INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,

MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)

ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue VI, June 2026

Soil-to-Plant Transfer of Naturally Occurring Radionuclides in West

Africa: Mechanisms, Transfer Factors, Food-Chain Contamination, And

Human Health Implications

Getrude Ashia Bijimi¹; Godwin Joseph Ibeh²; Dahiru Dahuwa³;

¹Department of Physics Faculty of Natural and Applied Sciences, Veritas University Abuja, F.C.T.,

Nigeria.

²Department of Physics, Nigerian Defense Academy, Kaduna state, Nigeria.

³Department of Physics Federal University of Health Sciences Azare Bauchi State Nigeria.

DOI: https://doi.org/10.51583/IJLTEMAS.2026.150600296

Received: 28 June 2026; Accepted: 03 July 2026; Published: 04 August 2026

ABSTRACT

Naturally occurring radionuclides (NORMs), including uranium-238 (²³⁸U), thorium-232 (²³²Th), radium-226

(²²⁶Ra), and potassium-40 (⁴⁰K), are widely found in terrestrial ecosystems and are a significant source of

environmental radiation exposure. Their movement from soil to plants is a crucial process through which

radionuclides enter the food chain, leading to internal radiation doses in humans. This review summarizes the

current understanding of the environmental distribution, mechanisms of soil-to-plant transfer, transfer factors,

and the radiological consequences of naturally occurring radionuclides in WestAfrica Peer-reviewed papers from

major scientific databases were used to undertake a structured literature review, with a focus on studies reporting

radiological risk assessments, soil-to-plant transfer factors, and radioactive activity concentrations. The research

that is now available suggests that a variety of factors, including soil physicochemical features, radionuclide

speciation, plant traits, climate, and agricultural methods, influence the uptake of radionuclides by plants. Due

to its vital biological role, potassium-40 often demonstrated the largest transfer to crops, while radionuclides

from the uranium and thorium family showed relatively lesser mobility but were nonetheless significant

contributors to long-term internal radiation exposure. The analysis also shows that while quantitative studies on

soil-to-plant transfer are still scarce and spatially unequal, environmental radioactivity evaluations dominate

research in West Africa. The majority of published studies are from Nigeria and Ghana, however there are still

significant knowledge gaps in many other West African nations. Regional radiological risk assessment is made

questionable by the absence of long-term environmental monitoring, locally determined transfer factor

databases, and standardized procedures. Harmonized radioecological studies, the creation of region-specific

transfer factors for important staple crops, integrated food-chain studies, and ongoing environmental monitoring

should be the top priorities for future study. By filling in these gaps, West African decision-making on public

health, food safety, and environmental radiation protection will be strengthened and exposure assessment

accuracy will increase.

Keywords: Naturally occurring radionuclides; Soil-to-plant transfer; Transfer factor; Environmental

radioactivity; Food chain; Radiological risk; West Africa.

INTRODUCTION

The Earth's crust is made up of naturally occurring radionuclides (NORMs), which can be found in rocks, soils,

sediments, water, air, and biological systems. The main primordial radionuclides of environmental importance

are potassium-40 (⁴⁰K), uranium-238 (²³⁸U), thorium-232 (²³²Th), and their radioactive decay products,

especially radon-222 (²²²Rn) and radium-226 (²²⁶Ra). NORMs have existed since the formation of the Earth and

are a constant source of background radiation exposure, in contrast to manmade radionuclides generated after

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nuclear accidents or weapons testing. Even though the concentrations of these radionuclides are typically low,

geological processes and human activities like mining, phosphate fertilizer production, oil and gas operations,

quarrying, and industrial mineral processing can greatly increase their environmental distribution (United

Nations Scientific Committee on the Effects of Atomic Radiation [1,2]

Complex geochemical and biological mechanisms control the mobility, bioavailability, and transmission of

naturally occurring radionuclides through terrestrial ecosystems. Before entering agricultural systems,

radionuclides may travel through soils, groundwater, surface water, and air pathways after being released into

the environment. These radionuclides are primarily stored in soil, which also acts as the main barrier preventing

them from entering crops through root uptake. Numerous interrelated elements, such as soil physicochemical

characteristics, radionuclide speciation, plant physiology, climate, and agricultural management techniques,

affect how much radioactive accumulation occurs in plants. Thus, one of the most significant processes

connecting environmental contamination with internal radiation exposure in humans is soil-to-plant transfer

[2,3].

The soil-to-plant transfer factor (TF) is still the most commonly utilized measure of radionuclide bioavailability

among the different radioecological metrics used to assess radionuclide migration. The TF is a key input

parameter in radioecological models that predict radionuclide movement through food chains, estimate internal

radiation doses, and evaluate radiological risks related to agricultural products. It quantitatively describes the

efficiency with which radionuclides are transferred from soil into plant tissues. Because local environmental

circumstances have a significant impact on radionuclide uptake, there is significant regional variability despite

the availability of internationally recognized transfer factor databases. As a result, radionuclide behavior in

tropical Africa may not be adequately represented by generalized transfer factors derived from temperate

ecosystems [2,4].

Natural radioactivity varies geographically throughout WestAfrica due to its varied geological formations, which

include phosphate deposits, granitic terrains, uranium-bearing rocks, and vast gold-mining belts. Concerns about

the environmental redistribution of naturally occurring radionuclides and their transfer into food systems have

also increased due to rapid population growth, agricultural intensification, artisanal and industrial mining,

growing urbanization, and rising groundwater demand. Activity concentrations of naturally occurring

radionuclides in soils, crops, groundwater, sediments, and mining settings have been documented in a number

of studies from Nigeria, Ghana, Burkina Faso, Mali, Senegal, and Togo. However, relatively few research have

measured soil-to-plant transfer factors or assessed radionuclide transport across agricultural food chains, while

the majority of studies have focused on environmental radioactivity measurements and radiological hazard

assessment. Additionally, there is still regional disparity in the published research, with many West African

nations lacking the baseline radioecological data needed for accurate environmental and public health

assessments [5].

In West Africa, radiological risk assessment is severely hampered by the scarcity of locally generated transfer

factors. Many current exposure models still rely on default transfer coefficients that were created in environments

that are very different from those seen throughout tropical Africa. Estimates of internal radiation dose may be

unclear due to variations in soil mineralogy, weathering intensity, climate, cropping systems, and agricultural

practices that can significantly affect radionuclide mobility and plant uptake. In order to address these

uncertainties, a thorough synthesis of the available data is necessary to determine what is already known, assess

regional trends, and identify areas that need more investigation [3,6].

The environmental distribution, soil-to-plant transfer, transfer factors, and radiological consequences of naturally

occurring radionuclides in West Africa are therefore summarized in this paper. In particular, it looks at the

variables influencing radionuclide mobility and plant uptake, compiles published data from nations in the region,

assesses the consequences for human exposure through the food chain, pinpoints significant knowledge gaps,

and suggests future research priorities to improve environmental monitoring, food safety evaluation, and

radiation protection techniques. This analysis offers a thorough regional viewpoint that promotes better

environmental management and evidence-based policies for long-term public health protection in West Africa

by using the existing radioecological data.

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Sources and Environmental Distribution of Naturally Occurring Radionuclides

Radionuclides that occur naturally (NORM), especially ⁴⁰K, ²³⁸U, and ²³²Th are found in a variety of

environmental compartments, such as rocks, soils, water, sediments, and vegetation, and are widely dispersed

across the Earth's crust. Both manmade activities like mining, agriculture, industrial operations, and oil and gas

extraction, as well as natural processes like weathering and geological formations, control their occurrence and

distribution. These sources affect radionuclides' mobility, bioavailability, and subsequent transfer across

terrestrial ecosystems, which ultimately determines how much of them accumulate in food crops and the

radiological risks they pose to people. The main anthropogenic and natural sources of these radionuclides, as

well as their environmental distribution, are covered in this part. This information serves as a foundation for

comprehending soil-to-plant transfer and food chain contamination.

Table 1. Summary of the Major Sources and Environmental Distribution of Naturally Occurring

Radionuclides (NORM)

Primary Origin

Major

Environmental

Compartments

Distribution

Mechanism

Implications for Soil-to-

Plant Transfer

Weathering of

igneous,

metamorphic, and

sedimentary rocks

Rocks, soils,

sediments

Mineral weathering,

erosion, and leaching

Determines the natural

radionuclide inventory of

soils and influences

baseline plant uptake.

Phosphate and potash

fertilizers, irrigation,

and organic

Cultivated soils,

crops

Fertilizer application, Enhances radionuclide

irrigation, and soil

amendment

bioavailability and

accumulation in edible

crops.

amendments

Extraction and

processing of mineral

ores and rocks

Mine soils,

tailings, dust,

nearby farmlands

Excavation, tailings

disposal, and dust

deposition

Increases radionuclide

concentrations in soils

and surrounding

vegetation.

Produced water,

drilling wastes,

scales, and sludge

Soils, sediments,

surface water

Waste disposal,

leakage, and

accidental spills

May elevate radionuclide

levels in agricultural soils

and crops near production

sites.

Cement production,

phosphate industries,

coal combustion, and

metal smelting

Industrial soils, fly

ash, sediments

Atmospheric

Contributes to localized

soil contamination and

radionuclide uptake by

plants.

deposition, industrial

effluents, and waste

disposal

Municipal landfills,

industrial waste

dumps, and sewage

sludge

Soils, leachates,

groundwater

Leaching, runoff, and Alters radionuclide

waste decomposition

distribution and may

increase crop

contamination in nearby

areas.

Weathering, flooding,

erosion, and

sediment transport

Soils, rivers,

wetlands, and

floodplains

Water movement,

wind erosion, and

sediment deposition

Controls radionuclide

mobility and spatial

variability in agricultural

ecosystems.

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Combined natural

and anthropogenic

inputs

Soil, water,

sediment, air, and

vegetation

Biogeochemical

cycling

Acts as the immediate

reservoir from which

radionuclides become

available for plant uptake

and food-chain transfer.

Cement production,

phosphate industries,

coal combustion, and

metal smelting

Industrial soils, fly

ash, sediments

Atmospheric

Contributes to localized

soil contamination and

radionuclide uptake by

plants.

deposition, industrial

effluents, and waste

disposal

The main human and natural sources of naturally occurring radionuclides (²³⁸U, ²³²Th, ⁴⁰K), their environmental

distribution, and their effects on soil-to-plant transmission are summarized in Table 1. The main natural source

is generally found in geological formations, although activities related to agriculture, mining, industry, and oil

and gas can increase the mobility and bioavailability of radionuclides, increasing the likelihood that they will

enter the food chain.

Mechanisms of Soil-to-Plant Transfer of Naturally Occurring Radionuclides

40

The movement of naturally occurring radionuclides (NORM), especially K, ²³⁸U, and ²³²Th is an important

factor controlling the flow of radioactivity through terrestrial ecosystems and into the human food chain is the

transfer from soil to plants. Plant roots are the main way that radionuclides are absorbed, and the intricate

relationships between radionuclide properties, soil qualities, plant physiology, and environmental factors all

affect this uptake. As a result, the quantity of radionuclides that accumulate in crops varies significantly

depending on the type of soil, plant species, and climate [3,7].

The soil-to-plant transfer factor (TF), a crucial indicator for radioecological modeling, environmental

monitoring, and radiological risk assessment, is frequently used to quantify the efficiency of radioactive uptake.

Therefore, forecasting radionuclide bioavailability, evaluating food chain contamination, and creating efficient

radiation protection techniques all depend on an understanding of the mechanisms governing radionuclide

transfer. The main mechanisms and variables controlling the movement of ⁴⁰K, ²³⁸U, and ²³²Th from soil to plants

are examined in the following sections.

3.1 Overview of Soil-to-Plant Transfer

The term "soil-to-plant transfer" describes the biological and physicochemical processes that transfer

radionuclides from soil into plant tissues. It is a vital route in terrestrial ecosystems, allowing naturally occurring

radionuclides (⁴⁰K, ²³⁸U, and ²³²Th) to enter the food chain and causing internal radiation exposure in humans

and animals when contaminated agricultural products are consumed [2,3].

Figure 1. Overview of soil to plant-soil-human of naturally occurring radionuclides

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Due to the combined effects of radionuclide chemistry, soil features, plant traits, and meteorological

circumstances, the degree of radioactive transfer varies significantly among various environmental situations.

As a result, the soil-to-plant transfer process has emerged as a crucial element of radioecological research,

environmental monitoring initiatives, and radiological risk assessments. It offers important data for forecasting

radionuclide behavior, assessing food safety, and bolstering radiation protection tactics [7,4].

3.2 Root and Foliar Uptake Mechanisms

The main route that naturally occurring radionuclides reach plants is through root absorption. Through

mechanisms such mass flow, diffusion, root interception, and membrane transport, radionuclides discharged into

the soil solution are absorbed along with water and vital nutrients. Radionuclide speciation and bioavailability,

which establish the percentage available for absorption by plant roots, govern the degree of uptake [2,3].

Figure 2. Mechanisms of Soil-to-Plant Transer of Naturally Occuring Radionuclides

During ingestion, each radionuclide behaves quite differently. Because it is chemically identical to stable

potassium, a crucial macronutrient needed for plant growth, potassium-40 (K) is easily absorbed. On the other

hand, because of their strong adsorption to soil minerals and restricted solubility, uranium (U) and thorium (Th)

show relatively modest absorption. However, under oxidizing conditions, uranium may become more mobile by

forming soluble uranyl complexes, which would increase its availability for root absorption [7].

Radionuclides are carried to aerial plant organs via the xylem after root absorption, where they accumulate at

varying amounts based on the type of tissue, plant species, and radionuclide properties. Foliar uptake can also

happen through the deposition of airborne particles and aerosols on leaf surfaces, even though root uptake is the

primary transfer pathway in agricultural systems. This pathway may contribute to radioactive buildup in regions

impacted by dust emissions from mining, quarrying, or industrial activity, but it is often less important for

naturally occurring radionuclides [4].

Factors Influencing Soil-to-Plant Transfer

Radionuclide mobility, bioavailability, absorption, translocation, and accumulation within plant tissues are all

determined by a number of interrelated processes that affect the transport of naturally occurring radionuclides

(⁴⁰K, ²³⁸U, and ²³²Th) from soil to plants. The significance of comprehending the mechanisms governing

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radionuclide behavior in terrestrial ecosystems is highlighted by the significant differences in soil-to-plant

transfer that are seen among various crops, soil types, and environmental conditions [3,7].

These regulating factors can be broadly divided into four groups: radionuclide properties, which affect chemical

behavior and mobility; plant factors, which determine uptake efficiency and internal distribution; soil factors,

which control radionuclide availability in the rhizosphere; and environmental factors, which alter soil-plant

interactions under different climatic conditions. Together, these elements control how radionuclides move up the

food chain and are essential for monitoring environmental radioactivity and evaluating radiological risk.

Soil Factors

The mobility, bioavailability, and subsequent uptake of naturally occurring radionuclides by plants are all

significantly influenced by the characteristics of the soil. The physicochemical properties of soils affect the

availability of radionuclides for root absorption by regulating their release from the solid phase into the soil

solution. Much of the observed regional variability in soil-to-plant transfer factors documented across various

agricultural and natural environments can be attributed to variations in soil parameters [2,3].

Soil pH, organic matter content, clay mineralogy, cation exchange capacity (CEC), redox potential, soil moisture,

and texture are some of the interconnected characteristics that control the impact of soil on radionuclide transport.

The amount of radionuclides available for plant absorption is ultimately determined by these parameters' effects

on radionuclide speciation, adsorption-desorption processes, complexation, and movement within the

rhizosphere. Therefore, forecasting radionuclide behavior and enhancing radiological risk assessments related

to damaged agricultural systems require a thorough understanding of these soil features.

Soil pH

One of the most important variables influencing the mobility and bioavailability of naturally occurring

radionuclides is soil pH. While neutral to alkaline conditions favor adsorption onto soil minerals and decrease

mobility, acidic soils typically improve the solubility of uranium and other radionuclides, hence improving their

availability for plant uptake. Because of its poor solubility and strong affinity for soil particles, thorium remains

largely immobile over a wide pH range, whereas the availability of exchangeable potassium in the soil is the key

factor influencing the uptake of ⁴⁰K [3,7].

Organic Matter

Radionuclide transmission is influenced by organic matter by complexation, adsorption, and the creation of

stable organo-metallic complexes. In general, a high organic matter concentration decreases radionuclide

mobility by increasing sorption sites; yet, in some environmental circumstances, soluble organic ligands may

increase uranium mobility through complex formation. Thus, the impact of organic matter is contingent upon its

composition, level of humification, and current soil chemistry [2,3].

Clay Mineralogy

Due to their large specific surface area and quantity of negatively charged adsorption sites, clay minerals have a

strong control over radionuclide retention. Uranium and thorium are efficiently adsorbed by minerals such

montmorillonite, illite, and kaolinite, which lowers their mobility and bioavailability. On the other hand,

radionuclide mobility and transfer to plants are typically higher in sandy soils with low clay concentration [3].

Cation Exchange Capacity (CEC)

An essential measure of radionuclide availability, cation exchange capacity (CEC) represents the soil's capability

to hold onto positively charged ions. High CEC soils have a higher capacity to retain ions, which lowers

radioactive concentrations in the soil solution and restricts plant absorption. Conversely, soils with low CEC

frequently show higher soil-to-plant transfer factors and increased radionuclide mobility [3,8].

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Redox Potential

Uranium's chemical speciation and mobility are greatly influenced by redox conditions, but thorium is less

affected. Uranium is mostly found in soluble uranyl (푈푈₂²⁺) complexes under oxidizing conditions, which are

easily transported in the soil solution. Uranium's bioavailability and subsequent plant uptake are reduced when

it is reduced to the less soluble tetravalent form (U⁺) [2,7].

Soil Moisture

The disintegration, diffusion, and migration of radionuclides toward plant roots are all regulated by soil moisture.

While excessive moisture can change soil redox conditions and radionuclide speciation, adequate moisture

improves radionuclide transport through mass flow and facilitates root uptake. Radionuclide bioavailability and

transfer efficiency can thus be affected by seasonal variations in soil water content [3]

Soil Texture

Through its impacts on water retention, permeability, and adsorption capacity, soil texture affects radionuclide

mobility. Due to their greater surface area and higher adsorption capacity, fine-textured soils rich in clay and silt

typically retain radionuclides better than coarse-textured sandy soils. As a result, under similar environmental

conditions, sandy soils frequently show higher soil-to-plant transfer and radioactive mobility [3,7].

Plant Factors

The uptake, translocation, and accumulation of naturally occurring radionuclides (⁴⁰K, ²³⁸U, and ²³²Th ) are

significantly influenced by plant properties. Due to differences in root shape, nutrient uptake techniques,

physiological processes, and growth characteristics, significant variability in radionuclide concentrations have

been recorded among plant species, cultivars, and tissues even under similar soil circumstances. The

heterogeneity of transfer factors described in the literature can be attributed to these biological differences, which

have a direct impact on radionuclide bioavailability and the effectiveness of soil-to-plant transfer [4]. Plant

species and genotype, root architecture, age and growth stage, physiological status, and nutrient need are the

main plant-related factors affecting radionuclide transfer. Predicting radionuclide accumulation in edible crops

and enhancing the precision of radiological risk assessments require an understanding of these factors'

contributions.

Plant Species and Genotype

Due to variations in root membrane transporters, nutrient acquisition tactics, and physiological adaptations,

different plant species and cultivars have different capacity for radionuclide uptake. As a result, even when

produced under identical soil conditions, transfer factors vary significantly between cereals, vegetables, legumes,

and forage crops. According to Dirican et al. [3] and Mahmoud & El-Zohry [7], these interspecific variations

demonstrate the significance of plant genetics in affecting radionuclide accumulation and food-chain transfer.

Root Architecture and Morphology

The amount of soil explored and the effectiveness of water and nutrient acquisition are influenced by root

architecture. In general, plants with more root hairs and deeper or more branched root systems have more

interaction with the soil solution, which increases the chance of radionuclide absorption. Additionally, root

morphology influences ion transport and rhizosphere chemistry, which in turn affects radionuclide uptake and

translocation.

Plant Age and Growth Stage

Food demand and physiological activity vary with growth stage. This makes radionuclide uptake varies during

plant development. Redistribution to reproductive organs may happen during grain or fruit development, but

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higher transpiration and nutrient uptake during active vegetative growth improve radioactive absorption. Thus,

when assessing soil-to-plant transfer parameters, the sample stage should be taken into account [2,7].

Physiological Status

Radionuclide transport within plants is directly impacted by physiological activities such as transpiration,

photosynthesis, and nutrition metabolism. High transpiration rates enhance xylem-mediated transfer of

radionuclides from roots to shoots, while physiological stress can alter membrane permeability, transporter

function, and ion homeostasis, consequently changing radionuclide accumulation in different plant tissues.

Nutrient Demand and Competition

Chemically identical ions compete for common transport channels; this makes nutrient availability to have a

significant impact on radionuclide uptake. For instance, the availability of calcium, magnesium, phosphate, and

iron can change the uptake of uranium and thorium by affecting their chemical speciation and competition at the

root surface, while potassium deficiency increases the uptake of K through increased activity of potassium

transporters. The bioavailability and transport of radionuclides in agricultural systems are significantly

influenced by these ion interactions.

Radionuclide Properties

The behavior of radionuclides in the environment and their subsequent transfer from soil to plants are largely

determined by their physicochemical characteristics. Radionuclide mobility, adsorption, desorption, and

bioavailability are influenced by factors such chemical speciation, oxidation state, ionic charge, ionic radius,

solubility, and affinity for soil constituents. As a result, even in equivalent soil and climate circumstances,

radionuclides exhibit significant differences in their uptake, transport, and accumulation within plant tissues

[2,3]. Chemical speciation, oxidation state, solubility, ionic radius and charge, and complexation behavior are

the main radionuclide-related parameters affecting soil-to-plant transmission. The chemical forms of

radionuclides in the soil solution, their interactions with organic matter and soil minerals, and their accessibility

to plant roots are all determined by these characteristics. Therefore, forecasting radionuclide mobility, assessing

transfer factors, and enhancing radiological risk assessments all depend on an understanding of these

fundamental features.

Chemical Speciation

One of the most significant factors influencing radionuclide mobility and bioavailability is chemical speciation,

which establishes the chemical forms that radionuclides take in the soil solution. In general, radionuclides that

are soluble complexes or free ions are more readily absorbed by plants than those that are heavily adsorbed onto

mineral surfaces or integrated into stable mineral lattices. According to Chen et al. [9] and Smedley et al. [10],

thorium is mostly found as insoluble hydroxides and oxides, which results in relatively decreased mobility and

plant uptake, while uranium is mostly found as soluble uranyl (푈푈₂²⁺) complexes under oxidizing

circumstances.

Oxidation State

While thorium is nearly always found in the tetravalent state, uranium's environmental behavior is substantially

influenced by its oxidation state. Highly soluble uranyl-carbonate complexes are formed by hexavalent uranium,

which easily move through soils and become available for plant absorption. Conversely, in reducing conditions,

tetravalent uranium forms sparingly soluble minerals, which reduces its mobility and bioavailability. According

to Chen et al. [9] and Smedley et al. [10], these redox changes are therefore essential for controlling uranium

transport within the soil-plant system.

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Solubility

The concentration of radionuclides in the soil solution and, hence, their accessibility to plant roots is determined

by their solubility. While poorly soluble radionuclide species stay attached to soil particles and have reduced

transfer factors, soluble species are more easily carried through soil water by mass flow and diffusion, promoting

root uptake. Radionuclide solubility and subsequent plant accumulation are greatly influenced by changes in soil

chemistry, especially pH and carbonate concentration [3,9].

Ionic Radius and Charge

Radionuclides' interactions with plant membrane transporters and their adsorption behavior are influenced by

their ionic charge and radius. Since potassium-40 is chemically the same as stable potassium (K⁺), it is effectively

absorbed through potassium transport systems and typically has higher transfer factors than uranium and

+

thorium. On the other hand, the higher ionic charge of 푈푈₂²⁺and 푈ℎ₄increases their electrostatic attraction to

negatively charged organic matter and clay minerals, decreasing their mobility and plant uptake [2,3].

Complexation and Sorption Behaviour

Depending on the stability of the complexes created, complexation with carbonate, phosphate, sulfate, and

dissolved organic materials can either increase or decrease radionuclide mobility. Similarly, sorption onto soil

organic matter, iron and manganese oxides, and clay minerals lowers radioactive concentrations in the soil

solution, which restricts plant uptake. In terrestrial ecosystems, radionuclide transport, bioavailability, and soil-

to-plant transfer are ultimately controlled by the dynamic balance between complexation and sorption [9,11].

Environmental and Climatic Factors

The mobility, bioavailability, and transfer of naturally occurring radionuclides from soil to plants are greatly

impacted by environmental and climatic factors, which alter soil physicochemical characteristics, plant

physiological processes, and radionuclide speciation. The transport and distribution of radionuclides within the

soil–plant system are altered by variations in temperature, rainfall, irrigation techniques, seasonal shifts, and

atmospheric deposition. This contributes to the temporal and spatial variability of soil-to-plant transfer factors

reported across various ecosystems [3,4]. Radionuclide transmission is a dynamic process rather than a static

event since the impact of environmental elements is frequently linked to soil and plant features. Therefore,

assessing these characteristics is crucial for enhancing environmental monitoring and radiological risk

assessment, forecasting radionuclide behavior under changing climatic conditions, and refining radioecological

models.

Temperature

Temperature affects root growth, microbial activity, soil chemical reactions, and plant metabolism, all of which

have an impact on radionuclide transmission. In general, higher temperatures improve transpiration and nutrient

uptake, which may increase radionuclide absorption and translocation inside plants. By changing soil solution

chemistry and reaction kinetics, temperature also affects radionuclide speciation and bioavailability [12].

Rainfall

Rainfall affects soil moisture, infiltration, leaching, and surface runoff, all of which control radionuclide

mobility. While heavy rainfall may drain soluble radionuclides beyond the root zone or redistribute them through

erosion and sediment movement, moderate rainfall encourages radionuclide transfer to the rhizosphere,

improving plant absorption. Thus, seasonal and geographical differences in soil-to-plant transmission are mostly

influenced by rainfall patterns [2,10].

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Irrigation Practices

Through changes in soil moisture, pH, and redox conditions, irrigation quality, quantity, and frequency affect

radionuclide availability. While proper irrigation management can lower radionuclide accumulation through

regulated water application and enhanced drainage, irrigation with groundwater or surface water containing

naturally occurring radionuclides may gradually raise radionuclide concentrations in agricultural soils [2,7].

Seasonal Variation

Throughout the year, seasonal variations affect soil qualities, plant development, and climate, all of which have

an impact on radionuclide transmission. Radionuclide mobility and plant physiological activity are impacted by

temperature, rainfall, and soil moisture variations, which result in variations in uptake between growing seasons.

Therefore, when comparing radionuclide concentrations between studies and assessing transfer factors, seasonal

variations should be taken into account [4].

Atmospheric Deposition

Radionuclides can also enter vegetation by atmospheric deposition, which occurs when dust, aerosols, and

airborne particles settle on leaf surfaces. In regions impacted by wind erosion, industrial pollution, mining, and

quarrying, this route is especially crucial. Foliar deposition may contribute to radioactive accumulation in leafy

vegetables and other crops exposed to contaminated airborne particles, even if root uptake continues to be the

primary route for naturally occurring radionuclides [1,13].

Soil-to-Plant Transfer Factor (TF)

One of the most used radioecological metrics for assessing the movement of naturally occurring radionuclides

from soil to plants is the soil-to-plant transfer factor (TF). By comparing the activity concentration in plant

tissues to that in the same soil under similar conditions, it offers a quantitative estimate of radionuclide

bioavailability. TF is an integrative metric that represents the combined impact of environmental factors, plant

physiology, soil physicochemical features, and radionuclide properties on radioactive uptake [1]. The soil-to-

plant transfer factor is mathematically expressed as:

푪

풊

푻푭_풊=

1.

푪

풔

푻푭_풊= Transfer factor for plant organ i

퐶_푖= Activity concentration in the specific plant organ (Bqkg^-1dry weight)

퐶_푠= Activity concentration in the corresponding soil (Bqkg^-1dry weight)

The radionuclide transfer efficiency is shown by the value of TF. While a lower TF denotes stronger retention

within the soil matrix and decreased bioavailability, a larger TF suggests increased mobility and accumulation

of radionuclides in plant tissues. TF values, however, are not constant and can differ significantly depending on

radionuclides, crop species, soil types, climate, agricultural practices, and analytical techniques. As a result, it is

important to evaluate TF value comparisons in light of the environmental circumstances that led to their

determination [13]. In addition to measuring radionuclide uptake, the TF is a crucial input parameter in

radioecological models that support environmental monitoring and radiological risk assessment, estimate

internal radiation doses from dietary intake, assess contamination of agricultural products, and forecast food-

chain transfer. The TF is still one of the major indices that international organizations, such as the International

Atomic Energy Agency (IAEA), propose for evaluating radionuclide transport in terrestrial ecosystems because

of its ease of use and wide range of applications.

Table 2. Major Studies on Soil-to-Plant Transfer of Naturally Occurring Radionuclides in Nigeria

Study Area

Crop(s)

Radionuclide(s) Major Findings

Author(s)

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Mean TFs of 26.58 (⁴⁰K), 0.62 (²²⁶Ra),

and 0.39 (²³²Th) were reported. ⁴⁰K

exhibited substantially higher transfer

than the other radionuclides.

Mahmoud &

El-Zohry,

[7]

Southwestern

Nigeria

Amaranthus

hybridus

⁴⁰K, ²²⁶Ra, ²³²Th

High

Ajayi [14]

Transfer factors varied significantly

background

radiation area,

Oyo State

Food crops

Maize

⁴⁰K, ²²⁶Ra, ²³²Th among crop species, reflecting differences

in radionuclide uptake efficiency.

Tropical

ecosystem,

abandoned

tin-mining

area

Adesiji &

Ademola

[15]

Soil characteristics significantly

influenced radionuclide transfer, with

leaves showing higher accumulation than

grains.

⁴⁰K, ²³⁸U, ²³²Th

Medicinal plant species accumulated

²³⁸U, ²³²Th,⁴⁰K,

Davis et al.

[16]

Minna and

Kaduna States

Medicinal

plants

radionuclides differently, demonstrating

¹³⁷Cs

species-dependent transfer characteristics.

Mean TF values followed the order ²³²Th

⁴⁰K, ²²⁶Ra, ²³²Th (0.666) > ²²⁶Ra (0.557) > ⁴⁰K (0.473); all

values were below unity.

Waida et al.

[17]

Bassa LGA,

Plateau State

Edible food

crops

Kwara State

(gold and

beryllium

Mining activities influenced radionuclide

mobility and transfer, although estimated

radiological risks remained within

international safety limits.

Orosun et al.

[13]

Guinea corn

(Sorghum

bicolor)

⁴⁰K, ²³⁸U, ²³²Th

mining sites)

Yam,

Oladele et

al. [18]

Significant interspecies variability in TFs

was observed, with crop type and soil

⁴⁰K, ²²⁶Ra, ²³²Th physicochemical properties identified as

the principal determinants of radionuclide

transfer

cassava,

maize, rice,

vegetables,

banana,

Southwestern

Nigeria

pawpaw

Leaves recorded the highest transfer of

Olabimtan

et al. [19]

Rice (root,

stem, leaf

and grain)

⁴⁰K, whereas roots accumulated relatively

⁴⁰K, ²³⁸U, ²³²Th

Kano State

higher uranium-series radionuclides,

demonstrating organ-specific uptake.

Vegetation,

meat and

milk

Moran-

Hunter [20]

Estimated soil-to-vegetation TFs were

Southwestern

Nigeria

²³⁸U, ²³²Th

0.020 (²³⁸U) and 0.090 (²³²Th), indicating

relatively low transfer into the food chain.

pathways

Table 3. Published Studies on Soil-to-Plant Transfer and Environmental Distribution of Naturally Occurring

Radionuclides in Ghana

Transfer

Factor (TF)

Radionuclide(s)

Major Findings

Sources

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⁴⁰K: 0.04–

0.28; ²³⁸U:

0.06–0.12;

²³²Th: 0.01–

0.10

Uranium showed greater soil-

to-cassava transfer than

thorium, while ⁴⁰K showed

the widest variation among

samples.

Doyi et al.

[21]

⁴⁰K, ²³⁸U, ²³²Th

Transfer factors from

fertilized soils to vegetables

were evaluated. Lettuce

showed higher ²²⁶Ra transfer,

while cauliflower showed the

highest ⁴⁰K and ²²⁸Ra transfer.

Adjirackor et

al. [22]

²²⁶Ra, ²²⁸Ra, ⁴⁰K

Reported

Transfer factors differed

between mining and non-

mining areas, showing the

influence of geology and

mining activities on

Ankapong et

al. [23]

²³⁸U, ²³²Th

radionuclide uptake.

Mean soil activities were 59 ±

16 Bq kg⁻¹ for ²³⁸U, 48 ± 15

Bq kg⁻¹ for ²³²Th, and 286 ±

Soil: ²³⁸U, ²³²Th,

⁴⁰K; Water: ²²⁶Ra,

²²⁸Th, ⁴⁰K

Faanu et al.

[24]

Not reported 57 Bq kg⁻¹ for ⁴⁰K. Total

annual effective dose was

below the ICRP public dose

limit.

Mean activities were 65.1 ±

2.2 Bq kg^-1for ²³⁸U, 71.8 ±

2.2 Bq kg^-1for ²³²Th, and

Faanu et al.

[24]

²³⁸U, ²³²Th, ⁴⁰K

²²⁶Ra, ²³²Th, ⁴⁰K

²³⁸U, ²³²Th, ⁴⁰K

Not reported 1168.3 Bq kg^-1for ⁴⁰K. Total

annual effective dose was

0.918 mSv, below the 1 mSv

public exposure limit.

Artisanal gold mining

influenced environmental

Estimated

for ²²⁶Ra in

vegetation

radioactivity. Water posed

greater radiological concern

than soil, with some samples

exceeding WHO screening

levels.

Akuo-ko et

al. [25]

Mean soil activities were

25.51 Bq kg⁻¹ for ²³⁸U, 28.04

Bq kg^-1for ²³²Th, and 238.98

Adukpo et al.

[26]

Not reported Bq kg^-1for ⁴⁰K. Annual

effective dose from water

remained within

recommended limits.

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Mean activities were 8.65 Bq

kg⁻¹ for ²³⁸U, 12.5 Bq kg^-1for

²³²Th, and 214 Bq kg^-1for

⁴⁰K. Hazard indices and

ELCR were within

Doyi et al.

[21]

²³⁸U, ²³²Th, ⁴⁰K

Not reported

recommended limits.

Radionuclide concentrations

in maize were measured and

radiological implications

assessed, but soil-to-plant

transfer factors were not

calculated.

Acquah &

Pooko-

Aikins [27]

⁴⁰K, ²²⁶Ra, ²³²Th

Note: TF = transfer factor. Studies marked “Not reported” are relevant to environmental distribution and

radiological assessment but did not calculate soil-to-plant transfer factors.

Table 4. Published Studies on Environmental Distribution, Naturally Occurring Radionuclides

(NORMs), and Radiological Assessment in Burkina Faso

Major Findings

Sources

Activity concentrations of ²³⁸U, ²³²Th and Beogo et al.

⁴⁰K were measured using HPGe gamma-

ray spectrometry. Three high-background

radiation zones associated with uranium,

thorium and potassium were identified.

Most radiological hazard indices (Raeq,

H_ex, H_in, AEDE and ELCR) were below

internationally recommended limits,

although Niapsi recorded slightly

[28]

elevated dose indices.

Uranium activity concentrations (181.89– Beogo et al.

191.37 Bq kg^-1) were approximately five

times the global average, while thorium

concentrations were nearly twice the

global average. Absorbed dose rate,

internal hazard index, annual effective

dose and excess lifetime cancer risk

exceeded recommended limits, indicating

elevated radiological hazards.

[28]

High concentrations of uranium and

thorium were observed relative to world

averages. Radiological assessment

indicated elevated absorbed dose rate,

annual effective dose and excess lifetime

cancer risk, whereas radium equivalent

activity and external hazard index

remained within acceptable limits.

Beogo et al.

[28]

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Activity concentrations of naturally

occurring radionuclides were below

UNSCEAR global averages. Calculated

absorbed dose rates and annual effective

doses indicated low terrestrial radiation

exposure and minimal radiological risk.

Yaméogo et

al. [29]

Mean activity concentrations and all

calculated radiological hazard indices

were below internationally accepted

limits, indicating negligible radiological

risk around the gold mining area.

Kaboré et

al. [30]

Naturally occurring radionuclides were

Nabayaogo

detected in waste rock and ore-processing et al. [31]

sludge at relatively low concentrations.

Radiation exposure to mine workers did

not exceed natural background levels,

and waste rock was considered suitable

for reuse in road construction.

Factors Influencing Soil-to-Plant Transfer of Naturally Occurring Radionuclides

A complex interplay of soil properties, radionuclide chemistry, plant physiology, and environmental factors

controls the movement of naturally occurring radionuclides from soil to plants. Thus, even for the same crop

species and radionuclide, soil-to-plant transfer factors (TFs) show significant temporal and geographical

heterogeneity. Predicting radionuclide mobility, evaluating food-chain contamination, and enhancing

radiological risk assessment all depend on an understanding of these regulating mechanisms. Since radionuclide

uptake is dependent on site-specific environmental circumstances and agricultural methods, international

guideline acknowledges that no single transfer factor is universally applicable [1,3].

Soil Physicochemical Properties

Radionuclide mobility and bioavailability are largely influenced by the physicochemical characteristics of the

soil. Radionuclide adsorption, desorption, dissolution, and complexation are controlled by factors including soil

pH, organic matter concentration, clay mineralogy, cation exchange capacity, soil texture, moisture content, and

redox potential. While clay-rich and organic matter-rich soils immobilize radionuclides through adsorption and

ion-exchange reactions, decreasing plant uptake, acidic soils typically increase the mobility of uranium and

radium. Recent studies also show that the spatial distribution and bioavailability of naturally occurring

radionuclides are strongly influenced by soil mineralogy and geological composition [3].

Radionuclide Characteristics

The oxidation state, ionic radius, chemical speciation, valence, and half-life of radionuclides all have a

significant impact on how they behave in the environment. Since potassium is a necessary plant macronutrient

and frequently produces higher transfer factors than uranium-238 and thorium-232, potassium-40 is easily

absorbed. Because of its great affinity for organic matter and soil minerals, thorium typically has the lowest

mobility, while uranium exhibits intermediate mobility based on its oxidation state and the development of

soluble carbonate complexes [3,13].

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Plant Species and Physiological Characteristics

The ability of different plant species to absorb, translocate, and accumulate radionuclides varies greatly due to

differences in development stage, metabolic activity, transpiration rate, root shape, and nutrient uptake processes.

While shallow-rooted species mostly reflect radioactive concentrations in surface soils, deep-rooted crops may

have access to radionuclides from deeper soil layers. Because of limited translocation through the vascular

system, roots often show higher activity concentrations than edible tissues when it comes to radionuclide

accumulation [3,13].

Agricultural and Environmental Conditions

Radionuclide bioavailability is significantly influenced by agricultural practices. Radionuclide mobility is

impacted by soil chemistry changes brought about by the use of phosphate fertilizers, irrigation, liming, organic

additions, and tillage. By affecting weathering processes, microbial activity, and root formation, climate factors

like temperature, rainfall, and seasonal moisture dynamics further control radionuclide transfer. Radionuclide

concentrations in agricultural soils may rise as a result of mining and mineral processing operations, raising the

possibility of food chain transmission [13].

Competitive Uptake and Elemental Interactions

Competitive interactions between radionuclides and chemically similar nutritional elements in the soil solution

also affect radionuclide uptake. Phosphate affects uranium mobility by adsorption and complexation processes,

potassium competes with caesium, and calcium competes with radium. As a result, in addition to radioactive

concentration, radionuclide transfer also depends on nutritional availability and the larger geochemical

environment, which adds to the variation in transfer factors found in different ecosystems [3].

Analytical and Methodological Factors

Variability in reported transfer factors is also significantly influenced by variations in sampling strategy,

experimental design, and analytical methods. Calculated TF values can be greatly impacted by variables such

sampling depth, plant growth stage, sample preparation, moisture adjustment, analytical equipment, and the use

of fresh- versus dry-weight measurements. Therefore, for a meaningful comparison of transfer factors across

studies and geographical regions, standardized analytical methodologies and quality assurance procedures are

necessary [1].

Synthesis of Published Studies and Research Gaps in West Africa

The distribution, transmission, and radiological evaluation of naturally occurring radionuclides in West Africa

vary significantly, according to published research. Despite significant contributions from Burkina Faso, Ghana,

and Nigeria to the regional body of evidence, research is nonetheless methodologically inconsistent and

geographically dispersed. Relatively few studies have measured radionuclide transmission through terrestrial

food chains, while the majority have concentrated on assessing radiological hazard indices and activity

concentrations of naturally occurring radionuclides in environmental media.

Uneven Geographical Distribution of Research

Nigeria and Ghana account for the majority of published studies on naturally occurring radionuclides in West

Africa, according to the country-specific study. Groundwater, food crops, mining environments, agricultural

soils, and environmental dose assessment are all included in these investigations. Peer-reviewed studies from

Benin, Côte d'Ivoire, Guinea, Guinea-Bissau, Liberia, Sierra Leone, The Gambia, and Cabo Verde are either

nonexistent or extremely rare, whereas Burkina Faso and Mali have comparatively few published studies. This

unequal geographic distribution makes it difficult to compare radionuclide behavior across various geological

and climatic zones and restricts the creation of an extensive regional radioecological database [7,8,9].

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Predominance of Environmental Radioactivity Studies

According to the reviewed literature, the majority of studies have focused on determining the activity

concentrations of ²²²Ra, ²³²Th, and ⁴⁰K in mining environments, soils, sediments, and water. This has been

followed by the estimation of radiological hazard indices like excess lifetime cancer risk (ELCR), radium

equivalent activity (Ra_eq), absorbed dose rate (ADR), annual effective dose equivalent (AEDE), external hazard

index (H_ex), internal hazard index (H_in), and external hazard index. These evaluations offer useful data on

radiation exposure in the environment, but they don't provide much information about radionuclide transport

through agricultural food chains and subsequent internal human exposure [11].

Limited Soil-to-Plant Transfer Investigationsy

The scarcity of studies documenting soil-to-plant transfer factors (TFs) is one of the biggest knowledge gaps

found. The majority of research from Burkina Faso and Mali concentrated solely on environmental radioactivity

and radiological hazard assessment, while Ghana and a few studies from Nigeria indicated transfer factors for

specific crops. In most of West Africa, there is still a lack of quantitative data on radionuclide uptake by major

crops such maize, rice, cassava, sorghum, millet, yam, and vegetables. This restriction adds a great deal of

uncertainty to internal dosage assessment and food-chain modeling.

Insufficient Crop Diversity

Current studies are often limited to a small number of agricultural goods and assess only one or two crop species

within specific research regions. Despite their significance in regional diets, major staple crops consumed

throughout West Africa such as millet, sorghum, cowpea, groundnut, yam, cocoyam, plantain, and leafy

vegetables have gotten very little attention. As a result, it is still difficult to determine radionuclide transfer

coefficients that are typical of West African food systems.

Lack of Standardized Methodologies

Studies varied significantly in terms of reporting units, sample preparation, analytical methods, sampling

procedures, and transfer factor computations. Although the most common analytical method is high-purity

germanium (HPGe) gamma spectrometry, direct comparison between studies is complicated by differences in

sampling depth, soil characterization, plant sampling protocols, moisture correction, and quality assurance

procedures. The creation of trustworthy regional transfer databases is hampered by the lack of standardized

procedures.

Limited Integration of Soil Properties with Radionuclide Transfer

Relatively few studies concurrently characterize soil parameters like pH, cation exchange capacity, organic

carbon, clay mineralogy, redox potential, and particle-size distribution with radionuclide transfer measurements,

despite the fact that soil physicochemical properties have a significant impact on radionuclide bioavailability. As

a result, our mechanistic knowledge of radionuclide mobility in tropical West African soil is still lacking.

Scarcity of Long-Term Monitoring Programmes

The majority of the studies that are currently accessible are cross-sectional and reflect individual sampling

campaigns. Long-term monitoring of radioactive concentrations in soils, crops, irrigation water, and groundwater

is virtually lacking. Detecting temporal variations related to mining operations, fertilizer application, temperature

fluctuation, land-use change, and environmental deterioration requires this kind of monitoring.

Limited Human Dose and Health Risk Assessments

Few studies combined radionuclide transfer data with dietary consumption patterns to estimate committed

effective dose, lifetime cancer risk, or age-specific internal exposure, despite the fact that several studies

measured exterior radiation exposure. Despite their increased susceptibility to ionizing radiation, there are still

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very few studies that specifically address newborns, young children, pregnant women, and other susceptible

populations.

Need for Region-Specific Transfer Factors

In West Africa, a lot of radioecological risk estimates are still based on default transfer factors from the IAEA or

other international databases. Although these values offer helpful benchmarks, they might not fully capture

radionuclide behavior in West Africa's distinct climatic, geological, pedological, and agricultural contexts.

Therefore, creating transfer factors for important staple crops that are derived locally has to be prioritized in

regional research.

Human Exposure Pathways

Humans can be exposed to naturally occurring radionuclides by eating, breathing, or being exposed to them.

Geological circumstances, environmental contaminants, dietary practices, occupational activities, and lifestyle

all affect each pathway's relative contribution. The risk of long-term exposure to naturally occurring

radionuclides is increased in West Africa due to artisanal mining, agriculture, groundwater usage, and reliance

on locally produced foods. As a result, measuring internal and exterior radiation doses and assessing related

public health hazards require an understanding of these routes [5].

Ingestion

The main way that naturally occurring radionuclides reach the human body under typical environmental

circumstances is by ingestion. Regular use of potable water, seafood, livestock products, and crops can expose

humans to radionuclides. While radionuclides of the uranium and thorium series typically exist at lower

concentrations but may contribute more significantly to internal radiation exposure due to their radiotoxicity,

potassium-40 typically contributes the highest activity concentrations since it is an essential food. Therefore,

radionuclide content, food consumption habits, and regional agricultural techniques all affect dietary exposure

[5].

Inhalation

Radon gas and dust containing radionuclides can be inhaled. Airborne particles enriched with naturally occurring

radionuclides can be produced by mining, quarrying, agriculture, and wind erosion. Because its decay products

accumulate in the respiratory system and raise the risk of lung cancer after extended exposure, radon (²²²Rn),

which is created from the decay of ²²⁶Ra, is especially significant. Mining communities and inadequately

ventilated interior spaces are especially vulnerable to this pathway [31,32].

External Irradiation

Gamma radiation from naturally occurring radionuclides found in soils, rocks, sediments, and building materials

causes external irradiation. The main sources of gamma radiation on land are uranium-238, thorium-232, and

potassium-40. The majority of studies conducted in West Africa report radiation levels within internationally

recommended limits; however, some mining environments and geological formations rich in phosphate and

uranium have been found to have elevated exposures, which calls for ongoing environmental monitoring [1,33].

Occupational Exposure

Workers engaged in mining, mineral processing, phosphate industries, and oil and gas operations where naturally

occurring radioactive materials (NORMs) are concentrated are primarily affected by occupational exposure.

Inhalation, ingestion, and external radiation exposure can all happen at the same time. Continuous monitoring,

engineering controls, and suitable radiation protection measures are crucial for reducing long-term health

concerns, even when occupational doses often stay below legal limits [2].

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Cumulative Exposure

Instead of a single channel, human exposure typically arises from the combined effects of eating, inhalation, and

external irradiation. In order to evaluate the overall effective dosage, a thorough radiological risk assessment

incorporates environmental radionuclide concentrations with transfer factors, food intake rates, occupancy

factors, and age-specific dose coefficients. In areas impacted by naturally occurring radionuclides, such

integrated evaluations offer a more practical foundation for environmental management and public health

protection [5].

Health Effects of Naturally Occurring Radionuclides

Human health may be negatively impacted by exposure to naturally occurring radionuclides, depending on the

kind of radionuclide, activity concentration, exposure route, length of exposure, and individual susceptibility.

Long-term exposure to high amounts of naturally occurring radioactive materials (NORMs) may raise the risk

of stochastic consequences, especially cancer, even though natural background radiation is an inevitable aspect

of the environment. Because radionuclides can build up in particular organs and constantly irradiate nearby

tissues, internal exposure through ingestion and inhalation is typically more concerning than exterior irradiation

[1,2,33].

Cancer Risk

Long-term exposure to uranium, radium, radon, and their decay products has been linked to higher risks of

kidney, lung, and bone malignancies. According to WHO [32], ingestion of contaminated food and drinking

water may increase internal radiation exposure and long-term cancer risk, while radon inhalation is

acknowledged as the second most common cause of lung cancer after tobacco use.

Organ Toxicity

Radionuclides that occur naturally tend to build up in particular organs. Because of its chemical resemblance to

calcium, radium is mostly deposited in bones, while uranium mostly builds up in the kidneys, where extended

exposure may induce both chemical and radiological damage. The biological effects of long-term radionuclide

exposure are influenced by several organ-specific behaviors [33].

Sensitive Populations

Due to rapid tissue growth, physiological variations, or chronic exposure, radiation-induced health problems are

more likely to affect infants, children, pregnant women, and occupational exposed workers. Therefore, accurate

radiological risk assessment and efficient public health protection depend on age-specific dose assessment [33].

Public Health Implications

The majority of West African research reports environmental radionuclide quantities that fall within globally

advised bounds. However, there may be increased exposure concerns in specific locations connected to mining,

phosphate resources, and uranium-rich geological formations. Thus, evidence-based radiation protection and

food safety policies require ongoing environmental monitoring, food surveillance, groundwater evaluation, and

the creation of locally derived transfer factors [5].

Future Research Directions

Development of Local Transfer Factors

The creation of locally developed soil-to-plant transfer factors (TFs) for important staple crops grown in various

agroecological environments in West Africa should be the main focus of future research. The application of

generalized transfer coefficients from temperate environments would be less uncertain and radioecological

models would be more reliable using region-specific TF measurements [1,2,33].

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Integrated Environmental Monitoring

To better understand radionuclide transport across terrestrial food chains, extensive research incorporating soils,

irrigation water, crops, groundwater, and food items are needed. These interdisciplinary methods would increase

estimates of internal radiation exposure and bolster environmental monitoring [5].

Long-Term Monitoring

Single sample efforts provide the basis for the majority of existing research. Therefore, long-term environmental

surveillance is necessary to assess temporal variations in radionuclide distribution and related radiological risks,

especially in mining regions, phosphate-bearing formations, and naturally high-background radiation areas [34].

Methodological Harmonization

Standardized sampling techniques, analytical techniques, quality assurance procedures, and reporting

frameworks should be used in future research to assist the creation of regional radioecological databases and

enable study comparison. Transfer factor datasets and environmental risk assessments will be more reliable with

harmonized approaches [3]

Public Health Research

With a focus on infants, children, pregnant women, and populations living in mining and high-background

radiation areas, future research should incorporate dietary exposure assessment, age-dependent dose modeling,

and epidemiological studies. These investigations are crucial for bolstering evidence-based radiation protection

and food safety regulations [5,35].

Regional Collaboration

Strengthening collaboration among research institutions, regulatory agencies, and international organizations

will facilitate data sharing, harmonized monitoring programmes, and coordinated radioecological research.

Regional cooperation is essential for developing comprehensive environmental radionuclide databases and

improving radiation protection strategies across West Africa [5].

CONCLUSION

In West Africa, naturally occurring radionuclides continue to be a significant source of environmental radiation

exposure, and their transfer from soil to plants is a crucial route for human consumption through the food chain.

This research shows that soil qualities, radionuclide chemistry, plant traits, and environmental factors all

influence the mobility and bioavailability of radionuclides, leading to significant diversity in soil-to-plant

transfer factors. The reviewed papers show that while quantitative studies of soil-to-plant transmission are still

scarce and spatially unequal, research in West Africa has mostly concentrated on environmental radioactivity

and radiological hazard assessment. The majority of published research comes from Nigeria and Ghana, although

there are still large information gaps in many other West African nations. Regional exposure and risk evaluations

are also made questionable by the absence of long-term monitoring programs, locally generated transfer factors,

and standardized procedures. Standardized radioecological studies, the creation of region-specific transfer factor

databases for important staple crops, integrated food-chain evaluations, and ongoing environmental monitoring

should be the main focus of future research. By filling in these gaps, radiological risk assessment will be

strengthened, evidence-based food safety and environmental management will be supported, and radiation

protection policies throughout West Africa will be improved.

REFERENCES

1. Chen, J. (2024). A summary of UNSCEAR evaluation on medical exposure to ionizing radiation and call

for more representative data. Radiation Medicine and Protection, 5(01), 7-10.

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2. Joint, F. A. O. (2010). Handbook of Parameter Values for the Prediction of Radionuclide Transfer in

Terrestrial and Freshwater Environments.

3. Dirican, A., Dikmen, H., Şahin, M., Gülay, Y., Özkök, Y. Ö., Kaya, N., & Vural, M. (2024). Transfer factors

of 238U, 232Th, 40K, 210Pb to crops and radiation impact assessment in semi-arid environment. Journal

of Radioanalytical and Nuclear Chemistry, 333(11), 5597-5606.

4. Wais, T. Y., Namq, B. F., Najam, L. A., Othman, S. Q., Hussein, Z. A., Al-Taii, H. A., ... & Kumar, A.

(2025). Investigation of natural radionuclide transfer from soil to wheat. Scientific Reports, 15(1), 35785.

5. Lawluvi, H., Boateng, B. B. A., Nyankah, E., & Warmann, E. S. (2026). Environmental pathways of

radionuclide transfer in food chains in west Africa: Current knowledge and research gaps.

6. Orosun, M. M., Usikalu, M. R., Oyewumi, K. J., Omeje, M., Awolola, G. V., Ajibola, O., & Tibbett, M.

(2022). Soil-to-plant transfer of 40K, 238U and 232Th and radiological risk assessment of selected mining

sites in Nigeria. Heliyon, 8(11).

7. Mahmoud, M. H., & El-Zohry, M. A. (2025). Radionuclide Uptake and Soil-to-Plant Transfer Factor of

Naturally Occurring Radionuclides (²³⁸U, ²³²Th and ⁴⁰K) in Leafy Vegetables from FarmingAreas in Sohag,

Upper Egypt. Arab Journal of Nuclear Sciences and Applications, 58(3), 46-57.

8. Nair, P. R., Kumar, B. M., & Nair, V. D. (2022). Soils and agroforestry: general principles. In An

Introduction to Agroforestry: Four Decades of Scientific Developments (pp. 367-382). Cham: Springer

International Publishing.

9. Chen, L., Liu, J., Zhang, W., Zhou, J., Luo, D., & Li, Z. (2021). Uranium (U) source, speciation, uptake,

toxicity and bioremediation strategies in soil-plant system: a review. Journal of Hazardous Materials, 413,

125319.

10. Smedley, P. L., & Kinniburgh, D. G. (2023). Uranium in natural waters and the environment: Distribution,

speciation and impact. Applied Geochemistry, 148, 105534.

11. Patel, K. S., Sharma, S., Maity, J. P., Martín-Ramos, P., Fiket, Ž., Bhattacharya, P., & Zhu, Y. (2023).

Occurrence of uranium, thorium and rare earth elements in the environment: A review. Frontiers in

environmental Science, 10, 1058053.

12. Sparks, D. L., Singh, B., & Siebecker, M. G. (2022). Environmental soil chemistry. Elsevier.

13. Orosun, M. M., Oladipo, M. O. A., Isinkaye, M. O., Yusuf, N. M., & Khandaker, M. U. (2022). Soil-to-

plant transfer of ⁴⁰K, ²³⁸U and ²³²Th and radiological risk assessment of selected mining sites in Nigeria.

Scientific Reports, 12, 18874. https://doi.org/10.1038/s41598-022-23357-8

14. Ajayi, O. S. (2009). Measurement of activity concentrations of 40K, 226Ra and 232Th for assessment of

radiation hazards from soils of the southwestern region of Nigeria. Radiation and Environmental

Biophysics, 48(3), 323-332.

15. Adesiji, N. E., & Ademola, J. A. (2019). Soil-to-maize transfer factor of natural radionuclides in a tropical

ecosystem of Nigeria. Nigeria Journal of Pure and Applied Physics, 9(1), 6-10.

16. Davis, R. A., Rippner, D. A., Hausner, S. H., Parikh, S. J., McElrone, A. J., & Sutcliffe, J. L. (2017). In

vivo tracking of copper-64 radiolabeled nanoparticles in Lactuca sativa. Environmental science &

technology, 51(21), 12537-12546.

17. Waida, J., Rilwan, U., Galadima, O. O., Omita, E., Sawuta, J. M., Ojike, P. E., & Rebecca, R. (2022).

Transfer of K40, Ra226 and Th232 from soil to plants and water resulting from mining activities in Bassa,

Plateau State, Nigeria (health implications on the inhabitants). J. Eco. Heal. Env, 10(2), 5-11.

18. Oladele, B. B., Ugbede, F. O., Arogunjo, A. M., Ajayi, O. S., & Pereira, A. (2023). Gamma spectroscopy

study of soil-plant transfer factor characteristics of 40K, 232Th and 226Ra in some crops cultivated in

southwestern region of Nigeria. Heliyon, 9(9).

19. Olabimtan, S. O., Chifu, E. N., Nasir, M., & Hafeez, Y. H. (2023). Assessment of activity concentrations

and soil-to-plant transfer factors of natural radioactivity in rice plant components grown in Kano State,

Nigeria. Nigerian Journal of Physics, 32(4), 1-12.

20. Moran-Hunter, C. (2008). Transfer of radionuclides from soil to vegetation in selected Irish ecosystems.

21. Doyi, I. N. Y., Essumang, D. K., Agyapong, A. K., & Asumadu-Sarkodie, S. (2018). Soil-to-cassava

transfer of naturally occurring radionuclides from communities along Ghana's oil and gas rich Tano

Basin. Journal of environmental radioactivity, 182, 138-141.

22. Adjirackor, T., Darko, E. O., & Sam, F. (2017). Naturally occurring radionuclide transfer from soil to

vegetables in some farmlands in Ghana and statistical analysis. Radiation Protection and

Environment, 40(1), 34-43.

Page 3985

www.rsisinternational.org

INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,

MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)

ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue VI, June 2026

23. Ankapong, E., Gyamfi, O., Agyei, V., Dodd, M., Akoto, O., & Darko, G. (2024). Soil-to-plant transfer

factors of uranium and thorium in mining and non-mining districts of Ghana. Journal of Environmental

Radioactivity, 280, 107566.

24. Faanu, A., Adukpo, O. K., Tettey-Larbi, L., Lawluvi, H., Kpeglo, D. O., Darko, E. O., ... & Agyeman, L.

(2016). Natural radioactivity levels in soils, rocks and water at a mining concession of Perseus gold mine

and surrounding towns in Central Region of Ghana. SpringerPlus, 5(1), 98.

25. Akuo-ko, E. O., Otoo, F., Glover, E. T., Amponsem, E., Tettey-Larbi, L., Ganbaatar, T., ... & Kovács, T.

(2025). Radiological implications of industrial activities on soil and water: an environmental analytical

chemistry perspective in artisanal gold-mining regions of Atiwa West. Applied Sciences, 15(18), 9857.

26. Adukpo, O. K., Faanu, A., Lawluvi, H., Tettey-Larbi, L., Emi-Reynolds, G., Darko, E. O., ... & Doe, A. I.

(2015). Distribution and assessment of radionuclides in sediments, soil and water from the lower basin of

river Pra in the Central and Western Regions of Ghana. Journal of radioanalytical and nuclear

chemistry, 303(3), 1679-1685.

27. Acquah, G. F., & Pooko-Aikins, M. (2013). Foodstuffs and cancer: Analysis of radionuclides and its

radiation levels in common Ghanaian maize. International Journal of Sciences Basic and Applied

Research (IJSBAR), 12(1), 1-7.

28. Beogo, C. E., Cisse, O. I., & Zougmore, F. (2022). Assessment of radiological hazards from soil samples

in the Northeastern area of Burkina Faso. SN Applied Sciences, 4(3), 73.

29. Yaméogo, Z., Nabayaogo, D., Kaboré, O., Bangou, C., Zebo, I., & Zoungrana, M. (2022). Measurements

of natural radioactivity and exposure rates in soil samples from Ouagadougou, Burkina Faso. J Mater

Environ Sci, 13(1), 129-138.

30. Kabore, K., Bambara, L. T., Zongo, I., Cisse, O., Zougmore, F., & Darko, E. O. (2022). Natural

radioactivity level and evaluation of radiological hazard in the soil around a gold mining area in the North

Region of Burkina Faso. International Journal of Global Environmental Issues, 21(2-4), 343-356.

31. Nabayaogo, D., Oliveira, J. M., & Carvalho, F. P. (2022). Environmental radioactivity in gold mining in

Burkina Faso and potential recycling of mining waste rocks. International Journal of Environmental

Studies, 79(6), 1067-1077.

32. World Health Organization. (2009). WHO handbook on indoor radon: a public health perspective. World

Health Organization.

33. ICRP (International Commission on Radiological Protection). (2017). Occupational intakes of

radionuclides: part 3. ICRP publication 137. Ann. ICRP, 46, 1-487.

34. Belaid, N., Tsabaris, C., Trabelsi, R., & Zouari, K. (2026). Radiological survey and environmental risk

assessment around the fertilizer and phosphoric acid former plant of Sfax, Tunisia. Euro-Mediterranean

Journal for Environmental Integration, 11(4), 151.

35. Mihalik, J., Chelaifa, H., Alzaabi, M., & Alkaabi, A. K. (2024). Challenges in radioecology following the

new trends in UAE’s agriculture and environmental changes: a review. Environmental Science and

Pollution Research, 31(49), 58779-58794.

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www.rsisinternational.org