Review and Human Health Risk Assessment of Heavy Metals Accumulation in Vegetables Grown in Vinh Quynh, Vietnam

Abstract

Human health risk assessment is a process to estimate the nature and probability of adverse health effects in humans exposed to chemicals present in contaminated environmental media, now or in the future. In this study we reviewed and utilized already reported data by previous investigations to apply Health Risk Assessment methodology for assessing the potential health risk from heavy metals' exposure and accumulation in vegetables grown in Vinh Quynh district of Vietnam. As per estimations of non-carcinogenic effects, all the values of HIs for adults and children were higher than 1, especially for children. For carcinogenic effects, the UCL Risk values showed that there was one extra cancer death in 10,000 people exposed with Arsenic in study area. Calculations showed that people in study area are under the potential health risk from heavy metals, which are accumulated in vegetables.

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Review and Human Health Risk Assessment of Heavy Metals
Accumulation in Vegetables Grown in Vinh Quynh, Vietnam
B THANH LONG1, D QUANG TRI1, C YI CHING1, N CAO DON2 AND P KUMAR MISHRA3
1Department of Environmental Engineering, Da-Yeh University, Taiwan
2Department of Water Resources Engineering, Thuyloi University, Vietnam
3Department of wood science, Mendel University in Brno, Czech Republic
Email: doanquangtrikttv@gmail.com, builong.khmt@gmail.com, donnc@wru.edu.vn, pawan.mishra@mendelu.cz
Abstract: Human health risk assessment is a process to estimate the nature and probability of adverse health effects
in humans exposed to chemicals present in contaminated environmental media, now or in the future. In this study we
reviewed and utilized already reported data by previous investigations to apply Health Risk Assessment
methodology for assessing the potential health risk from heavy metals’ exposure and accumulation in vegetables
grown in Vinh Quynh district of Vietnam. As per estimations of non-carcinogenic effects, all the values of HIs for
adults and children were higher than 1, especially for children. For carcinogenic effects, the UCL Risk values
showed that there was one extra cancer death in 10,000 people exposed with Arsenic in study area. Calculations
showed that people in study area are under the potential health risk from heavy metals, which are accumulated in
vegetables.
Keywords: Health Risk Assessment, heavy metals, vegetables, adverse health effects.
1. Introduction
World’s urban communities are growing faster than
global population as the urbanization progresses in the
undeveloped regions (UN-HABITAT, 2004). Rapid
urbanization and industrialization releases enormous
volumes of wastewater, which is increasingly utilized as
a valuable resource for irrigation in urban and peri-
urban agriculture. Wastewater may contain various
heavy metals including Zn, Cu, Pb, Mn, Ni, Cr, Cd,
depending upon the types of activities it is associated
with. Continuous irrigation of agricultural land with
sewage and industrial wastewater may cause heavy
metal accumulation in the soil and vegetables (Singh et
al., 2004; Sharma et al., 2007; Marshall et al., 2007).
These effluents are rich in toxic metals and are a chief
contributor to metals loading in waste irrigated and
amended soils (Mapanda et al., 2005).
Health risk assessment of heavy metals in contaminated
vegetables is being carried out in developed countries
(Milacic and Kralj, 2003; Navneet, 2005; Kachenko and
Singh, 2005; Zhuang et al., 2009; Tangahu et al., 2011).
However, little is explored in developing countries
(Lock and de Zeeuw, 2001). In Vietnam very few
published data is available on heavy metal
contamination in vegetables. Environmental abetment
practice is almost missing due to the lack of
environmental management and un-operational
environmental pollution laws.
Health risk assessment of heavy metals in contaminated
vegetables is being carried out in developed countries
(Milacic and Kralj, 2003; Navneet, 2005; Kachenko and
Singh, 2005; Zhuang et al., 2009; Tangahu et al., 2011).
However, little is explored in developing countries
(Lock and de Zeeuw, 2001). In Vietnam very few
published data is available on heavy metal
contamination in vegetables. Environmental abetment
practice is almost missing due to the lack of
environmental management and un-operational
environmental pollution laws.
The objectives of this study are to (1) review heavy
metals and their effects on human health; sources which
cause their accumulation in vegetables and in human
body; and some case related to assessment of health risk
from heavy metals in food in the world; (2) describe the
research and general water assessment for irrigation and
vegetables quality at study area Vinh Quynh – Thanh
Tri –Hanoi. Application of Health Risk Assessment
guideline to assess potential health risks of consuming
vegetables in the study area includes Target Hazard
Quotient (THQ) for non-carcinogenic chemicals and
Upper Confidence Limit on Risk (UCL Risk) for
carcinogenic chemicals to assess potential health risk of
consuming vegetables which heavy metals accumulated
in.
2. Materials and Methods
2.1. Description of study site

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Review and Human Health Risk Assessment of Heavy Metals Accumulation in
Vegetables Grown in Vinh Quynh, Vietnam
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
Vinh Quynh is a commune of Thanh Tri district, a low
ground with average elevation about 4.2 – 4.5m above
sea level. Terrain is mainly delta which deposited by
alluvia of Red river (Fig. 1). Vinh Quynh commune has
650.5 hectares natural areas, in which 337 hectares is
agricultural soil. Regarding administrative units, Vinh
Quynh was separated to 3 hamlets and 13 communities.
Counting to 2006, Vinh Quynh has 4,414 residences
with 18,462 people. Labors are mainly farmers; others
work as merchants or workers at factory in here. Out of
total agricultural area (337 hectares), area of vegetables
cultivation is 75.66 hectares (Nguyen, 2008).
2.2. Data Collection
In Vietnam, reusing wastewater for irrigation in
agriculture has been a traditional method since long
time ago, and people are using it till now. The amount
of urban wastewater in Hanoi, in particular, is about
710,000 - 760,000 m3/day (Lai, 2010) and is almost not
treated before pouring. Wastewater pours into To Lich
River by system of different sewers and canals and is
used directly. Reusing wastewater for irrigation in
agriculture brings benefits for farmers. Some of the
advantages are: improvement of the economic
efficiency; conservation of freshwater sources; natural
treatment; usage of nutrients contained in wastewater;
reduction of treatment costs and environmental impacts.
Besides, there are some disadvantages also, which
include exposure of plants and environment to toxic
substance. This leads to potential risk to not only human
health but also to environment. Vietnam also follows
traditional irrigation method of directly using urban
untreated wastewater (Kretschmer et al., 2000).
The irrigation water samples were taken at three points
signed VQN01; VQN02 and VQN03 in Vinh Quynh
community. Some parameters were measured on-site.
Particularly, heavy metal contents were analyzed by
IPC-MS method. Besides, vegetables were sampled at 4
points in Vinh Quynh and separated into edible and
inedible parts. The data and method based on some
previous study at research area and on-site observation
of author.
Table 1 demonstrates dissolved heavy metals’ pollution,
especially the concentration of Mercury (Hg) and
Arsenic (As) (VQ N02) surpassed the standard.
According to this table, the total heavy metals
concentration in samples affirmed that it was in a
warning situation of heavy metals’ pollution. With VQ
N02 sample (at watercress field) most of analysis
parameters even reached the standard or exceeded it, for
example Fe (60.436 mg/l) exceeded 40 times; As (0.150
mg/l) exceeded 3 times; Pb (0.158 mg/l) exceeded 3.16
times and Hg (0.0018 mg/l) exceeded 1.8 times.
Regarding VQ N01 sample, there were four parameters
conformed to the standard (pH, Cr, Zn and Cd), three
parameter that reached the standard (Cu and Pb) and
four parameters exceeded the standard (Fe (3.537 mg/l)
exceeded 2.4 times and Hg (0.0015 mg/l) exceeded 1.5
times; as for as, it was higher than standard by
0.001mg/l.
2.3. Method
The method was described in four steps: Hazard
Identification, Dose-Response Assessment, Exposure
Assessment and Risk Characterization. Health risk
assessment process was shown in Fig. 2.
Step 1: Hazard Identification
The step identifies the type of adverse health effects that
can be caused by exposure to some agents, and to
characterize the quality and weight of evidence
supporting this identification.
Step 2: Dose - Response Assessment
The dose-response assessment involves describing the
quantitative relationship between the amount of
exposure to a chemical and the extent of toxic injury or
disease. Typically, as the dose increases, the measured
response also increases. At low doses, there may be no
response. At some level of dose, the responses begin to
show up in a small fraction of the study population or at
a low probability rate (US EPA, 2012).
For Non-carcinogenic effects:
The acceptable safety level is known as the Reference
Dose (RfD). An estimate of a daily exposure level for
human population, including sensitive sub-population,
that is likely to be without an appreciable risk of
deleterious health effects during a lifetime. The position
of the EPA is that humans are as sensitive as the most
sensitive test species unless other data are available (US
EPA, 2005; US EPA, 2012).
For Carcinogenic effects:
The key risk assessment parameter derived from the
carcinogenic risk assessment process is the “slope
factor”. The slope factor is a toxicity value that
quantitatively defines the relationship between dose and
response, which means a plausible upper bound estimate
of the probability that an individual will develop cancer
if exposed to a chemical for a lifetime of 70 years (US
EPA, 2012).
Step 3: Exposure Assessment
Exposure assessment involves describing the nature and
size of various populations exposed to a chemical agent,
and the magnitude and duration of their exposures (US
EPA, 2005; US EPA, 2012).
For Non-carcinogen Effects:

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B THANH LONG, D QUANG TRI, C YI CHING, N CAO DON AND P KUMAR MISHRA
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
We use Average Daily Dose (ADD) for quantifying
exposure. We estimate ADD by averaging the total dose
for the length of the exposure in years:
BWxAT
CxCRxEFxED
ADD 
(1)
Where: C is Concentration of chemical in vegetables
(mg/kg); CR is Contact rate (kg/day); EF is Exposure
frequency (days/year); ED is Exposure duration (years);
BW is Body weight (kg); AT is Averaging time (period
in days over which the exposure is averaged) and unit of
ADD is mg/kg/day (Gerba, 2006).
For Carcinogenic effects:
We use Lifetime Average Daily Dose (LADD) for
quantifying exposure. We estimate the Lifetime
Average Daily Dose by averaging the total exposure
over the lifetime of the individual (expected 70 years)
(US EPA, 2012):
xBWx
CxCRxEFxED
LADD 36570

(2)
Where: C is Concentration of chemical in vegetables
(mg/kg); CR is Contact rate (kg/day); EF is Exposure
frequency (days/year); ED is Exposure duration (years);
BW is Body weight (kg) and unit of LADD is
mg/kg/day.
Step 4: Risk Characterization
Exposure Assessments and Toxicity Assessments are
integrated to give a probability of a negative effect. Risk
characterization is conducted for individual chemicals
and then summed up for mixtures of chemicals –
Additive is assumed (US EPA, 2005; US EPA, 2012).
For Non-carcinogenic effects
The Average Daily Dose is compared to the RfD. If
ADD is < RfD, then it is not problematic- except when
dealing with multiple chemicals. We estimate the Target
Hazard quotient (THQ) by determining how much
higher is the exposure compared to the “safe” dose
(Reference dose, RfD) (US EPA, 2012):
RfD
ADD
THQ 
(3)
When exposure involves more than one chemical, the
sum of the individual hazard quotients for each
chemical is used as a measure of the potential for harm.
This sum is called the hazard index (HI):



1i
ii
THQHI
(4)
For Carcinogenic effects:
It needs to determine the “Upper Confidence Limit on
Risk” (US EPA, 2012).
UCL Risk = q*LADD (5)
Where q is Slope Factor (mg/kg/day)-1
3. Results and Discussion
3.1. Hazard Identification
The study on effects of arsenic pollution in domestic
water on Red river delta inhabitant’s health, diseases,
and solutions pointed out that arsenic content in filtered
water exceeded standard (>10 µg/l) and was still used
for domestic purpose by 2/3 of the studied residences. In
addition, water used by 14.7% residences for drinking
had arsenic content higher than 50 µg/l mainly in Vinh
Phuc, Hanoi and Nam Dinh. Chronic arsenic poisoned
disease’s fraction (soft level) in inhabitants who used
polluted water for ingestion was 1.6%. Result of health
check for 3,700 people who used underground water
with arsenic concentration higher than 0.05 mg/l at 8
provinces of Red river delta showed that diseases
related to ingestion of arsenic were found, including
64.7% cardiasthenia, 32.8% vascular complications,
32.7% pregnant pathology, 25.6% trichorrhea, 19%
dysaesthesiae, 3.6% keratosis, 4.6% hyperpigmentation
and 4.1% tumors (Nguyen, 2011).
Besides arsenic, cadmium was found in children’s toy in
Hanoi. Its content was 7,390µg/kg that is 123 times
more than standard (60µg/kg) according to National
Technical Regulation on safety of toys. Children will be
poisoned with Cd by long-lasting exposure to it
(BUSTA, 2012). The study (Nguyen and Ngo, 2010) on
accumulation of heavy metals in soil and irrigation
water at outskirt area of Hanoi showed that water
quality is directly related to soil and vegetables’ quality.
Table 2 describes that total Cu content in vegetable
samples was lower than 1mg/kg when FAO/WHO 1993
standard (FAO, 2004) is 5 mg/kg. Regarding Zn
content, it was in range of 1.792 mg/kg to 2.828 mg/kg,
which is much lower than the standard (10 mg/kg).
Similarly, the average values of Cd, Hg, and Pb content
were lower than the standard and it was proved that no
vegetable sample was polluted by these elements.
Particularly for As content, when we compared it with
the newest standard of Ministry of Agriculture and
Rural Development, it was found that there were two
vegetable samples (VQ R03C and VQ R03D) in which
the As content surpassed the standard (1.491 mg/kg and
1.215 mg/kg in edible part, respectively). While
comparing to FAO/ WHO 1993 standard (FAO, 2004),
all values exceeded standard.
In Table 2, it can be certainly recognized that the
average value of As in vegetables is 0.871 and 0.623
mg/kg in edible and inedible part, respectively. These

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Review and Human Health Risk Assessment of Heavy Metals Accumulation in
Vegetables Grown in Vinh Quynh, Vietnam
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
values accepted the standard of Decision 99/2008/QĐ-
BNN (MARD, 2008) and are used in calculation of this
study. Nevertheless, average content of as in edible part
exceeded standard of FAO about 5 times and 3 times in
inedible part. However, it was conformable with the
standard (MARD, 2008).
Based on Proposition 65 lists (OEHHA, 2012), in this
study, the author examines non-carcinogenic effects of
four heavy metals (As, Cd, Pb, and Hg) and
carcinogenic effects of As. Regarding the scope of this
study, it examines for consumers, not for producers,
including adults and children. In addition, United
Nations Convention on the Rights of the Child in 1989
defined a child as being under 18 (CRIN, 1990). The
parameters used for calculation are enlisted in Table 3.
3.2. Dose-Response Assessment
Non-carcinogenic effects:
Based on the previous studies and Integrated Risk
Information System of US EPA, the Oral RfDs of these
heavy metals are specified in Table 4.
Carcinogenic effects:
The Oral Slope Factor of As was determined according
to the IRIS of US EPA and the value is 1.5 (mg/kg/day)-
1 for both adults and children (IRIS 1994).
3.3. Exposure Assessment
Non-carcinogenic effects:
The calculation results of Heavy metals’ ADD of adults
and children are shown in Table 5. Table 5 expresses
ADD values of different heavy metals for the adult. The
highest ADD was for as which in 5, 10 and 15 years are
0.00045; 0.0009 and 0.00134 mg/kg/day, respectively.
In addition, the lowest ADD was for Hg which is
6.43x10-7; 1.29x10-6 and 1.93x10-6 mg/kg/day in 5, 10
and 15 years, respectively. Besides, the ADD of Pb was
significant, too. According to the results, the ADD of As
for adults was 145 times higher than that of Cd, 697
times higher than Hg and 7.6 times higher than Pb.
Similar to the adults, the ADD for children was still
different for each heavy metal. The figure 4.2 points out
that the highest ADD was of as which in 5, 10, and 15
years are 0.00242; 0.00484 and 0.00726 mg/kg/day.
Moreover, the lowest ADD was of Hg with 3.47x10-6,
6.94x10-6, and 1.04x10-5 mg/kg/day in 5, 10, and 15
years.
Furthermore, comparing ADD of heavy metal with each
other revealed that results are similar to adults’ results.
The ADD for children was much more and 5 times
higher than ADD for adults for each heavy metal. This
led to the distinctions of ADD values between adults
and children who are different depending upon body
weight, contact rate, and average time. These
parameters have smaller value for children than that of
adults. Therefore, the exposure content of children was
obviously much higher than exposure content of adults
in each period of time.
Carcinogenic effects:
Regarding non-carcinogenic effects, ADD value was
identified. For carcinogenic effects, LADD was
calculated. All parameters are similar to ADD
calculation, but they are little different. Average time is
taken as 70 years for both children and adults, which is
same as in ADD calculation. The calculation results are
shown in Table 6.
Table 6 expresses LADD of As for adults and children
after 5, 10, and 15 years. The LADD for children was
higher than LADD for adults. After 5 years, the
difference was not much, with 0.000384 mg/kg/day for
adults and 0.000519 mg/kg/day for children. However,
after 10 and 15 years, the difference was larger.
Specifically, after 10 and 15 years, the LADD of adults
were 0.000768 and 0.001152 mg/kg/day; the LADD of
children were 0.010372 and 0.001556 mg/kg/day,
respectively. In addition, the results indicated that the
LADD for children was 1.35 times higher than LADD
for adults. Therefore, children could be exposed more
than the adults could.
3.4. Risk Characterization
Non-carcinogenic effects:
Before calculating HI, we need to identify the Target
Hazard Quotient (THQ) based on formulation in step 4.
HI is the sum of THQ of each heavy metal, which is
calculated for each period time. The results of THQ and
HI are expressed in Table 7.
In Table 7, the THQ of each heavy metal is compared
with the standard level. Out of four heavy metals, only
the THQ of As exceeds 1 that is the standard. In detail,
the THQ for children was very high with 8.0671,
16.134, and 24.201 after 5, 10, and 15 years,
respectively. The THQ for adults was much lower than
THQ for children but still higher than the standard level.
The values were 1.4939, 2.9878, and 4.4817 after 5, 10,
and 15 years, respectively. This proved that both adults
and children living in the study areas were at potential
health risk from As.
Contrary to THQ of As, the THQs of other heavy metals
were much lower than 1. Especially, the THQs of Cd
were 0.0031, 0.0062, and 0.0093 for adults and 0.0167,
0.0333, and 0.05 for children after 5, 10, and 15 years,
respectively. Next, the THQs of Hg were 0.0021,
0.0043, and 0.0064 for adults and 0.0116, 0.0231, and
0.0347 for children after each period time. Finally, the
THQs of Pb were 0.0169, 0.0339, and 0.0508 for adults

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International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
and 0.0915, 0.1829, and 0.2744 for children after 5, 10,
and 15 years, respectively. Thus, it can be said that
adults and children in study area were not at potential
health risk from Cd, Hg, and Pb.
Figure 3 showed the results of Hazard Index of the case
study. After considering THQs of heavy metals
separately, Hazard Index (HI) is calculated to have a
general conclusion about potential health risk from
heavy metals in study area. HI is sum of THQs of each
heavy metal calculated in 5, 10, and 15 years.
Moreover, the values of HI are described in the Figure
above. It shows that the HIs were 1.5161, 3.0322, and
4.5482 for adults and 8.1868, 16.374, and 24.561for
children in 5, 10, and 15 years, respectively. In addition,
all the value were higher than 1, especially HIs for
children. Also, the HIs for children were 5 times higher
than HIs for adults in each period time. In conclusion,
citizens in study area were exposed to heavy metals and
potential health risk from them.
Carcinogenic effects:
Results of non-carcinogenic effects certainly show that
citizens were at potential health risk from heavy metals.
Particularly for carcinogenic effects, we identified
Upper Confidence Level of Risk (UCL Risk) based on
Slope Factor and LADD in previous steps. The values
of UCL Risk of As are shown in Table 8.
According to Table 8, the UCL Risk for adults in 5, 10,
and 15 years were 5.8x10-4, 11.5x10-4, and 17.3x10-4,
respectively. For children, the respective UCL Risk
values were 7.8x10-4, 15.6x10-4, and 23.3x10-4.
Moreover, the results also showed that the UCL Risk
values were rather high and the values for children were
higher than the value for adults in each period time.
When compared with the Risk Level, which US EPA
issued, it was the weight-of-evidence judgment of the
likelihood that the substance is a human carcinogen.
Human carcinogenic risk is presented in drinking water
or air concentration providing cancer risks of 1 in
10,000; 1 in 100,000 or 1 in 1,000,000 that is described
in Table 9.
Consequently, both UCL Risk values for children and
adults were in the range from 5.8x10-4 to 23.3 x10-4,
which were higher than 10-4 and belonged to Level 1 of
Risk in Table. Therefore, the cancer risk was of 1 in
10,000 that means there was 1 extra cancer death per
10,000 people exposed to As in study area which was
10 times higher than Virtually Safe Dose of US EPA (1
extra cancer death per 1 million people exposed) and
California (1 extra death per 100,000 people exposed)
used.
4. Conclusions
The result of ADD values revealed that heavy metals
intake by children is higher than intake by adults.
Longer the time of exposure to heavy metals, higher the
amount that people will receive. The study showed that
all the values of HIs for adults and children were higher
than 1, especially HIs for children. Thus, citizens in
study area had signs of developmental effects. In regard
to carcinogenic effects, the UCL Risk values started that
the cancer risk was of 1 extra cancer death per 10,000
people exposed As in study area; which was 10 times
higher than Virtually Safe Dose of US EPA and
California.
5. Acknowledgements
We are grateful to thank Professor Chen Yi Ching for
giving the opportunity and facilities to carry out this
study. The research was financially supported in part by
Da-Yeh University of Taiwan.
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?NewsId=19044&Page=3.
[20] Bac Giang Union of Sciences and Technology
Association (BUSTA), “Be careful with Cadmium
in children toys”, 2012. Available at:
http://www.busta.vn/node/819.
[21] X.H. Nguyen and L.P. Ngo, “Study on
Accumulation of Heavy Metals in Soil and
Irrigation Water at Outskirt Area of Hanoi City”,
Journal of Agriculture and Rural Development,
Vol.2, pp. 23-29, 2010.
[22] Food and Agriculture Organization of the United
Nations (FAO), “Worldwide Regulations for
Mycotoxins in Food and Feed”. FAO Food and
Nutrition, 81p, 2004. Available at:
http://www.fao.org/docrep/007/y5499e/y5499e00.H
TM.
[23] Ministry of Agriculture and Rural Development
(MARD), “Regulations of the management for
production bases of vegetable, fruit and tea”,
Decision No 99/2008/QĐ-BNN, 2008.
[24] Office of Environmental Health Hazard Assessment
(OEHHA), “Proposition 65: No Significant Risk
Levels for Carcinogens and Maximum Allowable
Dose Levels for Chemicals Causing Reproductive
Toxicity”, California Environmental Protection
Agency, 2012.
[25] Child Rights International Network (CRIN),
“Convention on the Rights of the Child, 1990.
Available at:
http://www.crin.org/docs/resources/treaties/uncrc.as
p.
[26] Integrated Risk Information System (IRIS),
“Cadmium (CASRN 7440-43-9); Arsenic,
inorganic (CASRN 7440-38-2); Mercury, elemental
(CASRN 7439-97-6); Lead and compounds
(inorganic) (CASRN 7439-92-1)”, United States
Environmental Protection Agency (US EPA), 1994.
Available at: http://www.epa.gov/iris/.
Figure 1: Map of study area

729
B THANH LONG, D QUANG TRI, C YI CHING, N CAO DON AND P KUMAR MISHRA
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
Figure 2: Four basic steps of health risk assessment
Figure 3: The HI of adults and children
Table 1: The analysis results of irrigated water samples
at Vinh Quynh (mg/l) (Nguyen and Ngo, 2010)
Para
meter
VQ N01
VQ N02
VQ N03
QCV
N
08:20
08
D
T
D
T
D
T
B1
pH
7.54
7.54
7.92
7.92
7.58
7.58
5.5-9
Cr
0.017
0.017
0.021
0.111
0.014
0.014
0.5
Fe
0.993
3.537
1.593
60.436
0.804
1.640
1.5
Cu
0.004
0.046
0.002
0.139
0.003
0.032
0.5
Zn
0.023
0.161
0.000
0.676
0.018
0.087
1.5
As
0.023
0.051
0.102
0.150
0.021
0.026
0.05
Cd
0.000
0.000
0.000
0.002
0.000
0.000
0.01
Hg
0.000
0.0015
0.0018
0.0018
0.0002
0.0004
0.001
Pb
0.000
0.047
0.001
0.158
0.000
0.039
0.05
Quote: QCVN 08:2008/BTNMT: National technical
regulation on Surface water quality of Ministry of
Natural Resources and Environment.
B1: Applied for agriculture irrigation or others
required similar water quality
D: Dissolved; T: Total
Table 2: Heavy metals’ content in some vegetable
samples at Vinh Quynh (mg/kg) (Nguyen and Ngo,
2010)
No
Sample
Cu
Zn
As
Cd
Hg
Pb
1
VQ
R01
M
A
0.431
2.092
0.490
0.002
0.003
0.183
B
0.294
1.437
0.222
0.005
0.000
0.111
2
VQ
R02
CX
A
0.132
1.843
0.289
0.002
0.001
0.044
B
0.098
2.603
0.908
0.003
0.003
0.158
3
VQ
R03
C
A
0.248
1.505
1.491
0.005
0.001
0.118
B
0.289
1.564
0.778
0.004
0.000
0.203
4
VQ
R03
D
A
0.666
2.769
1.215
0.015
0.000
0.116
B
0.404
1.751
0.583
0.005
0.000
0.059
Average
A
0.369
2.052
0.871
0.006
0.001
0.115
B
0.271
1.839
0.623
0.004
0.001
0.133
FAO/WHO
1993
5.0
10
0.2
0.02
0. 005
0.5 –
1.0
99/2008/QĐ
-BNN*
30.0
40.0
1.0
1.0
0.05
2.0
Quote:
* Decision No 99/2008/QD-BNN promulgated on
2008/10/15 of Ministry of Agriculture and Rural
development on Regulations of the management for
Production and Trade bases of vegetable, fruit and tea
(MARD, 2008)
A: Edible part; B: Inedible part

730
Review and Human Health Risk Assessment of Heavy Metals Accumulation in
Vegetables Grown in Vinh Quynh, Vietnam
International Journal of Earth Sciences and Engineering
ISSN 0974-5904, Vol. 08, No. 02, April, 2015, pp. 723-730
Table 3: The parameters that use in calculation for
adults and children (1Pediatrics, 2010; 2National
Institute of Nutrition, 2012)
Parameter
Unit
Adults
(≥18 years old)
Children
(<18 years old)
Average
Body Weight
(BW)1
kg
54
20
Contact Rate
(CR)2
kg/day
1/3
1/6
Exposure
Frequency
(EF)2
day/year
365
365
Exposure
Duration
(ED)
year
5
5
10
10
15
15
Exposed
Average
Time (AT)
day
21900
5475
Table 4: The Reference Dose of four heavy metals
(Zhuang et al., 2009; IRIS, 1994)
No.
Heavy metal
Reference Dose (RfD)
(mg/kg/day)
1
Arsenic (As)
0.0003
2
Lead (Pb)
0.0035
3
Cadmium (Cd)
0.001
4
Mercury (Hg)
0.0003
Table 5: The Heavy metals’ ADD of adults and children
Objects
EU
As
Cd
Hg
Pb
Adults
5
0.00045
3.09x10-6
6.43x10-7
5.9x10-5
10
0.0009
6.17x10-6
1.29x10-6
0.00012
15
0.00134
9.26x10-6
1.93x10-6
0.00018
Children
5
0.00242
1.67x10-5
3.47x10-6
0.00032
10
0.00484
3.33x10-5
6.94x10-6
0.00064
15
0.00726
0.00005
1.04x10-5
0.00096
Table 6: The calculation results of LADD of As for
adults and children
Heavy metals
ED
Adults
Children
As
5
0.000384
0.000519
10
0.000768
0.010372
15
0.001152
0.001556
Table 7: The Target Hazard Quotient (THQ) and
Hazard Index (HI) of each heavy metal of adults and
children
Objects
ED
As
Cd
Hg
Pb
HI
Adults
5
1.4939
0.0031
0.0021
0.0169
1.5161
10
2.9878
0.0062
0.0043
0.0339
3.0322
15
4.4817
0.0093
0.0064
0.0508
4.5482
Children
5
8.0671
0.0167
0.0116
0.0915
8.1868
10
16.134
0.0333
0.0231
0.1829
16.374
15
24.201
0.05
0.0347
0.2744
24.561
RfD
(mg/kg/day)
0.0003
0.001
0.0003
0.0035
Table 8: The Upper Confidence Level of Risk of Arsenic
Objects
ED
LADD (As)
UCL Risk
Adults
5
0.00038
5.8x10-4
10
0.00077
11.5 x10-4
15
0.00115
17.3 x10-4
Children
5
0.00052
7.8 x10-4
10
0.00104
15.6 x10-4
15
0.00156
23.3 x10-4
Slope Factor
(mg/kg/day)-1
1.5
Table 9: Risk Lever for Carcinogenic effects of As
(IRIS, 1994)
No.
Risk Level
1
E-4 (1 in 10,000)
2
E-5 (1 in 100,000)
3
E-6 (1 in 1,000,000)