ESTONIAN ENVIRONMENTAL REVIEW 2009

a deficiency in the technical condition of a bore well and
water storage tank; chlorination was used to stabilize the
water quality. Deviations in smaller public water supply
systems from the required microbiological parameters
are the result of depreciation of drinking water pipes
and reservoirs and technical malfunctions in distribution
networks. In Estonia, there have been no infectious
waterborne outbreaks caused by public water supplies
in 14 years. The last recorded infectious outbreak was in
1993, when 614 people in Sõmeru in Lääne-Viru County
fell ill with hepatitis A. With regard to microbiological
indicators, the depreciation of public water supply systems
impacts water quality.
Of the chemical indicators of drinking water, 104
water supplies did not conform to the fluoride content
requirements in 2008. Of these, in 103 water supplies
the problem involved excessive fluoride content (over
1.5 mg/l) – and in the case of 7, excess boron was involved
– and in one supply (city of Narva water supply) the total
trihalomethane C content.
With regard to indicators, the most frequent problem
in water supplies was non-conformity of iron, manganese
and chlorides to the requirements. These compounds
are of natural origin or are due to the poor condition of
pipes. The high iron and manganese content of drinking
water causes deviation in colour, taste and opacity. In the
Cambrian-Vendian groundwater complex in northern
Estonia, occasional high radionuclide content has been
noted, as a result of which the effective radiation dose
exceeds the limit of 0.1 mSv per year established by
Estonian law for drinking water.
Besides drinking water, the quality of bathing water
also impacts human health; it is in general good. The
number of analyses that have disclosed substandard bathing
water has decreased over the years and is under 5%.
Table 10.2. Number of people who use drinking water from public water supplies not in conformity to the
requirements (%). Data: Health Protection Inspectorate.
Years
Non-conformity with regard to
microbiological indicators (%)
Non-conformity with regard to
chemical indicators (%)
2002 0.02 1.3 35.3
2003 0.006 2.3 28
2004 0.004 2.5 29.6
2005 0.01 2 29
2006 0.01 7 27
2007 0.01 8.9 26
2008 0.1 8.6 21.6
Non-conformity with regard to
indicators (%)
164
10.4. Ionizing radiation
The more radiation the human body absorbs, the more
cellular damage occurs and the higher the risk of tumours
and hereditary diseases.
A predominant part of the ionizing radiation that surrounds
us is of natural origin, but manmade radio-isotopes
also exist. Manmade radionuclides are released into the
environment due to human activity, as it is unlikely that
radiation will leak into the environment from manmade
radiation sources. Possible sources of radioactive contamination
are primarily considered to be nuclear power
plants in Russia (Sosnovyi Bor); in Finland (Loviisa) and
in Lithuania (Ignalina).
C
Trihalomethanes – undesirable byproducts of chlorination of water with a high content of organic matter.
The activity of radionuclides found in nature is routinely
measured, but traditionally the yardstick for whether the
environment is polluted or not is the manmade radionuclide
Cs-137. The caesium found in the environment
originates in equal parts from the extensive atmospheric
nuclear testing conducted in the mid-20 th century and
the Chernobyl nuclear power plant disaster in 1986. Due
to the action of wind and forest and bog fires, pollution
that has fallen to earth re-enters the atmosphere. Caesium
levels (microbecquerels per cubic metre) are measured
in Estonia in tropospheric air at three points (Harku,
Narva-Jõesuu and Tõravere). The systematic several-fold
variation in the results measured at Narva-Jõesuu and
Harku (3.7 microBq/m 3 in the former, 1.5 microBq/m 3
in the latter in 2005–2007) can be attributed to the fact
that the Cs-137 from Chernobyl fell here primarily in
north-eastern Estonia.