Terrestrial gamma dose rate in Pahang state Malaysia

H. T. Gabdo • A. T. Ramli • M. S. Sanusi •

M. A. Saleh • N. N. Garba

Received: 4 October 2013 / Published online: 24 January 2014

� Akademiai Kiado, Budapest, Hungary 2014

Abstract Environmental terrestrial gamma radiations

(TGR) were measured in Pahang state Malaysia between

January and April 2013. The TGR dose rates ranged from 26

to 750 nGy h-1. The measurements were done based on

geology and soil types of the area. The mean TGR dose rate

was found to be 176 ± 5 nGy h-1. Few areas of relatively

enhanced activity were located in Raub, Temerloh, Bentong

and Rompin districts. These areas have external gamma dose

rates of between 500 and 750 nGy h-1. An Isodose map of

the state was produced using ArcGIS9 software version 9.3.

To evaluate the radiological hazard due to terrestrial gamma

dose, the annual effective dose equivalent and the mean

population weighted dose rate were calculated and found to

be 0.22 mSv year-1 and 168 nGy h-1 respectively.

Keywords Environmental terrestrial gamma radiation

(TGR) � Dose rate � Mean dose rate

Introduction

Human beings exposure to naturally occurring radiation,

which accounts for 85 % of the total radiation exposure,

arises from two different sources. The first source comes

from cosmic radiation from the outer space. The interac-

tions of cosmic-ray particles in the atmosphere can create a

number of radioactive nuclei such as 3H, 7Be, and 14C [1].

The radiation dose from cosmic rays increases with latitude

and altitude so that polar and mountain dwellers as well as

aircrew and frequent air travelers receive higher doses of

cosmic radiation [2]. The other main contributor is the

terrestrial radioactive materials which originate from the

formation of the earth and are present everywhere in the

earth’s crust, and in the human body itself. Apart from the

exposure from direct cosmic rays and cosmo-genic radio-

nuclide, natural exposures arise mainly from the primordial

radionuclide’s (234U, 232Th and 40K) which are spread

widely and are present in almost all geological materials in

the earth’s environment [3].

Knowledge on terrestrial gamma radiation and radio-

activity is important in health physics. TGR Isodose map

is important in determining the radiological status of an

area [4]. Natural environmental radioactivity and the

associated external exposure due to gamma radiation

depend primarily on the ecological and geographical

conditions [5]. The presence of naturally occurring ra-

dionuclides in the environment may result in an external

and internal dose received by a population exposed to

them directly and via the ingestion/inhalation pathways.

The assessment of the radiological impact on a population,

as result of the radiation emitted by these radionuclides, is

important since they contributes to the collective dose of

the population [6]. This assessment is based on the ter-

restrial radionuclides 238U, 232Th, as well and their decay

products and 40K appear at different levels in the soils of

each region in the world. This paper tried to show the

dose rate distribution and its radiological hazards in Pa-

hang state, Malaysia.

H. T. Gabdo (&) � A. T. Ramli � M. S. Sanusi �M. A. Saleh � N. N. Garba

Department of Physics, Universiti Teknologi Malaysia (UTM),

Skudai Johor, Malaysia

e-mail: tghamman2@gmail.com

H. T. Gabdo

Department of Physics, Federal College of Education, Yola,

Nigeria

N. N. Garba

Department of Physics, Ahmadu Bello University, Zaria, Nigeria

123

J Radioanal Nucl Chem (2014) 299:1793–1798

DOI 10.1007/s10967-014-2928-1

The study area

Pahang is the largest State in Peninsular Malaysia and

the third largest state after Sabah and Sarawak, which

covers an area of 35,960 sq. km with a population of

1,500,817 inhabitants [7]. The State is bounded on the

north by Kelantan and Terengganu, the east by the South

China Sea, the south by Johor and Negeri Sembilan and

the west by Selangor and Perak. Spanning north to the

south of the state is the Titiwangsa mountain range that

also forms a natural divider between the Peninsula’s

Eastern and Western regions. Pahang’s highest point is

Gunung Tahan (2,187 m). It is also Peninsular Malaysia’s

highest peak.

Pahang state is divided into eleven districts with Cam-

eron highlands district the smallest and Jerantut district the

largest. Kuantan is the administrative capital. Pahang

largest river is Pahang river which passes through most part

of the state and it is the longest river in peninsular

Malaysia.

Materials and methods

The TGR dose rate was measured 1 m above the ground by

using Ludlum detector model 19, micro roentgen (lR) m,

manufactured by Ludlum, USA. It uses (2.54 9 2.54 cm2)

sodium iodide (NaI) crystal doped with thallium (Tl). The

instrument was calibrated by Malaysia Nuclear Agency; it

is a Secondary Standard Dissymmetry Laboratory (SSDL).

A global positioning system receiver Garmin model GPS

map 76 was use for locating the latitude and longitude of

each survey point.

The dose rates were measured from locations with dif-

ferent soil types (Fig. 1) and geological background

(Fig. 2) randomly. Figure 3, shows the external gamma

survey locations covering the entire state. The results of

TGR measurements are presented as an Isodose contour

map (Fig. 4) which was drawn using Arc GIS 9 software

version 9.3 and modified according to geological and soil

information (from previous aerial survey), where in 1956

an Arial survey was conducted part of which was to

Fig. 1 Soil map of Pahang state [10]

1794 J Radioanal Nucl Chem (2014) 299:1793–1798

123

indicate the presence of radioactive minerals in Malaya

(present Malaysia). The result from survey shows large

radioactive anomalies in Pahang state due to presence of

intrusive igneous rocks.

Results and discussion

The value of terrestrial gamma radiation dose rates mea-

sured from the 640 outdoor locations, ranged from 26 to

750 nGy h-1, with a mean value of 176 ± 5 nGy h-1.

This value is three times the world and two times the

Malaysian average of 59 and 92 nGy h-1 respectively as

reported by [4]. Few areas of enhanced activity ranging

between 500 and 750 nGy h-1 were noted in Sg. Kelau,

Kg. Temeliah, Sg. Jeruas, in Raub District others also Kg.

Sementih and Jenut Cemperus in Temerloh District. Others

are Genting Highland, Hutan Rizab Lentang, Hutan Rizab

Bukit Tinggi and Ladang Tuan in Bentong District. Felda

Bukit Mendi in Bera district; and Muadzam shah, in

Rompin district.

The highest measurement of 750 nGy h-1 was obtained

in Sungai Kelau, Raub District and the lowest 26 nGy h-1

was found in Ladang Ken Sin in the same district. The

mean values of terrestrial gamma radiation dose rates for

the eleven districts are presented in Table 1 while Fig. 5

shows the population of each district in relation to the mean

dose rate in the district. The mean value of terrestrial

gamma radiation dose rates in Pahang state, Malaysia and

the world are presented in Table 2. The district of Cameron

highlands appear to have the highest mean TGR dose rates

value of 285 ± 13 nGy h-1 due to it acid intrusive

Fig. 2 Geology map of Pahang state [11]

J Radioanal Nucl Chem (2014) 299:1793–1798 1795

123

geological feature while the district of Maran with Triassic

geological feature has the lowest TGR dose rate of

102 ± 9 nGy h-1. The highest mean TGR dose rate value

based on geological background was found in areas with

acid or basic intrusive geological features. These areas are

igneous acidic and extensively intruded by granitic rocks.

The granite is relatively rich in radioactive minerals [5].

Using the conversion coefficient factor for the absorbed

dose in air to effective dose of 0.7 Sv Gy-1, and the out-

door occupancy factor of 0.2 [5] the annual effective dose

equivalent (AEDE) outdoors is calculated by using Eq. 1.

AEDE ðmSv year�1Þ ¼ Dose rate ðnGy h�1Þ � 24 h� OF

� 0:7� 10�6;

ð1Þ

where AEDE is annual effective dose equivalent in mSv,

and OF is occupancy factor which is 0.2 for outdoor. The

average annual effective dose equivalent outdoors received

in habited areas of Pahang state is 0.22 mSv year-1 this is

higher than the world annual effective dose outdoor

equivalent average value of 0.07 mSv year-1 [5]. This is

not expected to contribute significant additional hazard

from the radiological health point of view. The annual dose

limit for members of the public according to [8] is

1 mSv year-1 and this limit is not applicable to doses

received from natural resources.

The information on population distribution was com-

bined with the mean gamma radiation dose rate value for

each of the district to yield a population-weighted mean

dose rate for Pahang state which is 168 nGy h-1. The mean

population weighted dose rate, Dw was obtained from the

relation in Eq. (2).

Dw ¼P

~DPP

P; ð2Þ

where ~D the mean dose rate for each district and P is the

corresponding population [9]. This is lower than the geo-

graphical mean dose rate which is: 176 ± 5 nGy h-1.

Malaysia is one of the countries that have higher than usual

values of terrestrial gamma radiation dose rate [5]. The

world average value is 59 nGy h-1 and Malaysian average

value is 92 nGy h-1. This higher value obtained in Pahang

state is probably due to the geological predominance of

igneous acidic intrusive granitic rocks in the state.

Fig. 3 Survey location points

1796 J Radioanal Nucl Chem (2014) 299:1793–1798

123

Fig. 4 Isodose map of Pahang state

Fig. 5 Pictorial representation of mean dose rate versus population of the 11 districts of Pahang state

J Radioanal Nucl Chem (2014) 299:1793–1798 1797

123

Conclusion

The mean terrestrial gamma radiation dose rate in Pahang

state is about two times the Malaysian average and about

three times higher than the world average value. The higher

values of terrestrial gamma radiation dose rate are associ-

ated with soils of granitic origin and with acid intrusive

geology.

Acknowledgments This project is funded by the Atomic Energy

Licensing Board (AELB) of Malaysia. Under grant title: Kajian

Pemetaam Isodose 2013. This project also used various facilities

provided by Universiti Teknologi Malaysia (UTM). The authors

would also like to thank Mr. Joseph Yong for his hard work and

endurance during the survey.

References

1. National Council on Radiation Protection and Measurements

(1977) Environmental radiation measurement, NCRP Report No.

50. NCRP, Washington, DC

2. Appleton D (2004) Natural radioactivity and health, the risk

poses by exposure to ionizing radiation. Earthwise, issue 21,

British Geological Survey�NERC, 2004

3. Wilson WF (1994) A guide to naturally occurring radioactive

material. Pennwell Books, Oklahoma, p 128

4. Ramli AT, Ahmad TA, Lee MH (2003) Statistical prediction of

terrestrial gamma radiation dose rate based on geological features

and soil types in Kota Tingi district, Malaysia. Appl Radiat Isot

59(2003):393–405

5. United Nations Scientific Committee on the Effects of Atomic

Radiation (2000) Report to the general assembly. Annex B:

exposures from natural radiation sources. UNSCEAR, NY,

ISBN-10: 9211422388

6. United Nations Scientific Committee on the Effect of Atomic

Radiation (UNSCEAR) (1998) Sources effect and risk of ionizing

radiation, New York

7. Department of Statistics Malaysia (2010) Total population by

ethnic group, mukim and state, Malaysia, 2010 Negeri, Pahang

State

8. International Commission on Radiological Protection (ICRP)

(1991) 1990 Recommendation of the International Commission

on Radiological Protection. ICRU Publication 60, Pergamon

Press, Oxford

9. Lee SK, Wagiran H, Ramli AT, Apriantoro NH, Wood AK

(2009) Radiological monitoring: terrestrial natural radionuclides

in Kinta District, Perak, Malaysia. J Environ Radioact

100(2009):368–374

10. Director General geological survey Malaysia (2002) Reconnais-

sance soil map of peninsular Malaysia

11. Santok Singh D (1985) Director General geological survey

Malaysia 1985. Geological map of peninsular Malaysia 8th edn.

Table 1 Mean terrestrial gamma dose rate and population of each

district of Pahang state

S.

no.

Districts Mean dose rate

(nGy h-1)

r(nGy h-1)

Population

1 Cameron

highlands

285 ±13 36,978

2 Raub 235 ±17 91,731

3 Lipis 135 ±8 86,484

4 Temerloh 192 ±14 158,724

5 Jerantut 158 ±9 88,035

6 Bentong 250 ±19 114,397

7 Bera 139 ±10 94,105

8 Rompin 169 ±11 109,848

9 Pekan 154 ±14 105,587

10 Maran 102 ±9 111,056

11 Kuantan 149 ±13 443,796

Table 2 Mean dose rate for Pahang state, Malaysia and some

countries of the world

Country Mean dose rate (nGy h-1) Reference

Pahang state 176 This study

Malaysia 92 [5]

China 62 [6]

India 56 [6]

Japan 53 [6]

USA 47 [6]

Egypt 22 [6]

Greece 56 [6]

Portugal 84 [6]

Russia 65 [6]

Spain 76 [6]

World 59 [5]

1798 J Radioanal Nucl Chem (2014) 299:1793–1798

123