European Foundation of Oncology and Environmental Sciences “B. Ramazzini”
description
Transcript of European Foundation of Oncology and Environmental Sciences “B. Ramazzini”
European Foundation of Oncology and Environmental Sciences “B. Ramazzini”
Cesare Maltoni Cancer Research Center
June 28 2007
The potential carcinogenic risks of
electromagnetic fields: what we know and what
we still must learn
Bologna Summer Event
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Power frequency EMF:
what we know
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Power frequency EMF: epidemiological evidence
The first epidemiological study of childhood cancer and EMF was published in 1979.
Since then more than 20 studies have been conducted
The present position on EMF and the epidemiology of childhood leukemia is summarized in a pooled analysis of measurement and calculated field studies published by Ahlbom et al (3247 cases in total).
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Pooled results from Ahlbom et al
20.14.4
24.2
368
44
1.87 (1.1-3.2)2.13 (0.9-4.9)
2.00 (1.3-3.1)
1.15 (0.9-1.5)0.79 (0.3-2.3)
1.11 (0.8-1.5)
1.05 (0.9-1.3)1.58 (0.8-3.3)
1.08 (0.9-1.3)
Measurements studiesCalculated field studies
All studies
Summary
00.22.71.5
2105
2 cs/0 ct6.21
0 cs/10 ct3.74
0 cs/8 ct4.111.060.57
2.680 cs/19 ct
1.751.75
DenmarkFinlandNorwaySweden
Calculated field studies
10.30.90
4.44.7
13204
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1.552.00
0 cs/0 ct1.003.44
1.391.67
4 cs/0 ct0.981.01
1.291.240.670.841.11
CanadaGermanyNew ZealandUKUSA
Measurement studies
ExpectedObserved
≥ 0.4 µT≥ 0.4 µT0.2-<0.4 µT0.1-<0.2 µTStudy
Numbers of subjectsRelative risks (and 95% confidence intervals)
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Animals Treatment Result Comments Authors
Species/strain No. Exposure Duration
Margonato et al.,
1995
Rats
S.D.
256 males
per group
0; 5 µT
(50 Hz)
32 weeks
(22 h/day)
No evidence of
carcinogenic effect
Yasui et al.,
1997
Rats F344
48 females
per group
0;0,5; 5 mT
(50 Hz)
2 years
(22 h/day)
No evidence of
carcinogenic effect
Mandeville et al.,
1997
Rats F344 50 males and
50 females
per group
0; 2; 20; 200;
2000 µT
(60 Hz)
2 years, GLP
(20 h/day)
No evidence of
carcinogenic effect
NTP, 1998 Rats F344
Mice B6C3F1
100 males and
100 females
per species and
per group
0; 2; 200;
1000 µT
2 years, GLP
(18.5 h/day)
Equivocal evidence
of carcinogenic effect
for thyroid C cell
tumour in male
treated with 2 or
200 µT
Only 1 sex (male); short duration (32 weeks)
Few animals;short duration (104 weeks)
Only 1 sex (male); short duration (104 weeks)
Short duration (104 weeks)
Power frequency EMF: experimental evidence
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There is an association between childhood leukemias and EMF exposure in the study populations.
However, it is not yet possible to establish a cause-correlation for two reasons:
1) the absence of a plausible mechanism
2) lack of support from laboratory evidence
Present position on power frequency EMF (part I)
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These factors led IARC to classify power frequency EMF as a possible carcinogen in 2001
Were there an accepted mechanism of action or robust supporting evidence from the laboratory, it is probable that EMF would have instead been classified as an established carcinogenic agent.
Present position on power frequency EMF (part II)
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Radio frequency EMF (RFEMF):
what we know
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1978-1995: Various epidemiological studies conducted on military personnel exposed to radar waves and on children living near radio-television aerials indicate a possible increase in limphomas/leukaemia
2001-2002: Initial epidemiological data on tumours of acustic nerves have been reassuringly negative
RFEMF: epidemiological evidence (part I)
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2004: Preliminary results of an epidemiological study condicted in Sweden report an increase in tumours of the acustic nerve in population exposed to cellular telephones (RFEMF) (Ahlbom, 2004)
2006: Pooled analysis of two case-control studies on use of cellular and cordless telephones showed an increase risk of malignant brain-tumours diagnosed in 1997-2003, highest in the group with > 10 years latency period
RFEMF: epidemiological evidence (part II)
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Animals Treatment Result Comments Authors
Species/strain No. Exposure Duration
Chou et al., 1992
Rats S.D.
100 males per group
(2,450MHz)
25 months (21.5 h/day)
Excess of primary malignant tumors
Repacholi et al.,
1997
MiceEm-Pim1
100 females per group
(900 MHz)
18 months (1h/day)
No evidence of carcinogenic effect
Utteridge et al., 2002
120 females per group
(900 MHz)
2 years (1h/day)
No evidence of carcinogenic effect for mammary tumors
Bartsch et al.,
60 females
(23 h/day)
Only 1 sex (male); short duration (110 weeks)
Only 1 sex (female); short duration (78 weeks)
Few animalsshort duration (sacrificed within 1 year)
2002
MiceEm-Pim1; w.t.
Rats S.D. per group
(900 MHzand DMBA)
Increase risk of lymphomas
Only 1 sex (male); short duration (104 weeks)
RFEMF: experimental evidence
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Present position on RFEMF
Use of cell phones for < 10 years have not demonstrated an increase in cancer
There is however some evidence regarding long-term use and lengthy latency period
absence of evidence ≠ absence of risk
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EMF and RFEMF:
what we still must learn
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EMF and RFEMF represent what are known as diffused carcinogenic risks.
We use this term to describe carcinogenic risks of low potency, but to which almost the entire population of the planet may be exposed.
Diffused carcinogenic risks
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1) agents which are slightly carcinogenic at any dose;
2) low or extremely low doses of strong carcinogenic agents;
3) mixtures of small doses of any carcinogenic agents.
Examples of diffused carcinogenic risks
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In the case of diffused carcinogenic risks, it is not sufficient to follow the standard protocol used in ordinary experiments,
but rather it is necessary to conduct what we define as mega-experiments.
Tools for identifying diffused carcinogenic risks
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Characteristics of mega-experiments
reproduce the various conditions of human exposure
use vast numbers of animals per group, in order to express variations in the effects more sharply
are conducted until the natural death of the rodents, to allow an agent to express its full carcinogenic potential
evaluate all neoplastic and non-neoplastic pathologies
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35 years of mega-experiments at the ERF
agent # rodents
vinyl chloride > 7,000
vitamins > 8,000
coca-cola > 2,000
gamma radiation > 10,000
irradiated food > 2,000
electromagnetic fields > 9,000
extremely low frequency > 7,000
radiofrequency > 2,000
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Integrated project of the European Ramazzini
Foundation (ERF)
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ERF mega-experiments to evaluate EMF (50Hz)
7,133 TOTAL
50Hz-magnetic field and aflatoxin B1
642BT 4 CEM
50Hz-magnetic field and 10 gamma rads
657BT 3 CEM
50Hz-magnetic field and formaldehyde
805BT 2 CEM
50Hz-magnetic field5,029BT 1 CEM
TreatmentNumber of animals (M+F)
Experiment Duration
Lifespan
Lifespan
Lifespan
Lifespan
Age at start
embryo
embryo
embryo
embryo
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ERF mega-experiment on EMF (50Hz)
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ERF mega-experiment to evaluate RFERF (1.8 GHz)
2,448TOTAL
0 Volt/meter (control) 817IV
5 Volt/meter 811III
25 Volt/meter 411II
50 Volt/meter409I
Treatment (Volt/meter)Number of animals (M+F)
Group number
Experiment BT 1 CEMRF
Duration
Lifespan
Lifespan
Lifespan
Lifespan
Age at start
embryo
embryo
embryo
embryo
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ERF mega-experiment on RFEMF (1.8 GHz)
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The epidemiological evidence concerning EMF and long-term exposure to RFEMF show there are reasonable grounds for concern for the possibility of adverse effects
The absence of epidemiological evidence concerning short-term exposure RFEMF ≠ the absence of risk
While we await the results of the experiments currently underway (2009-2011), the precautionary principle guides us to “undertake provisional risk management measures…without having to wait until the reality and seriousness of those adverse effects become fully apparent”
Conclusions