Risk Assessment of Radiation-Induced Stomach

Cancer in Population of Belarus

M.V.MalkoInstitute of Power

National Academy of Sciences of Belarus, Minsk, Belarus

The incidence in stomach cancers in the Belarusian population are presented in the report. It is found that approximately 2,740 additional stomach cancers appeared in Belarus in 1990-2007 (95% CI from 2,020 to 3,470 cases). The number of stomach cancers registered in Belarus in this period is about 67,076 cases (64,335 expected cases).

According to performed assessment the relative risk of additional or radiation-induced stomach cancers averaged for the period 1986-2001 is equal to 1.03 (95% CI from 1.04 to 1.05). The excessive absolute risk of stomach cancers, EAR, averaged for the same period is assessed as 67 cases per 104 PYSv (95% CI from 49 cases to 85 cases per 104 PYSv). The averaged excessive relative risk, ERR, is estimated equal to 1.9% per 1 mSv (95% CI from 1.4 to 2.4 % per 1 mSv) and the averaged attributive risk, AR, is estimated equal to 4.1% (95% CI from 3.0 to 5.1%).

Contaminated areas in Belarus with the level of caesium-137 equal to 37 kBq/m2 (1 Ci/km2) or higher (in square kilometers)

Oblast Level of contamination, Bq/m2 (Ci/m2)

37–185 (1-5)

185-555 (5-15)

555-1,480 (15-40)

>1,480 (>40)

Brest 3,800 470

Vitebsk 35

Gomel 16,870 6,740 2,760 1,625

Grodno 1,690 12

Minsk 2,030 48

Mogilev 5,490 2,900 1,450 525

Total 29,915 10,170 4,210 2,150

Deposition of the isotope 137Cs in separate provinces of Belarus as a result of the Chernobyl accident

(Assessment of M.Malko)

Regions of BelarusAbsolute

amount of deposited

137Cs, Bq

Relative amount of deposited

137Cs (in %)

Brest 6.31014 3.9

Vitebsk 4,31012 0.03

Gomel 1.11016 66.5

Grodno 2.11014 1.3

Misk region together with the city Minsk

2.71014 1.7

Mogilev 4.31015 26.6

Republic of Belarus 1.61016 100

By calculation of doses of the whole body irradiation all radionuclides that gave some measurable contribution to the summary exposition in 1986 were considered. They are 131I, 132Te, 103Ru, 106Ru, 140Ba, 134Cs and 137Cs. The short-lived isotopes 131I, 132Te, 103Ru, 106Ru, 140Ba and 134Cs determined approximately 85% of the summary exposition dose in the period from 26 April 1986 to 31 August 1986. The isotope 137Cs was taken after the accident at the Chernobyl NPP as an indicator of the radioactive contamination. Therefore, only this isotope is mentioned here and below by characterizing of radioactive contamination despite the fact that contribution of other isotopes to irradiation doses is also considered.

Irradiation doses of inhabitants of rural settlements situated in contaminated areas of Belarus in mSv (Assessment of M.Malko)

Year Contamination level, kBq/m2 (Ci/km2)

3.7 (0.1) 37 (1) 37-185 (1-5)

185-555(5-15)

555-1,480(15-40)

1,480(40)

1986 0.0972 0.9719 2.896 8.339 23.62 38.87

1987 0.0468 0.4681 1.395 4.016 11.37 18.72

1988 0.0296 0.2957 0.8812 2.537 7.186 11.83

1989 0.0181 0.1806 0.5382 1.549 4.388 7.224

1990 0.0104 0.1042 0.3104 0.8938 2.531 4.167

1991 0.0089 0.0885 0.2639 0.7597 2.152 3.542

1992 0.0079 0.0772 0.2302 0.6628 1.877 3.090

1993 0.0069 0.0686 0.2043 0.5883 1.666 2.743

1994 0.0062 0.0621 0.1849 0.5324 1.508 2.482

1995 0.0057 0.0570 0.1698 0.4890 1.385 2.280

1996 0.0053 0.0531 0.1583 0.4556 1.290 2.124

1997 0.0049 0.0495 0.1475 0.4247 1.203 1.980

1998 0.0047 0.0469 0.1397 0.4021 1.139 1.875

1999 0.0044 0.0443 0.1319 0.3799 1.076 1.771

2000 0.0043 0.0425 0.1267 0.3647 1.033 1.700

2001 0.0041 0.0405 0.1206 0.3472 0.9833 1.619

1986-2001 0.2651 2.651 7.899 22.74 64.41 106.0

Assessment (M.Malko)of irradiation doses of inhabitants of rural settlement Vysoki Barok

(Krasnapolye district, Mogilev region) and Chudziany (Cherikau district, Mogilev region)

Year Irradiation doses, mSv

Vysoki Barok

Chudziany

Contamination level, kBq/m2

(Ci/km2)

2,479 (67) 5,420 (146.5)

1986 65.1 142.4

1987 31.4 68.6

1988 19.8 43.3

1989 12.1 26.5

1990 7.0 15.3

1986-1990 135.4 296.1

Comparison of average irradiation doses of inhabitants of the Belarusian, Russian and the

Ukrainian rural settlements situated in areas with contamination levels in 137Cs ranges from 555 to

1,480 kBq/m2 (15 – 40 Ci/km2)

Countries Average doses of the whole body irradiation, mSv

1986 1986 – 1995

1986 – 2000

Belarus 23.7 57.8 63.4

Russia 20 60.4

Ukraine 26 74

Numbers of the Belarusian evacuees, liquidators and resettled persons as well as their

equivalent irradiation doses

Group of people Number of persons

Average irradiation dose, mSv

Collective irradiation

dose,personSv

Evacuated inhabitants of 30-km zone

24,725 20 495

Liquidators:including liquida-tors in 1986-1987:1988-1989:

116,567

78,38038,187

42.6

53.6 20

4,965

4,200765

Resettled persons 110,275 60 6,600

Evacuees, liquidators and resettled persons combined together

251567 48 12,000

Republic Belarus as a whole

10,000,000 2.3 23,000

Temporal patterns of the irradiation dose delivering in Belarus in 1986-2001

0

5

10

15

20

25

30

35

40

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

Years

Fra

cti

on

of

do

se

in 1

98

6-2

00

1, %

Collective doses of the whole body irradiation of populations of Belarus in 1986-2007 as a result of the Chernobyl

Region, city HCollDD

CollMEH

CollMIH Coll

EvH CollHRe CollLqH CollH

Person-sievert Brest 1,250 -55 96 0 378 204 1,873 Vitebsk 6.5 0 124.5 0 295 220 646 Gomel 6,030 -350 -500 640 1,711 2,171 9,702 Grodno 293.5 -13 62.5 0 384 174 901 Minsk 303 -14 174 0 1,837 1,394 3,694 Mogilev 2,592 -103 -196 0 1,296 590 4,179 city Minsk 200 -20 239 0 676 610 1,705 Alltogether 10,675 -555 0 640 6,577 5,363 22,700

Collective and population doses of the whole body irradiation of populations of Belarus in 1986-2007 as a result of the Chernobyl

Region, city Collective doses, person-sievert Population doses, mSv

Mixed Males Females Mixed Males Females Brest 1,873 988 885 1.27 1.43 1.13 Vitebsk 646 421 225 0.46 0.64 0.31 Gomel 9,702 5,711 3,991 6.48 8.11 5.03 Grodno 901 515 386 0.77 0.93 0.62 Minsk 3,694 2,474 1,220 2.36 3.37 1.47 Mogilev 4,179 2,277 1,902 3.39 3.93 2.91 city Minsk 1,705 1,125 580 1.03 1.44 0.66 Alltogether 22,700 13,511 9,189 2.27 2.88 1.74

In Belarus cancer registration is considered mandatory, and it has been carried out since 1953. However till the beginning of the 1970‘s it was performed on the basis of the required official statistical reports without the formation of computer databases in which personified cancer cases could be stored.

In 1973, the formation of computer files on the magnetic tapes and disks was initiated in Belarus and information on each new cancer case, registered in the current year, was entered into them.

“Cards of dispensary follow-up” (Form 30-6-Y (onco)) filled in and coded in the oncological dispensaries of Belarus were as information basis for these computer files.

At the republican level the Belarusian Cancer Registry collects data from 9 oncological dispensaries, oncological department of Grodno Regional hospital and the N.N.Alexandrov National Cancer Center of Belarus (for Minsk region), which are responsible for registration and coding of all cancer patient permanently residing in their areas.

Incidence rates of stomach cancer in population of the city Minsk in 1970-1988, 2002-2007

y = 0.007490x + 14.543163

R2 = 0.002103

22

24

26

28

30

32

34

36

38

1960 1970 1980 1990 2000 2010

Years

Cas

es in

100

,000

per

son

s

Incidence rates of stomach cancer in the population of the city Minsk in 1970-2007

22

24

26

28

30

32

34

36

38

1960 1970 1980 1990 2000 2010

Years

Cases in

100,0

00 p

ers

on

s

expected observed

Incidence rates of stomach cancers in the population of Vitebsk region in 1970-2007

30

35

40

45

50

55

60

1960 1970 1980 1990 2000 2010

Years

Cases in

100,0

00 p

ers

on

s

expected observed

Incidence rates of stomach cancers in the population of Grodno region in 1970-2007

25

30

35

40

45

50

1960 1970 1980 1990 2000 2010

Years

Cas

es in

100

,000

per

son

s

expected observed

Incidence rates of stomach cancer in the population of Brest region in 1970-2007.

25

30

35

40

45

50

1960 1970 1980 1990 2000 2010

Years

Ca

se

s i

n 1

00

,00

0 p

ers

on

sexpected observed

Incidence rates of stomach cancer in the population of Minsk region in 1970-2007

30

35

40

45

50

1960 1970 1980 1990 2000 2010

Years

Ca

se

s in

10

0,0

00

pe

rso

ns

expected observed

15.5

Incidence rates of stomach cancer in the population of Mogilev region in 1970-2007

30

35

40

45

50

55

60

65

1960 1970 1980 1990 2000 2010

Years

Ca

se

sx

in

10

0,0

00

pe

rso

ns

expected observed

Incidence rates of stomach cancer in the population of Gomel region

30

35

40

45

50

55

1960 1970 1980 1990 2000 2010

Years

Ca

se

s i

n 1

00

,00

0 p

ers

on

sexpected observed

Observed incidence rates of stomach cancers in regions of Belarus averaged for

the period 1990-2007

20

25

30

35

40

45

Brest Gomel Grodno cityMinsk

Minsk Mogilev Vitebsk

Cases in

100,0

00 p

ers

on

s

Expected incidences of stomach cancers in regions of Belarus averaged for 1990-2007

20

25

30

35

40

45

Brest Gomel Grodno cityMinsk

Minsk Mogilev Vitebsk

Cas

es in

100

,000

per

son

s

expected observed

Incidence in stomach cancer in populations of the Belarusian population in 1990 - 2007 Region Observed Expected O-E RR Low Upper Brest 8,651 8,393 258 1.031 1.000 1.062 Gomel 10,889 9,660 1,229 1.127 1.097 1.159 Grodno 7,387 7,168 219 1.031 0.998 1.065 city Minsk 9,328 9,183 145 1.016 0.987 1.045 Minsk 11,571 11,130 441 1.04 1.013 1.067 Mogilev 8,856 8,564 292 1.034 1.004 1.065 Vitebsk 10,394 10,237 157 1.015 0.988 1.043 Combined 67,076 64,335 2,741 1.043 1.031 1.054

Relative risk of stomach cancer in populations of Belarusian regions in 1990-2007

y = 0.017x + 1.0037

R2 = 0.8664

1

1.02

1.04

1.06

1.08

1.1

1.12

1.14

0 1 2 3 4 5 6 7

Population doses, mSv

Rel

ativ

e ri

sk

Number of additional stomach cancer in Belarus in 1990-2007

y = 1166.5x + 13.304

R2 = 0.9195

0

200

400

600

800

1000

1200

1400

0 0.2 0.4 0.6 0.8 1

Collective equivalent dose (x 10,000 PSv)

nu

mb

er

of

ca

nc

ers

Comparison of radiation risks of stomach cancer estimated for the Belarusian population and for atomic bomb survivors Belarus ATB* Period of time 1990-2007 1958-1988 Contingent Mixed Mixed PY 171,700,000 2,764,731 H(Coll), 104 PGy 3,24104 104 h(population), Gy 0.0032 ~0.2 Duration of irradiation 1.27108 sec 2.6 sec Dose rate, Gy/sec 0.25 10-10 0.1 Observed 67,075 4,730 Expected 64,335 4,579 O - E 2,740 151 RR 1.04 1.03 95% CI of RR 1.03 ÷ 1.05 EAR/104 PYGy, 49 9.5** 95% CI of EAR 34 ÷ 60 6.1 ÷ 14 ERR/Gy 13 0.34** 95% CI of ERR 9.8 ÷17 0.22 ÷ 0.47 AR% 4.1 3.2 95% CI of AR,% 3 ÷ 5.1

* D.L.Preston, E.Ron, S.Tokukoko et al. Solid Cancer Incidence in Atomic Bomb Survivors: 1958 – 1998. Radiation Research, vol.168, pp.1-64 (2007). ** Estimates for atomic bomb survivors irradiated at the age 30 years and attained age 70 years.

CONCLUSIONS

1. The accident at the Chernobyl NPP caused in Belarus approximately 2,700 radiation-induced stomach cancers in 1990 – 2007.

2. Radiation risks of radiation-induced stomach cancers caused in Belarus by the Chernobyl accident are by some factors higher than observed in atomic bomb survivors.

2. Radiation risks of stomach cancer established for atomic bomb survivors (acute irradiation) are not relevant for irradiation of normal population. Using radiation risks observed for survived inhabitants of Hiroshima and Nagasaki underestimates real number of radiation-induced stomach cancers in case of population exposed to chronic irradiation.

4. Using the Dose and Dose Rate Effectiveness Factor higher than 1 additionally underestimates number of radiation-induced stomach cancers caused as a result of chronic irradiation of normal population.