Lens Opacities in Children of Belarus Affected by the Chernobyl Accident
A. N. ARINCHIN and L. A. OSPENNIKOVA
Research Clinical Institute of Radiation Medicine and Endocrinology,
Ministry of Health, Republic of Belarus; Aksakovschina, 223032 Minsk, Belarus.
changes in dark adaptation of visual irritation threshold[5, 11].
The process of the lens growth has a number of
peculiarities: new lens fibers are being formed due tocell-division of single layer epithelium located on theinterior surface of the lens bag covering the anteriorlens surface. Each newly developing lens fiber islocated under the lens bag both on the anterior andposterior lens surface. Taking into account that the lensis surrounded by the bag from all the sides, previously
formed fibers cannot be torn away from the tissue
component and remain in its structure for the whole oflife. At the same time, constant formation of new fibers
from the peripherally located epithelium layer leads tothe following: older fibers are being gradually pushedaside from the lens bag to the central part of the lens.
So, in the process of growth, the more consolidated
part of the lens is being formed, i.e. the nucleus
consisting partially from already atrophied lens fibers,
as well as surrounding it younger peripheral corticallayers. Cell-division of lens epithelium and theformation of new lens fibers is occurring during almost
the whole of life. Alongside with this, the increase inlens weight, the changes in its dimensions andchemical structure are observed with age. Averagewater content in the lens makes about 65% and issubject to considerable age fluctuations. Besides thelens, to such tissues also belong cartilage, cornea, teeth,
the wall of a large blood vessel, etc. In mineral lensstructure, univalent Na and K cations prevail
considerably over the two-valent Ca and Mg cations;among anions, sulfates prevail over chlorides andphosphates [1].
N.A.Vishnevsky (ref.[7]) distinguishes five stages
in the development of radiation cataract:
1. initial stage - accumulation of focal vacuoles andopacities between the lens capsule and the cortex in
the center of the lens;
2. clusters of focal vacuoles and opacities between thelens capsule and the cortex begin to extend andacquire the form of irregular disk which resembles
the tufa at biomicroscopy, the observed decrease invisual acuity being negligible in this case;
3. opacity acquires the form of a cup or a ring-shapedroll with darker optical edges. At biomicroscopy,
tufa-like opacity has the form of meniscus. Visualacuity decreases;
4. at electroophtalmoscopy, in the center of the lens,Introduction.
Eleven years following the Chernobyl accident, theincrease in the incidence of thyroid disease, thyroid
carcinoma in particular, has become evident anduniversally recognized. The mentioned pathology is
given much prominence by physicians and scientists
involved into the problems of oncology andthyroidology all over the world. Such great attention to
thyroid problems has both positive and negative sides.
In particular, in the majority of the research projects
conducted both in Belarus and outside the Republic,priority is given to thyroid disease, though othermedical aspects of the Chernobyl accident are studied
insufficiently.
Reports about the increase in cataracts among the
Ukrainian population living in the region of theChernobyl Atomic Power Plant have been met withcertain skepticism [14]. At the same time, American
specialists do not exclude the possibility of radiation
genesis of lensopathias revealed among the citizens of
the Ukraine at the result of complex joint
clinic-epidemiological study conducted by Americanand Ukranian specialists in 1991 [16].
It is well known that radiation cataract is one of thedirect effects of ionizing radiation. Organ of sight,
according to literature reports, is highly radiosensitive.
The most radio-vulnerable part of an eye is lens inwhich cataract is developing in response to both
external and internal exposure. In children, focal lens
opacities are localized in embryonic nucleus, but inelderly people, alongside with embryonic nucleus, they
are also localized in adult nucleus and cortical layers.
Lens opacity is the result of biochemical changes
occurring in it, and it is caused by lens fibers damage[10].
The data available in radiation medicine show thateye damage occurs, mainly, due to considerable dosesof radiant energy. Single effect of 200 rad X-ray,
induces the development of radiation cataract with longlatent period [8]. Skin, mucous membranes and cornea
respond to radiation earlier and at considerably lower
doses. During the acute period, conjunctivitis, keratitis
and eyelid dermatitis develop. In two years,
teleangiectasia is observed.
Retina, as well as nervous elements of an eye, aremore radio-resistant. The earliest radiation effect is
manifested by changes in the retina electrical potential
and in threshold phosphen values, as well as by168

disk-like opacity is seen with a tender rim within the
periphery. At biomicroscopy, focal vacuoles andopacities under the anterior capsule in the center ofthe lens, as well as anterior and posterior surfaces,
are getting more consolidated; the slot in the middle
is being filled with homogenic contents;
5. extensive, pelliculated opacities.
It has been ascertained that cataractogenic thresholdis determined not only by individual radiation
sensitivity and localization of radiation effect, but also
by the quality of exposure, its dose in the exposed focus
and the duration of the exposure [10].
Studies of the health status in individuals affectedby the atomic bombing in Hiroshima and Nagasaki
conducted by the research board of the Hannan Chuo
Hospital, the city of Osaka, Japan, showed that eye
disease was observed in 18% of the exposed population
which is 5 times more frequent than among thenon-exposed [17]. However, in this case, radiationinfluence differed considerably from that in Chernobyl.
In the late period after the accident, the main
dose-forming nuclide is 137Cs which penetrates into
the body with food-stuffs (milk, vegetables, meat) andis distributed in the following way: 80% ofincorporated radionuclide is being accumulated in themuscular tissue, 10% - in the osseous tissue, and theremaining part of it circulating freely in blood [2,3,4].
Cesium, as well as potassium, belongs to the group ofalkaline elements with the diffuse type of distribution
in the body and participates in intracellular metabolism[12]. With average beta-exposure energy of 170.8 keV,137
Cs is able to influence electric and metabolic
processes occurring in various tissues and organs.
Therefore, the aim of the investigation was to study
the frequency and character of lens opacities inchildren permanently residing in the contaminatedterritories of the Republic of Belarus with anomalously
high coefficients of transition of 137Cs radionuclides
through the food chain.

Selection of regions
During
1992-1995,
complexclinic-ophthalmological examination of 134 children
aged 6-15 permanently residing in Stolin and Luninets
districts of the Brest region, was conducted on the baseof the Clinic of the Research Institute of Radiation
Medicine and Endocrinology. The control group wasrepresented by 92 children of the same age
permanently residing in Braslav district of the Vitebsk
region who were examined under the same conditions.
Selection of study regions was determined by thecharacter of radiation situation and peculiarities of the
exposure dose formation. Stolin and Luninets districtsin the Brest region are located in the south of the
Republic of Belarus in the zone of wood-lands and arecharacterized by insufficient levels of local radioactive
contamination and by automorphic type of soils whichhave high coefficients of 137Cs radionuclide transition
into the food chain (Table 1). Actual dosimetric andradiation-hygiene characteristics of the examinedchildren is given in Table 2.
All the examined children were permanently living
at the controlled territories. Each child was interviewed
about his/her dietary habits. The conducted interview
showed that milk, potatoes and leafy vegetables werethe most frequently consumpted food-stuffs.
Practically all of these food-stuffs were from privatehouseholds (private cows and personal plots) and wereconsumpted without any limitations. During thepost-accidental period, the consumption of mushrooms
and forest berries was observed among the examined
individuals. As it is seen from the given data, theexposure dose formation was realized, mainly, throughthe internal component and was caused byincorporation of 137Cs radionuclides. According to thedata of individual monitoring of 137Cs activity in thebody(conducted
with
the
help
of
Whole-Body-Counter), its constant level has been
ascertained in the examined children during thepost-accidental period.
Material and methods.
General clinical examination
Table 1.
Radiation characteristics of the examined settlements in 1992
137

RegionDistrict

Settlement

Brest

StolinLuninets

Vitebsk

Braslav

OlmanyBarsukovo
Perinovo
Akhremovtsy

Cs content insoil, kBq/m2
363
377
137
3.7

Local exposure dose rate, µR/hourminaverage
max
19.5
27.3
37.8
19.5
39.0
46.8
3.9
15.6
27.3
8
-

Table 2. Dosimetric and radiation-hygiene characteristics of the examined children
137
137

Cs excretion Annual effective radiation dose,mSv
level withurine, Bq/l external internal
total

Group

Cs bodyburden, kBq

Index of 137Cs
activity, kBq/kg

Main

24.4
(1.2-173.9)

0.56(0.03-3.03)

239.9(24-928)

Control

0.74(0.004-1.07)

0.02(0.00007-0.037)

4.4(3.7-7.8)

0.49
1.65
2.2
(0.32-0.72(0.09-8.8)(0.4-9.7)
)
0.05
0.06
0.009
(0.0002-0.1) (0.009-0.11)

Note: the figures in brackets give minimal and maximal values

169

Accumulated effective
radiation dose, mSv
external internal
total
3.4
(2.3-5.2)

12.0
15.4
(0.7-63.0) (3.2-71.0)

0.06

0.35
0.4
(0.002-0.8) (0.06-0.9)

Examination of children was conducted at the
Hospital of the Research Clinical Institute of Radiation
Medicine and Endocrinology and included clinicalexamination of a pediatrician, collection andassessment of life anamnesis, anthropometry,hematological,
hormonal
andbiochemical
investigations, ultrasound study of the thyroid gland
and abdominal organs, urine analysis on 137Cs
radionuclide content, measurement of 137Cs
radionuclide activity in the body using theWhole-Body-Counter.
Study of life anamnesis showed that in theexamined children no factors were observed that could
cause the development of lens pathology, i.e.
roentgenological investigations of the cranium,
exposure for medical aims, chemiotherapy, anddiabetes mellitus.

distinctions with the help of Student′s criterion;• calculation of 2 series correlation coefficient (withthe use of Fisher′s transformation for N<50);• calculation of correlation matrix (10*10
parameters);• calculation of coefficients and derivation of theequation of 2 series regression with representationof the correlation field on the chart;• methods of non-parametric statistics (signs test,
Spearman′s rank correlation, Mann-Witney′s test).

Results
At the result of the conducted ophthalmologicalexamination, lens changes have been revealed which
can be classified as opacities in the form of vacuoles,
flakes, dots and spokes (strokes). Vacuoles, as well as
flaky, focal and stroke-like opacities, were observed
both in the nucleus and in cortical lens layers and, as arule, were not accompanied by clinical changes, suchas, first of all, the drop in visual acuity. Their number ina lens varied considerably and ranges from 1 to 20.
While analyzing the obtained data, the following
gradation for the number of total opacities in two lenses
was used: 1-5, 6-10 and >10. Opacities also differed bytheir size which, due to measurement complications,were determined at the level of qualitative evaluation:
small, medium and large.
Table 3 shows the distribution of children with
lensopathias of the main control group.
From the given Table, it is seen that in the maingroup, the number of children with lensopathias
accounted to 82.1% which is by 12.5% more than in thecontrol. It should be mentioned that in the main group,
the number of children with lensopathias of both lenses
was by 24.4% more as compared with the control. At
the same time, prevalence of one lens opacities didn’t
differ significantly in children of the examined groups.
The number of children with large opacities in the formof flakes and strokes accounted to 34 (25.4%) in themain group, while in the control, only one child had a

Ophthalmological methods
Ophthalmological examination included theassessment of visual acuity of a patient, as well as
biomicroscopy performed with the help of a slit lamp at
maximal mydriasis. The revealed lensopathias were
determined in accordance with the 3-d International
Classification of lens opacities (lensopathias) [15]. The
obtained results were introduced into the protocol of
ophthalmological examination.

Statistical processing and data analysis
The data of clinical, laboratory, instrumental,
ophthalmological and dosimetric studies wereintroduced into the computerized data base [9].
Statistical programs accompanying the data base allow
to perform the retrieval arbitrarily with subsequentstatistical processing:• primary statistical processing of a variation series(N, arithmetical mean, root-mean-square deviation,mean error, confidence interval, mode, median,asymmetry and excess coefficients, character ofvariants′ distribution);• determination of the significance of 2 series
Table 3 Distribution of the examined children with lensopathias
Examined group
Presence of lensMain
opacitiesn%left lens
16
11.9
right lens
22
16.4
both lenses
72
53.7
Total
110
82.1

Control
n
20
17
27
64

%
21.7
18.5
29.3
69.6

Table 4. Distribution of the examined children with regard to multiplicity of total opacities in both thelensesNumber of total opacities in both the lenses
Examined
1-5
6-10
>10
group
n
%
n
%
n
%
Main
77
57.5
24
17.9
9
6.7
Control
56
60.9
7
7.6
1
1.1
170

Table 5. Distribution of the examined children with regard to lensopathias localization
Examined group
Part (zone) of lensControl
Main
Right eyeLeft eyeRight eyeLeft eye
Anterior capsule
2 (2.1%)1 (1%)
6 (4.5%)5 (3.7%)
Zone of splitting
1 (0.7%)
Anterior cortical zone
2 (2.1%)3 (3.3%)24 (17.9%)
15 (11.2%)
Adult nucleus
3 (3.3%)6 (6.6%)
12 (8.9%)4 (3.0%)
Embryonic nucleus
19 (20.6%)
13 (14.1%)
25 (18.7%)
24 (17.9%)
Posterior cortical zone
21 (22.8%)
25 (27.2%)
47 (35.1%)
48 (35.8%)
Posterior capsule
10 (10.9%)
12 (13.0%)
23 (17.2%)
26 (19.4%)

137

Cs body burden

38
36
34
32
30
28
26
24
22

from 1 to 5

from 6 to 10 from 11 to 15>15

Total number of opacities in bo

Fig.1. Relationship between the number of lens opacities and the level of 137Cs radionuclide
activity in the body of the examined children
cortical zone. Therefore, analogic transfer of thedamaged fibers and the increase in the number of actual
opacities in the posterior cortical zone at the expense of
the anterior one may possibly occur.
To determine the character of lensopathias
development with age, individual dynamic
ophthalmological examination of 21 children from themain group was conducted. The examination lasted
three years, with one year interval. The increase in thenumber of opacities in 9 children (42.9%) and lack ofdynamics in 12 children (57.1%) has been ascertained.
So,
lensopathia
progression
isobserved,
approximately, in half of the cases, which reflects theunfavorable dynamics of the given pathology inchildren with the enhanced risk of radiation effect.
The data about the relationship between the total
number of lensopathias of both the lenses and the levelof 137Cs radionuclide activity in the body, are ofparticular interest (Fig.1).
As it is seen from the given Figure, with the growthof the level of 137Cs radionuclide activity in the body,the total number of opacities in both the lenses
increases. This may be the indication of a certain
interrelation
existing between the radionuclide
incorporation and its influence on the organ of sight.
Primary cataract was diagnosed in 3 children

large stroke-like opacity (1.1%).
Frequency of occurrence of multiple lensopathias in
the examined children differs considerably (Table 4).
It has been ascertained that the number of children
with the total number of opacities from 1 to 5 was
identical in both the examined groups. With 6-10
opacities, the number of children in the main group was
2.4 times more than that in the control. More than 10
total opacities occurred 6 times more frequently also inchildren of the main group.
Location of opacities in different zones of lens isbeing assessed differently with regard to the indicationof radiation effect. Posterior cortical zone opacities are
considered to be more significant in this respect. In thisconnection, the data on opacity prevalence in all partsof the lens have been analyzed in the examinedchildren (Table 5).
As it is seen from Table 5, opacities of the posteriorcortical zone of lens occurred more frequently andwere more pronounced in children of the main group.
The second place was occupied by focal embryonicnucleus opacities. No significant distinctions between
the opacity prevalence in different zones of localizationof the right and left lenses were revealed. In theprocess of lens growth, fibers which are being formedin the anterior cortical zone, migrate to the posterior

171

first, but later, the bigger changes were observed inolder animals. Doses higher than 9 Gy, lead to lens
opacities more frequently in younger animals.
Sensitivity of mice lens to chronic radiation effect wasmore pronounced in the second half of the life ascompared with the first half of the life with 137Cs
incorporation. Though, it is hardly possible to transfer
these data on a human being. At the same time, taking
into account that lens radiosensitivity of animals andhuman beings is similar to a certain extent, the data ofthese experiments arouse concern.
Local fixation of incorporated radionuclides in lenstissues for the whole of their life may appear to be thepossible mechanism explaining their negative effect.
This leads to gradual destruction of neighboring lenstissues which tends to increase with age. As the result,less pronounced focal opacities may be formed first,
with subsequent development into larger - flaky andstroke-like opacities. Taking into account that the lenstissue lacks intensive metabolism, the possibility of
fixed radionuclide elimination is not large.
As a rule, the level of dose loads in the examinedchildren do not correspond to the universally
recognized dose level at which irradiation cataract
develops. According to the IAEA data, based on the
results of the studies conducted in Hiroshima andNagasaki, the dose of 200 mSv absorbed by lens is
considered to be clinically significant exposure dose
which induces the development of ophtalmologicaldisorders in children. From the above mentioned data it
follows that actual accumulated exposure doses in theexamined children were, approximately, 12.5 times
lower. Nevertheless, during the examination,
considerable structural lens changes have been
revealed in these children, such as an increase in thenumber of opacities and the degree of their diffusion.
In case of radionuclide incorporation, conditions of
exposure dose formation are being changed
considerably. These include physico-chemical
properties of radionuclide, its organotropy,
peculiarities of metabolism, character of its distribution
in the body, etc. From the point of view of
microdosimetry, protracted fixation of radionuclide in
the tissue may lead to the formation of high local
exposure dose which causes the development ofstructural and functional changes. It is not excluded
that such mechanism of radiation effect is functioning
in this case.

(2.2%) of the main group permanently residing in thevillage of Olmany, Stolin district, aged 11, 12 and 15
years, accordingly. The accumulated total effective
exposure dose at the time of diagnosis made 15.3, 17.1
and 25.9 mSv, accordingly. The disease could be
attributed to the 1-st stage of the irradiation cataract
development (according to N.A.Vishnevsky) and wascharacterized by vast accumulation of focal vacuoles
and opacities between the lens capsule and the cortex
not only in the center of the lens, but also within its
periphery. The reduction in visual acuity in the given
children was negligible.

Discussion
Questions of the effect of small radiation doses onlens and the mechanism of this effect remain to be open
for discussion. It is possible to assume the possibility ofrelatively high damaging effect of ionizing radiation
with internal exposure. V.I.Gerasimov [6] studied
quantitative value of possible non-stochastic effect in
the form of lens damage in mice at chronic internal
exposure from 137Cs and 90Sr. Statistically significant
decrease in light-transmitting eye capacity in animals
from experimental groups was observed, which may
testify to the cataractogenic effect of studied internal
exposure doses.
The above mentioned effect of small radiation
doses may be connected with the occurrence of
non-lethal damages in the genetic apparatus of lens
fibers which leads to the accumulation of functionallydefective cells with reduced vital capacity. It causes thedamage of normal regeneration of tissue and increases
the lens opacity.
Peculiarities of lens metabolism are characterized
by bradytrophia which means that some tissues have anegligible number of capillaries or do not vascularize
at all [13]. Bradytrophic tissues are characterized by
the following features:• progressing dehydration during the lifetime;• consolidation of structure;• formation of inclusions of organic and inorganic
substances in gradually consolidated parts oftissue;• concentration of tissue colloids due to progressing
consolidation of tissue;• loss of nitrogen contents as the result of
dehydration of substances;• lack of blood in dehydrating tissues of the body.
Numerous literature reports show the age-specificrelationship of lens changes in animals affected byradiation. With the exposure dose of more than 3Gy[6], the latent period of cataract development is almost
linearly dependent on age; and in younger
experimental animals, this period is shorter. With thedose of X-ray exposure of 2-3 Gy, the lens changes
occurred more frequently in old animals. Higher doses(3-9 Gy) caused the lens opacity in younger animals

Conclusions
1. Frequency of occurrence of lensopathias in children
from the main group made 82.1% which is by 12.5%
more than in the control, mostly due to opacities inboth lenses.
2. The number of children with large opacities
markedly prevailed in the main group (25.4%) ascompared with the control (1.1%).

172

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3. The number of children with multiple opacities(more than 6) was larger in the main group and made24.3% (8.7% - in the control).
4. Predominant localizations of lensopathias were:posterior cortical zone, posterior capsule and anteriorcortical zone.
5. Positive relationship between the level of 137Cs
radionuclide activity in the body and the intensity oflens opacity has been revealed in the examinedchildren.
6. Individual lensopathia dynamics in children of themain group was characterized by aggravation of thedisease in 42.9% of cases; no changes were marked
in 57.1%.
7. Primary cataract was revealed in 3 children of themain group (2.2%) and was characterized by a large
number of opacities between the lens capsule and thecortex, both in the center of the lens and within its
periphery, which explains the lack of pronounced
sight decrease.

Study perspectives
Taking into account the importance of the obtained
data, it is planned to continue the study in the following
main directions:
1. conduction of prospective observation over thechildren with lensopathias and the elaboration ofmodel of the development of lens pathology withage;
2. conduction of biodosimetric studies in the given
group of children;
3. to study the role of chemical factors of theenvironment in the formation of lens pathology inchildren;
4. elaboration of measures of lensopathia prophylactics
and correction in the given category of children.
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