yeganeh et al.

Agricultural, industrial, and urban developments have raised the possibility ofmetals accumulation in food crops and as a consequence, their risk for humanhealth and well-being (Huang et al. 2007). Excessive levels of potential toxic elements(PTEs) not only could restrain the growth of crops, but also affect their quality and

safety throughout the food chain. In addition, the chronic low-level intake of PTEscan pose detrimental effects on human health (Huang et al. 2007). Many metalssuch as Fe, Cu, Co, Mn, Zn, and Cr are essential for humans but can also cause toxiceffects at high doses (Caussyet al. 2003). Other metals such as Hg, Pb, Cd, and Asare not known to be essential for plants or animals (Caussyet al. 2003).

The most probable human health effects of oral exposure to As are gastroin-testinal irritation, peripheral neuropathy, vascular lesions, anemia, and a group ofskin diseases. Arsenic is also considered a carcinogen via the oral route (Pais and

Jones 2000). Little information is available on the effects due to dermal contact withinorganic As. The primary toxicological effect of oral exposure to Cd is proteinuria

(i.e., excess protein in the urine). Cadmium ingestion causes nausea, vomiting, sali-vation, abdominal pain, cramps, and diarrhea (ATSDR 2000). Oral exposure to Nican result in an increased incidence of allergic contact dermatitis, eczema, and res-piratory effects in humans. Trivalent chromium exhibits very low toxicity and occursnaturally in many fresh vegetables, fruits, meat, grains, and yeast (ANL 2001).

Lead toxicity causes encephalopathy accompanied by lethargy, vomiting, irri-tability, loss of appetite and dizziness, progressing to ataxia, and a reduced level ofconsciousness, which may progress to coma and death. Encephalopathy can occurat blood lead levels of 100120 gPb/dL in adults and 80100gPb/dL in children(ATSDR 2000). The toxicity of Hg significantly impacts the nervous system of un-born and new-born children. Mercury appears to be transported from the mothers

tissues to the baby during pregnancy and breast-feeding (Mercury 2001). Recentstudies have suggested that a subtle effect like delayed mental development occursat much lower Hg concentrations than formerly believed (Mercury 2001).

RISK ASSESSMENT

The methods proposed to estimate the potential health risks of contaminantsare divided mainly into carcinogenic and non-carcinogenic effects (USEPA 1989).Standard cancer risk assessment methods can be used to quantify the magnitude

of risk (USEPA 1989). On the other hand, non-cancer risk assessment methods donot provide quantitative estimates on the probability of experiencing non-cancereffects from contaminant exposures. The non-cancer risk is typically based on thetotal hazard quotient (THQ), which is a ratio of determined dose of a pollutantto the reference dose (RfD) (USEPA 2000). A THQ ratio less than 1 indicatesan exposure that is likely to be without an appreciable risk of deleterious effectsduring a lifetime (Barnes and Dourson 1988). As the frequency and magnitude ofexposures exceeding the RfD increases, the liklihood of adverse effects increases.The method for the determination of THQ was provided in the USEPA Region 6risk-based concentrations (USEPA 2007).

The carcinogenicity assessment predicts the carcinogenic hazard potential of a

substance and quantitative estimates of risk from oral and inhalation exposures

548 Hum. Ecol. Risk Assess. Vol. 18, No. 3, 2012


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Health Risk of Metals in Hamedan Province, Iran

(USEPA 2000). The information includes a weight-of-evidence judgment of thepossibility that the agent is a human carcinogen and the conditions under whichcarcinogenic effects may be expressed. Acceptable risk levels for carcinogens rangefrom 104 (risk of developing cancer over a human lifetime is 1 in 10,000) to 106

(risk of developing cancer over a human lifetime is 1 in 1,000,000) (USEPA 2000).Risk assessment methods are some ways to estimate and predict the possibility

of health risks of metals in a system for humans. There is no information availableabout risks of metals for humans residing in Hamedan Province. Each metal cancause some problems for human health via different routes, such as ingestion of

water, food, or incidental ingestion of soil, dermal contact with soil and water, orinhalation of soil particulates. In some cases the total concentration of some metalssuch as As in soil is high but because of low availability, this metal cannot enter thefood chain, but may influence human health by other pathways.

Wheat and potatoes are two major foodstuffs in Iran and make up a major part

of the peoples diet. Therefore, the objective of this study was to estimate the healthrisks of As, Pb, Cd, Ni, Hg, Se, and Cr via soil and water dermal contact, inhalationof soil particulates, and consumption of water and wheat, potatoes, and maize innorthwest Iran, using the THQ and cancer risk assessment estimates suggested bythe USEPA (1989).

METHODS AND MATERIALS

Study Site

This study was carried out in Hamedan Province, northwest Iran, which has acold, semi-arid climate. Total population of the region is about 1.76 million people.The major crops grown in the region are wheat, potatoes, and maize.

Metal Exposures in Individual Media

To assess the total daily intakes of metals for the residents of Hamedan Province,the contributions of different potential exposure pathways were assessed individuallyand then combined to provide estimates of the total daily intake of each metal fromall sources for each receptor age group. These exposure routes included foodstuffs,drinking water, dermal contact with metals in soil and water, and inhalation of soilparticulates.

Soil, Water, and Food Crops Sample Analysis

At harvest time, 79 samples from edible parts of wheat (39 samples), maize(12 samples), and potatoes (28 samples) were collected from different areas ofHamedan Province. In addition, 286 soil samples and 11 drinking water samples

were collected from the region. In this study according to land use, soil samplingwas done by a random-systematic method. In this method, according to intensityand type of land use the grid distances were 2.5 km (around cities with different landuses), 5 km (ranges), and 10 km (irrigated and non-irrigated farms). Soil samples

were taken from corners of each grid. According to proximity to soil sampling points,

plant sampling points were selected, it means that we had paired soil:plant samples.

Hum. Ecol. Risk Assess. Vol. 18, No. 3, 2012 549


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M. Yeganeh et al.

Water samples were collected from the vicinity of big cities and agricultural lands.Total concentrations of As, Pb, Cd, Ni, Hg, Se, and Cr were determined in the soiland water samples. For determination of total Hg and As, one gram of soil sample

was digested with a mixed acid (1:3:4 HNO3: HCl: H2O2) (Shi et al. 2005). The total

concentrations of other metals in soil samples were determined by digestion of 1gram of soil with mixed acid (3:1 HNO3: HCl) (Burtet al. 2003).

To determine Hg contents in wheat, potatoes, and maize, tuber, and grain samples(1 g) were digested in HNO3 and H2O2 (Han et al. 2006) and for other metalsamples (1 g) were digested in 3:1 HNO3:HClO4 (Li et al. 2006). The concentrationsof the metals (except for Hg and As) in the soil, plant extracts, and water samples

were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) (Demirak et al. 2006). Concentrations of Hg and As in soil, plants, and watersamples were determined by hydride generation atomic fluorescence spectrometry(HG-AFS) (Fu et al. 2008).

In addition, the data used to determine the dietary intake were 95% upperconfidence limits on the means. These data were calculated using PRO UCL, version4.00.02 software. Distributions that were used for UCLs are shown in Table 1.

Quality Analysis and Quality Control

The accuracy of trace elements analysis was controlled by analyzing standardsolutions with certified concentrations of each element and including blanks indigestion batches.

Exposure Assessment

Intakes of metals via ingestion route

Intakes of metals via consumption of wheat, potatoes, maize, water, and soil wereestimated using Eq. (1) (USEPA 1989).

Intake (mg kg1d1) = (CF IR FI EF ED)/(BWAT) (1)

where CF = contaminant concentration in food or water (mg g1), IR= ingestionrate (g d1) or (g L1), FI = fraction ingested from contaminated source (unitless),EF = exposure frequency (d y1), ED = exposure duration (y), BW = bodyweight(kg), AT (d) = averaging time that is the period over which exposure is averagedand calculated as: AT = 365 (d y1) ED (y) for non-cancer hazard assessment, AT

(d) = 365 (d y1) 70 (y) for cancer risk assessment.The fraction ingested from the contaminated source (FI) represents the fraction

of consumed foodstuffs. The average FI value is 0.25, and the worst-case value is0.4. The value 0.4, which can be representing the upper 95th percentile, was used(USEPA 1989).

Intakes of metals via dermal contact with soil and water

The intakes of metals via dermal contact with soil were estimated using Eq. (2)(USEPA 2004b).

DADs = (CS CF SAAFABS EF ED)/(BWAT) (2)



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Table1.

The95%upperconfidencelimits(95%UCL)on

means,minimumandmaxim

umconcentrationofmetals

(mg/kg

FW)incropand(mg/kgDW)soil,andthemean

ofmetalsconcentration(g/L)inwaterofHamedanPro

vince.

As

Pb

Cd

Ni

Hg

Se

Cr

Cu

Zn

Soil(95%UCL)

16.67

26.35

0.16

71.08

0.06

N

.D.

99.39

37.19

81.83

distributions

lognormal

lognormal

lognormal

lo

gnormal

nonparametric

N

.D.

lognormal

lognormal

lognormal

Errorbars

3.21

2.52

0.66

0.95

2.06

1

.26

2.32

1.62

1.57

Min.

4.65

13

0.1

26

0.054

N.D.

(0.01)

30

4.10

35

Max.

85

1800

0.88

140

0.32

N.D.

(0.06)

180

75

200

MACa

100

1.5

50

1

100

60

200

Water(95%UCL)

1.29

0.76

9.5

103

0.27

0.31

0

.61

0.78

1.06

74.78

distributions

lognormal

lognormal

lognormal

lo

gnormal

lognormal

logn

ormal

lognormal

lognormal

lognormal

Errorbars

0.23

0.14

0.28

0.11

0.058

0

.55

0.42

0.21

0.13

Min.

0.2

0.15

0.001

0.14

0.13

0.5

0.11

0.56

16.91

Max.

3.13

1.21

0.03

0.38

0.63

0

.87

1.38

1.40

201.96

WHOguidelines

50

50

5

50b

1

10

50

1000

5000

Wheat(95%UCL)

N.D.

0.56

0.02

0.50

0.074

0

.29

2.08

5.17

25.15

distributions

N.D.

lognormal

lognormal

normal

nonparametric

nonparametric

normal

lognormal

normal

Errorbars

1.20

1.31

1.11

1.26

1.15

1

.96

1.23

1.11

1.02

Min.

N.D.(0.07)

0.01

0.01

0.1

0.001

0.1

0.9

2.93

9.7

Max.

0.4

0.12

0.04

0.9

0.19

0.4

2.6

7.68

48.4

Po

tato(95%UCL)

N.D.

0.02

0.02

0.31

0.008

0.062

0.44

1.58

3.27

distributions

N.D.

normal

lognormal

normal

nonparametric

nonparametric

normal

lognormal

lognormal

Errorbars

0.35

0.23

0.89

0.22

2

0

.57

0.46

0.15

0.12

Min.

N.D.(0.02)

0.01

0.01

0.2

0.001

0.1

0.9

3.55

7.4

Max.

N.D.(0.05)

0.11

016

2.5

0.009

0.4

2.5

10.89

16.2

Maize(95%UCL)

N.D.

N.D.

N.D.

0.40

0.004

N

.D.

1.08

3.06

26.83

distributions

N.D.

N.D.

N.D.

normal

nonparametric

N

.D.

normal

lognormal

lognormal

Errorbars

0.12

0.14

0.56

0.23

0.05

0

.94

0.86

0.21

0.09

Min.

N.D.(0.05)

N.D.(0.003

N.D.(0.002)

0.1

0.001

N.D.

(0.03)

0.7

.97

12.4

Max.

0.12

0.03

N.D.

0.6

0.01

0.2

1.2

6.82

37.80

Criticalvalue

120

1020

1030

0.05

110

1030

100500

N

.D.=non-detected.

am

aximumallowableconcentrationoftraceelementsinagriculturalsoilsproposedorgiveninthedirectivesinGermany1992forsoilswith

pH

>

6andUSA1993.

bO

fficialJournalEuropeanCommunities(1990).

551


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M. Yeganeh et al.

where DADs = dermal absorbed dose (mg kg1d1) via contact with soil, CS =

contaminant concentration in soil (mg kg1), CF = conversion factor (106 kgmg1), SA= skin surface area available for contact (cm2 event1), AF = soil to skinadherence factor (mg cm2), ABS = absorption factor (unitless). The absorption

factor (ABS) is 3% for As and 1% for other metals (SDEF 1991).The risk via dermal contact with water was estimated using Eq. (3) (USEPA

2004b).

DADw = (DAevent EV ED EF SA)/(BWAT) (3)

where DADw = dermal absorbed dose (mg kg1d1) via contact with water, EV=

event frequency (event d1), DA event= absorbed dose per event (mg cm2event).

This parameter is calculated as follows:

DAevent= Kp CW Tevent

where Kp is the dermal permeability coefficient of a compound in water (cm h

1),CW = elements concentration in water (mg cm3), T event = event duration(h/event).

Intakes of metals via inhalation of soil particulates

Intakes of metals via inhalation of soil particulates were estimated using Eq. (4)(USEPA 2004a RAGS B).

Intake (mg kg1d1) = (CS ED EF IRair 1/PEF)/(BW AT) (4)

where CS represents the chemical concentration in soil (mg kg1), ED is exposure

duration (d y1

), IRair represents the rate of inhalation (m3

d1

), PEF = particulateemission factor (m3kg1). Considering the lack of site-specific data for the particulateemission factor, we used the default value of 4.63 109 m3kg1 for the risk estimations(USEPA 2004a RAGS B).

Risk Assessment

The non-carcinogenic effects were determined by dividing the intakes from Eqs.(14) by the reference dose (RfD) of each contaminant as shown in Eq. (5) (USEPA1989).

HQ= intake/RfD (5)

where HQ= non-cancer hazard quotient, RfD = reference dose (mg kg1 d1).The carcinogenic effect of each HM was calculated by multiplying the intakes

from Eqs. (14) by the slope factor (Eq. (6)) (USEPA 1989).

Risk = CDI SF (6)

where CDI = chronic daily intake averaged over 70 years (mg kg1 day1), SF =slope factor (mg kg1day1)1.

The oral RfD presented for Cr applies to CrIII, which is based on the assumptionthat any CrVI ingested from the foodstuffs is converted to CrIII in the stomach (Kabata-Pendias 2001). The organic Hg compound methylmercury represents to humans

the most important toxic form of Hg (Mercury 2001). Therefore in this study, based



8/23


on assumed worst conditions, we used the methylmercury oral RfD. For calculatingthe risk related to soil ingestion, we used the mean of methylmercury and mercurychloride (0.0002 mg kg 1d1) oral RfDs.

We applied the RfD of 0.00035 mg kg1 d1 derived from the toxicological studies

of Mushak et al. (1989) for adults. On the other hand, the USEPA and the Centersfor Disease Control and Prevention (CDC 2000) have determined that childhoodblood Pb concentrations at or greater than 10 micrograms of Pb per deciliter ofblood (g dl1) present risks to childrens health. To predict blood Pb concentrationand the probability of a childs blood Pb concentration exceeding 10 g/dL basedon a given multimedia exposure scenario, we used the Integrated Exposure UptakeBiokinetic Model for Pb in Children (IEUBK) (USEPA 2004b). The data used consistof metals concentration in soil, water, and foodstuff according to Tables 1 and 2.

We considered that children older than 2 years old eat potatoes, wheat, and corn.For calculating the cancer and non-cancer risks corresponding to dermal expo-

sure to soil and water, we derived the dermal RfD and SFs by using Eqs. (7) amd (8)(USEPA 2004b RAGS E):

Dermal RfD (mg/kg-d) = RfDo ABS (GI) (7)

Dermal SF (mg/kg-d)1 = SFo/ABS(GI) (8)

where RfDo and SF0 are oral RfD (mg kg1d1) and oral SF (mg kg1d1)1, respec-

tively, ABS (GI) = Fraction of contaminant absorbed in the gastrointestinal (GI)tract (dimensionless). The recommended GI absorption values (ABSGI) for thosecompounds with chemical-specific dermal absorption factors from soil are presentedin Exhibit 4-1 of RAGS E (USEPA 2004b).

To convert the inhalation reference concentration (mg cm3) to an inhalation

reference dose (mg kg1d1), we assumed 20 m3 d1 as the inhalation rate for aperson with 70 kg bodyweight (route-to-route extrapolation) (DOD 2009).

The non-cancer and cancer risks of metals from multiple sources and pathways,were calculated using Eqs. (9) and (10), respectively (USEPA 2007):

HI = sum [HQj] = sum [Ej/RfDj] (9)

HI = sum [Ej SFj] (10)

where Ej, RfDj, and SFj are daily intake, reference dose, and slope factor for eachmetal, respectively.

RESULTS AND DISCUSSION

Concentrations of Metals in Soil, Water, and Crops

The concentrations of all the metal in soil are less than their critical values, whichwere introduced by Germany (German Federal Ministry of the Environment 1992)(Table 1). Shown in Table 1 are the summery statistics of measured data for thestudy area. The 95% UCL on mean concentrations in soil in all cases other than forNi are less than critical limits. The concentration of Cr in soil is very close to criticallimits. Metal concentrations in drinking water are less than the corresponding crit-ical limits (WHO 1996). Also in foodstuff, except for Cr and Hg, the 95% UCL on

mean concentrations are less than the critical limits introduced by Kabata-Pendias



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Table2.

Receptorparametersusedtoestimatedailyexposures.

Children

Children

Children

Children

Teenagers

Teenagers

Average

Average

Old

Old

Girls

Boys

Girls

Boys

Girls

Boys

women

men

women

men

Parameters

Units

55

Source

Exposure

duration(food

ingestion)

years

4

4

7

7

4

4

27

27

15

15

Aghili20

09

Exposureduration

(dermal-soil)

years

6

6

24

24

24

24

24

24

24

24

USEPA1997

Exposureduration

(dermal-soil)

years

6

6

24

24

24

24

24

24

24

24

USEPA2004a,RAGSB

Bo

dyweight

Kg

17

.5

18.7

35

29

56

59.1

61

76.4

60.6

65.1

Roohani

2012

Soilingestionrate

mgd1

20

0

200

100

100

100

100

100

100

100

100

SDEF1991

Drinkingwaterintake

Ld1

2.5

2.5

5

5

5

5

5

5

5

5

Foodnaa

ndmagiran

Skinsurfacearea

(dermal-soil)

cm2event1

2800

2800

5700

5700

5700

5700

5700

5700

5700

5700

SDEF1991

Soiladhesiontoskin

mgcm2

0.2

0.2

0.7

0.7

0.7

0.7

0.7

0.7

0.7

0.7

SDEF1991

Eventfrequency

(dermal-water)

Eventd1

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

0.5

observation

Exposure

duration(dermal-

water)

years

6

6

7

7

4

4

27

27

15

15

EFH2009

Exposure

frequency(food

ingestion)

dy1

36

5

365

365

365

365

365

365

365

365

365

observation

Tevent

hevent1

0.5

0.5

0.33

0.33

0.33

0.33

0.33

0.33

0.33

0.33

observation

Exposureduration

(inhalationofsoil

particulates)

years

6

6

24

24

24

24

24

24

24

24

EFH2009

Inhalationrate

m3d1

5

5

20

20

20

20

20

20

17.28

17.28

EFH2009

144

144

144

144

144

144

USEPA

1991

(sporting)

(sportin

g)

(sporting)

(sporting)

(sporting)(sporting)

www.dezmed.com

Wheat

gd1

151.9

151.9

531.51

531.51

531.51

531.51

531.51

531.51

531.51531.51Foodnaa

ndmagiran

Potatoes

gd1

35

35

123.29

123.29

123.29

123.29

123.29

123.29

123.29123.29Foodnaa

ndmagiran

maize

gd1

0.63

0.63

2.19

2.19

2.19

2.19

2.19

2.19

2.19

2.19

Foodnaa

ndmagiran

Skinsurfacearea

(dermalwater)

cm2

6600

6600

18000

18000

18000

18000

18000

18000

18000

18000USEPA2004b,RAGSE

554


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(2001). Concentrations of Cr in wheat (2.08 mg kg1) and maize (1.08 mg kg1) aregreater than the lower boundary of the critical range (110 mg kg1) for this metalaccording to the German Federal Ministry of the Environment (1992). Mercury con-centration in wheat (0.074 mg kg1) is greater than the critical value (0.05 mg kg1,

Kabata-Pendias 2001) Tables 2 and 3 show the parameters have been used for cal-culations. Analyzing the interpolation soil maps shows that As, Cd, Zn, and Pb havea geological and agricultural origin and Cr and Ni originated from bedrocks (Kho-dakarami 2010). Agricultural activities such as over-use of fertilizers can increase theamount of these elements in soil. Khodakarami (2010) estimated the backgroundconcentration of metals in this area. His study shows that the mean concentrationof Cr is naturally high in all bedrocks and the lowest concentration in bedrocks ofthis region is related to Cd. Shown in Table 4 are the mean concentrations of eachmetal in bedrocks .

Total Intake

Total intake of metals via different pathways is given in Table 5. The total intakeof each metal was smaller than the corresponding critical values. For example, thetotal intakes for As in children (1 104 mg kg bw1 d1) and adults (4 105 mgkg bw1 d1) were less than the tolerable upper intake of 0.0010.010 mg kg bw1

d1 (Civantos et al. 1995; Fincher and Koorker 1987). Concentration of As in edibleparts of wheat, potatoes, and maize was less than the detection limit of AAS. In allreceptor groups, soil ingestion was the main route for As intake and its contributionto the total intake was 55%. Drinking water is the second important pathway of

As, contributing about 44% of the total intake. Lead total intake in children (2

103 mg kgbw1 d1), adults (3.5 103 mg kgbw1 d1), and >55 year-old receptorgroups (2 103 mg kgbw1 d1) are less than the Pb intake limit recommendedby FAO/WHO (1991), which is 3.57 103 mg kgbw1 d1. For children, food isthe predominant contributor to the total daily intakes for each metal. For example,drinking water, dermal contact, soil ingestion, dermal absorption, and inhalationof soil particulates contribute 5.4, 1.2 106, 19, 1.1 103, and 2 107% ofthe total daily intake of Pb for children, respectively. Similar trends were observedfor the other receptor groups although soil ingestion in adults and >55-year-oldreceptor groups had a lower contribution to total intake of Pb because the rate ofsoil ingestion in children is greater than for adults.

The total intakes of Cd in children (8 103

mg kgbw1

d1

), adults (1.5 1049 104 mg kgbw1 d1), and >55-year-old age groups (8 105 mg kgbw1

d1) were less than the Cd intake limit recommended by FAO/WHO (1991), which is0.0173 mg kgbw1 d1. For all receptor groups, the plant foods are the predominantcontributor to the total daily intake of Cd and accounting for greater than 87%of the total daily intake. Water and soil pathways through drinking of water andincidental ingestion of soil contribute 0.34%, 0.17%, and 0.57%, 0.03%, in childrenand adults, respectively, and other pathways account for negligible effect in the totaldaily intake.

Total daily intakes of Ni are 2 103, 1.7 1033.7 103, and 2 103

mg kgbw1 d1 in children, adults, and >55-year-old receptor groups, respectively,

which is much less than the Ni intake limit recommended by dietary reference intake



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Table3.

Otherparametersusedinequations.

Cd

Pb

Hg

Ni

Zn

Cr

Se

As

Cu

Sour

ce

Kp

(cmh1)

1

103

1

104

1

103

2

10

4

6

1041

1031

1031

103

1

103USEPA2004a,RAGSE,

OralRfD

1

103(food)

0.00035

1

104

0.02

1.5

0.005

3

104

IRIS,Mercury2001

(mgkg1d1)5

104(water)

2

104

Mustaketal.(1

989)

(soilingestion)

OralSF

8.5

103

1.5

USEPA2005

(mgkg1d1)

TAC

De

rmalRfD

2.5

105

8.5

103

5.8

105

8

10

5

0.0195

5

1032.85

104

USEPA2004b,

RAGSE

(mgkg1d1)

2.5

105

(conversionfromoral

(water)

RfDs)

De

rmalSF

15.2

8.5

103

1.58

USEPA2004b,

RAGSE,

(mgkg1d1)

(conversionfrom

oralSFs)

InhalationRfD

5.7

106

0.05

2

104

0.002

1.5

8.57

106

DOD2009(routetoroute

(mgkg1d1)

extrapolation)

InhalationSF

5.7

106

4.2

102

5.7

106

1

.2

101

OEHHA(nodate),TAC

(mgkg1d1)

AB

S(unitless)

0.01

0.01

0.01

0.01

0.01

0.01

0.01

0.03

0.01

SDEF1991

556


12/23


Table 4. Background concentration of metals in bedrocks of study region

(mg kg1).

Bedrock

Magmatic andmetamorphic Shale and

Metal Alluvium rocks Limestone Sandstone marl

Co 9.15 21 19 3.18 2.19Cr 6.83 101 3.106 3.99 9.99Cu 6.30 2.33 8.36 9.40 9.37Ni 7.57 6.69 3.72 74 3.71Pb 55.23 26 3.23 25 15.25V 7.93 8.121 3.113 7.111 9.114Zn 2.67 6.86 6.75 82 4.78

Fe 4.3 4.4 08.4 9.3 1.4Cd 12.0 16.0 23.0 13.0 25.0As 5.14 6.16 5.15 4.12 4.13

Reference: Khodakarami (2010).

(ATSDR 2000), which is 0.017 mg kgbw1 d1. For all receptor groups, consumptionof wheat, potatoes, and maize are the predominant contributor (>90%) of the totaldaily intake. Incidental ingestion of soil and drinking water are the second and thirdimportant pathways for the total daily intake of Ni.

The total daily intakes of Hg in children, adults, and>55-year-old receptor groups

are 2.5 104

, 2.1 104

5.6 104

, and 2.5 104

mg kgbw1

d1

, respectively.Plant foods, drinking water, and incidental ingestion of soil are the most importantpathways of Hg.

The intakes of Se through consumption of wheat, potatoes, and drinking waterare 1 103, 1 1038 104, and 1 103 mg kgbw1 d1 in children, adults,and >55-year-old receptor groups, respectively. Selenium concentrations in soil andmaize were less than the detection limit of AES and ICP-MASS.

The total intakes of Cr in children, adults, and >55-year-old receptor groups are8 103, 0.0148 103, and 7 103 mg kgbw1 d1, respectively. Plant foods with96.9% in children and 98.2% in adults have the predominant contribution to thetotal daily intake of Cr.

For all the metals and in all the receptor groups, contribution of dermal contactwith soil and water and inhalation of soil particulates is very low and therefore,their effects on the total health risk estimations is negligible. Loutfy et al. (2006)also showed that plant foods are the major pathway of non-occupational humanexposure to metals, accounting for about 90% of the total intakes of metals.

Risk Characterization

The non-cancer and cancer risk related to metals from different pathways fordifferent population groups are shown in Figures 13. Among the metals and differ-ent ingestion routes, Hg, through consumption of wheat, has greater potential for

health risk (Figure 2b). The chronic intake of Hg via consumption of wheat is also



13/23

Table5.

Totalintake(mgkgb

w1d1)ofmetalsviadifferentpathways.

As

P

b

Cd

Ni

Hg

Se

Cr

Cu

Zn

Dietaryintakeviaconsum

ptionofpotatoes(mgkgbw1d1)

Girls

55men

N.D.

3.8

105

3.8

105

5.9104

1.5

105

1.2

104

8.3

104

3.0

103

6.2

103

Dietaryintakeviaconsumptionofwheat(mgkgbw1d1)

Girls

55men

N.D.

4.6

103

1.6

104

4.1103

6.0

104

2.4

103

1.7

102

4.2

102

0.21

Girls

55men

N.D.

N.D.

N.D.

1.4

105

1.4

107

N.D.

3.9

105

1.1

104

9.7

104

Girls

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Risk Assessment for Tunde