1

National Toxicology Program
National Institutes of HealthPublic Health Service
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

March 12, 2018

Comments on:
NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESISSTUDIES IN Hsd:SPRAGUE DAWLEY SD RATSEXPOSED TO WHOLE-BODY RADIO FREQUENCY RADIATION
AT A FREQUENCY (900 MHz) AND MODULATIONS (GSM AND CDMA) USED BY
CELL PHONESNTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESISSTUDIES IN B6C3F1/N MICE EXPOSEDTO WHOLE-BODY RADIO FREQUENCY RADIATION AT A FREQUENCY (1,900
MHz) AND MODULATIONS (GSM AND CDMA) USED BY CELL PHONES
We have read these two reports with interest. They show increased incidence of malignant
schwannoma in the heart and brain glioma in male rats exposed either to GSM-modulated orCDMA modulated cell phone radiofrequency (RF) radiation for two years. There are also
increased incidences of some other tumor types and diseases. We discuss in the following
some of the major findings.
The reports the results on schwannoma and glioma are of special concern since they
corroborate human epidemiology findings. Thus, it is noteworthy that similar tumors were
found in the NTP study as in epidemiological studies on human use of wireless phones;
mobile phones or cordless phones (DECT). Malignant schwannoma in the heart is a similar
type of tumor as vestibular schwannoma in humans, also called acoustic neuroma, althoughacoustic neuroma is usually benign and may rarely undergo malignant transformation.
In the following we give an updated evaluation on the scientific evidence for increased risk
for glioma and vestibular schwannoma (acoustic neuroma) associated with use of wirelessphones. In our opinion also certain aspects on human epidemiology on this issue need to befurther clarified and elaborated in the NTP report.
Our study group has since the end of the 1990’s published results from case- control studies
on use of wireless phones and brain tumor risk (Hardell et al 1999). An increased risk forbrain tumors was found for ipsilateral use of mobile phones, the same side of the brain as thephone was used. A statistically significant increased risk was published for malignant brain
tumors (Hardell et al 2002) and vestibular schwannoma (Hardell et al 2003). Further scientificevidence on the association has more recently been discussed by Carlberg and Hardell (2017).
BackgroundThe brain is the main target for exposure to RF radiation during use of handheld wirelessphones; both mobile and cordless phones (Cardis et al 2008, Gandhi et al 2012). An increased
risk for brain tumors has been of concern for a long time. In May 2011 RF radiation in thefrequency range 30 kHz–300 GHz was evaluated to be a Group 2B, i.e. a ‘possible’ humancarcinogen, by the International Agency for Research on Cancer (IARC) at the World Health2

Organization (WHO) (Baan et al 2011, IARC 2013). This was based on an increased risk forglioma and acoustic neuroma in human epidemiological studies.
The IARC cancer classification includes all sources of RF radiation. The exposure frommobile phone base stations, Wi-Fi access points, smart phones, laptops and tablets can belong-term, sometimes around the clock, at home, at work place, at school, and in theenvironment. For children this risk may be accentuated because of a cumulative effect during
a long lifetime use (Hedendahl et al 2015).
The exposure guideline used by many agencies was established in 1998 by the International
Commission on Non-Ionizing Radiation Protection (ICNIRP) and was based only on
established short-term thermal (heating) effects from RF radiation neglecting non-thermal
biological effects (ICNIRP 1988). The ICNIRP guidelines were updated in 2009 but still do
not cover cancer and other long-term or non-thermal effects (ICNIRP 2009), see also Hardell(2017).
ICNIRP gives the guideline 2 to 10 W/m2 for RF radiation depending on frequency. This is
only based on a short-term immediate thermal effect (ICNIRP 2009). ICNIRP is a private
non-governmental organisation (NGO) based in Germany. New expert members can only beelected by members of the organization. Many of the ICNIRP members have ties to theindustry that is dependent on the ICNIRP guidelines. The guidelines are of huge economic
and strategic importance to the military, telecom/IT and power industry.
In contrast to ICNIRP, the BioInitiative Reports from 2007, updated in 2012, based theevaluation also on non-thermal health effects from RF radiation (BioInitiative Working Group
2007, 2012). The scientific benchmark for possible health risks was defined to be 30 to 60µW/m2. In 2012, the Bioinitiative Working Group proposed a precautionary target level of 3–
6 μW/m2, using a safety factor of 10. Using the significantly higher guideline by ICNIRP
gives a ‘green card’ to roll out the wireless digital technology thereby not considering nonthermal health effects from RF radiation.
Since the IARC evaluation in 2011 more studies have been published that support a causal
association between RF radiation and brain and head tumors. Thus, it is pertinent to make an
up-dated presentation in the NTP reports on current evidence on cancer risks associated withuse of wireless phones.
A Danish cohort study on ‘mobile phone users’ (Johansen et al 2001, Schüz et al 2006) is notincluded here due to serious methodological shortcomings in the study design, see (Söderqvist
et al 2012). The study by Benson et al (2013) is of limited value since use of cordless phones
was not included, mobile phone use was assessed only at baseline and no information on
tumor laterality including ipsilateral versus contralateral use were given. In spite of the many
shortcomings an increased risk for acoustic neuroma was reported. The study will not be
further discussed below.
First human epidemiology studies on specific tumor types are discussed. Then NTPs-study
findings are presented and finally an evaluation of the combined evidence from human andanimal studies.

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GliomaHuman studies
Glioma is the most common malignant brain tumor and represents about 60 % of all central
nervous system (CNS) tumors. Most of these are astrocytic tumors divided into low-grade(WHO grades I-II) and high-grade (WHO grades III-IV). The most common glioma type is
glioblastoma multiforme (WHO grade IV) with the peak incidence in the age group 45-75
years and median survival less than one year (Ohgaki, Kleihues 2005). No substantial
increasing survival has been obtained during recent years. Three research groups haveprovided results in case-control studies on glioma, Interphone (Interphone 2010), Coureau etal (2014) and the Hardell group in Sweden (Hardell, Carlberg 2009, 2015a; Hardell et al
2006, 2011a, 2011b).
Random effects model was used for meta-analyses of published studies, based on test forheterogeneity in the overall group (“all mobile”), see also http://www.bioinitiative.org/. Notethat only our group assessed also use of cordless phones. Thus the reference category in ourstudies included cases and controls with no use of wireless phones in contrast to the otherstudies investigating only mobile phone use. Including cordless phone use in the ‘unexposed’group would bias the risk estimates towards unity (Hardell el at 2011a)
In Table 1 results for highest cumulative use in hours of mobile phones are given. All studies
reported statistically significant increased risk for glioma and the meta-analysis yielded odds
ratio (OR) = 1.90, 95 % confidence interval (CI) = 1.31-2.76. For ipsilateral mobile phone use
the risk increased further to OR = 2.54, 95 % CI = 1.83-3.52 in the meta-analysis based on
247 exposed cases and 202 exposed controls. Further support for the increased risk of glioma
associated with mobile phone use has been obtained in additional analyses of parts of theInterphone study (Cardis et al 2011, Grell et al 2016, Momoli et al 2017).
Table 1. Numbers of exposed cases (Ca) and controls (Co) and odds ratio (OR) with 95 %confidence interval (CI) for glioma in case-control studies in the highest category of
cumulative use in hours for mobile phone use.

Interphone 2010
Cumulative use ≥1,640 h
Coureau et al 2014
Cumulative use >896 h
Hardell, Carlberg 2015
Cumulative use ≥1,640 h
Meta-analysis
Cumulative use ≥1,640 h**≥896 h used for Coureau et al.

All
Ca/Co

95 % CI

Ipsilateral
Ca/Co
OR

OR

95 % CI

210/1541.40

1.03 – 1.89

100/62

1.96

1.22 – 3.16

24/22

2.89

1.41 – 5.93

9/7

2.11

0.73 – 6.08

211/301

2.13

1.61 – 2.82

138/133

3.11

2.18 – 4.44445/477

1.90

1.31 – 2.76

247/202

2.54

1.83 – 3.52

We analyzed survival of the patients in our studies and found shorter survival in patients withglioblastoma multiforme associated with use of wireless phones compared with patients withno use (Carlberg, Hardell 2014). Interestingly mutation of the p53 gene involved in diseaseprogression has been reported in glioblastoma multiforme in patients with mobile phone use

4>3 hours per day. The mutation was statistically significant correlated with shorter overall
survival time (Akhavan-Sigari et al 2014).
NTP study
No increased incidence of glioma was reported in the mice study (NTP TR 596).
In male rats (NTP TR 595) malignant glioma and glia cell hyperplasia occurred in all groups
exposed to GSM-modulated cell phone RF radiation for 2 years. No lesions were seen in
sham controls. In female rats glial cell hyperplasia occurred in one rat (3 W/kg) but none insham controls. One malignant glioma occurred in one rat in the 6 W/kg group but none insham controls. These results were not statistically significant.
In male rates exposed to CDMA-modulated cell phone RF radiation for 2 years there was anincreased incidence of malignant glioma with a statistically significant trend, p = 0.044. In
females three malignant glioma occurred in the 1.5 W/kg group, but none in the other exposedgroups or sham control. Glial cell hyperplasia was seen in most exposed groups, although notstatistically significant.
Evaluation
Based on human epidemiology studies and the NTP animal study there is clear evidence that
RF radiation causes glioma in humans.
Meningioma
Human studies
Meningioma is an encapsulated, well-demarked and rarely malignant tumor. It is the mostcommon benign brain tumor that accounts for about 30 % of intracranial neoplasms. It
develops from the pia and arachnoid membranes that cover CNS. It is slow growing and gives
neurological symptoms by compression of adjacent structures. Most common are headaches
and seizures. The incidence is about two times higher in women than in men and meningioma
develops mostly among middle aged and older persons (Cea-Soriano et al 2012). The same
research groups as for glioma included also meningioma in their case-control studies with aseparate publication on meningioma by Carlberg, Hardell (2015). Results of the metaanalyses for cumulative exposure in highest exposure category are given in Table 2. A
statistically significant increased risk was obtained for ipsilateral mobile phone use with OR =1.49, 95 % CI = 1.08-2.06.
Table 2. Numbers of exposed cases (Ca) and controls (Co) and odds ratio (OR) with 95 %confidence interval (CI) for meningioma in case-control studies in the highest category of
cumulative use in hours for mobile phone use.
All
Ipsilateral
Ca/Co
OR
95 % CI
Ca/Co
OR
95 % CI
Interphone 2010
Cumulative use ≥1,640 h
130/107 1.15 0.81 – 1.62
46/35
1.45 0.80 – 2.61
Coureau et al 2014
Cumulative use >896 h
13/9
2.57 1.02 – 6.44
6/4
2.29 0.58 – 8.97
Carlberg et al 2013
Cumulative use ≥1,640 h
141/301 1.24 0.93 – 1.66
67/133
1.46 0.98 – 2.17
Meta-analysis
Cumulative use ≥1,640 h*
284/417 1.27 0.98 – 1.66
119/172 1.49 1.08 – 2.06*≥896 h used for Coureau et al.

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NTP study
No increased incidence was reported in mice (NTP TR 596).
In the rat study (NTP TR 595) increased incidence of malignant or benign granular cell tumors
occurred in the males exposed to GSM-modulated cell phone RF radiation for 2 years. This
was not statistically significant, trend p = 0.343. In female rats granular cell tumors malignant
or benign were not associated with RF radiation, p trend = 0.594.
Evaluation
Based on human epidemiology studies and the NTP animal study there is equivocal evidence
that RF radiation causes meningioma in humans (may be related to exposure).
Rate/incidence of brain tumors
The Swedish Cancer Register has not shown increasing incidence of brain tumors in a study
for the time period 1979-2008, and has been used to dismiss epidemiological evidence on arisk (Deltour et al 2012). We have previously published that descriptive studies cannot be
used to dismiss results in analytical epidemiology with individual exposure histories such as
in case-control studies. We have also published the deficiencies in reporting of brain tumors
to the Swedish Cancer Register (Hardell, Carlberg 2015b). Results for more recent time
periods have now been published. These articles discuss also results from studies in othercountries.
We used the Swedish National Inpatient Register (IPR) and Causes of Death Register (CDR)
to study the incidence of brain tumors comparing with the Swedish Cancer Register data forthe time period 1998–2013 using joinpoint regression analysis (Hardell, Carlberg 2015b). In
the IPR we found a joinpoint in 2007 with Annual Percentage Change (APC) +4.25%, 95%
CI +1.98, +6.57% during 2007–2013 for tumors of unknown type in the brain or CNS. Figure
1 shows time trends in IPR for brain tumors of unknown type (D43), red line, and mobile
phone communication; number of out-going mobile phone minutes in millions per year
(blue line). The figure shows increasing rates of brain tumors with some latency in relation toincreasing use of mobile phones.

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Figure 1. Number of out-going mobile phone minutes in millions during 1999–2013(http://statistik.pts.se/pts2013/download/Svensk%20Telemarknad%202013.pdf ; accessedon 1 April 2015) and joinpoint regression analysis of number of patients per 100,000
inhabitants according to the Swedish National Inpatient Register for all ages during 1999–
2013 diagnosed with D43 = tumor of unknown type in the brain or CNS(http://www.socialstyrelsen.se/statistik/statistikdatabas/diagnoserislutenvard ; accessed on
1 April 2015).
In the Causes of Death Register (CDR) joinpoint regression found one joinpoint in 2008 with
APC during 2008–2013 +22.60%, 95% CI +9.68, +37.03%. These tumor diagnoses would bebased on clinical examination, mainly CT and/or MRI, but without histopathology or
cytology. No statistically significant increasing incidence was found in the Swedish Cancer
Register during these years. We postulated that a large part of brain tumors of unknown typeare never reported to the Cancer Register. Furthermore, the frequency of diagnoses based on
autopsy has declined substantially due to a general decline of autopsies in Sweden adding
further to missing cases. We conclude that the Swedish Cancer Register is not reliable to be
used to dismiss results in epidemiological studies on the use of wireless phones and brain
tumor risk.
In Figure 2 we show rates per 100,000 of deaths in unknown type of brain tumor (D43), redline, and number of out-going mobile phone minutes in millions (blue line) during 1999–
2013. We postulate that the increasing rate of patients deceased with brain tumor may be
associated with the increasing use of mobile phones.

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Figure 2. Number of out-going mobile phone minutes in millions during 1999–2013(http://statistik.pts.se/pts2013/download/Svensk%20Telemarknad%202013.pdf ; accessedon 1 April 2015) and joinpoint regression analysis of age-standardized death rates per
100,000 inhabitants according to the Swedish Causes of Death Register for all ages during
1999–2013 diagnosed with D43 = tumor of unknown type in the brain or CNS(http://www.socialstyrelsen.se/
statistik/statistikdatabas/dodsorsaker ; accessed on 1 April 2015).
In an up-dated further analysis we used the Swedish Inpatient Register (IPR) to analyze rates
of brain tumors of unknown type (D43) during 1998-2015 in different age groups (Hardell,
Carlberg 2017). Average Annual Percentage Change (AAPC) per 100,000 increased with
+2.06 %, 95 % confidence interval (CI) +1.27, +2.86 % in both genders combined. A
joinpoint was found in 2007 with APC 1998-2007 of +0.16 %, 95 % CI -0.94, +1.28%, and2007-2015 of +4.24 %, 95 % CI +2.87, +5.63 %. Highest AAPC was found in the age group
20-39 years.
In the Swedish Cancer Register the age-standardized incidence rate per 100,000 increased forbrain tumors, ICD-code 193.0, during 1998-2015 with AAPC in men +0.49 %, 95 % CI
+0.05, +0.94 %, and in women +0.33 %, 95 % CI -0.29, +0.45 % (Hardell, Carlberg 2017).
The cases with brain tumor of unknown type lack morphological examination. Brain tumor
diagnosis was based on cytology/histopathology in 83 % for men and in 87 % for women in
1980. This frequency increased to 90 % in men and 88 % in women in 2015. During the sametime period CT and MRI imaging techniques were introduced and morphology is not always
necessary for diagnosis. If all brain tumors based on clinical diagnosis with CT or MRI had
been reported to the Cancer Register the frequency of diagnoses based on cytology/histology
would have decreased in the register. The results indicate underreporting of brain tumor cases
to the Cancer Register. The real incidence would be higher. Thus, incidence trends based on

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the Cancer Register should be used with caution. Our results support mobile and cordlessphones as risk factors for brain tumors with a reasonable latency period.
Figure 3 shows joinpoint regression analysis of age-standardized incidence rates per 100,000
in men aged 60–79 years with astrocytoma grade III or IV in the Swedish Cancer Registerduring 1998–2015, and Figure 4 results in women.

Figure 3. Joinpoint regression analysis of age-standardized incidence rates per 100,000 in
men aged 60–79 years with astrocytoma grade III or IV in the Swedish Cancer Registerduring 1998–2015. APC/AAPC +1.68 %, 95 % CI +0.39, +2.99 %.
(http://www.socialstyrelsen.se/statistik/statistikdatabas/cancer).
https://doi.org/10.1371/journal.pone.0185461.g005

9Figure 4. Joinpoint regression analysis of age-standardized incidence rates per 100,000 inwomen aged 60–79 years with astrocytoma grade III or IV in the Swedish Cancer Registerduring 1998–2015. APC/AAPC + 1.38 %, 95 % CI +0.32, +2.45 %.
(http://www.socialstyrelsen.se/statistik/statistikdatabas/cancer).
https://doi.org/10.1371/journal.pone.0185461.g006

Evaluation
Increasing rates/incidences of brain tumors in Sweden, a country with among the earliest useof wireless phones in the world, have been published. Similar findings have been reported
from other countries. The results give some evidence that RF radiation causes brain tumors inhumans.
Acoustic neuroma (vestibular schwannoma)
Human studies
Acoustic neuroma, also called vestibular schwannoma, is a benign tumor located on the eightcranial nerve from the inner ear to the brain. It is usually encapsulated and grows in relation to
the auditory and vestibular portions of the nerve. It grows slowly and due to the narrowanatomical space may give compression of vital brain stem structures. First symptoms ofacoustic neuroma are usually tinnitus and hearing problems. Results for use of mobile phones
in Interphone (2011) and Hardell et al (2013a) are given in Table 3. Statistically significant
increased risk was found for cumulative ipsilateral use > 1,640 h yielding OR = 2.71, 95 % CI
= 1.72-4.28.

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Table 3. Numbers of exposed cases (Ca) and controls (Co) and odds ratio (OR) with 95 %confidence interval (CI) for acoustic neuroma in case-control studies in the highest categoryof cumulative use in hours for mobile phone use.

Interphone 2010
Cumulative use ≥1,640 h
Hardell et al 2013
Cumulative use ≥1,640 h
Meta-analysis
Cumulative use ≥1,640 h

All
Ca/Co

OR

95 % CI

Ipsilateral
Ca/Co
OR

95 % CI

77/1071.32

0.88 – 1.97

47/46

2.33

1.23 – 4.40

27/3012.40

1.39 – 4.16

19/1333.18

1.65 – 6.12

104/408

1.73

0.96 – 3.09

66/1792.71

1.72 – 4.28

The study by Moon et al (2014) was not included in the meta-analysis since data on
cumulative mobile phone use with numbers of cases and controls were not given. Support ofan increased risk was seen in the case-case part of the study (Moon et al 2014), as also
reported by Sato et al (2011) in their case-case analysis. Pettersson el al made a case-control
study on acoustic neuroma in Sweden not overlapping our study (Pettersson et al 2014). An
increased risk for highest category of cumulative use of both mobile phone (> 680 h OR =1.46, 95 % CI = 0.98-2.17) and cordless phone (>900 hours OR = 1.67, 95 % CI = 1.13-2.49)
was found. We did not include that study in our meta-analysis due to the many scientificshortcomings in the study, e.g. laterality analysis was not made for cordless phone and thenumbers in the laterality analysis for mobile phone are not consistent in text and tables andobviously not correct, and the ‘unexposed’ reference category included subjects using either
mobile or cordless phone (Hardell, Carlberg 2014).
The Danish part of Interphone study reported mean tumor volume 1.66 cm3 among regularmobile phone users and 1.39 cm3 for non-users (p = 0.03) (Christensen et al 2004). We
analyzed percentage change in tumor volume per year of latency and 100 h of cumulative use(Hardell et al 2013). For all types of wireless phones the percentage of tumor volume
increased, statistically significant for analogue mobile phones. Moon et al (2014) reported
statistically significant larger mean tumor volume for heavy users (11.32 + 15.43 cm3)
compared with light users (4.88 + 5.60 cm3) based on daily amount of mobile phone use (p =0.026). Similar results were found for cumulative hours of use. Taken together these results
support tumor promotion by RF radiation.
NTP study
No malignant schwannoma was reported in the mice study (NTP TR 596).
In the rat study (NTP TR 595) there was an increased incidence of malignant schwannoma in
the heart in males exposed to GSM modulated cell phone RF radiation for 2 years; trend p =0.041. The tumor was found in all exposed male rats, whereas no malignant schwannoma wasfound in sham controls. Endocardial hyperplastic Schwann cell lesions, that are preneoplastic,
were found in one 1.5 W/kg and in two 6 W/kg males, but no in sham control. Two female
rats were diagnosed with malignant schwannoma in the heat in the 3 w/kg group, no wasfound in the two other exposure groups or in sham control, p trend = 0.640.
Evaluation
Based on human epidemiology studies and the NTP animal study there is clear evidence that
RF radiation causes vestibular schwannoma (acoustic neuroma) in humans

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Pituitary tumor
Human studies
In a case-control study from Japan no statistically significant increased risks were found foruse of mobile phone (Takebayashi et al 2008). A somewhat increased risk was found in thehighest cumulative call time in hours, OR = 1.33, 95 % CI = 0.58-3.09. The cases were aged
30-69 years and diagnosed during 2000-2004.
In a UK case-control study with patients diagnosed during 2001-2005 overall no statisticallysignificant increased risks were found (Schoemaker, Swerdlow 2009). In the group with > 10
years of use a somewhat increased risk was found for analog mobile phone use, OR = 1.2, 95% CI = 0.6-2.4, and digital mobile phone use with OR = 2.5, 95 % CI = 0.7-9.1.
In a case-control study from China with cases diagnosed 2006-2010 mobile phone use yielded
an increased risk for pituitary tumor, OR = 7.6, 95 % CI = 2.6-21.4 and duration of use gave
OR = 8.5, 95 % CI = 2.8-24.4 (Leng, Zhang 2016). However no more data were given.
The incidence of pituitary tumors increased during the time period 2004-2009 in USA(Gittleman et al 2014). The incidence is increasing in Sweden especially sine 2000, see Fig 5.
There seems to be a drop during the latest year, but this may be explained by a time lag in thereporting to the Swedish Cancer Register.

Figure 5. Age-standardized incidence of pituitary tumors (ICD-7 195.3) in Sweden 19702016 for men and women, all ages, according to the Swedish Cancer Register(http://www.socialstyrelsen.se/statistik/statistikdatabas/cancer).

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NTP
In male rats exposed to GSM-modulated cell phone RF radiation for 2 years (NTP TR 595)
increased incidence of pituitary adenoma was found in all exposed groups, although notstatistically significant. In females the incidence of adenoma in 1.5 W/kg and 6 W/kg were
statistically significant decreased.
In male rats exposed to CDMA-modulated RF radiation for 2 years an increased incidence of
pituitary adenoma was found in the 1.5 W/kg (p=0.208) and 3W/kg (p=0.030). In females
there was a statistically decreased incidence of adenoma or carcinoma in the 3 W/kg group(p=0.030).
In male mice (NTP TR 596) exposed to CDMA-modulated RF radiation for 2 years two
adenoma and one carcinoma occurred in pars distalia of the pituitary gland. No carcinoma or
adenoma occurred in the sham control or the other two exposure groups. No increased
incidence was seen in female mice.
Evaluation:
Based on human epidemiology studies and the NTP animal study there is equivocal evidence
that RF radiation causes pituitary tumor in humans (may be related to exposure).
Thyroid cancer
Human studies
The incidence of thyroid cancer is increasing in many countries, especially the papillary typethat is the most radiosensitive type. We used the Swedish Cancer Register to study theincidence of thyroid cancer during 1970-2013 using joinpoint regression analysis (Carlberg etal 2016). In women, the incidence increased statistically significantly during the whole study
period; AAPC +1.19 % (95 % CI +0.56, +1.83 %). Two joinpoints were detected, 1979 and2001, with a high increase of the incidence during the last period 2001-2013 with an APC of+5.34 % (95 % CI +3.93, +6.77 %).
In the age group 20-39 years joinpoint regression analysis of age-standardized incidence of
thyroid cancer in women, aged 20–39 years, APC increased with + 10.77 % (95 % CI +5.75,+16.04 %) during the time period 2006-2013, see Figure 6.

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Figure 6. Joinpoint regression analysis of age-standardized incidence of thyroid cancer for
women, aged 20–39 years, 1970–2013. Incidence per 100,000 inhabitants for ICD-7 code 194
according to the Swedish Cancer Register(http://www.socialstyrelsen.se/statistik/statistikdatabas/cancer)
Analyses based on data from the Cancer Register showed that the increasing trend in Sweden
was mainly caused by thyroid cancer of the papillary type. The incidence increased
statistically significantly in women with an AAPC of +4.38 % (95 % CI +2.95, +5.84 %)during 1993-2013, see Figure 7. One joinpoint was detected in 2006; 1993-2006 APC +1.69% (95 % CI +0.32, +3.08 %), 2006-2013 APC +9.58 % (95 % CI +5.85, +13.44 %). The
incidence increased in men during 1993-2013 with an AAPC of +3.95 % (95 % CI +2.20,+5.73%).

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Figure 7. Joinpoint regression analysis of age-standardized incidence of papillary thyroid
cancer for women, all ages, 1993–2013. Incidence per 100,000 inhabitants for ICD-7 code
194; data obtained from the Swedish Cancer Register
AAPC for all men during 1970-2013 was +0.77 % (95 % CI -0.03, +1.58 %). One joinpoint
was detected in 2005 with a statistically significant increase in incidence during 2005-2013;
APC +7.56 % (95 % CI +3.34, +11.96 %). Based on NORDCAN data, there was astatistically significant increase in the incidence of thyroid cancer in the Nordic countries
during the same time period. In both women and men a joinpoint was detected in 2006. The
incidence increased during 2006-2013 in women; APC +6.16 % (95 % CI +3.94, +8.42 %)and in men; APC +6.84 % (95 % CI +3.69, +10.08 %), thus showing similar results as theSwedish Cancer Register.
We postulate that the whole increase cannot be attributed to better diagnostic procedures. In
Figure 8 Swedish data are shown on number of out-going mobile phone minutes during 20012013 and the incidence of thyroid cancer in men (green line) and in women (red line). Clearly,
with a lag time of some years after the increasing number of out-going calls, the thyroid
cancer incidence is increasing.
Increasing exposure to ionizing radiation, e.g. medical CT scans, and to RF radiation should
be further studied as causative factors to this emerging thyroid cancer health problem.

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Figure 8. Number of out-going mobile phone minutes and incidence of thyroid cancer 2001–
2013. Mobile phone minutes in millions in the Nordic countries(http://statistik.pts.se/PTSnordic/NordicBaltic2014/) and incidence per 100,000 person-years
for all ages 2001–2013 according to NORDCAN(http://www-dep.iarc.fr/NORDCAN/english/frame.asp). Joinpoint regression analyses basedon the time period 1970–2013
Figure 9 shows three developments in the antenna design in mobile phones that may be of
relevance in thyroid carcinogenesis. The second generation (2G) mobile phones started in the
1990s with the external retractable monopole or helical antennas. The 2G GSM band operated
at 800/900 MHz frequency band, later accompanied by 1,800 MHz band. Around the turn ofthe millennium, the external antennas were starting to disappear, replaced with new phonemodels with internal planar or microstrip antennas. The first internal antenna was introduced
in 1998 and the first dual-band mobile phone, with the internal antenna, was introduced on themarket in 1999 (Garg et al 2001). The internal antennas were positioned at the top of thetelephone. With the emergence of the smartphones in the mid and late 2000s, the internalantenna location started to shift from the top of the phone to the bottom. Currently, themajority of smartphone models have their antenna positioned at the bottom of the phone, thus
closer the thyroid gland (grey in figure). This would have a major impact on increasingradiation to the thyroid gland from smartphones.

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Figure 9. Mobile phone antenna placements in regard to the thyroid glandSome published laboratory studies are of interest, Radiofrequency radiation at 2.45 GHz at a
non-thermal level modified the morphology of the thyroid gland in a study on rats. The
central and peripheral follicles presented increased in size and the thickness of peripheral
septa decreased. Peripheral follicles increased in size with repeated exposure at 3 W power(Misa-Agustiño et al 2015).
In another study on rats, whole body exposure to 900 MHz pulse-modulated RF radiation thatwas similar to that emitted by the global system for mobile communications (GSM) mobile
phones caused pathological changes in the thyroid gland. The gland structure was altered andcaspase-dependent pathways of apoptosis were enhanced (Eşmekaya et al 2010).
NTP studies
In mice (NTP TR 596) no increased incidence was reported.
In female rats (NTP TR 595) a statistically significant increased incidence of C-cell
hyperplasia was found in the 2 years GSM exposed groups (1.5, 3 and 6 W/kg, respectively).
In males a statistically non-significant increased incidence was seen in the 1.5 W/kg exposuregroup.
Evaluation
C-cell hyperplasia as a precursor to familial medullary thyroid cancer in humans is wellestablished. C-cell hyperplasia may be a precursor to other types of thyroid cancer but its roleis not well established. Based on human cancer statistics and the NTP animal study there issome evidence that thyroid cancer is caused by RF radiation in humans.
Malignant lymphoma
Human studies
Few studies exist on malignant lymphoma and exposure to RF radiation. In a case-control
study male and female subjects aged 18-74 years living in Sweden were included during aperiod from 1 December 1999 to 30 April 2002 (Hardell et al 2005). Controls were selectedfrom the national population registry. Exposure to different agents was assessed byquestionnaire. In total, 910 (91%) cases and 1016 (92%) controls participated. NHL of the Bcell type was not associated with the use of cellular or cordless telephones. Regarding T-cell
NHL and >5 year latency period, the use of analogue cellular phones yielded: OR = 1.46,
95%; 95 % CI = 0.58-3.70, digital: OR=1.92, 95%; CI=0.77-4.80 and cordless phones:
OR=2.47; 95 % CI=1.09-5.60. The corresponding results for certain, e.g. cutaneous and17leukaemia, T-cell lymphoma for analogue phones were: OR=3.41, 95%; CI=0.78-15.0,
digital: OR=6.12, 95%; CI=1.26-29.7 and cordless phones: OR=5.48, 95%; CI=1.26-23.9.
The results indicate an association between T-cell NHL and the use of cellular and cordlesstelephones, however based on low numbers and must be interpreted with caution. Regarding
B-cell NHL no association was found.
A case-control study in USA used a questionnaire to assess cellular telephone use in 551 NHL
cases and 462 frequency-matched population controls (Linet et al 2006). Compared to persons
who had never used cellular telephones, risks were not increased among individuals whose
lifetime use was more than 100 times (e.g., regular users, OR = 0.9, 95% CI= 0.6-1.4).
Among regular users compared to those who had never used hand-held cellular telephones,
risks of NHL were not statistically significantly associated with minutes per week, duration,
cumulative lifetime or year of first use, although NHL was non-significantly higher in men
who used cellular telephones for more than 8 years; OR = 2.4, 95 % CI = 0.8-7.0. Little
evidence linked use of cellular telephones with total, diffuse large B-cell lymphoma or
follicular NHL. No results were presented for T-cell lymphoma.
In USA primary central nervous system lymphoma (PCNSL) rates in immunocompetent men
and women aged 65+ years increased statistically significantly (1.7% and 1.6% per year,
respectively), but remained stable in other age groups during 1992-2011 (Shiels et al 2016).
Thus, the increasing rates could not be related to HIV or immune suppression in organtransplant patients.
In Sweden increasing incidence of PCNSL was reported for the time period 2000-2013 inimmunocompetent persons (Eloranta et al 2018). With 359 identified PCNSL cases (medianage 66 years), overall incidence was 0.26 (95% CI= 0.24-0.29) and the average annual
increase 4% (p = 0.002). The increasing trend was primarily observed among elderly
individuals (70+ years). Similarly, an increase in incidence of all brain tumors was noted only
among the elderly.
No etiologic factor has clearly been defined to explain the increasing incidence of brain
lymphoma. However, it has occurred during a time period when RF radiation to the brain
from wireless phones has increased.
It should be noted that in transgenic mouse an increased incidence of lymphoma exposed to
900 MHz GSM RF radiation was reported; p=0.006 versus sham group (Repacholi et al1997). No increased risk for malignant lymphoma was found in mice exposed to GSM 900
MHz but the incidence in the sham exposed group was higher than in the Repacholi et al(1997) study (Utteridge et al 2002).
NTP study
In NTP TR 595 no conclusive evidence of increased incidence of malignant lymphoma wasreported in rats.
In NTP TR 596 there were in female mice exposed to GSM modulated cell phone RF
radiation for 2 years increased incidences of malignant lymphoma in all exposed groups
compared to the controls. The increase was statistically significant in the 2.5 W/kg (p=0.004)
and 5 W/kg groups (p=0.035). In the CDMA modulated cell phone RF radiation for 2 years
the incidence increased in female mice in all exposed groups compared to the controls,
statistically significant in the 2.5 W/kg group (p=0.035).

18

Evaluation
Based on human epidemiology studies and the NTP study there is equivocal evidence thatmalignant lymphoma is caused by RF radiation in humans (may be related to exposure).
Skin (cutaneous tissue)
Human studies
Few studies exist on RF radiation and the risk for skin tumors. In a Danish cohort on mobile
phone subscribers from 1987-1995 followed to 2007 no increased risks of skin cancer wasseen (Poulsen et al 2013). The same cohort has also been used for studying brain tumor risk.
Due to serious methodological problems including misclassification of exposure it has been
evaluated to be uninformative (Söderqvist et al 2012, IARC 2013).
In a Swedish study on cutaneous malignant melanoma diagnosed during 2000-2003 noincreased risk was seen overall (Hardell et al 2011c). In the shortest latency period >1-5 years
and highest cumulative use > 365 hours wireless phone use (mobile phone and/or cordlessphone) yielded OR = 1.6, 95 % CI = 0.96-2.9. For melanoma in the most exposed anatomicalarea during use of the handheld phone, temporal, ear, cheek, the risk increased to OR = 2.1,
95 % CI = 1.1-3.8. The risk was overall highest for cases with first use of a wireless phone
before 20 years of age, OR = 2.7, 95 % CI = 0.6-12, although based on low numbers. No
interaction was seen with known risk factors for malignant lymphoma such as hair and eye
color, skin type or sunburns as teenager.
Figure 10 displays the rapidly increasing incidence of malignant melanoma in Sweden in bothgenders. The increase is most marked from early 2000.

19

Figure 10. Age-standardized incidence of malignant melanoma (ICD-7 190) in Sweden 19702016 for men and women, all ages, according to the Swedish Cancer Register(http://www.socialstyrelsen.se/statistik/statistikdatabas/cancer).
NTP study
Male rats exposed to GSM modulated cell phone RF radiation for 2 years (NTP TR 595)
showed higher incidences of fibroma, fibrosarcoma, myxosarcoma, or malignant fibrous
histiocytoma in the skin (subcutaneous tissue) in all exposed groups. The increased rates were
not statistically significant. No statistically significant results were found in female rats.
The incidences of malignant fibrous histiocytoma were higher in 5 W/kg and 10 W/kg mice
exposed to GSM modulated cell phone RF radiation for 2 years (NTP TR 596). The results
were not statistically significant. The incidences of fibrosarcoma, sarcoma or malignant
fibrous histiocytoma were higher in exposed mice compared with sham control, although notstatistically significant, p trend = 0.093. No increased incidence was seen in female mice.
Evaluation
Based on human epidemiology studies and NTP animal studies there is equivocal evidence
that RF radiation causes skin cancer in humans (may be related to exposure).
Conclusion
Based on case-control studies there is a consistent finding of increased risk for glioma andacoustic neuroma associated with use of mobile phones. Similar results are found for cordlessphones in the Hardell group studies. These results are supported by the results in the NTP
animal study (https://ntp.niehs.nih.gov/ntp/about_ntp/trpanel/2018/march/tr595peerdraft.pdf,
https://ntp.niehs.nih.gov/ntp/about_ntp/trpanel/2018/march/tr596peerdraft.pdf). Malignant
vestibular schwannoma is a similar tumor type as acoustic neuroma, also called vestibular
schwannoma.
The findings are less consistent for meningioma although somewhat increased risk was seenin the meta-analysis of ipsilateral mobile phone use. A longer follow-up time is necessary forthis type of slow growing tumor.
The results on glioma and acoustic neuroma are supported by results from other animalstudies showing co-carcinogenic and tumor promoting effects from RF radiation (Tillman etal 2010, Lerchl et al 2015). The NTP study showed genotoxicity of RF radiation in rats andmice exposed to RF radiation (Smith-Roe et al 2017) and now presented in more detail. That
result supports previous findings of DNA strand breaks in rat brain cells exposed to RF
radiation (Lai, Singh 1997).
One mechanism in carcinogenesis could be oxidative stress with production of reactive
oxygen species (ROS) as summarised by Yakymenko et al (2016). This could be an indirect
mechanism for the increased brain and head tumor risk (Megha et al 2015) since ROS maygive DNA damage.
By now carcinogenicity has been shown in human epidemiological studies replicated inanimal studies. Laboratory studies on RF radiation have shown increased ROS production thatcan cause DNA damage. We published in 2013 the conclusion that RF radiation should be20

regarded as a human carcinogen Group 1 according to IARC definition, based on scientificevidence (Hardell, Carlberg 2013b) further supported in our up-dated article (Carlberg,
Hardell 2017). That conclusion is reinforced by the current evaluation.
Overall evaluation of levels of evidence of carcinogenic activity
Glioma: Clear evidence
Meningioma: Equivocal evidence
Vestibular schwannoma (acoustic neuroma): Clear evidence
Pituitary tumor (adenoma): Equivocal evidence
Thyroid cancer: Some evidence
Malignant lymphoma: Equivocal evidence
Skin (cutaneous tissue): Equivocal evidence
Multi-site carcinogen: Some evidence
Based on the IARC preamble to the monographs, RF radiation should be classified as Group
1: The agent is carcinogenic to humans.
’This category is used when there is sufficient evidence of carcinogenicity in humans.
Exceptionally, an agent may be placed in this category when evidence of carcinogenicity inhumans is less than sufficient but there is sufficient evidence of carcinogenicity inexperimental animals and strong evidence in exposed humans that the agent acts through a
relevant mechanism of carcinogenicity.’(http://monographs.iarc.fr/ENG/Preamble/currentb6evalrationale0706.php)
Respectfully submitted
Pro Bono Publico

Lennart Hardell, MD, PhD
Department of Oncology, University Hospital
SE-701 85 Örebro, Sweden
Present address:
The Environment and Cancer Research Foundation
Studievägen 35
SE 702 17 Örebro, Sweden
www.environmentandcancer.com

Michael Carlberg, MSc
Department of Oncology, University Hospital
SE-701 85 Örebro, Sweden
And

21

The Environment and Cancer Research Foundation
Studievägen 35
SE 702 17 Örebro, Sweden
www.environmentandcancer.com

Lena Hedendahl, MD
Independent Environment and Health Research Luleå
Östra Skolgatan 12, 972 53 Luleå, Sweden
And
The Environment and Cancer Research Foundation
Studievägen 35
SE 702 17 Örebro, Sweden
www.environmentandcancer.com

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