Levels of contamination in agricultural products

Radionuclide concentrations in both vegetable and animal agricultural food products presented below are compared with national standards. National regulations for temporary permissible levels in drinking water and food products are indicated in Table V for the former USSR (1986–1991), in Tables VI and VII for Belarus (adopted in 1992), and in Table VIII for the Russian Federation (adopted in 1993).

It should be noted that, due to the extensive implementation of protective measures in animal production, only a small quantity of milk was produced with ¹³⁷Cs content above the permissible levels. The distribution of settlements according to mean ¹³⁷Cs activity concentration in milk in Ukraine is shown in Fig. 10 and the changes with time in ¹³⁷Cs content in milk from contaminated regions of the Russian Federation are shown in Fig. 11.

TABLE V. TEMPORARY PERMISSIBLE LEVELS (TPLs) IN DRINKING WATER AND FOOD PRODUCTS (Bq.L^-1 or Bq.kg^-1). USSR REGULATIONS

Product 06/05/86* 30/05/86** 15/12/87*** 22/01/91

Drinking water 3700 370 20 20

Milk 3700 370 370 370

Condensed milk – 18500 1110 1110 Dried milk – 3700 1850 1850

Curds 37000 370 370 370

Sour cream 18500 3700 370 370 Vegetable oil – 7400 370 185

Margarine – 7400 370 185 Animal fat – – 370 185

Cheese 74000 7400 370 370 Butter 74000 7400 1110 370 Meat, meat products – 3700 1850 740

Meat (beef) – – 2960 740 Meat (pork, mutton) – – 1850 740

Poultry – 3700 1850 740

Egg – 1850 1850 740

Fish 37000 3700 1850 740 Vegetables – 3700 740 600 Leafy vegetables 37000 3700 740 600

Root vegetables – – 740 600

Potatoes – 3700 740 600

Fruits berries (fresh) – 3700 740 600 Fruit, berries (dried) – 3700 1110 2900

Juice – 3700 740 –

Jam – – 740 –

Grain, flour, cereals – 370 370 370 Bread, bread products – 370 370 370

Sugar – 1850 370 370

Mushrooms – 18500 1850 1480 Mushrooms (dried) – – 11100 7400

Wild growing berries – – 1850 1480 Tinned food (vegetables, fruit) – – 740 600

Honey – – 740 600

Herbs – 18500 – 7400

Baby food – – 370 185

* The TPL dated 6 May 1986 limited ¹³¹I concentration in food (based on a permissible thyroid dose in children of 0.3 Gy).

** The TPL dated 30 May 1986 limited the total beta activity in food (based on a permissible annual internal dose of 50 mS or 5 rem).

*** The TPL dated 15 December 1987 and later limited the content of caesium radionuclides in food.

TABLE VI. TEMPORARY PERMISSIBLE LEVELS (TPLs) FOR CAESIUM RADIONUCLIDES IN DRINKING WATER AND FOOD PRODUCTS (Bq.L^-1 or Bq.kg^-1).

BELARUS REGULATIONS, 1992

Product TPL (Bq.L^-1 or Bq.kg^-1)

Drinking water 18,5 Milk and other dairy products 111

Dried milk 740

Meat and meat products 600 Potatoes and tubers 370 Bread and bread products 185 Flour, cereals, sugar and honey 370 Vegetable oil, animal fat, margarine 185 Vegetable, garden fruit and berries, wild berries 185 Tinned garden vegetables, fruit and berries 185 Dried mushrooms 3700

Baby food 37

Other food 370

TABLE VII. TEMPORARY PERMISSIBLE LEVELS (TPLs) IN RAW PRODUCTS AND FOOD FOR CAESIUM RADIONUCLIDES AND ⁹⁰Sr. BELARUS REPUBLIC, 1992

Products TPL

137Cs (Bq.kg^-1) ⁹⁰Sr (Bq.kg^-1)

Milk 370 18

Meat 600 –

Vegetable raw products ( fruit, vegetables) 370 –

Grain 600 11

Grain for baby food 55 3.7 Other raw products 370 –

TABLE VIII. TEMPORARY PERMISSIBLE LEVELS (TPLs) FOR CAESIUM RADIONUCLIDES AND ⁹⁰Sr IN FOODSTUFFS (Bq.L^-1 or Bq.kg^-1). RUSSIAN REGULATIONS, 1993

Products TPL (Bq.L^-1 or Bq.kg^-1)

137Cs ⁹⁰Sr

Milk, curd, sour cream, vegetable oil, margarine, animal fat, cheese, butter, grain, flour, cereals, bread, bread products, sugar

370 37

Baby food 185 3.7

Other 600 100

TABLE IX. THE RADIONUCLIDE CONCENTRATION IN SOME FRESH AGRICULTURAL PRODUCTS ON THE TERRITORY OF THE VILLAGE OF STAROYE SELO, ROVNO REGION, UKRAINE (1994) [12]

Product

137Cs Concentration

(Bq.kg^-1)

90Sr Concentration (Bq.kg^-1)

137Cs Transfer coefficient (Bq.kg

-1)/(kBq.m^-2)

90Sr Transfer coefficient (Bq.kg^-1)/(kBq.m^-2) min. avg. max. min. avg. max. min. avg. max. min. avg. max.

Potato _{92 128 188 5 7 9 0.3 0.8 1.1 1.0 1.8 3.9}

Garden beet 24 47 72 0.7 1 1.5 0.09 0.32 0.71 0.12 0.33 0.80

Beetroot 8 25 48 0.4 1 1.5 0.05 0.15 0.28 0.13 0.22 0.28

Hay _{4033 8391 15910} 15 18 26 17 57 156 2.7 5.1 13.4

Fig. 10. Distribution of Ukrainian settlements according to mean ¹³⁷Cs concentration in locally produced milk in 1992–1994.

A study of the dynamics of the change in ¹³⁷Cs content in agricultural products has been carried out in the Russian Federation on the basis of 1987–1992 data from the five most severely affected districts in the Bryansk region (Gordeevo, Klimovo, Klintsy, Krasnaya Gora, and Novozybkov) and from three districts in the Kaluga region (Khvastovichy, Ulyanovo and Zhizdra) (Fig. 12). As the districts in question are quite different in their levels of agricultural product contamination, soil characteristics, the types of agricultural countermeasure applied and the extent of their implementation, such an analysis makes it possible to evaluate not only the parameters involved in changes in the ¹³⁷Cs content in agricultural products, but also the influence of factors determining the changes in the biological availability of radionuclides to

Fig. 11. Dynamics of mean ¹³⁷Cs concentration in milk in contaminated districts of the Russian Federation.

Fig. 12. Dynamics of mean ¹³⁷Cs concentration in vegetable products.

Fig. 13. Distribution of Ukrainian settlements according to mean ¹³⁷Cs concentration in locally produced potato in 1992–1994.

Fig. 13 shows the distribution of Ukrainian settlements according to mean ¹³⁷Cs activity concentration in locally produced potato between 1992 and 1994 and Table IX shows the transfer coefficients and levels of contamination of agricultural products in the Rovno region, which is characterized by unusually high transfer coefficients.

The results obtained show that the dynamics of ¹³⁷Cs and other radionuclides in agricultural products following an accident with radioactive release into the environment depend on natural biochemical processes and on weather-related and climatic conditions as well as on the scope of protective measures. The significance of these factors in different periods of post-accident contamination of the environment may be quite different, depending on the types of agricultural countermeasure applied and the extent of their implementation. In those regions where countermeasures have been extensively implemented, the decrease in radionuclide concentration in agricultural products was mainly determined by the efficacy of the countermeasures. Their implementation was responsible for up to 60% of the overall decrease in the contamination levels during the period under consideration. In those regions where the implementation of countermeasures was limited, approximately 70% of the decrease in the contamination levels of agricultural products was due to natural biochemical processes determining the radionuclide sorption on the absorbing soil complex, rather than to the countermeasures [17, 22].

2.3. Radioactive contamination of forest