Investor Presentaiton
Doses to workers
The average effective dose to the more than 20,000 emergency
workers involved in mitigation and other activities at the FDNPS
site from March 2011 to the end of March 2012 was about 13 mSv.
About 36 per cent received an effective dose of more than 10 mSv,
while 0.8 per cent (174 workers) were assessed to have received
more than 100 mSv in this period. Annual effective doses have
been considerably lower since April 2012, with average annual
effective doses declining from about 6 mSv in the year to the end
of March 2013 to about 2.5 mSv in the year to the end of March
2020. No worker has received an annual effective dose of more
than 50 mSv since April 2013.
Absorbed doses to the thyroid of a small number of emergency
workers who received the highest doses have been reassessed,
in particular using individual-specific measurements of thyroid
size, and this has led to changes in the assessed doses to the
thyroid of these individuals.
Health effects
Since the UNSCEAR 2013 Report, no adverse health effects
among Fukushima residents have been documented that could
be directly attributed to radiation exposure from the accident.
Exposure to radiation could lead to an increased incidence of
disease in the exposed population; however for example, with
cancer, it is not generally possible to distinguish by observation
or testing whether or not the disease of a specific patient has
been caused by the radiation exposure. The Committee has
therefore assessed the risks resulting from radiation exposure
following the accident by estimating whether any increased
incidence of a particular disease, calculated theoretically from
the estimated doses, would be detectable compared to the
normal statistical variability in the baseline incidence of the
disease in that population. The Committee's conclusion is that
its revised estimates of dose are such that future radiation-
associated health effects are unlikely to be detectable.
Following the accident, the greatest concern was whether the
exposure to radiation resulting from the accident would lead to
an increase in rates of thyroid cancer in the population in Japan.
Although a substantial number of thyroid cancers have been
detected among exposed children, the Committee believes that,
on the balance of available evidence, the (relative to expected)
large increase in thyroid cancers is the result of ultrasensitive
screening procedures that have revealed the prevalence
of thyroid abnormalities in the population not previously
recognized, and is not a result of radiation exposure. The
Committee also concluded that no detectable excesses of other
types of cancer that are sensitive to radiation, such as leukaemia
or breast cancer, were likely because of the generally low levels
of radiation exposure in the Fukushima Prefecture population.
There has been no credible evidence of excess birth defects,
stillbirths, premature births or low birthweights related to
radiation exposure. Increases in the incidence of cardiovascular
and metabolic conditions have been observed among those
evacuated following the accident but are probably associated
with concomitant social and lifestyle changes and not
attributable to radiation exposure. Excess psychological distress
also occurred in the aftermath of the combined earthquake,
tsunami and FDNPS accident. However, the report does not
address other health consequences, such as mental health or
financial impacts, which are beyond the Committee's mandate.
Thyroid (ultrasound) screening
No adverse health effects among Fukushima
residents have been documented that could
be directly attributed to radiation exposure
from the accident.
In particular, an increase in the incidence of cancers is also unlikely
to be detectable in workers for leukaemia, total solid cancers or
thyroid cancer. The Committee has insufficient information to
reach an informed judgement on the risk of cataracts.
On the balance of available evidence, the
large increase, relative to that expected, in
the number of thyroid cancers detected among
exposed children is the result of intensive
thyroid screening, not of radiation exposure.View entire presentation