BIOMEDICAL AND ENVIRONMENTAL SCIENCES 21, 319-324 (2008)
Heavy Metal Accumulation in Medicinal Plants Collected from
Environmentally Different Sites
JYOTI BARTHWAL,SMITHA NAIR, AND POONAM KAKKAR1
Herbal Research Section, Industrial Toxicology Research Centre, P. O Box-80, MG Marg, Lucknow, India
Objective To estimate the heavy metal content in soil and selected medicinal plants procured from environmentally
different sites of the same city. Methods Soil and plant samples of Abutilon indicum, Calotropis procera, Euphorbia hirta,
Peristrophe bycaliculata, and Tinospora cordifolia were collected from 3 environmentally different sites of the city: heavy
traffic area (HTA), industrial area (IA), and residential area (RA). Pb, Cd, Cr, and Ni were estimated in soil and plant samples
by inductively coupled plasma emission spectrometry and compared. Results The level of heavy metal was higher in soil
than in plant parts studied. Accumulation of heavy metals varied from plant to plant. Pb was the highest in Calotropis procera
root from HTA site and the lowest in Peristrophe bycaliculata whole plant from IA site. It was also lower in residential area
than in heavy traffic area. Conclusion The level of heavy metal content differed in the same medicinal plant collected from
environmentally different sites of the same city. Thus, it reiterates our belief that every medicinal plant sample should be tested
for contaminant load before processing it further for medication.
Key words: Heavy metals; Medicinal plants; Lead; Cadmium; Chromium; Herbal raw material
In the last quarter of the century, there has been a
growing interest in the use of substances of natural
origin especially herbs for therapeutic purposes. It has
also been observed that our natural resources have
been contaminated due to excessive use and disposal
of chemicals. These chemical residues have the
capacity not only to affect adversely the potency of
herbs but also to cause abiotic and biotic changes at
different levels of the ecosystem. A well-documented
incidence is that of Itai-Itai disease due to residue built
up of Cd2+ in rice. The geoclimatic/environmental
conditions of the region and the agricultural practices
decide the level of heavy metals that could
accumulate in herbal raw materials. Studies in our
laboratory have shown that Cd contamination causes
not only its residue built up in wheat seedlings but
also affects the uptake of other micronutrients and
levels of macromolecules affecting the quality of
crop[2-3]. Heavy metal contamination of soil and
groundwater is not at all uncommon today. They
interact with soil matrix and may persist for a long
period of time creating long-term hazards. Their
bioavailability in soil is increasingly used as a key
indicator of potential risks that contaminant pose to
both the environment and human health. Our research
group has been involved in evaluating levels of heavy
metals in therapeutically important medicinal plants,
herbal tea, and its ingredients. This study was taken
up to find the bioaccumulation of heavy metals in
selected Indian medicinal plants and its correlation to
the heavy metal load in soil. Efforts were also made to
study any variation in heavy metal content of medicinal
plants collected from residential area, industrial area
and traffic congested area of the same city.
MATERIALS AND METHODS
Experts from National Botanical Research
Institute, Lucknow, ensured the identity of selected
five medicinal plants for the study. The selection of
plants was based on their therapeutic importance in
traditional system of medicine. Samples were
collected from the residential, traffic congested and
industrial sites of Lucknow city along with soil from
the same place. The three areas identified were: a)
heavy traffic area (HTA) situated in the center of the
city, b) residential area (RA) with large open fields
and construction activities, c) industrial area (IA)
1Correspondence should be addressed to: Dr. (Mrs.) P. Kakkar, Head, Herbal Research, Industrial Toxicology Research Centre, Post Box No. 80,
M.G. Marg, Lucknow-226 001, India. Tel: (+91)-0522-2213786, 2627586*269. Fax: (+91)-0522-2628227. E-mail: firstname.lastname@example.org
Biographical note of the first author: Ms. Jyoti BARTHWAL is M. Sc, Environmental Science. She has been involved in estimation of
heavy metals in therapeutically important medicinal plants.
Copyright © 2008 by China CDC
320 BARTHWAL, NAIR, AND KAKKAR
near highway where small and medium size
industries operate. Soil samples were also collected
from the place of collection of plants.
Plant and soil samples were dried, powdered, and
weighed before processing them for analysis. All the
chemicals used like HNO3, perchloric acid, and metal
standard etc., were of analytical (AR) grade (E. Merck,
Germany). Deionised water was used throughout the
study and the glassware was of Borosil “A” grade.
Mixed working standard (1 and 10 ?g/mL) solutions
were freshly prepared by diluting the stock solutions
of 1000 ?g/mL. One gram of each powdered plant
sample and soil sample was accurately weighed on an
electronic balance (Shimadzu LEBROR AEX 200G,
Japan). These were put separately into 100 mL
digestion flasks. A digestion mixture comprising of
conc. HNO3 and perchloric acid in the ratio of 6:1 was
used for wet digestion of the samples and 10 mL of
this was added to each of the flasks. Blank and spiked
samples were also processed
simultaneously. The flasks were first heated on a hot
plate in a fume chamber slowly and then vigorously till
1 mL remained at the bottom. If the solution turned
brownish, another 10 mL of digestion mixture was
added and the process repeated till a white residue was
obtained. The residue was dissolved and made up to 10
mL with 0.1 N HNO3 in a volumetric flask. The
solutions were then analyzed with an inductively
coupled plasma emission spectrometer (8440 Plasma
Labtam). All necessary precautions were adopted to
avoid any possible contamination of the sample as per
the AOAC guidelines, 1998. The detection limit of
the instrument for each metal was Cr 0.006 µg/g, Ni
0.010 µg/g, Pb 0.042 µg/g, and Cd 0.0025 µg/g.
All the samples were analyzed in triplicate and
mean values along with standard deviation (±) are
shown in bars in the figures. Percent accumulation by
plants as compared with their respective soil sample
for each metal was also calculated.
Medicinal plant samples collected from identified
sites of Lucknow city along with the soil samples were
subjected to heavy metal estimation, i.e Cd, Ni, Cr, and
Pb. Table 1 summarizes botanical as well as the
common name of the plant, its part used, major
chemical constituents and medicinal uses. Different
plant parts were taken depending on their therapeutic
usage to get an idea regarding pattern of bioaccumulation
of heavy metal due to environmental pollution.
Medicinal Plants Analyzed in the Study
Plant Species Common Name Plant Part Therapeutic Uses
Abutilon indicum Linn Country Mallow Seeds
Used in Piles, Laxative, Aphrodisiac, Expectorant, in Chronic
Calotropis procera R BrMadar Tree Root
Useful for Treating Chronic Cases of Dyspepsia, Flatulence,
Constipation, Loss of Appetite, Indigestion and Mucus in Stool
Euphorbia hirta Linn Spurge Whole Plant
Post Natal Complaints, Breast Pain, Skin Eruptions, Antiprotozoal,
Antiviral, and Antidysentric
Peristrophe bycaliculata Nees
Tinospora cordifolia Miers
Note. Cited from Chopra et al..
Is Said to Be an Antidote to Snake Poison
Stomachic, Antiperiodic, Antipyretic, Alterative, and Aphrodisiac
Figs. 1(a-c) shows accumulation of Pb, Cd, Cr,
and Ni in Abutilon indicum seeds and soil. Pb was
found to be 3-4 µg/g in soil samples from all sites
whereas in plants it ranged 0.5-1 µg/g, which is below
the permissible limit of 10 µg/g recommended by
WHO. Cd was the lowest in both soil and plant from
HTA site (Fig. 1a). Cr ranged 0.1-1.21 µg/g whereas
Ni ranged 0.45-1.7 µg/g. Both Cr and Ni were the
lowest in the plant sample from the RA site (Fig. 1b).
Pb content in soil collected with Calotropis
procera was 3.8-4.8 µg/g where as roots of
Calotropis procera from HTA site (Fig. 1d) showed 2
µg/g. Samples from HTA site contained 0.25 µg/g Cd,
which is below permissible limit of 0.3 µg/g
recommended by WHO. The soil sample here
showed Cd content of 1.15 µg/g. No Cd was detected
in root samples from RA site (Fig. 1e). Cr was the
highest in the soil as well as plant sample of RA site
(Fig. 1e) whereas Ni was the highest in soil sample of
HTA site. A clear correlation between metal contents
in the soil and plant could not be seen.
Euphorbia hirta used extensively to treat postnatal
HEAVY METAL ACCUMULATION IN MEDICINAL PLANTS
FIG. 1. Heavy metal content in plant part and soil of Abutilon indicum (a-c) and Calotropis procera (d-f)
collected from environmentally different sites.
complaints contained 1-1.9 µg/g Pb (Figs. 2a-c). Soil
collected from RA and IA sites contained an equal
level of Pb. However, the plants collected from the
same site showed a difference in the Pb content (Figs.
2b and 2c). Cr and Ni were the lowest in the soil as
well as plant sample from IA site, whereas Cd was
0.12 µg/g and 0.17 µg/g respectively, in plant and soil
samples of RA site (Fig. 2b).
This plant used as an antidote for snake poison
showed 2.5-3.0 µg/g of Pb in soil samples whereas in
whole plant the level ranged 0.38 -1.25 µg/g (Figs. 2d-f).
Cd present in the plants from HTA site was 0.28 µg/g,
which was marginally below the permissible limit of 0.3
µg/g. The level of Cd in the plants was 0.07 µg/g in the
322 BARTHWAL, NAIR, AND KAKKAR
sample from RA site and 0.06 µg/g in the sample from
IA site (Figs. 2e and 2f). Here the level of heavy metals in
the soil of these sites was also low, ranging 0.1-0.5 µg/g.
Cr and Ni were the lowest in the sample from IA site.
FIG. 2. Heavy metal content in plant part and soil of Peristrophe bycaliculata (a-c) and Euphorbia
hirta (d-f) collected from environmentally different sites.
Pb in Tinospora cordifolia (Stem), one of the most
extensively used plants in Ayurveda and other
traditional systems of medicine having properties
ranging from antipyretic to health promoter, was lower
than 2.5 µg/g, both in soil and plant samples. Cd was
below the permissible limits recommended by WHO in
all the three samples (Figs. 3a-c), whereas Cr and Ni
levels did not vary much with the trend found in other
plants studied. As is evident from the data, although
there is variation in the levels of heavy metal detected
from three selected sites, no significant difference was
found in the Cr and Ni content. Pb and Cd were more in
the soil of HTA and IA sites, possibly due to heavy
vehicular traffic or industrial activity.
Attempts to correlate level of Cd and Pb in plant
to that present in soil showed that 71% Cd and 33%
Pb were found in HTA site samples compared to that
of soil in case of Abutilon indicum (Fig. 4a) whereas
in Calotropis procera (Fig. 4b), there was no
accumulation of Cd and the level of Pb was 25%
HEAVY METAL ACCUMULATION IN MEDICINAL PLANTS
compared to that of soil of RA site. In IA site samples,
Cd was 68% compared to that of soil. Similarly in
Euphorbia hirta (Fig. 4d), Pb was the highest (67%)
in HTA site samples and Cd was the highest in RA
site samples (70%) compared to that of soil. In
Peristrophe bycaliculata (Fig. 4c), Cd was 58% in
RA site and 31% in HTA site samples as compared to
soil. In Tinospora cordifolia (Fig. 4e), Pb was 32% in
FIG. 3. Heavy metal content in Tinospora cordifolia and soil from HTA site (a), RA site (b), and IA site (c).
FIG. 4. Percent accumulation of Pb and Cd in medicinal plant samples as compared to soil collected
from (A) HTA site (B) RA site and (C) IA site.
324 BARTHWAL, NAIR, AND KAKKAR
RA site and 27% in IA site samples as compared to
the level of Pb in soil collected from these areas.
The highest Pb content, among the plant samples
from three sites was found in root of Calotropis
procera (2 µg/g collected from HTA site of Lucknow
city with soil Pb content of 4.8 µg/g). Cd content in
this sample was 0.25 µg/g, which was also the
highest among the three plant samples, soil Cd
content in the sample from HTA site was 1.15 µg/g.
In contrast, maximum Cd was found in the soil for
Tinospora cardifolia collected from RA site. Both Pb
and Cd detected in our study were below the
permissible limit recommended by WHO.
Plants are a good source for bioaccumulation of
heavy metals. On one hand, this property has been
used for phytoremediation, on the other hand, it
may prove to be hazardous when plants are consumed
as food or therapeutic agent in traditional medicine.
Although there is a great concern about heavy metal
contamination of herbal raw materials, information
regarding permissible limit is available only for Pb
It is clear from the data generated in this study
that there is variation in the bioaccumulation of heavy
metals in samples collected from environmentally
different sites of Lucknow city. No clear correlation
was found in this limited study between the level of
heavy metals in plants/soil and collection site and
bioaccumulation of Pb and Cd in the medicinal plants.
Accumulation of Pb in plants in relation to soil
content was higher in 4 out of 5 plant species tested
in HTA site area with a heavy vehicular traffic. All
the samples tested showed a low level of Pb and Cd,
which is well within the permissible limit given by
WHO (1998). On comparison of the medicinal plants
tested, Cd content was the highest in Peristrophe
bycaliculata collected from heavy vehicular traffic
site and industrial area but well within WHO
permissible limit (0.3 ?g/g). The lowest Cd content
was detected in Calotropis procera sample from
industrial area site and below detection limit in
sample from RA site, indicating that accumulation of
Cd in Calotropis procera is minimum as compared to
other plants studied. At the same time, the highest
content of Pb was found in C. procera from HTA site
followed by Euphorbia hirta from the same site. The
lowest level of Pb was detected in Pristrophe
bycaliculata, (less than 0.4 ?g/g) whereas the soil
from the same site had more than 3.0 ?g/g Pb content,
clearly showing that there is a different accumulation
of heavy metals in medicinal plants exposed to same
environmental conditions and soil is not the only
source for bioaccumulation of heavy metals. Thus,
the findings emphasize on the need for checking
each medicinal plant sample for heavy metal load,
as there is a considerable difference in their level in
samples collected from the same city during the
The authors thank director, I. T. R. C., Lucknow,
India for his interest in this work, and the support
extended by Dr. R. C. MURTHY, Head, Metal
analysis laboratory, I. T. R. C. in carrying out this
work. The authors are grateful to I. T. R. C.
Publication Committee for reviewing this work.
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(Received June 19, 2007 Accepted May 2, 2008)