Repères - N°48 / March 2021 - The IRSN magazine - 18

HEALTH

Following a nuclear accident, people
may have ingested or inhaled
radioelements. Whole body counting
measures internal contamination.

An IRSN Emergency Response Officer reassures a person and collects
information while screening for internal contamination with X- and
gamma-emitting radionuclides.

Population protection

What progress has been made
in ten years?
Preventive iodine intake, health monitoring... Radiation protection measures in the event
of a nuclear accident are implemented since 2011. In addition, one major recommendation
for health surveillance is that national cancer registries be maintained for all categories
of the population.

reventive intake of stable iodine, in
the form of potassium iodine (KI), is
one of the population protection strategies used during the emergency phase of
a nuclear threat or accident with releases.
By saturating the thyroid with stable
iodine, this countermeasure prevents the
gland from uptake and fixation of radioactive iodine, and limits the occurrence
of thyroid cancer.
Its implementation in France has been
recommended since 1997. As soon as there
is an alert, an adult should take two 65 mg
tablets. Intake may be repeated once if
exposure exceeds 24 hours. The dosage for
children is adapted according to their age.
Fukushima Daiichi showed that this measure is insufficient for people awaiting evacuation or who cannot be evacuated in the
event of prolonged or repeated releases. In
2014, the Institute initiated the PRIODAC1
project, funded by the French Investments
for the Future Program (PIA). " We needed
Page 18 - Repères No. 48 - March 2021

to find a KI dosage allowing repeated intake
and verify its effectiveness and safety, "
explained Marc Benderitter who specializes
in radiopathology. He has been in charge
of this major project, which includes preclinical studies of pharmacokinetics, therapeutic effectiveness, and toxicology.
Rat pups model newborns, while female
rats in gestation represent pregnant women,
and young, adult, and aged rats cover the
rest of the population. Preclinical regulatory toxicology studies complete the program. PRIODAC aims to change the KI
dosage for repeated intake by all categories
of the population and to modify the marketing authorization by 2022.

Questioning screening practices

How can the risk of thyroid cancer be
assessed in the event of releases? Japan
opted for systematic screening. " The World
Health Organization (WHO) now advises
against this type of monitoring,2 " reported

Dominique Laurier, expert in the biological
effects of radiation. This recommendation
follows on from long-term feedback.
After the Chernobyl accident, studies
showed an increase in thyroid cancer, especially in young people exposed to releases.
In 2011, Japan wanted to reassure its population. Without precise estimates of the
extent of the accident, that summer it
launched a vast screening campaign using
ultrasound scanning, a very sensitive technique. Three hundred thousand boys and
girls were screened. The fifth screening
campaign is currently underway. What
are the results? For every thyroid nodule
discovered, a biopsy is taken. In case of
malignancy, the gland is either fully or
partially removed. In ten years, two hundred surgical procedures have been carried
out. Is this world record due to the accident
or a result of this uncommon strategy of
operating even before symptoms appear,
criticized more and more? " This screening

Repères - N°48 / March 2021 - The IRSN magazine

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