**3. Results and discussion**

### **3.1 Results**

The measured radioactivity levels of the three naturally occurring radionuclides, 226Ra, 232Th, and 40K, identified in the sampled milk under investigation including their uncertainty are presented in **Table 1**.

The obtained results of the radioactivity concentration indicate that 226Ra activity in powdered milk varied from 14.2 5.9 Bq kg<sup>1</sup> to 26.8 8.3 Bq kg<sup>1</sup> with a mean activity concentration of 19.3 7.2 Bq kg<sup>1</sup> , and 232Th activity varied from 8.8 3.6 Bq kg<sup>1</sup> to 15.0 5.9 Bq kg<sup>1</sup> with a mean activity concentration of 12.1 4.8 Bq kg<sup>1</sup> , while 40K varied from 317.5 77.6 Bq kg<sup>1</sup> to 589.8 94.6 Bq kg<sup>1</sup> with a mean activity level of 468.0 72.7 Bq kg<sup>1</sup> . The 226Ra radioactivity concentration in liquid milk varied from 12.2 4.7 Bq kg<sup>1</sup> to 21.2 8.3 Bq kg<sup>1</sup> with a mean activity concentration of 16.6 6.3 Bq kg<sup>1</sup> , and 232Th activity concentration varied from 6.8 3.0 Bq kg<sup>1</sup> to 13.2 6.1 Bq kg<sup>1</sup> with a mean activity concentration of 10.6 4.3 Bq kg<sup>1</sup> , while 40K varied from 218.6 39.4 Bq kg<sup>1</sup> to 484.2 67.9 Bq kg<sup>1</sup> with a mean activity level of 317.6 58.5 Bq kg<sup>1</sup> . It was observed that 40K samples have the highest activity concentration trailed by 226Ra samples, while 232Th samples had the least activity level. Evaluation of the three naturally occurring radionuclide concentrations in the milk samples with the UNSEAR 2000 permissible limit for powdered milks and liquid milk samples shows that all 226Ra and 232Th activity levels in both samples are well below the permissible limits, while 40K exceeded the permissible limit in Peak milk, Peak Chocolate, Cowbell Chocolate, Loya, Miksi, Coast, Real, and Nunu milk for powdered milk and exceeded the permissible limit for liquid milk in Vital and Nutric milk. It is pertinent to note that the activity levels determined in the current study are above the values gotten for milk consumed in some countries like Saudi Arabia [7]; Iran/France [14]; Jordan [15]; Egypt [16]; and Syria [17], while the values are comparable to those milk consumed in other countries like New Zealand [14] and Brazil [18]. Conversely, this result shows that the mean activity concentrations in the various milk brands sampled are well within their international permissible limits. The difference in the radioactivity levels in the various brands of milk sampled suggests that the source of raw materials used for the production of the milks is a contributory factor.

The estimated Radium equivalent (*Raeq*), annual gonadal dose equivalent (AGED), internal hazard (*Hin*) indices, annual effective dose equivalent (AEDE) received, and excess lifetime cancer risk (ELCR) for the various milk products sampled are presented in **Table 2**.

measured and is based on the estimation that 1.0 Bqkg�<sup>1</sup> of 226Ra, 0.7 Bq kg�<sup>1</sup> of 232Th, and 13.0 Bq kg�<sup>1</sup> of 40K produce equal radiation dose rates [23, 24]. The radium equivalent activity concentration is given as [23]:

*Specific activity concentration of the powdered and liquid milk products commonly consumed in Nigeria.*

**Mean activity conc. 16.6** � **6.3 10.6** � **4.3 317.6** � **58.5**

**S/N Powdered milk sample Radioactivity concentration (Bq kg**�**<sup>1</sup>**

*DOI: http://dx.doi.org/10.5772/intechopen.92279*

*Economic Approach to Risk Analysis of Naturally Occurring Radioactive Materials (NORMs)…*

 Peak milk 26.8 � 8.3 9.5 � 2.2 536.1 � 84.3 Peak Chocó milk 17.6 � 6.9 12.3 � 4.1 424.7 � 67.9 Cowbell milk 17.4 � 7.1 13.1 � 5.4 317.5 � 77.6 Cowbell Chocó milk 16.4 � 6.7 8.8 � 3.6 544.2 � 83.4 Nunu milk 26.5 � 6.5 10.1 � 4.9 513.5 � 74.3 Loya milk 14.2 � 5.9 14.7 � 6.1 413.3 � 83.3 Miksi milk 15.1 � 7.2 12.8 � 5.5 589.8 � 94.6 Coast 18.6 � 6.0 13.3 � 6.3 422.4 � 64.4 Real milk 21.0 � 8.5 15.0 � 5.9 519.9 � 95.6 Dano milk (Demark) 19.5 � 8.4 10.9 � 4.2 398.4 � 66.3

**Mean activity conc. 19.3** � **7.2 12.1** � **4.8 468.0** � **72.7**

**S/N Liquid milk sample Radioactivity concentration (Bq l**�**<sup>1</sup>**

 Hollandia milk 12.2 � 4.7 12.6 � 5.8 321.4 � 66.3 Vital milk 21.2 � 8.4 9.9 � 3.8 476.1 � 84.1 Nutric milk 15.0 � 5.9 8.9 � 3.2 484.2 � 67.9 Peak milk 13.2 � 4.6 8.0 � 3.1 218.7 � 49.0 Three Crown milk 17.2 � 8.3 13.2 � 5.7 324.2 � 51.9 Olympic milk 16.3 � 4.5 12.5 � 4.6 268.9 � 58.6 Coast milk 18.1 � 5.5 13.2 � 6.1 312.8 � 49.3 Nunu milk 17.5 � 6.3 9.9 � 3.6 218.6 � 39.4 Condensed Peak milk 19.2 � 8.4 10.6 � 4.2 272.9 � 50.1 Bridel milk (France) 15.8 � 6.5 11.3 � 4.6 282.2 � 73.3 Lady Liberty (USA) 14.2 � 6.1 6.8 � 3.0 313.3 � 53.3

**)**

**)**

**226Ra 232Th 40K**

**226Ra 232Th 40K**

where *CRa*, *CTh*, and *CK* are the radioactivity concentrations in Bq kg�<sup>1</sup> of 226Ra,

The consumption of any foodstuff whose *Raeq* concentration exceeds 370 Bq kg�<sup>1</sup>

72.6 � 19.7 Bq kg�<sup>1</sup> in powdered milk brands, while in liquid milk brand, the range of value is 41.5 � 12.9 Bq l�<sup>1</sup> in Peak milk to 72.0 � 20.3 Bq l�<sup>1</sup> in Nutric milk with a

should be discouraged to avoid radiation hazards. The result of the estimated radium equivalent dose rates in **Table 2** shows a value range of 60.6 � 20.8 Bq kg�<sup>1</sup>

in Cowbell milk to 82.5 � 24.3 Bq kg�<sup>1</sup> in real milk with a mean value of

232Th, and 40K, respectively.

**Table 1.**

**65**

Raeq ¼ CRa þ 1*:*43 CTh þ 0*:*0770 CK (1)

## **3.2 Radium equivalent activity (***Raeq***)**

The model of the radium equivalent activity establishes the use of a single index to define the gamma output or compare the specific activities of materials containing 226Ra, 232Th, and 40K by a single quantity, which takes into consideration the radiation risk associated with these NORMs [19–22]. The radium equivalent activity represents a weighted factor of activities of the three natural radionuclides


*Economic Approach to Risk Analysis of Naturally Occurring Radioactive Materials (NORMs)… DOI: http://dx.doi.org/10.5772/intechopen.92279*

#### **Table 1.**

both the standard and sample measurement was used to correct the computed

The measured radioactivity levels of the three naturally occurring radionuclides, 226Ra, 232Th, and 40K, identified in the sampled milk under investigation including

The obtained results of the radioactivity concentration indicate that 226Ra activity in powdered milk varied from 14.2 5.9 Bq kg<sup>1</sup> to 26.8 8.3 Bq kg<sup>1</sup> with a

, while 40K varied from 317.5 77.6 Bq kg<sup>1</sup> to

8.8 3.6 Bq kg<sup>1</sup> to 15.0 5.9 Bq kg<sup>1</sup> with a mean activity concentration of

589.8 94.6 Bq kg<sup>1</sup> with a mean activity level of 468.0 72.7 Bq kg<sup>1</sup>

radioactivity concentration in liquid milk varied from 12.2 4.7 Bq kg<sup>1</sup> to 21.2 8.3 Bq kg<sup>1</sup> with a mean activity concentration of 16.6 6.3 Bq kg<sup>1</sup>

218.6 39.4 Bq kg<sup>1</sup> to 484.2 67.9 Bq kg<sup>1</sup> with a mean activity level of

232Th activity concentration varied from 6.8 3.0 Bq kg<sup>1</sup> to 13.2 6.1 Bq kg<sup>1</sup>

concentration trailed by 226Ra samples, while 232Th samples had the least activity level. Evaluation of the three naturally occurring radionuclide concentrations in the milk samples with the UNSEAR 2000 permissible limit for powdered milks and liquid milk samples shows that all 226Ra and 232Th activity levels in both samples are well below the permissible limits, while 40K exceeded the permissible limit in Peak milk, Peak Chocolate, Cowbell Chocolate, Loya, Miksi, Coast, Real, and Nunu milk for powdered milk and exceeded the permissible limit for liquid milk in Vital and Nutric milk. It is pertinent to note that the activity levels determined in the current study are above the values gotten for milk consumed in some countries like Saudi Arabia [7]; Iran/France [14]; Jordan [15]; Egypt [16]; and Syria [17], while the values are comparable to those milk consumed in other countries like New Zealand [14] and Brazil [18]. Conversely, this result shows that the mean activity concentrations in the various milk brands sampled are well within their international permissible limits. The difference in the radioactivity levels in the various brands of milk sampled suggests that the source of raw materials used for the production of

The estimated Radium equivalent (*Raeq*), annual gonadal dose equivalent (AGED), internal hazard (*Hin*) indices, annual effective dose equivalent (AEDE) received, and excess lifetime cancer risk (ELCR) for the various milk products

The model of the radium equivalent activity establishes the use of a single index

containing 226Ra, 232Th, and 40K by a single quantity, which takes into consideration the radiation risk associated with these NORMs [19–22]. The radium equivalent activity represents a weighted factor of activities of the three natural radionuclides

to define the gamma output or compare the specific activities of materials

. It was observed that 40K samples have the highest activity

, and 232Th activity varied from

, while 40K varied from

. The 226Ra

, and

sample activity concentration in agreement with Arogunjo et al. [13].

*Multifunctionality and Impacts of Organic and Conventional Agriculture*

**3. Results and discussion**

their uncertainty are presented in **Table 1**.

mean activity concentration of 19.3 7.2 Bq kg<sup>1</sup>

with a mean activity concentration of 10.6 4.3 Bq kg<sup>1</sup>

**3.1 Results**

12.1 4.8 Bq kg<sup>1</sup>

317.6 58.5 Bq kg<sup>1</sup>

the milks is a contributory factor.

sampled are presented in **Table 2**.

**64**

**3.2 Radium equivalent activity (***Raeq***)**

*Specific activity concentration of the powdered and liquid milk products commonly consumed in Nigeria.*

measured and is based on the estimation that 1.0 Bqkg�<sup>1</sup> of 226Ra, 0.7 Bq kg�<sup>1</sup> of 232Th, and 13.0 Bq kg�<sup>1</sup> of 40K produce equal radiation dose rates [23, 24].

The radium equivalent activity concentration is given as [23]:

$$\mathbf{R}\mathbf{a}\_{\rm eq} = \mathbf{C}\_{\rm Ra} + \mathbf{1.43}\,\mathbf{C}\_{\rm Th} + \mathbf{0.0770}\,\mathbf{C}\_{\rm K} \tag{1}$$

where *CRa*, *CTh*, and *CK* are the radioactivity concentrations in Bq kg�<sup>1</sup> of 226Ra, 232Th, and 40K, respectively.

The consumption of any foodstuff whose *Raeq* concentration exceeds 370 Bq kg�<sup>1</sup> should be discouraged to avoid radiation hazards. The result of the estimated radium equivalent dose rates in **Table 2** shows a value range of 60.6 � 20.8 Bq kg�<sup>1</sup> in Cowbell milk to 82.5 � 24.3 Bq kg�<sup>1</sup> in real milk with a mean value of 72.6 � 19.7 Bq kg�<sup>1</sup> in powdered milk brands, while in liquid milk brand, the range of value is 41.5 � 12.9 Bq l�<sup>1</sup> in Peak milk to 72.0 � 20.3 Bq l�<sup>1</sup> in Nutric milk with a


radionuclides (226Ra, 232Th, and 40K) to the liquid milk samples were computed to be 24, 36, and 40%, respectively, which shows that 232Th contributes the highest radioactivity dosage to both the powdered and liquid milk activity concentration.

*Economic Approach to Risk Analysis of Naturally Occurring Radioactive Materials (NORMs)…*

The gonads, the active bone marrow, and the bone surface cells are classified as

) owing to the specific activities of 226Ra, 232Th, and 40K was

AGED <sup>μ</sup>S vy�<sup>1</sup> <sup>¼</sup> <sup>3</sup>*:*09CRa <sup>þ</sup> <sup>4</sup>*:*18CTh <sup>þ</sup> <sup>0</sup>*:*314CK (2)

organs of interest by UNSCEAR (2003). The annual gonadal dose equivalent

*Percentage contribution of the three natural radionuclides measured in powdered milk.*

*Percentage contribution of the three natural radionuclides measured in liquid milk.*

**3.3 Annual gonad equivalent dose (AGED)**

*DOI: http://dx.doi.org/10.5772/intechopen.92279*

(AGED, mS vy�<sup>1</sup>

**Figure 1.**

**Figure 2.**

**67**

computed using [25]:

## *Multifunctionality and Impacts of Organic and Conventional Agriculture*

#### **Table 2.**

*Mean radium equivalent and summary of computed radiological risk parameter of milk samples.*

mean value of 56.2 17.0 Bq l<sup>1</sup> . All the values obtained are within the international acceptable limit for Raeq and therefore comply with the radium equivalent standard for radioactivity concentration. The percentage contributions of the three naturally occurring radionuclides in the powdered and liquid milk samples are shown in **Figures 1** and **2**, respectively. These percentages were calculated based on the estimation that 1 Bq kg<sup>1</sup> of 226Ra, 0.7 Bq kg<sup>1</sup> of 232Th, and 13 Bq kg<sup>1</sup> of 40K produce the same radiation dose rates in the radium equivalent [24]; the average percentage contribution of 40K is 42%, and for 226Ra the percentage contribution to the entire milk content is 20%, while 232Th percentage contribution to the powdered milk samples is 38%. The percentage contribution of the three natural

*Economic Approach to Risk Analysis of Naturally Occurring Radioactive Materials (NORMs)… DOI: http://dx.doi.org/10.5772/intechopen.92279*

radionuclides (226Ra, 232Th, and 40K) to the liquid milk samples were computed to be 24, 36, and 40%, respectively, which shows that 232Th contributes the highest radioactivity dosage to both the powdered and liquid milk activity concentration.
