INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS IN ESTIMATION OF ELEMENTS INTAKE TO THE HUMAN BODY WITH FOODSTUFFS *

A. Kist, L. Zhuk, E. Danilova, N. Osinskaya, T. Rakhmanova, S. Agzamova, R. Abdurasulov, S. Khusnitdinova, S. Jalalova, Kh. Useinova, A. Mukhina

Institute of Nuclear Physics, Ulughbek, Tashkent, 702132, Uzbekistan

Introduction

Estimation of trace elements (including toxic ones) intake to human body is an extremely important problem because deficiency or high levels of these elements intake may cause diseases in humans. There are many studies in this field including the recommendation of the International Commission on Radiological Protection¹ and Recommended Dietary Allowance (RDA) of joint FAO/IAEA/WHO Expert Committee². There are very averaged data. Actually each region may have quite different levels of elements intake³. It is given by the fact that some part of foodstuffs is produced in contaminated by industrial activity regions. Most of locally produced foodstuffs in Uzbekistan are from small private family farms. Meat, vegetables, and fruits on local markets (bazaars) is sometime checked from the veterinary point of view or on nitrates content. Metals are not checked. This a reason to start this study.

To estimate ranges of elements intake we started this work including the ìreference areaî (despite it is difficult to find rather clean and natural areas) and studied area. As a reference area Tashkent (the capital of Uzbekistan) district has been chosen. As a studied area has been selected region of the Almalyk with elevated level of contamination and worse in health status (non ferrous metals factory, phosphate fertilizer factory, etc.).

EXPERIMENAL

Sample collection and preparation

According to the inventory of typical diet (Uzbekistan Ministry of Health) samples of following foodstuffs were collected and analysed: legumes, wheat, rice, sleets, bread, local home made bread (pancake), pasta, potatoes, cabbage, cucumbers, tomatoes, beet, carrots, melons, water melons, berries and fruits (fresh and dried), grape (fresh and dried), meat (beef and mouton), chicken, fresh fish, milk, eggs, and drinking water. Samples were taken from studied area (Almalyk) and reference area (Tashkent) from local small markets (bazaars). To have representative samples each kind of samples were bought from different seller and different bazaar in small amounts or a single pieces (eggs). Collection has been carried out in two runs. In the first run (pilot run) were taken samples of all foodstuffs. In total was collected 10 ñ 15 samples of each kind of foodstuffs. In the second run were carried most informative samples (as it followed from the results of analyses of pilot run samples) ñ meet, some vegetables, eggs, milk, etc. In this run were additionally collected 10 ñ 15 samples of mentioned above foodstuffs.

Protocols for samples pre-treatment (sampling technique, cleaning, storage conditions, drying, etc.) according to type of samples were elaborated for:

1. Bread, legumes, rice, wheat, pasta, dried fruits;
2. Fruits and vegetables;
3. Meat (mouton, beef, fish) and eggs;
4. Milk and water

In general we tried to finish the process of samples preparation in day of sampling or, at least, next day to prevent spoiling.

Analysis

Samples were dried, packed and analysed using Instrumental Neutron Activation Analysis (INAA). Spectra were measured using HPGe detector.

Samples (packed into bags made of polyethylene film and high purity aluminium foil) were irradiated at the flux 6^.10¹³ n^.cm^-2.s^-1. The following elements were determined: Ag, Au, Br, Ca, Co, Cr, Cs, Cu, Fe, Hg, Hf, K, La, Mo, Mn, Na, Ni, Rb, Sb, Sc, Se, Th, U, and Zn. Irradiation/measurements scheme was as follows:

1. Irradiation time = 15 s, ìcoolingî time = 10 min for determination of I (¹²⁸I), and Cl (³⁸Cl). Measuring time = 100 s.

2. After additional ìcoolingî for 2 h for determination of Na (²⁴Na), K (⁴²K), Mn (⁵⁶ Mn), and Cu (⁶⁴Cu). Measuring time = 100 s.

3. Irradiation time 15 hours, ìcoolingî time 10 days for determination of Ca (⁴⁷Sc), Br (⁸² Br), Mo (⁹⁹Mo), La (¹⁴⁰La), Au (¹⁹⁸Au), and U (²³⁹Np). Measuring time = 200 s.

4. After additional ìcoolingî for 1 month for determination of Sc (⁴⁶Sc), Cr (⁵¹ Cr), Fe (⁵⁹Fe), Ni (⁵⁸Co), Co (⁶⁰Co), Zn (⁶⁵Zn), Se (⁷⁵Se), Rb (⁸⁶Rb), Sb (¹²⁴Sb), Cs (¹³⁴Cs), Hg (²⁰³Hg), Th (²³³Pa), U (²³⁹ Np), Hf (¹⁸¹ Hf). Measuring time = 400 s.

Standards were made by placing of microvolumes of the elements to be determined on the strips of ashless paper. In addition the comparator methods (Zn) has been used.

The analytical quality was tested using Research Material-IAEA-336 and AQCS Cabbage Material-IAEA-359.

RESULTS

In the Table 1 are compared individual foodstuffs according to the element concentrations. Significantly elevated are levels of Cu, Zn, and other elements in locally produced foodstuffs in studied area (presence of non ferrous metals factory). In some cases elevated levels are in reference area which needs additional discussions and studies, especially, in case of wheat and bread.

Despite of very wide interval of determined element concentrations obtained results allow to estimate the range of elements intake. In Table 2 are given ranges of total daily intake for several elements. This table does not contain all determined elements because in different foodstuffs different number of elements was determined (some elements were under limit of determination). Table 3 gives total elements daily intake including two trace elements containing preparations. In the table were included elements which were determined in all foodstuffs and for which were given data of trace elements in preparations.

CONCLUSIONS

… A number of foodstuffs have similar composition because these foodstuffs are produced in other regions of Uzbekistan or imported from other countries. During the marketing process (foodstuffs distribution) the differences in elemental composition are more or less smoothed.

… Some foodstuffs from Tashkent have elevated concentration of some elements (including toxic ones), probably, because of impact of local enterprises.

… Agriculture activity around Almalyk is weak because of low productivity given by the environment contamination. That means that some pilot samples of fruits and vegetables may be collected from more distant places but under main winter direction.

… Locally produced and more contaminated in Almalyk are meat (beef, mutton, chicken), fish, eggs, and milk.

… Intake of some elements, especially in contaminated area, is significantly higher than recommendations of ICRP¹ and FAO/IAEA/WHO².

… Results were discussed with local experts from environmental, nature protection and health Authorities and results were found as very important and many of them as unexpected which serves as the reason for continuation of the study in more wide scale.

Table 1. Comparison of foodstuffs composition.

Foodstuff	Elevated levels in
	Studied area	Reference area
Wheat	Br	Co
Bread	Ag, Au,	Cu, Zn
Home bread	Ag, Rb,	Br, Cu, Th
Pasta	Br, Cr, Cu, Mn, Na, Rb, Se, Zn	Au, Hf, Sc
Beans	Au, Ca, Mn	Cr, Cs, Hf, La, Rb, Sb, Se
Peas	Br, Hf, La	Ca, Cr, Cs, Cu, Hg, Mo, Na, Rb, Sb, Sc
Rice	Cr, Hg, Se	Br, Ca, Mo, Na, Rb, Sb
Cabbage	Ag, Au, La	Br, Cu, Hg, K, Mo, Zn
Onion	Ag, Ca, Na, Rb, Sb,	Br, Cr, Hf, K, La, Sc,
Potato	Sc	Ca, Fe, Sb
Carrot	Br, Cu, K, Mn, Na, Zn	Au, Ca, Co, Mo
Tomato		Br, K, Sb, Sc,
Cucumber	Na	Co, Cr, Cs, Cu, Fe, Hf, La, Sb, Sc, Zn
Raisin	Cr, Fe, Hf, La, Mn, Sc, Th	Br
Dry apricot	Fe, Hf, Sb	Br, Ca, K, Zn
Apricot	Cu,	Au, Br, Co, Fe, La, Rb, Sb, Zn
Apple	Ca, Co, K, Mn, Sb	Ag, Au, Br, Cs, Rb
Water melon	Cu, K, Na	Br, Co, Fe, Hg, Hf, La, Rb, Sb, Sc, Zn
Beef	Cr, Cu, Hg, Hf, Mn, Sb, Sc, Zn	Au, Br,
Mouton	Co, Cr, Cu, Fe, Hf, Na, Rb, Sb, Sc, Se, Zn	Ag, Au, Cs
Chicken	Au, Br, Co, Cu, Fe, Hg, Mn, Sb, Sc, Se, Zn	Cr,
Eggs (white)	Fe, Hg,	Au, Br, Ca, Cr, K
Eggs (yolk)	Hg, Se	Ca, Cr, Rb
Milk	Br, Co, Cu, Zn	Au, Ca, Cs, Rb, Sc
Fish	Cr, Cu, Hg, Mn, Sb, Zn	Co, Cs, Rb, Sc

Tab. 2. Ranges of studied elements daily intake

Element	Minimal	Mean	Maximal	RDA^1 ICRP	RDA^2 FAO/IAEA/WHO
Br, mg	1.9	5.4	12	7.5
Co mg	3.4	30	66	300	3
Cr mg	44	126	290	150	35
Cu mg	3.9	23	50	3.5	0.89
Fe mg	7.8	22	44	12 - 16	11
K g	2.0	4.2	6.2	3.3	5.4
Mn mg	1.1	3	5	3.7	5
Na g	0.39	0.65	1.6	4.4	2.3
Rb mg	0.44	1.7	4.8	2.2
Sb mg	16	163	710	~50
Sc mg	2.2	7.7	23
Zn mg	10	16	37	13	11

Tab. 3. Total daily intake together with two trace elements containing preparations

Element	Intake with food preparation*			Total intake together with food			RDA	RDA
	Vitamin	Fish oil	Total	Minimal	Mean	Maximal	ICRP^1	FAO/IAEA/WHO^2
Cr ug	120	100	220	260	350	510	150	35
Cu mg	2	2	4	7.9	27	54	3.5	0.89
Fe mg	18		18	26	40	62	12 - 16	11
Mn mg	2	3	5	6.1	8	10	3.7	5
Zn mg		10	10	20	26	47	13	11

* According to the data announced by producer.

REFERENCES

[1] Report of the Task Group on Reference Man, International Commission on Radiological Protection, No 23, Pergamon Press, Oxford, New York, Toronto, Sydney, Braunschweig, 1975, 496 p.

[2] Trace Elements in Human Nutrition and Health, Joint FAO/IAEA/WHO Publication by the Expert Committee, WHO, Geneva, 1966.

[3] Co-ordinated research project on Use nuclear and related analytical techniques in studying human health impacts of toxic elements consumed through foodstuffs contaminated by industrial activities, Report on the First Research Co-ordinating Meeting, NAHRES-75, IAEA, Vienna, 2003.

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* This study has been carried out within the framework of the IAEA CRP RC - 863 ìUse of Nuclear and Related Analytical Techniques in Studying Human Health Impacts of Toxic Elements Consumed Through Foodstuffs Contaminated by Industrial Activitiesî, and STCU Project Uzb-109