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Vol. 8(7), pp. 137-140, September 2014
DOI: 10.5897/AJBR2014.0766
Article Number: 565A69047414
ISSN 1996-0778
Copyright © 2014
Author(s) retain the copyright of this article
http://www.academicjournals.org/AJBR
African Journal of Biochemistry Research
Full Length Research Paper
Lead and cadmium residue determination in spices
available in Tripoli City markets (Libya)
Mohamed Ziyaina1*, Ahlam Rajab2, Khadija Alkhweldi2, Wafia Algami2, Omer Al-Toumi3 and
Barbara Rasco1
1School of Food Science, Washington State University, Pullman, WA 99163, USA.
2National Medical Research Center, Al- Zawia, Libya.
3Faculty of Veterinary Medicine and Agriculture Sciences, Al-Zawia University, Libya.
Received 28 March, 2014; Accepted 2 September, 2014
In recent years, there has been a growing interest in monitoring heavy metal contamination in food
products. Spices can improve the taste of food and can also be a source of many bioactive compounds
but can unfortunately, also be contaminated with dangerous materials, potentially heavy metals. This
study was conducted to investigate lead (Pb) and cadmium (Cd) contamination in selected spices
commonly consumed in Libya including Capsicum frutescens (chili pepper), Piper nigrum (black
pepper), Curcuma longa (turmeric) and mixed spices (HRARAT) which consist of a combination of:
Alpinia officinarum, Zingiber officinale and Cinnamomum zeylanicum. Spices were analyzed by atomic
absorption spectroscopy after digestion with nitric acid/hydrogen peroxide. The highest levels of lead
(Pb) was found in Curcuma longa and Capsicum frutescens in wholesale markets (1.05 ± 0.01 mg/kg,
0.96 ± 0.06 mg/kg). Cadmium (Cd) levels exceeded FAO/WHO permissible limit. C. longa and P. nigrum
sold in retail markets had a high concentration of Cd (0.36 ± 0.09, 0.35 ± 0.07 mg/kg, respectively)
followed by 0.32 ± 0.04 mg/kg for C. frutescens. Mixed spices purchased from wholesale markets also
had high levels of Cd (0.31 ± 0.08 mg/kg). C. longa and C. frutescens may pose a food safety risk due to
high levels of lead and cadmium. Cadmium levels exceeded FAO/WHO recommendations (0.2 ppm) for
P. nigrum, C. alonga and HRARAT.
Key words: Heavy metals, lead, cadmium determination, spice, Libya.
INTRODUCTION
In the last decade, interest has grown concerning the
dangerous effects of heavy metals on human health
resulting from environmental pollution and the prevalence
of heavy metals in trace food components such as spices
that could result from environmental exposure from the
atmosphere, soil and water that eventually find its way
into food creating a health risk for humans and animals
(Kabata-Pendias, 2011). These toxic metals reach agricul-
tural crops during cultivation, or through industrial acti-
vities such as mining, from industrial waste, waste water,
pesticides and packaging material (Bradl, 2005; Sarpong
et al., 2012; Siegel, 2002). There are several metals of
particular concern: lead (Pb), cadmium (Cd), tin (Sn),
arsenic (As) and mercury (Hg). Cadmium and lead are
*Corresponding author. E-mail: m.ziyaina@email.wsu.edu, food.science@wsu.edu. Tel: (509)-335-3843 or (509)3394184. Fax:
(509) 335-4815.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0
International License
138 Afr. J. Biochem. Res.
among the most toxic (Siegel, 2002; Sullivan et al., 2007)
due in part to the fact that they accumulate in biological
tissues and increase from lower to higher trophic levels, a
phenomenon known as biomagnification (Sullivan et al.,
2007). Heavy metal damages human health in two ways.
The first is disruption of normal cellular processes leading
to toxicity. The second, particularly for cadmium and lead
is bioaccumulation, particularly in the liver or kidney, where
these metals are excreted at a slower rate as compared
to uptake (Apostoli, 2006; Zelikoff and Thomas, 1998).
Important food sources of toxic metals are plant foods
including spices. Spices are derived from buds, barks,
rhizomes, fruits, seeds and other parts of the plant (Peter,
2001). Spices are responsible for making food dishes
more distinctive, palatable and aromatic and may contain
toxic metals derived from the surroundings through
production, processing and marketing (Inam et al., 2013;
Ziyaina, 2007). The use of spices and herbs has increased
markedly in most regions of the world, including Europe
and North America (Nkansah, 2010) with importation
from South Asia and developing countries increasing.
Several recent food borne incidents have involved both
intentionally and unintentionally adulterated spices and
herbs with heavy metals added to improve color. Contami-
nated spices are dumped onto markets in developing
countries that have limited ability to test for adulterants.
Due to the risk, it is important to evaluate the levels of
lead and cadmium in milled spices (red pepper, black
pepper, turmeric and mixed spices (HARART) that are
commonly consumed in Libya and have a history of
adulteration and also to determine the sources and
distribution of these metal contaminants in milled species.
Libya, outside of Egypt, is the largest market for spices
in North Africa. Central markets in Tripoli serve the entire
region from Algeria to Tunisia and into Chad and countries
further south and west. India commands 40% of the world
chilli market, 11% of the turmeric market and 5% of the
black pepper market (www.marketsandmarkets.com).
Much of the Capsicum spp. and Piper spp. sold in Libya
is sourced from India, Pakistan and Turkey. High levels of
contamination with toxins and filth have been previously
reported (fda.gov) possibly due from contaminated
irrigation water, and as a result of these perceived risks,
a survey was conducted in the Libyan market to assess
potential food safety risk.
The objective of this study was to determine the
prevalence of lead and cadmium in selected ground
spices available in Libyan retail markets.
MATERIAL AND METHODS
Sample collection
Table 1 lists the spices and the part of the plant used. Some of the
most consumed spices in Libya include Capsicum frutescens, Piper
nigrum, Curcum alonga and mixed spices (Ziyaina, 2007). The
study focused on the contamination assessment of spices that are
imported and traded within Libyan markets in 2011. Twenty four
samples of each type of spice were collected upon the arrival of
these spices to Libya from seven wholesale markets, which are the
main sources of spices entering into the country. An additional 36
samples for each type of spice were collected from several retailers
in metropolitan Tripoli, Libya.
Sample preparation
Homogenized spice samples were dried in an oven at 100°C for 24
h and then 5 g was accurately weighed into a beaker. Concentrated
nitric acid (HNO3) (65%) was added (5.0 ml) followed by 2.5 ml of
30% hydrogen peroxide (H2O2). Samples were left at room tempera-
ture for a few minutes and then heated on an electric heater
(120°C) and mixed. Five (5) ml of 65% HNO3 was added and the
digests reheated (120°C, few minutes), followed by the addition 10
ml of distilled water. Sample digests were then filtered through
Whatman No. 42 filter paper and <0.45 ml and diluted to volume
(Yash, 1998). Pb (217 nm) and Cd (228.8 nm) were determined by
atomic absorption spectrometry (Varian AAS240, USA). The
standard solution for analyses and development of a calibration
curve was prepared by diluting a stock solution of 1000 mg L-1 of
the examined heavy metals. All chemicals used in this experiment
were from Sigma Aldrich, St. Louis MO, USA).
Statistical analysis
Means and standard deviations were computed using SAS.LMC.
statistical software (SAS Institute Inc, Cary, NC USA) and the
Duncan’s multiple range test (MRT).
RESULTS AND DISCUSSION
The range and average Pb and Cd in spices from two
sources (retailer and wholesale markets) are presented in
Tables 2 and 3.
In retail markets, a significant (P<0.01) number of
spices contained lead. C. longa and C. frutescens from
wholesale markets had the highest levels of contamination.
Mixed spices had the lowest concentration of lead, but
the levels were still relatively high (0.65 ± 0.09 mg/kg).
These values were below the maximum permissible level
(10 ppm) recommended by FAO/WHO (2006). Never-
theless, it is important to take the necessary steps to
perform routine monitoring of the levels of lead in these
spices in order to avert a public health risk since high
levels of Pb have been found in other studies on herbs
and spice plants from different parts of the world (Seddigi
et al., 2013). Chizzola and others (2003) found that heavy
metals including Pb were generally within an acceptable
range in herbs, spices and medicinal plants on Austrian
markets (Chizzola et al., 2003). On the other hand,
studies conducted in Poland found the average lead
content to be about 1.49 mg/kg in cinnamon, which
exceeds the maximum permissible level (Krejpcio et al.,
2007).
As shown in Table 2, mixed spices sold in retail
markets have a high concentration of Cd (0.36 ± 0.09
mg/kg). The Cd content in black pepper, turmeric and
mixed spices were over the maximum permissible limit
Ziyaina et al. 139
Table 1. The names of spices surveyed.
Scientific name
Commercial name
Part used
Capsicum frutescens
Red Pepper
Fruits
Piper nigrum
Black pepper
Seeds
Curcuma longa
Turmeric
Rhizome
Mixed spices
Alpiniaofficinarum
Galangal
Rhizome
Zingiberofficinale
Ginger
Rhizome
Cinnamomumzeylanicum
Cinnamon
Bark
Table 2. Concentration of lead (Pb) in spices from Libyan markets.
Spice
Element (mg/kg)
Source
Max.
Min.
Average ± S.D
Capsicum frutescens
Pb
Wholesale
0.95
0.81
0.88 ± 0.07
Retailer
1.02
0.90
0.96 ± 0.06
Piper nigrum
Pb
Wholesale
0.80
0.66
0.73 ± 0.07
Retailer
0.90
0.69
0.82± 0.13
Curcuma longa
Pb
Wholesale
0.70
0.56
0.63 ± 0.01
Retailer
1.06
0.96
1.005 ± 0.01
*Mixed spices
Pb
Wholesale
1.00
0.84
0.92 ± 0.08
Retailer
0.74
1.04
0.89 ± 0.09
*Mixed spices: Alpinia officinarum, Zingiber officinale and Cinnamomum zeylanicum.
Table 3. Concentration of cadmium (Cd) in spices from Libyan markets.
Spice name
Element (mg/kg)
Source
Maximum limit
Minimum limit
Average ± S.D
Capsicum frutescens
Cd
Wholesale
0.17
0.06
0.14 ± 0.01
Retailer
0.22
0.16
0.19 ± 0.08
Piper nigrum
Cd
Wholesale
0.19
0.11
0.15 ± 0.07
Retailer
0.39
0.25
0.32 ± 0.04
Curcuma longa
Cd
Wholesale
0.24
0.14
0.19 ± 0.08
Retailer
0.39
0.32
0.35 ± 0.07
Mixed spices
Cd
Wholesale
0.40
0.22
0.31 ± 0.08
Retailer
0.51
0.42
0.36 ± 0.09
(0.2 ppm) recommended by FAO/WHO 2006 (Table 2).
The average values of Cd were close to those found in a
study by Bempah (2012) that reported the highest
concentration of Cd to be 0.44 mg/kg in Ocimum viride.
The values found here for Libyan markets are high, but
lower than what has been found in other markets. In one
study in India, the average concentrations of Cd in
medicinal plants and spices ranged from 0.684 to 2.751
mg/kg (Subramanian et al., 2012). Other studies have
found high Cd concentrations in Piper nigrum (206 mg kg-
1) and cinnamon (124 mg kg-1). Cadmium concentrations
in medicinal plants were variable, but often high: in Italy
(10-750 mg kg-1), Egypt (50-300 mg kg-1) and Brazil
(<0.2-0.74 mg kg-) (Abou-Arab et al., 2000; Caldas et al.,
2004).
In general, heavy metal content in spices reflects
140 Afr. J. Biochem. Res.
environmental pollution levels, bioaccumulation in plant
tissue, application of lead or heavy metal containing
materials such as arsenate based pesticides (Krejpcio et
al., 2007; Nkansah, 2010). High levels of heavy metals
could be due to the use of heavy metal-containing fertile-
zers or from a practice of growing plants with sewage
sludge (Ibrahim et al., 2012; Inam et al., 2013).
Conclusion
The levels found in this study for lead in C. longa, C.
frutescens, and mixed spices (Alpinia officinarum,
Zingiber officinale and Cinnamomum zeylanicum) were
below those recommended by FAO. However, levels of
cadmium exceeded FAO recommendations for P. nigrum,
C. longa, and mixed spices. Differences observed between
Cd and Pb levels for spices sold in retail and wholesale
markets indicate that the quality of spices across the
value chain in Libya is highly variable and that a number
of sources supply the market, some of which are conta-
minated and some of which are not.
Further studies should be conducted to estimate intake
of these and other spices by consumers in the Libya and
regionally where a similar cuisine is eaten and where
there is a similar lack of control on imported ingredients
to ascertain whether there is a health risk.
Conflict of Interests
The author(s) have not declared any conflict of interests.
ACKNOWLEDGEMENTS
This work was completely supported by National Agency
for Scientific Research (Libya). Authors would like to
acknowledge Dr. Islam Mohammed and Dr. Sadeq Naji
for their help.
REFERENCES
Abou-Arab AA, Abou Donia MA (2000). Heavy metals in Egyptian
spices and medicinal plants and the effect of processing on their
levels. J. Agric. Food. Chem. 48(6):2300-2304.
Apostoli P (2006). Elemental speciation in human health risk
assessment. Geneva: Geneva World Health Organization.
Bradl HB (2005). Heavy metals in the environment. Amsterdam:
Elsevier Academic Press.
Caldas ED, Machado LL (2004). Cadmium mercury and lead in
medicinal herbs in Brazil. Food Chem. Toxicol. 42(4):599-603.
Chizzola R, Michitsch H, Franz C (2003). Monitoring of metallic
micronutrients and heavy metals in herbs, spices and medicinal
plants from Austria. Eur. Food Res. Tech. 216(5):407-411.
Ibrahim GI, Hassan LM, Baban SO, Fadhil SS (2012). Effect of Heavy
Metal Content of some Common Spices Available in Local Markets in
Erbil City on Human Consumption. Raf. J. Sci.23(3):106-114.
Inam F, Deo S, Narkhede N (2013). Analysis of minerals and heavy
metals in some spices collected from local market. J.of. Phar.and
Bio.Sci. 8(2):40-43.
Kabata-Pendias A (2011). Trace elements in soils and plants. Boca
Raton: CRC Press.
Krejpcio Z, Krol E, Sionkowski S, Krejpcio Z, Krol E, Sionkowski S
(2007). Evaluation of heavy metals contents in spices and herbs
available on the Polish market. Polish J. Environ. Stud. 16(1):97-100.
Nkansah MA (2010). Heavy metal content of some common spices
available in markets in the Kumasi metropolis of Ghana. AJSIR
American.J.of. Scie. and. Indus. Res. 1(2):158-163.
Peter KV (2001). Handbook of herbs and spices. Cambridge:
Woodhead.
Sarpong K, Dartey E, Boateng G, Dapaah H (2012). Profile of
hazardous metals in twenty (20) selected medicinal plant samples
sold at Kumasi central market, Ashanti region, Ghana.
Seddigi ZS, Kandhro, GA, Shah F, Danish E, Soylak M (2013).
Assessment of metal contents in spices and herbs from Saudi Arabia.
Toxicol. Ind. Health.
Siegel FR (2002). Environmental geochemistry of potentially toxic
metals. Berlin; New York: Springer.
Subramanian R, Gayathri S, Rathnavel C, Raj V (2012). Analysis of
mineral and heavy metals in some medicinal plants collected from
local market. Asian Pacific. J. Tropical Bio. S74-S78.
Sullivan PJ, James JC, Franklin JA, Paul ER (2007). Toxic legacy
synthetic toxins in the food, water, and air of American cities.
Yash K (1998). Handbook of reference methods for plant analysis. Boca
Raton: CRC Press.
Zelikoff JT, Thomas PT (1998). Immunotoxicology of environmental and
occupational metals. London Bristol, PA: London Bristol, PA: Taylor &
Francis.
Ziyaina M (2007). Effect of packaging materials and the change in
temperature on microbial load in some spices. Master Thesis Tripoli
University Libya 14,28.