The KiKK study
Childhood cancer
near German nuclear power plants

Sebastian Pflugbeil(member of the external expert committee of the KiKK-study)

KURRI, 20121

History 1: first big German study 1992 – no effect2History 2: Second big German study 1997 – no effect3

History 3:
Kernkraftwerke„Keine Häufung vonLeukämie bei Kindern“DÄ 9. April 1999

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History 45

KiKK study:
Epidemiologic study of childhood cancers
near German nuclear power plants• Commissioned by: Federal Office for Radiation Protection(Bundesamt für Strahlenschutz)• Conducted by German Childhood Cancer Registry (GCCR)• Start: April 2003

• Results presented in December 2007
• External advisory expert commission (12 people)

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First new publication about KiKK-study accepted October
2007
international7

First new publication about KiKK-study December 2007
national

8New study
KiKK

9Study design• Case-control study (3 controls per case,matched by age, sex and reactor site)• All cancers, sub group: leukaemias• All German commercial NPPs
• Children below age < 5• Longest possible study period (1980-2003)• One-tailed statistical test
• Proxy of radiation exposure:
Inverse distance of place of residence at diagnosis

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Study region =3 counties next to eachreactor site (16 sites)
altogether 41 counties

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Objective• Main question:
Increase of cancer rates with decreasing distance from NPP?
• Additional test:
Cancer rate greater for r < 5 km than for r > 5 km?
Cancer rate greater for r < 10 km than for r > 10 km?

12Method
Linear logistic regression model:ln(odds) = ß0+ß1/r
whereodds = cases / controls
r = distance from NPP; x = 1/r
ß0, ß1: parameters (ß1: trend parameter)

Negative distance trend if parameter ß1>0 (H0 <= 0)
The relative risk is the ratio of two odds:
RR = odds(x)/odds(x=0) = exp(ß0+ß1*x)/exp(ß0) = exp(ß1*x)

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Results (1)Diagnosis

ß1SE90% CI

P valuecases

controls

cancer

1.18 0.44

0.46, 1.900.0034

1592

4735

leukaemia

1.75 0.67

0.65, 2.850.0044

593

1766

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Results (2)•Significant negative distance trend for all cancers (p=0.0034) as
well as for leukaemia (p=0.0044)•

Relative risk for r < 5 km vs. r > 5 km is
RR=1.61 for all cancers and RR=2.19 for leukaemia, significant•

Relative risk for r < 10 km vs. r > 10 km is
RR=1.18 for all cancers and RR=1.33 for leukaemia, significant•

Negative distance trend also significant when NPP Krümmel with known leukaemia cluster - is excluded

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relative risk

distance from NPP (km)

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KiKK part 2: Questionnaire• A sub-group (360 cases, 696 controls) with selecteddiagnoses (leukaemia, lymphoma, and ZNS tumours) wasinterviewed with regard to the presence of known risk
factors for leukaemia• Study period: 1993-2003• None of the risk factors (confounders) had an appreciableinfluence on the distance trend, ie the main result – anegative distance trend – could not be explained byconfounders.
But: low power of the study due to small numbers

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Conclusions of the KiKK authors• Significantly increased cancer risk, mainly for leukaemia,
when living in the proximity (r < 5 km) of German NPPs
• Results not consistent with most international studies• Results unexpected given the level of radiation exposure• Causes unknown, but radiation can be ruled out on
principle. Unexplained Confounding? Chance result?

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Inconsistency?
Radiobiological knowledge?
• Meta-analysis by Baker et al. (2007), a pooled analysis of
37 studies from 9 countries (136 nuclear facilities), yieldedsignificant increase of leukemia for children below age 10• New findings of radiation effects at very low doses point tohigher risks from internal emitters (eg genomic instability,bystander effect).

22Meta-analysis (Baker et al., 2007)23

Inconsistency ?
• Baker and Hoel 2007
Increase of leukaemia incidence in the 15-km-radius:
children and jung adults < 26 y:
11%children< 10 y:23%• KiKKin the 10 km radiuschildren< 5 y:

33%

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Emissions give no clear explanation (1)25Emissions give no clear explanation (2)26Official dose calculations give no clear explanation27

Official dose estimates questionable:• Possible incomplete registration and measurement ofradionuclides emitted by NPP?
• Official dose calculations use simple propagation models:
two dimensional Gauss model might be in error up to factor 10or more.
• ICRP model for internal emitters might underestimate doses,
especially for alfa and low energy beta emitters, eg H-3(See UK Government CERRIE report (2004) on dose uncertainties).

• Therefore:
Official dose estimates might be low by a factor of 10 to 100 ormore! The question was not discussed in the KiKK-study

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Emission peaks in time of revisions are remarkable29

Indirect confirmation of the KiKK-study by 4 follower studies inGreat Britain, France, Switz and Germany (all together)
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Körblein, Strahlentelex 2012

Leukaemia incidence near nuclear plants in Germany (D), Great Britain (GB), Switzerland(CH, and France (F), Poisson-regressions
Körblein & Fairlie, International Journal of Cancer, Letter to the Editor

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Leukaemia around planned NPP, too ??
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Rehling in downwind direktion of the NPP Gundremmingen !
Really no increased leukaemia risk around planned NPP locations !
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Environmental ministry (S. Gabriel, SPD) in reaction on
the KiKK-study results: In Germany exist 100 leukaemia
clusters (trying to decrease the results of the KiKK-study)
Reality:
In Germany exist no leukaemia clusters (Euroclus-study;
German Children Cancer Registry; Breckow)
Exceptions:Elbmarsch-cluster around NPP Krümmel/GKSS andCluster in Sittensen (incompetent use of a Roentgendevice) – both connected with ionizing radiation

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Votum of the expert group about the KiKK-study (a)35Votum of the expert group about the KiKK-study (b)36Japan has the same problem with NPPs,
cancer and scientists
Iwasaki, T., Nishizawa K and Murata M 1995
Leukaemia and lymphoma mortality in the vicinity of nuclear
power stations in Japan 1973 – 1987
J.Radiol.Prot. 15, 271-88(nearly no effekt)
Hoffmann, W., Kuni H, Ziggel Heiko 1996
Letter to the editor:
Leukaemia and lymphoma mortality in the vicinity of nuclear
power stations in Japan 1973 – 1987
J.Radiol.Prot. 16 No3 213-215(significant effect, RR about 20% increased)German Society for Radiation Protection(Gesellschaft für Strahlenschutz e.V.)
Dr. Sebastian Pflugbeil, president
pflugbeil.kvt@t-online.de38