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Preliminary investigation of naturally occurringradionuclides in some traditional medicinal plantsused in Nigeria

R.L. Njinga a,*, S.A. Jonah b, M. Gomina a

a Department of Physics, Ibrahim Badamasi Babangida University, Lapai, Niger State, Nigeriab Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria

a r t i c l e i n f o

Article history:

Received 23 November 2014

Received in revised form

27 December 2014

Accepted 6 January 2015

Available online 19 January 2015

Keywords:

Activity concentration

Average annual committed effective

dose

Medicinal plants

Gamma spectroscopy

Radiological health risks

* Corresponding author.E-mail address: njingaraymond@yahoo.c

Peer review under responsibility of The Ehttp://dx.doi.org/10.1016/j.jrras.2015.01.0011687-8507/Copyright© 2015, The Egyptian Socopen access article under the CC BY-NC-ND li

a b s t r a c t

The preliminary investigation of the activity concentration of Naturally Occurring Radio-

active Materials (NORMs) in seven different medicinal plants; Anacardium occidentale, Aza-

dirachta indica, Daniella oliveri, Moringa oleifera, Psidium guajava, Terminalia catappa and

Vitellaria paradoxa by means of gamma spectroscopic analysis using a NaI[Tl] detector

shows that the activity concentration of 40K in the medicinal plants ranges from

74.59 ± 2.19 Bq/Kg to 324.18 ± 8.69 Bq/Kg with an average of 171.72 ± 6.09 Bq/Kg. The highest

activity concentration of 40K was recorded for A. indica while A. occidentale had the lowest

activity concentration. 226Ra activity concentration varies from 10.79 ± 4.24 Bq/Kg to

42.47 ± 2.76 Bq/Kg with an average of 25.02 ± 3.18 Bq/Kg. The lowest activity was recorded

for P. guajava while the highest activity was recorded for V. paradoxa. For the activity

concentration of 232Th, it ranges from 27.76 ± 1.02 Bq/Kg to 41.05 ± 1.05 Bq/Kg, with an

average of 35.09 ± 0.71 Bq/Kg. The lowest activity was recorded for V. paradoxa while the

highest activity was recorded for T. catappa. The average annual committed effective doses

due to ingestion of 226Ra, 232Th and 40K in the plants ranges from 0.00426 ± 0.00050 mSv/yr

to 0.00686 ± 0.00044 mSv/yr with an average of 0.00538 ± 0.00035 mSv/yr, the highest value

was recorded for A. occidentalewhile P. guajava has the lowest, the results determined for all

the plants are far below the worldwide average annual committed effective dose of

0.3 mSv/yr for an individual provided in UNSCEAR 2000 report indicating that the associ-

ated radiological health risk resulting from the intake of radionuclides in the medicinal

plants is insignificant. Consequently, the medicinal plants of this study are considered safe

in terms of the radiological health hazards.

Copyright © 2015, The Egyptian Society of Radiation Sciences and Applications. Production

and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/).

o.uk (R.L. Njinga).

gyptian Society of Radiation Sciences and Applications.

iety of Radiation Sciences and Applications. Production and hosting by Elsevier B.V. This is ancense (http://creativecommons.org/licenses/by-nc-nd/4.0/).

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5 209

1. Introduction

Emphasis on plant research has increased in recent times, and

a large body of evidence has been collected to show the sub-

stantial potential of medicinal plants used in different tradi-

tional systems all over the world. About 70e80% of the world

population, particularly in the developing countries rely on

non-conventional medicine in their primary healthcare

(Chan, 2003; Desideri, Meli, & Roselli, 2010). Natural radionu-

clides are found in every constituent of the environment; air,

water, soil, food and in humans (WNA, 2014).

According to the International Food Safety Authorities

Network (INFOSAN, 2011), plants used as food commonly have40K, 232Th and 238U and their progenies. It is expected that

similarities would be found in plants used for medicinal pur-

poses since plants are the primary pathway of natural radio-

nuclides entering into the human body through the food

chain. In a variety of concentrations, Naturally Occurring

Radioactive Materials (NORMs) have always been present in

every part of the earth and in the tissue of all living beings.

Natural radionuclides such as 238U, 232Th and 40K can be found

almost everywhere; in soil, public water supplies, oil and at-

mosphere thereby subjecting human beings to reasonable

exposure (Ali, 2008; Varier, 2009).

The role of NORMs in animal and plant metabolism has

long been established, but their effect and influence on

administration of medicinal plants had received relatively

little attention without due regard to possible side effects

because they have been perceived to be in smaller quantities

meanwhile mankind has continually use traditional herbal

medicine from medicinal plants for the treatment of various

diseases and aliments (Odugbemi, 2006, Odugbemi &

Akinsulire, 2008; Okoli, Aigbe, Ohaju-Obodo, & Mensah,

2007; Oladipo, Njinga, Baba, & Muhammad, 2012).

In Nigeria today, the use of herbal medicines for thera-

peutic purposes has increased drastically due to the fact that

medicinal plants are cheap, readily available and widely

distributed. Apart from the high cost of procuring available

allopathic medicines for treating even common health dis-

orders, other reasons for this shift are inaccessibility of

health institutions in the rural or remote locations in the

country and growing awareness of adverse reaction to some

allopathic drugs. Besides, Nigeria being in the tropics, has

forest that are full of cheap, easily available and sustainable

medicinal plants which can be used and have always been

used for the treatment of various diseases (Oni, Isola, Oni, &

Sowole, 2011).

The therapeutic effect of these medicinal plants for the

treatment of various diseases are based on the organic con-

stituent (such as essential oil, vitamins, glycosides, etc.) pre-

sent in them (Desideri, Meli, & Roselli, 2009; Lordford,

Emmanuel, Cyril, & Alfred, 2013), although, certain inorganic

elements (example Al, Br, Ca, Cl, Mn, Mg, etc.) have been

considered as essential in the formation of active constituent

which are responsible for the curative properties of the me-

dicinal plants (Serfor-Armah et al., 2003). It has been estab-

lished (Rajurkar & Pardesh, 1996) that there exists a

relationship between chelating agents (removal of metals)

and some chemotherapeutic agents. The effect of herbs is

related to their trace elements and their absorption into the

blood (Rajurkar & Pardesh, 1996).

During the process of photosynthesis both the stable

inorganic elements and the unstable ones (radioactive

element) find their way into these plants. Natural radionu-

clides are transferred and cycles through natural processes

and between the various environmental compartment by

entering into the ecosystem and food chain through direct or

indirect contamination of natural radionuclides (Adewumi,

2011; Elujoba, Odeleye, & Ogunyemi, 2005). It is possible for

plants to absorb radionuclides during nutrient absorption

through their roots and transport such nutrients via their

phloem to their active portions. The rate of natural radionu-

clides uptake is highly dependent on the activity concentra-

tion in the soil. The root uptake depends on soil properties

such as pH, mineralogical composition, organic matter con-

tent and nutrient status aswell asmetabolic and physiological

characteristics of the plant species (IAEA, 2006). Plants uptake

of radionuclides is one of many vectors for the migration of

natural radionuclides into humans from the environment via

the food chain. The study of the natural radionuclides levels of

medicinal plants in the environment are of interest within

plant evolution and thus provide information in the moni-

toring of environmental radioactivity (Lordford et al., 2013).

However, the study of NORMs in plants is not only important

because of the risk associated with it but also from the fact

that some of them can be used as biochemical tracer in

human food chain (Al-Kharouf, Al-Hamarneh, & Dababneh,

2008; CNSC, 2013).

The role of natural radionuclides in plant and animal

metabolism has been established and available in literature.

However the effect and influence of these natural radionu-

clides on administration of medicinal plants had received

little attention (Durugbo, Oyetoran, & Oyejide, 2012). The

possible side effects due to the intake of these medicinal

plants or herbal plants are not considered in the group of

edible plants that have been studied in the past by nutri-

tionist. Notwithstanding, many edible plants used as spices or

fruits such as ginger, onion, papaw and mango etc., have

medicinal properties and the ingestion of NORMs through the

use of plants had not been recognized or considered signifi-

cant in terms of quantity (Harb, 2009; Lordford et al., 2013;

UTEHS, 2014). Epidemiological studies have not demon-

strated adverse health effects in individuals exposed to small

doses (<0.1 Sv) delivered in a period of many years with the

exception of radiogenic health effects (primarily cancer)

which is evident in epidermiological studies for only doses

exceeding 0.05e0.1 Sv delivered at high dose rates (HPS, 2004;

Morah, 2007).

The linear non-threshold (LNT) model indicates levels of

risk to all levels of radiation (ICRP, 2005). Some scientists

considered that since humans evolved and survived

through this evolutionalised environment which consists of

some levels of radiation, some low levels of radiation are

beneficial to the human (Cuttler, 2004). However, medicinal

plants are usually administered in raw forms or in formu-

lations such as solutions, tablets or capsules. Undeniably,

the activity concentrations of NORMs in herbal formulations

are quite lower than in raw plants due to the preparation

processes which inevitably remove some of the

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5210

radionuclides (IAEA, 2003; Sussa, Damatto, Alencar, Mazilli,

& Silva, 2013).

The health effects of radiation exposures to NORMs from

intake of medicinal plants and herbal preparations in relation

to the level of NORMs in medicinal plants are associated with

most forms of leukemia and with cancer of many organs such

as the bone, lung, breast and thyroid in the long term since

approximately 10e15% of 210Pb and 214Pb ions, 99% of 226Ra

and 228Ra, 214Bi (bone seeker) and 210Po (soluble) reaches the

blood and/or the lung fluid stream and are distributed to the

whole body (UNSCEAR, 2000). Likewise, 238U has affinity for

electron donor and deposits itself in the tissues of the lung

and lining on the bones marrows which can lead to cancer of

the blood (leukemia). Also, 232Th, an alpha particle emitter

settles in the lining of the bones and can lead to bone cancer

(Cherry, Sorenson,& Phelps, 2012). 40K,, is not considered to be

of radiological significance since the body's control system of

blood pressure and volume is dependent on the activity con-

centration of potassium in the body.

This research work focused on determining the activity

concentration of naturally occurring radionuclides in selected

medicinal plants commonly used in northern Nigeria using

Sodium Iodide (NaI) g-Ray spectrometer in the health physics

and radiation biophysics department of the Center for Energy

Research and Training (CERT), Zaria. The studies would be to

determine the specific activity concentration of NORMs due to226Ra, 232Th and 40K present in the selected medicinal plants

and evaluate the annual effective doses due to ingestion of226Ra, 232Th and 40K.

2. Materials and methods

2.1. The study area

Lapai is located on the latitude 9� 240000N to 8� 90000N and

longitude 7� 00000E to 5�300000E with the average elevation of

168 m above the sea level. It has an area of 3051 km2 and a

Fig. 1 e GPS map of s

population of 110,127 at the 2006 census. The area is roughly

coterminous with the Lapai Emirate and share borders with

Paikoro LGA and Gurara LGA to the North, Agaie LGA to the

West, Kogi LGA to the South, and Abuja FCT to the East. The

points where the medicinal plant samples were obtained are

shown in Fig. 1 with the major roads and buildings within the

study area (see map's legend).

2.2. Sample collection

The various plants considered are; Anacardium occidentale,

Azadirachta indica, Daniella oliveri, Moringa oleifera, Psidium

guajava, Terminalia catappa and Vitellaria paradoxa; see Table 1

for more information. The plants parts shown in Table 1 were

collected from the site (shown in Fig. 1). Each sampling point

wasmarked using global positioning system (GPS) as shown in

Table 2. The samples were transferred into labeled poly-

ethylene bags from the field, rinsed with distilled water to rid

it of contaminants and dried on trays for a period of one week

before they were taken in labeled polyethylene bags to the

laboratory at the CERT, Zaria. The samples were transferred

into the laboratory after they were labeled accordingly as

shown in Table 2. The plant samples were properly oven dried

at temperature of 60 �C (±5 �C) for 5 day at the laboratory. Then

crushed to fine powder and filtered with a sieve so as to obtain

uniformly homogenous sample matrix.

The samples are then filled into the plastic container of

known weight. The weight of the sample and the container

were measured using the weighing balance. The weight of the

sample was obtained by subtracting the weight of the empty

container from the weight of the sample and the container.

The inner portion of the lid of the plastic container was then

coated with vaseline and the container sealed with the candle

wax followed by sealing with the masking tape to avoid any

possibility of the escape of radon (Rn). The sealed containers

were kept for a period of onemonth tomake sure the samples

attained secular radioactive equilibrium between Ra-226 and

its decay products in the uranium series, and Ra-228 and its

ampling points.

Table 1 e Scientific name and uses of selected traditional medicinal plants.

S/N Scientific name Common name Medicinal uses Part(s) used

1 Anacardium occidentale Cashew nut tree Malaria, elephantiasis, leprosy, ringworms, scurvy,

diabetes, warts, anthelmintics, typhoid fever

Bark, leaf, fruits

2 Azadirachta indica Neem tree Skin disease (acne vulgaris and eczema), fever, sore throat,

liver diseases, malaria, jaundice, syphilis, laxative

whole plant

3 Daniella oliveri Ilorin balsara,

African copaiba

Dysentry, diarrhea, toothache, urinary infection, astringent Bark, gum

4 Moringa oleifera Moringa, “Never die”,

Horse radish tree

Inflammatory diseases, asthma, antipyretic, cough, earache,

liver disease, veneral disease, diarrhea, diuretic emetic,

hysteria, catarrhal disease

whole plant

5 Psidium guajava Guava Fever, diarrhea, stomach ache, cough, laxative, dysentery,

irregular menstruation, malaria

whole plant

6 Terminalia catappa Umbrella tree Gonorrhea, ulcers, cough, catarrh, haemoptysis, cholagoghe,

astringent, cardiac tonic

Kernel, stem, bark

7 Vitelleria paradoxa Shea butter tree Nasal decongestion and catarrhal condition, anthelmintic,

hypertension, diuretic

Seeds

Table 2 e Medicinal plants sample data.

Sample ID (GPS point) Scientific name Part sampled GPS location

P01 (D) Anacardium occidentale Leaves 9� 030 37.8000 N 6� 340 24.5700 EP02 (E) Azadirachta indica Leaves 9� 030 19.4100 N 6� 340 16.3700 EP04 (B) Daniella oliveri Bark 9� 030 57.7600 N 6� 340 15.8000 EP05 (G) Moringa oleifera Leaves 9� 030 01.5400 N 6� 340 05.5100 EP06 (F) Psidium guajava Leaves 9� 030 08.6800 N 6� 340 39.6800 EP07 (A) Terminalia catappa Leaves 9� 040 01.1000 N 6� 340 18.6600 EP08 (C) Vitelleria paradoxa Leaves 9� 030 53.0700 N 6� 340 21.1900 E

The letters AeG represents the sampling points for each sample in Fig. 1.

0.05

0.06

0.07

0.08

Effic

ienc

y

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5 211

decay products in the thorium series (Lordford et al., 2013;

Tahir & Alaamer, 2009).

2.3. Analysis of medicinal plant samples

Gamma ray spectrometry was employed for the activity con-

centration measurements. The used detector assembly con-

sisted of a 7.62 � 7.62 cm NaI (Tl) detector housed in a 6 cm

thick lead-shield, cadmium-lined assembly with copper

sheets for the reduction of background radiation. The entire

assembly was coupled to a computer-based Multichannel

Analyzer (MCA) card system MAESTRO programmed used for

the data acquisition and spectra analysis. The analyzer was

calibrated with the IAEA supplied reference materials for the

quantitative determination of 40K, 226Ra and 232Th in the me-

dicinal plant samples. The systemwas set at a working energy

range of 0e3000 keV, which accommodated the energy range

of interest in the study. An energy resolution of 7.2%

(661.6 keV 137Cs) was obtained. Each sample was counted for

Table 3 e Standard gamma-ray sources (Varier, 2009).

S/No Source Half-life (T1/2) Gamma energy (MeV)

1 60Co 5.26 years 1.1732 and 1.332

2 137Cs 30 years 0.6616

3 54Mn 312.5 years 0.8348

4 133Ba 10.52 years 0.340 and 0.081

5 22Na 2.6 years 0.511 and 1.275

29,000 s (z8 h) in the set geometry. The activity concentration

of 226Ra and 232Th were determined by the g-lines of their

decay products: 214Bi (1760 KeV) and 208Tl (2614 KeV), respec-

tively. The activity concentration of 40K was determined from

its 1460 KeV g-line. The absolute detection efficiency of the

NaI (Tl) detector was determined using the standard sources

shown in Table 3 from the International Atomic Energy

Agency (IAEA). The absolute efficiency of the detector for the

g-ray energies were calculated from Equation (1),

3¼ nt Pg ðEÞN0e�ltd

(1)

0

0.01

0.02

0.03

0.04

0 200 400 600 800 1000 1200 1400 1600

Energy (KeV)

Abso

lute

Fig. 2 e The efficiency calibration curve for the NaI (Tl)

detector.

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5212

where n is the net area under the full energy peak of gamma-

ray energy E, t is the counting time, Pg (E) is the gamma-ray

emission probability at energy E, No is the activity of the

source (Becquerel), l is the decay constant¼ ln 2/T1/2 where T1/

2 is the half-life of the radionuclide, and td is the decay time.

The efficiency calibration curve for the NaI (Tl) detector is

shown in Fig. 2.

2.4. Energy calibration

Energy Calibration involves identifying the locations of stan-

dard photo-peaks in the raw spectrum, then creating an

adjusted (or calibrated) spectrum by interpolation from the

raw positions to the standard (or ideal) positions displaced by

the MAESTRO software. For a standard spectrum measured

from 0.0 to 3.0 MeV and digitised into 256 channels (0e255)

each channel has a range of 11.72 keV. This defines the stan-

dard channel range for each IAEA defined energy window. For

example, Potassium-40 in this research, having

(1.37 MeVe1.57 MeV) will be found in channels 116e133. In

order for this to work, the channel positions of the photo-

peaks in the raw spectra were entered as required. These

low and high channel limits was obtained visually by using

the View function of the raw spectra data. Fig. 3 shows the g-

ray spectra of two typical samples and detector calibration

with the MAESTRO software.

The activity concentration of gamma emitting radionu-

clide in the plants medicinal samples were found using a

gamma ray spectrometric analysis and calculated using the

expression:

Ai ¼ Ni

IðgÞ 3MT(2)

where: Ai ¼ Specific activity concentration of a certain radio-

active nuclide in the decay series, Ni ¼ Net peak area count

(minus background) of the sample, 3¼ Absolute efficiency of

the detector, I(g) ¼ Emission probability of a specific energy

Fig. 3 e A detector calibration and two typ

photo peak, T ¼ Time for collecting the spectrum of the

sample, M ¼ Weight of the sample.

2.5. Average committed effective dose

According to Lordford et al. 2013 the Average Annual

Committed Effective Dose (AACED) for ingestion of NORMs in

the medicinal plants is calculated using the expression:

Eave ¼ Cr �DCFing �Ai (3)

where; Eave ¼ Average annual committed effective dose,

Cr¼ Consumption rate of intake of NORMs from themedicinal

plants, DCFing ¼ Dose conversion coefficient for ingestion, for

each radionuclide (i.e., 4.5 � 10�5 mSv/Bq, 2.8 10�4 mSv/Bq,

2.3 � 10�4 mSv/Bq and 6.2 � 10�6 mSv/Bq for 238U, 226Ra, 232Th

and 40K respectively for an adult) (UNSCEAR, 2000) and

Ai ¼ Specific activity concentration of each radionuclides.

There is no standardized dosage for the use of medicinal

plants in Nigeria, however an increase in the consumption

rate of the medicinal plants by a patient who continually uses

these plants for treatment of common ailment would pro-

portionally increase his/her average annual committed

effective dose. Using Equation (3) by making Cr the subject of

the formula the threshold consumption rate for each of the

medicinal plant samples were obtained using the following

relation;

Cr ¼ 3EaveP3

i¼1½DCFi �Ai�(4)

where; Eave ¼ 0.3 mSv/yr is the threshold average annual

committed effective dose due to ingestion of NORMs in the

medicinal plants as published by UNSCEAR (2000), A1 A2 and

A3 are Specific activity concentrations of 40K, 226Ra and 232Th

respectively in the medicinal plant samples, DCF1, DCF2 and

DCF3 are the DCFing for40K, 226Ra and 232Th (i.e 6.2� 10�6 mSv/

Bq, 2.8� 10�4 mSv/Bq and 2.3� 10�4 mSv/Bq for 40K, 226Ra and232Th respectively).

ical samples spectrums with software.

Table 4 e Activity concentration and AACED in the medicinal plants.

Sample ID K-40 (Bq/Kg) Ra-226 (Bq/Kg) Th-232 (Bq/Kg) AACED (mSv/yr)

P01 74.59 ± 2.19 40.08 ± 4.12 38.69 ± 0.71 0.00686 ± 0.00044

P02 324.18 ± 8.69 19.22 ± 2.12 31.69 ± BDL 0.00489 ± 0.00022

P04 123.34 ± 6.22 30.69 ± 2.56 30.47 ± 0.24 0.00546 ± 0.00027

P05 184.59 ± 3.43 13.71 ± 1.96 39.48 ± 0.90 0.00469 ± 0.00026

P06 219.98 ± 9.28 10.79 ± 4.24 36.53 ± 1.10 0.00426 ± 0.00050

P07 145.59 ± 7.19 18.18 ± 3.52 41.05 ± BDL 0.00514 ± 0.00034

P08 129.78 ± 5.63 42.47 ± 3.76 27.76 ± 1.02 0.00636 ± 0.00044

Mean 171.72 ± 6.09 25.02 ± 3.18 35.09 ± 0.71 0.00538 ± 0.00035

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5 213

3. Results and discussion

The activity concentration of naturally occurring radionu-

clides in seven different medicinal plants commonly used in

Northern Nigeria has been determined and shown in Table 4.

As seen in Table 4, the activity concentration of 40K in the

medicinal plants ranges from 74.59 ± 2.19 Bq/Kg to

324.18 ± 8.69 Bq/Kg with a mean value of 171.72 ± 6.09 Bq/Kg.

The highest activity concentration of 40K was recorded for

sample P02 (A. indica) while sample P01 (A. occidentale) had the

lowest activity concentration. 226Ra activity concentration

varies from 10.79 ± 4.24 Bq/Kg to 42.47 ± 2.76 Bq/Kg with a

mean value of 25.02 ± 3.18 Bq/Kg. The lowest activity was

recorded for sample P06 (P. guajava) while the highest activity

was recorded for sample P08 (V. paradoxa). For the activity

concentration of 232Th, it ranges from 27.76 ± 1.02 Bq/Kg to

41.05 ± BDL Bq/Kg, with a mean value of 35.09 ± 0.71 Bq/Kg.

The lowest activity was recorded for sample P08 (V. paradoxa)

while the highest activity was recorded for sample P07 (T.

catappa).

Fig. 4 below shows the comparison of the activity concen-

tration of 40K, 226Ra and 232Th in each of the seven medicinal

plants of this study. Based on Fig. 4, the activity concentration

of K-40 was relatively high in all the samples followed almost

by Th-232 even though P08 and P01 showed a slight increase in

Ra-226 compared to K-40. However, Ra-226 was relatively low

across the seven medicinal plants analyzed.

Owing to the assumption that a unit consumption rate (Cr)

of 1 kg per annum was used, the Average Annual Committed

Effective Doses (AACED) due to ingestion of 40K, 226Ra and232Th in the medicinal plants were calculated using the

Fig. 4 e Activity concentration in the medicinal plant

samples.

corresponding values for each of the medicinal plants and are

presented in Table 4. From the results, the AACED ranges from

0.00426 ± 0.00050 mSv/yr to 0.00686 ± 0.00044 mSv/yr with a

mean value of 0.00538 ± 0.00035 mSv/yr.

The highest value was recorded for sample P01 (A. occi-

dentale) while sample P06 (P. guajava) recorded the lowest as

shown Fig. 5. The highest value observed for A. occidentalewas

due to the high activity concentration of 226Ra and 232Th in the

plant as they both registered higher DCFing of 2.8 10�4 mSv/Bq

and 2.3� 10�4 mSv/Bq respectively compared to 40Kwith 6.2�10�6mSv/Bq DCFing. This also explainswhyA. indica (P02) with

the highest recorded activity concentration of 324.18 ±8.69 Bq/Kg for 40K has lower average annual committed

effective dose of 0.00489 ± 0.00022 Bq/Kg.

The AACED due to ingestion of the natural radionuclides in

the medicinal plant samples are far below the world average

annual committed effective dose of 0.3mSv/yr for ingestion of

natural radionuclides provided in UNSCEAR 2000 report. Fig. 6

below presents the AAECD as a function of various con-

sumption rates within the range of 0e100 Kg/yr.

The threshold consumption rate (Table 5) is the limiting

value above which the value of the AACED becomes greater

than the 0.3 mSv for any of the medicinal plants. As indicated

in Table 5, the lower the AACED, the greater the threshold

value for the medicinal plants. Table 5 provide a baseline data

indicating that a patient with consumption rate below the

threshold values would be exposed to insignificant radiolog-

ical health risk while a patient whose consumption rate is

slightly higher than the threshold values is prone to signifi-

cant radiological health risk.

Table 6 below shows previously published work with the

activity concentration of NORMs in the medicinal plants from

different countries and their average values compared with

Fig. 5 e AACED due to NORMs in the medicinal plants.

Fig. 6 e AACED and consumption rate of the medicinal

plants.

Reference

40K

Range

Mean

4.6e324.2

171.7

This

work

66.4e1093.1

839.8

(Lord

ford

etal.,2013)

66.0e1216.0

976.3

(Sch

eibel&

Appoloni,2007)

.4e3582.0

654.7

(Desideri

etal.,2010)

26.0e1243.7

589.6

(Jevremovic,Laza

revic,Pavlovic,&

Orlic,2011)

J o u r n a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5214

this study. Table 6 indicates that the activity concentration of

NORMs in Ghana (Lordford et al., 2013) is higher as compared

to those with other countries and this work except for 40K in

Brazil (Scheibel & Appoloni, 2007) with the highest activity

concentration.

nce

ntrationsin

them

edicin

alplants.

Activityco

nce

ntration(Bq/kg)

226Ra

232Th

an

Range

Mean

Range

Mean

10.8e42.5

25.0

27.8e41.1

35.1

7

.8e

e42.0e70.6

56.2

5

ee

<11e43.0

21.7

6

.4e

ee

e5

.6e

e1.7e15.1

7.4

1

4. Conclusion

This research work provides baseline data for regulations and

quality control of medicinal plants used in Nigeria. The ac-

tivity concentration of 40K in themedicinal plants ranges from

74.59 ± 2.19 Bq/Kg to 324.18 ± 8.69 Bq/Kg with an average of

171.72 ± 6.09 Bq/Kg. The highest activity concentration of 40K

was recorded for A. indica while A. occidentale had the lowest

activity concentration. The activity concentration of 226Ra

varies from 10.79 ± 4.24 Bq/Kg to 42.47 ± 2.76 Bq/Kg with an

average of 25.02 ± 3.18 Bq/Kg and the lowest recorded for P.

guajavawhile the highest activity for V. paradoxa. For of 232Th,

it ranges from 27.76 ± 1.02 Bq/Kg to 41.05 ± BDL Bq/Kg, with an

average of 35.09 ± 0.71 Bq/Kg and the lowest recorded for V.

paradoxawhile the highest recorded for T. catappa. The AACED

ranges from 0.00426 ± 0.00050 mSv/yr to 0.00686 ± 0.00044

mSv/yr with an average of 0.00538 ± 0.00035 mSv/yr and the

highest value recorded for A. occidentalewhile the lowest for P.

guajava.

Table 5 e Threshold consumption rate and AACED for themedicinal plants.

Sample AACED for 1 Kg/yr(mSv/yr)

Thresholdconsumptionrate (Kg/yr)

P01 (A. occidentale) 0.00686 ± 0.00044 43.73

P02 (A. indica) 0.00489 ± 0.00022 61.31

P04 (D. oliveri) 0.00546 ± 0.00027 54.98

P05 (M. oleifera) 0.00469 ± 0.00026 64.01

P06 (P. guajava) 0.00426 ± 0.00050 70.37

P07 (T. catappa) 0.00514 ± 0.00034 58.33

P08 (V. paradoxa) 0.00636 ± 0.00044 47.17 Table

6e

Com

pariso

nofth

eactivityco

Country(region)

238U

Range

Me

Nigeria

ee

Ghana

20.4e46.9

31

Brazil

ee

Italy

<0.1e7.3

0

Serb

ia0.6e8.2

2

J o u rn a l o f R a d i a t i o n R e s e a r c h and A p p l i e d S c i e n c e s 8 ( 2 0 1 5 ) 2 0 8e2 1 5 215

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