The study by Bozok et al. (2023) [1] titled “The Effects of Long-term Prenatal Exposure to 900, 1800 and 2100 MHz Electromagnetic Field Radiation on Myocardial Tissue of Rats,” was the first to investigate the long-term effects of exposing pregnant Sprague Dawley rats (white rats) to common mobile phone frequencies on the myocardial tissue of their male offspring.
Six groups (n = 3) of pregnant Sprague Dawley rats were used in this study: Group 1: controls (no exposure); Group 2: 900 MHz, 24 h/day; Group 3: 1800 MHz, 6 h/day; Group 4: 1800 MHz, 12 h/day; Group 5: 1800 MHz, 24 h/day; Group 6: 2100 MHz, 24 h/day.
The animals were exposed for 20 days. After 60 days, the offspring were sacrificed, and their myocardial tissue was examined histopathologically and biochemically. The researchers observed atypical myocardial morphology in young animals from the exposed groups, including pyknotic nuclei (degenerated cell nuclei), cytoplasmic vacuolization [2], eosinophilic cytoplasm, and enlargement of myocardial fibers.
Notably, myocardial damage increased with increasing frequency (900, 1800, 2100 MHz) at an equal exposure duration (24 h/day) and with increasing exposure duration (6 h/day, 12 h/day, 24 h/day) at 1800 MHz. These results suggest a dose–response relationship. Young animals in the control group showed no damage; their myocardial tissue showed a typical structure with intact cell boundaries and endomysium.
The study was reviewed in ElektrosmogReport 3/2023 [3], where the results were evaluated as a constructive contribution to the understanding of the effects of radiofrequency electromagnetic field (RF-EMF) on heart muscle. However, shortly after the study was listed in the EMF Portal [4], the Competence Centre for Electromagnetic Fields (KEMF) of the German Federal Office for Radiation Protection (BfS) published a critical evaluation [5] that dismissed the study entirely. The evaluation concluded: “For this reason, the study does not provide a reliable contribution to the current state of knowledge regarding RF-EMF effects on the heart.”
However, the reasons given for dismissing the study do not address its purpose or findings. Therefore, this criticism must be rejected, as shown below.
Misrepresentation of Published Facts
- The BfS claims that it is unclear whether the pregnant rats were randomly assigned to the various exposure groups. This is incorrect. The study is explicitly described as a "randomized study" in the “Methods” section, in line with standard procedures to avoid bias.
- Furthermore, the BfS claims that the pregnant rats were distributed among the cages. This is false: a male rate was assigned to each female rat cage for mating purposes. As a result, pregnancies began at different times. Exposure only began once pregnancy was confirmed. Therefore, the following criticism by the BfS is also unfounded: “It is not mentioned … if exposure of the animals took place at the same time.” [5]. The procedure is indirectly described in the study.
- The BfS also claims that it is unclear whether the unexposed animals were kept under the same environmental conditions as the exposed ones. This can be inferred from the section “Animal Care and Welfare,” especially since the Health Guidelines for the Care and Use of Laboratory Animals are referenced.
- Another point of criticism is the small sample size, but it is well justified in the study’s “Discussion” section: “However, animal welfare should not be ignored in these animal studies. Thus, we used a minimal number of pregnant rats (n:3) per exposure group and we examined a minimal number of male pups (n:6) from these litters in our study.”
Neglect of the Overall Context
The BfS criticizes the use of malondialdehyde (MDA), a biomarker for lipid peroxidation, and glutathione (GSH), an antioxidant, as invalid biomarkers of reactive oxygen species (ROS), concluding that “based on the methods and data, it cannot be deduced that RF EMFs play a role in the formation of oxidative stress¹, as stated by the authors.”
However, this criticism fails to acknowledge the contextual relevance of MDA and GSH within the study. This will be briefly outlined below.
As previously mentioned, the authors' criticized statement is based on their research findings regarding a dose–response relationship between RF-EMF exposure and various types of heart muscle damage that do not occur in the absence of exposure. In addition, the consistency of these findings with similar results from other studies was demonstrated. These findings fulfill the essential Bradford Hill criteria [6] and thus largely confirm that RF-EMF exposure can be considered the cause of heart muscle damage. In other words, a causal relationship can be assumed.
Since other studies have repeatedly identified increased levels of ROS in organs exposed to RF-EMF, the authors examined corresponding ROS markers, such as MDA and GSH, at the biochemical level to further confirm the causal relationship. The MDA and GSH findings showed (with one exception) a (statistically significant) dose–response relationship analogous to the heart muscle damage: The MDA value, which indicates lipid peroxidation (cell membrane damage), increased significantly with exposure duration (dose), while the GSH value, which indicates antioxidant glutathione concentration in cells, decreased accordingly.
However, the BfS criticized the study, stating that MDA is primarily a marker for lipid peroxidation, not necessarily ROS, as MDA can also be produced in other ways [7]. Therefore, one cannot automatically conclude that MDA is an ROS marker. However, one can conclude that ROS is a lipid peroxidation marker and, consequently, a marker for corresponding MDA values. The situation is similar with GSH values because GSH is only considered a valid ROS biomarker in in vitro experiments.
Therefore, the authors' statement that RF-EMF promotes ROS formation cannot be formally derived from the MDA/GSH data alone (!), meaning in isolation from the aforementioned findings. This was not the authors’ sole basis for their claim. However, given that no heart muscle cell damage or lipid peroxidation occurred in the control group and that the exposed groups and the control group were otherwise exposed to the same test conditions, RF-EMF remains the only relevant factor that can explain the measured MDA and GSH values, as well as the dose–response relationship. Thus, the findings are consistent with the authors' assumption that RF-EMF exposure leads to an increase in ROS.
Since the BfS dismisses the authors' conclusion without considering the overall context of the argument, the BfS's criticism is incomprehensible and unjustified.
Failure to Consider the Relevance of Influencing Factors
The BfS also criticizes the omission of information regarding blinding, the age of the pregnant rats, cage placement, and whether the control group’s cage had a deactivated antenna. The BfS could have obtained these details from the study's authors. The BfS's conclusion that “a substantial risk of bias” [5] cannot be ruled out is suggestive and biased: The existence of a risk of bias cannot be assessed if nothing is known about how these influencing factors were considered. Conversely, one could easily conclude that, despite the undocumented influencing factors, the study is highly relevant.
In principle, a lack of information only justifies a neutral conclusion, such as “Cannot be conclusively assessed without further details.” A lack of information does not justify downgrading the study. It is entirely possible that all concerns could be resolved with more information.
Every study may omit certain factors. While this could be grounds for criticism, an essential aspect of evaluating a study's significance is often overlooked: Not all influencing factors carry the same weight in determining a study's significance. Their actual impact may range from significant to negligible.
A balanced assessment must consider the relevance of both documented and undocumented factors. As long as the relevance of the various influencing factors is not explained and their weighting for an assessment is not carried out, the BfS’s evaluation cannot be considered impartial.
Downgrading a study solely because of missing methodological details – without assessing their actual impact or acknowledging constructive findings – is like dismissing a flower that has not yet bloomed.
Summary
- Some of the BfS’s criticism is unfounded and invalid because it ignored facts that were clearly presented in the study.
- The BfS criticism disregards the study's overall logic. The authors' conclusions are questioned by taking isolated aspects out of context. Only through such dissection does the BfS manage to construct a misleading criticism.
- Furthermore, the BfS dismisses the study based on a few missing methodological details. The BfS does not know whether or how these details were considered. However, the BfS assumes that they are highly relevant to the study's validity. The BfS acknowledges that the missing information on these influencing factors is necessary “to adequately assess the study's quality” [5]. Despite this lack of information, the BfS negatively assesses the study's validity. Pretending to be ignorant in order to discredit findings is logically misleading and deceptive.
- A proper evaluation must consider and weigh the relevance of all influencing factors, both documented and undocumented. A few missing pieces of information do not justify dismissing the results.
Thus, the BfS’s final conclusion is based on pseudo-arguments. Moreover, its evaluation framework is all-or-nothing and maximalist. It dictates:
a) which variables must be addressed,
b) which correlations must be proven by which methods, and
c) that a study must be downgraded if one or more influencing factors are not considered or documented, or if correlations are not proven with absolute certainty.
This method disregards established principles of balanced scientific evaluation, resulting in biased, questionable, and susceptible judgments. It also opens the door to misuse for partisan purposes.
References
[1] Bozok S, Karaagac E, Sener D, Akakin D, Tumkaya L (2023). The effects of long-term prenatal exposure to 900, 1800, and 2100 MHz electromagnetic field radiation on myocardial tissue of rats. Toxicol Ind Health. 2023 Jan; 39(1):1-9. doi: 10.1177/07482337221139586. Epub 2022 Nov 16. PMID: 36383165. https://pubmed.ncbi.nlm.nih.gov/36383165/
[2] Vivien Hornawsky (2025). Vakuole: Definition, Bildung und Funktionen. Vgl. https://www.medi-karriere.de/wiki/vakuole/
[3] ElektrosmogReport 3/2023, published on EMF:data: https://www.emfdata.org/de/studien/detail&id=798, see also https://www.diagnose-funk.org/aktuelles/artikel-archiv/detail&newsid=2002
[4] EMF-Portal. Reference to the study by Bozok et al.: https://www.emf-portal.org/de/article/49027
[5] Competence Centre for Electromagnetic Fields (Kompetenzzentrum Elektromagnetische Felder (KEMF)) (2023): Spotlight on "The effects of long-term prenatal exposure to 900, 1800, and 2100 MHz electromagnetic field radiation on myocardial tissue of rats" by Bozok et al. in Toxicology and Industrial Health (2022). https://doris.bfs.de/jspui/bitstream/urn:nbn:de:0221-2023060938290/4/SL_Bozok_2022_EffectsOfLongterm_Deu.pdf and https://doris.bfs.de/jspui/bitstream/urn:nbn:de:0221-2023060938290/5/SL_Bozok_2022_EffectsOfLongterm_Eng.pdf
[6] Wikipedia. Bradford Hill criteria: https://en.wikipedia.org/wiki/Bradford_Hill_criteria
[7] Wikipedia. Thiobarbituric acid reactive substances (TBARS): https://en.wikipedia.org/wiki/TBARS
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¹ Oxidative stress occurs when the formation of oxidative ROS becomes so high that it can no longer be compensated for by the antioxidant substances in the cell. This leads to damage to the cell.