Mobile phone carrying locations and risk perception of men: A cross-sectional study.

Little was known about the relationship between carrying mobile phone handsets by men and their risk perception of radiofrequency-electromagnetic field (RF-EMF) exposure due to carrying handsets close to the body. This study aimed to determine where men usually carried their handsets and to assess the relationship to risk perception of RF-EMF. Participants completed a self-administered questionnaire about mobile phone use, handset carrying locations, and levels of risk perception to RF-EMF. Data were analysed using linear regression models to examine if risk perception differed by mobile phone carrying location. The participants were 356 men, aged 18-72 years. They owned a mobile phone for 2-29 years, with over three quarters (78.7%) having a mobile phone for over 20 years. The most common locations that men kept their handsets when they were 'indoors' were: on a table/desk (54.0%) or in close contact with the body (34.7%). When outside, 54.0% of men kept the handset in the front trouser pocket. While making or receiving calls, 85.0% of men held their mobile phone handset against the head and 15.0% either used earphones or loudspeaker. Men who carried their handset in close contact with the body perceived higher risks from RF-EMF exposure compared to those who kept it away from the body (p<0.01). A substantial proportion of men carried their mobile phone handsets in close proximity to reproductive organs i.e. front pocket of trousers (46.5%). Men who kept their handset with the hand (p < .05), and those who placed it in the T-shirt pocket (p < .05), while the phone was not in use, were more likely to perceive health risks from their behaviour, compared to those who kept it away from the body. However, whether this indicates a causal relationship, remains open.

Introduction

These days in most countries, almost every adult carries a (smart) mobile phone handset. Mobile phones are increasingly becoming one of the most ubiquitous digital tele-communication tools. According to the International Telecommunication Union, 85% of the global population have access to telecommunication networks and 57% to internet services [1]. In addition to making and receiving calls, digital technologies available in smartphones enable access to several services such as voice data (e.g., making or receiving a call), and video data (messenger, WhatsApp, YouTube, etc.) [2]. Mobile phones emit and receive the data via radiofrequency electromagnetic fields (RF-EMF).

Mobile phone usage related RF-EMF exposure and likely human health effects have long been of concern internationally [3, 4]. RF-EMF exposure from mobile phones may induce some heating effect and/or a sensation of warmth, depending upon a range of factors, including the distance between the mobile phone and part of the body exposed during active use [5, 6]. A recent systematic review reported that studies speculated that scrotal overheating might affect male fertility [7]. In another observational study, men who carried their mobile phones in their hip pockets or on their belts had lower sperm motility than men who did not carry a mobile phone or who carried their mobile phone elsewhere on the body [8]. In view of this, understanding of people’s habits of placing/carrying a mobile phone becomes important. Though the extent of mobile phone carrying habits have not been adequately assessed, some data showed that people tend to place or carry their mobile phone close to the body [5-7].

Previous studies that assessed people`s preferences of carrying mobile phones identified both cultural and gender differences as to where people carry them [9, 10]. For instance, among Australian women aged 15–40 years, almost three quarters (72%) carried the mobile phone in a pocket below waist level, with 57% doing so over the preceding week [10]. However, comparable data amongst men were scarce.

The speculated risk of mobile phones carrying and use in relation to fertility issues remains on the agenda in both mainstream media [11-13] and scientific literature [14-17]. Therefore, given the widespread use of mobile phones by men, it seems reasonable to investigate in more detail how men perceive their risks related to RF-EMF from carrying mobile phones close to body parts.

The general public is fairly aware of different RF-EMF sources and risk associated with RF-EMF exposures to the human body [4]. Studies have shown that non-experts’ risk perceptions of RF-EMF sources are influenced by subjective exposure perception [3, 4]. There seem to be some public concerns about the potential health effects of carrying or placing mobile phones close to the body [18]. Within this context, the relationship between mobile phone RF-EMF exposure perception, risk perception, and the actual mobile phones carrying habit (close to the body or not) becomes an important area of research. Hence, the current study aimed to determine: i) where men usually carried their mobile phones, and ii) whether this was related to their perceptions of risk concerning exposure to RF- EMF, primarily emanating from their own mobile phones.

Methods

Study design, participant recruitment and data collection

This study was a cross-sectional survey of 356 men who completed a self-administered hardcopy questionnaire. Sample size was estimated by a single population proportion formula with the assumption of 95% confidence level, 5% margin of error, 5% non-response rate, and 50% having carrying locations close to body parts, similar to those reported for women [10]. Participants were recruited to participate in the study via advertisements posted on notice boards at public libraries, universities, and hospitals across Melbourne, Australia. Participants were also individually approached at sporting clubs and invited to participate in the study. Data collection was undertaken between October 2018 and February 2019.

A structured questionnaire that inquired about socio-demographic variables (age, educational level, residential postcode, ethnicity, and occupational description) and mobile phone use and handset carrying location related information, was used in this survey. Mobile handset carrying locations of men were assessed by asking them to rate, on a Likert-scale (1 = never; 2 = rarely, 3 = occasionally, 4 = often, 5 = very often), how commonly they carry it with their hand, keep it on a table, in a bag, or in the pocket of their T-shirt, Jacket or Trousers (front or back pockets).

Risk perception

Participants were asked to rate their level of personal risk perception to RF-EMF exposure due to their own most-frequent mobile phone carrying behaviour. This was measured using questions also formatted on Likert-scales, using the question “On a scale of 1-to-10 (1 = not-at-all,.… 10 = very dangerous), how dangerous do you consider the RF-EMF from mobile phones communication devices are in terms of increasing cancer risks to people?” and “On a scale of 1–5 (1 = never, ….., 5 = very often), how often do you think that carrying a mobile phone in your most common carrying habit poses a health risk to yourself?”.

Prior research by Wiedemann and colleagues [19] showed that the thematic relevance, i.e. how often people think about a risk issue, is a good predictor of people’s real-life risk perception, reducing bias in the survey situation as concerns expressed in questionnaires do not always reflect concerns in everyday life. Using a similar Likert scale, we assessed how often people thought carrying their mobile phone posed a health risk to them, which was stated as: “On a scale of 1-to-5, (1 = never…..5 = very often), how often do you think that carrying a mobile phone in your most common carrying habit poses a health risk to yourself?”

Ethical considerations

Ethics approval was obtained from Monash University Human Research Ethics Committee (project ID:14080). Participants provided written informed consent.

Data analysis

Descriptive statistics are presented as frequencies, percentages, means (SD) and ranges depending on the distribution. Using postcodes, participants’ residential locations were classified into metropolitan or non-metropolitan areas according to the Australian Bureau of Statistics Geographical classification [20]. Overall, handset carrying locations of men were categorized into: while “not using the phone”, during “passive use” (e.g. listening to music/radio/podcast online with the phone), and while making or receiving calls (“active use”). Furthermore, mobile phone locations while making/receiving calls were classified into three main categories as either “against the ear with a hand”, “using earphones”, or “using speaker”. Handset carrying locations were rated based on frequency (never, rarely, occasionally, often, very often). For analysis purposes, these were categorized into binary variable taking often/very often, as a positive response.

Personal risk perception levels were calculated and compared by handset carrying locations and demographic variables. Data were analysed to examine if the risk perception of men differed significantly between occupational groups, and also by carrying locations. Between group differences were assessed using independent t-tests. Associations between outcome and predictor variables were investigated using linear regression models. Factors identified to be associated with outcome variables (p<0.2) were further investigated by using simultaneous multiple regression models. All analyses were performed using STATA version 15.0 (StataCorp, College Station, TX) and p-values <0.05 considered statistically significant.

Results

Characteristics of study participants

Participants were aged between 18 and 72 years. One participant who did not own a mobile phone was excluded from further analysis. Most participants (89.0%) were recruited from metropolitan areas of Melbourne, and over two-thirds (69.8%) were educated beyond high school. Nearly half of the participants (47.7%) were Caucasian; while 37.5% identified themselves as of Asian origin (Table 1).

Table 1

Participants’ socio-demographic characteristics.

Variables	Frequency (n)	Percentage (%)
Age, mean±SD (years)	33.3±11.1
18–24	72	20.2
25–34	154	43.3
35–44	73	20.5
45+	57	16.0
Ethnicity
Caucasian	167	47.4
Asian	132	37.5
Other	53	15.1
Residential location
Metropolitan	317	89.0
Non-metropolitan	5	1.4
Missing	34	9.6
Education
High school or less	57	16.1
Vocational training (diploma)	50	14.1
Bachelor`s degree	126	35.6
Postgraduate degree	121	34.2
Occupation
Administrative and Finance	53	15.0
Healthcare professional (medical or nursing)	46	13.0
Service Sector	78	22.1
Education and/or research	69	19.6
Student	70	19.8
Other	37	10.5
Years since first owned a mobile phone (mean±SD)	14.7±5.2	(range 2–29)
Mobile phone mode during daytime
Standby	339	96.3
Flight mode or turned off	13	3.7
Mobile phone mode during sleep
Standby	287	82.0
Flight mode	26	7.4
Switched off	87	10.6
Laterality while talking on the mobile phone
Right	140	56.7
Left	59	23.9
Almost equally	48	19.4

Mobile phone use and carrying locations

The participants owned a mobile phone for an average of 14.7 (SD 5.2) years, while over three quarters (78.7%) owned a mobile phone for over 20 years.

The handset carrying locations of men are presented in Fig 1. The most common locations that men kept their mobile phones when they are ‘indoors’ (at home or work), and the phone ‘not in use’, were on a table/desk (54.0%) and in close contact with the body (34.7% placed it either in pockets or held by hand). Of the men who keep their mobile phone in close contact to their body parts, 46.0% keep it in the trouser front pocket. When outside, and not using their mobile phone, 54.0% of men keep their mobile phones in the trouser front pocket, and 46.0% in a bag or in a vehicle or somewhere other than pockets.

Fig 1

Mobile phone locations when not in use or only passive use (*passive use: E.g. listening to music/radio/podcast online).

While using the mobile phone passively (e.g. listening to music with an earphone plugged into the handset), 50% placed it in the trouser front pocket. While sleeping, 82% of men kept their mobile phone on “standby”, 7.4% in “flight-mode” and 10.4% “switched-off”.

While making or receiving calls, most (85%) of the men held the handset against the head, of whom over half (56.7%) held it against the right ear, 23.9% with the left ear, and 19.4% against either ear almost equally (Fig 2). The rest (15%) either used earphones or a loudspeaker while making/receiving calls with their mobile phones.

Fig 2

Mobile phone carrying locations of men while making/receiving calls (active use).

Mobile phone use, risk perception and carrying location

Over a third (36.7%) of men rated their RF-EMF exposure as high or very high, and 21.5% considered it “dangerous” or “very dangerous” to talk using the mobile phone against the ear. Likewise, 14.1% of men perceived a high or very high risk of health issues related to their usual handset carrying location, and 13.2% considered changing the location in the future. Overall, 29% of men reported feeling a heating effect often or very often on body parts near where the mobile phone was carried, and 16.0% believed that carrying mobile phones could cause infertility.

Risk perception due to personal mobile phone carrying locations was higher amongst men who carried their mobile phone in close contact with their body, compared to those who carry it away from the body (Mean values for risk perception: 2.54 vs. 2.20; β = 0.336, p<0.01). For instance, about a third (31.6%) of men who often/very often kept their handset in the trouser pocket rated their risk to be high or very high, compared to 13.7% of those who did so less frequently. The proportion of those who reported a high/very high level of risk perception in relation to their phone carrying habits is presented in Fig 3. Among men who carry their phone in the trouser pocket, 33% reported a high/very high level of risk perception.

Fig 3

Mobile phone carrying locations and risk perception of men.

Table 2 presents linear regression models for the association between risk perception due to the mobile phone carrying location and predictor variables. After adjusting for potential confounders, the findings indicated that students (β = -0.650, p = 0.003) and participants who identified themselves as Caucasian (β = -0.554, p < .001) have lower risk perception levels. Men who carried their mobile phones with the hand when not using it (β = 0.377, p < .05), and those who placed it in the shirt pocket (β = 0.608, p < .05) were more likely to report higher risk perception levels, compared to those who placed it in a bag or on a table (Table 2). In addition, men who perceived risk due to their mobile phone carrying location were three times more likely (OR = 3.01; 95%CI 1.18–7.70) to report heat around the body part where the mobile phone was usually carried.

Table 2

Linear regression models for selected predictor variables and risk perception to own mobile phone carrying location.

	Risk perception to own mobile phone handset carrying location
	Univariate analysis		Multivariable analysis
	β	p-value	β	p-value
Age (years)	0.003	0.632	0.006	0.751
Educational status
Beyond high school vs. High school or less	0.110	0.397	-0.079	0.582
Ethnicity
Caucasian vs. non-Caucasian	-0.504	<0.001	-0.554	<0.001
Occupation
Admin & Finance	Ref		Ref
Healthcare worker	-0.3	0.102	-0.392	0.086
Service sector	-0.108	0.592	-0.073	0.720
Education/Researcher	-0.235	0.254	-0.219	0.286
Student	-0.608	0.003	-0.650	0.003
Other	-0.446	0.063	-0.387	0.114
Mobile phone carrying location when not in use
Bag/Table	Ref		Ref
Trouser pocket	0.170	0.221	0.180	0.192
T-Shirt (Jacket) pocket	0.547	0.103	0.608	0.046
Held in hand	0.355	0.053	0.377	0.041

Discussion

This study documented the most frequent locations men carried their mobile phones, when not in use, and carried off -body. Half the men, often or very often, carried their mobile phone handset in the trouser pocket. Men who carried their handset in close contact with their body perceived higher risks from overall RF-EMF exposure, compared to those who kept it away from the body. Men who carried their handset in close contact with their body perceived higher risks from RF-EMF exposure and their mobile phone handset carrying behaviour.

These findings are comparable to those reported by previous studies elsewhere [9, 10, 16, 17]. For example, up to 60% of men (compared to 16.4% of women) carried their mobile phones in their trouser pockets [9]. Similarly, higher proportion of women (61.1% compared to 10.1% of men) tended to carry their mobile phones in their hand bags [9, 10, 16, 17]. In Australia, the most common locations where women placed their mobile phones were off-the body (86%), in the hand (58%), a skirt/trouser pocket (57%), or against the breast (15%) when the mobile phone is not in use or during passive use [10].

The results of the current study would translate to a pattern of the whole body and reproductive organ specific RF-EMF exposures from mobile phone use and carrying behaviour, and resulting exposure and risk perceptions. There is some evidence that perception of risk may impact behaviour to some extent such as whether or not to carry the handset close to reproductive organs [8]. Men who kept their mobile phone away from body-parts while it was not in use were half as likely to perceive health risks from the specific behaviour. If one carries his mobile phone close to body parts, he might be prompted by being inquired about possible negative effects and may rate higher levels of risk perception.

In the current study, one in every six men believed that carrying mobile phones would cause infertility. This may not be surprising since a third of the participants also reported feeling heating on body parts near where the mobile phone was carried. This may be worrisome in modern days since smartphones are more prone to heating human tissues in contact as there is a trend in moving toward lower specific absorption rate (SAR) and higher battery capacity smartphones due to their increased uses other than making/receiving calls [6].

Students and those who identified themselves as Caucasian were less likely to consider their mobile phone carrying locations posed any health risks. In a study of women, younger age groups were found to be best informed about RF-EMF emissions from smartphones and other wireless devices [10]. Being well-informed and educated is known to be an important determinant of trust [21], and hence more educated people may acquire information, build trust, and are likely to report lower levels of risk perception. Men who carried their mobile phones in their T-shirt pockets and those who hand-held them, when it is not in use, were found to have higher levels of risk perception, compared to those who place their phone away from the body. Understanding the most common locations where men carry their mobile phones and whether their risk perception towards RF-EMF exposure and health effects depends on their phone carrying behaviour could help tailor prevention and future public health interventions.

This study, which employed a sample of men recruited from the general public, could form a baseline for future research. Furthermore, data presented in this study could help generate hypotheses regarding the effects of carrying mobile phones close to body parts on reproductive health outcomes in relation to the RF-EMF exposure. Given the ubiquity of mobile phone use and that the majority of men carried their mobile phones in close proximity to reproductive organs (e.g. testes), the relationship between resulting perceived RF-EMF exposures and associated health risks warrants further research. Similarly, reported local heating associated with carrying the mobile phone close to the body, especially reproductive organs, and the subsequent perceived physiological and psychological changes requires further investigation in the context of different phone carrying locations, preferably from larger and representative samples of men.

A limitation of the study was that all participants were men from the Greater Melbourne region, making our sample not representative of the entire Australian male population. Participants were recruited via advertisements and may be pre-selected based on their access to the invitations and voluntary expression of their interest for participation and hence may not be representative of the source population. In addition, the data were collected in the Australian summer season, the findings could be different if survey was conducted during other seasons (e.g., winter) as men may more often wear jackets or coats providing more options to keep their mobile phones elsewhere.

Conclusion

A substantial proportion of men carried their mobile phones in their front pockets of trousers, which is in close proximity to reproductive organs. Men perceived higher levels of health risks associated with RF-EMF exposures from mobile phones. Those who kept their handset away from body-parts, while the phone was not in use, were less likely to perceive health risks from their mobile phone carrying behaviours.

16 Sep 2021

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Reviewer #1: Summary:

In this article, the authors explore the relationship between mobile phone carrying and the risk perception of RF-EMF exposure due to carrying close to the body. The study is done by asking 356 participants (men) a self questionnaire for their mobile phone use. The authors describe statistics of overall usage when they use mobile phones indoor, outdoor, and when receiving calls. Finally, the authors analyze the survey data with the risk perception. The analysis is done mainly using correlation and linear regression models. They found that men generally carry their phone close to reproductive organs (trouser front pocket). And men who kept their phones away from their body were less likely to perceive health risks from their behaviour.

Overall feedback:

Overall, the dataset and descriptive statistics are well described in the article. However, the introduction part can be improved where authors can give solid statements of why readers should care about the survey. Moreover, there is still a lack of discussion in the article. The authors can improve and solidify the overall message of the paper.

Comments:

Introduction. The authors describe overall research in the introduction well but it is still hard to make a clear statement of why there is a need to analyze the survey from the reader's perspective. There is still a lack of a gap in the first paragraph. It would be better if authors can provide a more solid paragraph of why risk perception is needed in this study. I think it would be good for readers to have a one paragraph about health risks of carrying mobile phones, why risk perception is needed, and why surveys are needed.

Methods. The authors describe the dataset well. I do not see the statement of data availability. It would be good to make an anonymous survey available.

Results and discussions. The author explains why risk perception for men who carry phones close contact is higher. It would be good to explain the result more why they might have higher risk perception. In the discussion, it feels more like describing the data but not much insight with the collected data. Overall, I think the writing can be much stronger if authors provide some more evidence or further discussion. For example, why men who carry phones near their body are more likely to perceive more health risks? And here, if they perceive more risk, why do they still carry their phone near the pocket?

Reviewer #2: In order to publish a research article in a journal, a manuscript should describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. From this point of view, the article appears to be a survey study instead of a technically sound piece of scientific research. I believe that the article should not be classified as a research article.

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21 Dec 2021

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AR: The current version is formatted according to the formatting requirements

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“This research project is supported by the Centre for Population Health Research on Electromagnetic Energy (PRESEE), School of Public Health and Preventive Medicine, Monash University. The centre is funded by a grant from the National Health and Medical Research Council, Australia (APP 1060205).”

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AR: We have now deleted the funding in the acknowledgement section of the main manuscript. Please insert the following information regarding funding on our behalf. “This research project was supported by the Centre for Population Health Research on Electromagnetic Energy (PRESEE), School of Public Health and Preventive Medicine, Monash University. The centre was funded by a grant from the National Health and Medical Research Council, Australia (APP 1060205). The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.”

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________________________________________

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

AR: Thank you. We have now removed the phrase as the data related to these were not a core part of our study.

________________________________________

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

________________________________________

5. Review Comments to the Author

Reviewer #1: Summary:

In this article, the authors explore the relationship between mobile phone carrying and the risk perception of RF-EMF exposure due to carrying close to the body. The study is done by asking 356 participants (men) a self questionnaire for their mobile phone use. The authors describe statistics of overall usage when they use mobile phones indoor, outdoor, and when receiving calls. Finally, the authors analyze the survey data with the risk perception. The analysis is done mainly using correlation and linear regression models. They found that men generally carry their phone close to reproductive organs (trouser front pocket). And men who kept their phones away from their body were less likely to perceive health risks from their behaviour.

Overall feedback:

Overall, the dataset and descriptive statistics are well described in the article. However, the introduction part can be improved where authors can give solid statements of why readers should care about the survey. Moreover, there is still a lack of discussion in the article. The authors can improve and solidify the overall message of the paper.

AR: Thank you very much. In the current version of the manuscript, we have revised the introduction and the changes we made are reflected in the tracked changes

Comments:

Introduction. The authors describe overall research in the introduction well but it is still hard to make a clear statement of why there is a need to analyze the survey from the reader's perspective. There is still a lack of a gap in the first paragraph. It would be better if authors can provide a more solid paragraph of why risk perception is needed in this study. I think it would be good for readers to have a one paragraph about health risks of carrying mobile phones, why risk perception is needed, and why surveys are needed.

AR: We have now revised paragraph 1 and paragraph 2 of the introduction and we have added the following, “ According to the International Telecommunication Union, 85% of the global population have access to telecommunication networks and 57% to internet services (1). In addition to making and receiving calls, digital technologies available in smartphones enabled access to several services such as voice data (e.g., making or receiving a call), and video data (messenger, WhatsApp, YouTube, etc.) (2). Mobile phones emit and receive the data via radiofrequency electromagnetic fields (RF-EMF).

Mobile phone usage related RF-EMF exposure and likely human health effects have long been of concern internationally (3, 4). RF-EMF exposure from mobile phones may induce some heating effect and/or a sensation of warmth, depending upon a range of factors, including the distance between the mobile phone and part of the body exposed during active use (5, 6). A recent systematic review reported that studies speculated that scrotal overheating might affect male fertility (7). In another observational study, men who carried their mobile phones in their hip pockets or on their belts had lower sperm motility than men who did not carry a mobile phone or who carried their mobile phone elsewhere on the body (8). In view of this, understanding of people’s habits of placing/carrying a mobile phone becomes important.”

Methods. The authors describe the dataset well. I do not see the statement of data availability. It would be good to make an anonymous survey available.

AR: Thank you. Data would be made available once other upcoming analysis is completed

Results and discussions. The author explains why risk perception for men who carry phones close contact is higher. It would be good to explain the result more why they might have higher risk perception. In the discussion, it feels more like describing the data but not much insight with the collected data. Overall, I think the writing can be much stronger if authors provide some more evidence or further discussion. For example, why men who carry phones near their body are more likely to perceive more health risks? And here, if they perceive more risk, why do they still carry their phone near the pocket?

AR: This was a cross-sectional survey with limitations inherent to the design. It was not possible to tell which came first –exposure or outcome? In the case of carrying mobile phone close to body parts and risk perception, we suspect that if one carried his mobile phone close to body parts, he might be prompted by being inquired about it and hence reminded of negative perceived effects. Furthermore, risk perception may not be translated to action such as not carrying mobile phones close to body parts. We have revised the discussion section and it now reads as, “If one carries his mobile phone close to body parts, he might be prompted by being inquired about possible negative effects and may rate higher levels of risk perception.”

Reviewer #2:

In order to publish a research article in a journal, a manuscript should describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. From this point of view, the article appears to be a survey study instead of a technically sound piece of scientific research. I believe that the article should not be classified as a research article.

AR: We respectfully disagree with this comment. Although we agree that experimental studies are considered gold standard designs, cross-sectional studies are also valid study designs widely employed in Epidemiology, clinical, social and public health research.

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Submitted filename: Author_Response_PONE-D-21-18441.docx

Click here for additional data file.

12 Apr 2022

17 May 2022

Reviewer #3:

The authors present a cross-sectional study investigating a novel and interesting research question. In fact, due to their widespread use in almost any society, studies addressing research questions related to mobile phones and the resulting RF-EMF exposure are of considerable interest for public health. In my view, the authors satisfactorily addressed the comments by Reviewer 1 in the first round of reviews, even though of course this primarily needs to be evaluated by Reviewer 1. Moreover, I agree with their reply to Reviewer 2; in my opinion, there is no doubt that an observational study should be classified as a research article. Nevertheless, I would recommend that the authors take into account the following questions and remarks before the manuscript is released for publication.

AR: Thank you

Abstract: I would suggest to add the sampling strategy (convenience sampling) to the abstract. Ideally, apart from the number of participants also the response rate should be provided but I assume that this rate cannot be calculated because of the sampling method (making it vice versa even more important to mention the sampling strategy).

I would also suggest to add “by means of linear regression models” to the sentence “Data were analysed to examine if…”.

Could you, if the word count allows, provide specific numbers (regression coefficients, p-values) to the statement “Men who kept their handset away from the body parts […] were less likely to perceive health risks form their behaviour”?

AR: We have added the analysis model in the abstract and it reads as, “Data were analysed using linear regression models to examine if risk perception differed by mobile phone carrying location”. In addition, we have included information about the levels of significance. We have also revised the limitation section of the discussion to reflect the sampling limitations (see the last paragraph of discussion section).

Introduction:

Page 4, second sentence: Can you add the country where this study (women aged 15-40 years) was performed? I think this information may be of interest since in the previous sentence you mention cultural differences as to where individuals carry their phone.

AR: We have now added information that the study was from Australia

Methods:

Page 5, first paragraph: As mentioned above, it would be interesting to have a response rate. Do you happen to have any information on how many individuals you approached? In any case, I think the strategy of using a convenience sampling should be mentioned as a limitation of the study in the discussion section.

AR: We have now added this to the limitation section and it reads as, “Participants were recruited via advertisements and may be pre-selected based on their access to the invitations and voluntary expression of their interest for participation and hence may not be representative of the source population.”

Page 5, second paragraph: Could you specify “handset carrying location information” (for instance, for which specific locations did you ask?) or provide the full questionnaire in the supplement?

AR: We have revised the paragraph and added the following information: “Mobile handset carrying locations of men were assessed by asking them to rate, on a Likert-scale (1 = never; 2 = rarely, 3 = occasionally, 4 = often, 5 = very often), how commonly they carry it with their hand, keep it on a table, in a bag, or in the pocket of their T-shirt, Jacket or Trousers (front or back).”

Results:

Page 9, second paragraph. The statement “If the mobile phone was not in use, 34.7% placed it in close contact with the body…” comes a little bit as a surprise when in the sentence before you state that when not in use, 54% placed it on a table/desk and 46% in the trouser pocket. Do the 34.7% refer to not in use outdoors? Can you perhaps clarify this?

AR: We have revised the sentence and it now reads as, “Of the men who keep their mobile phone in close contact to their body parts, 46.0% keep it in the trouser front pocket.”

In my view, the high proportion (78.7%) of participants owning a mobile for more than 20 years appears pretty high? As far as I am aware, even though mobile phones became available in the 1990s, their widespread use did not kick in before the early 2000s (although I am not sure how the situation is in Australia), indicating that the majority of your participants seem to be (very) early adopters. Do you think this may point towards some form of selection bias in the sense that you recruited a relatively tech-savvy sample (which may differ with respect to phone use or risk perception compared to the general population)? In my view, it would be worthwhile to elaborate on this issue in a few sentences in the discussion part.

AR: Thank you for the comment. The high prevalence of use might be unique case to Australia. For example, in a study conducted over a decade ago 68% of children aged 10-11 years (in 2012), reported having owned or used a mobile phone.

What I also see as quite surprising is your finding that men carrying their phone close to the body reported higher risk perception levels than those placing it in a bag or table. Would you not expect that individuals more concerned about potential health effects carry their phone farther away from their body? I think this may also be an interesting question to be addressed in the discussion.

AR: We agree that one can expect risk may impact behaviour to some extent such as not to carry the handset close to reproductive organs if one perceived risk. However, being a cross-sectional study, it may be that one was prompted about the possible risks and rated a higher risk if already carrying the phone in close proximity to the body. This was discussed in the earlier version of the manuscript (discussion section: paragraph 2), and reads as, “There is some evidence that perception of risk may impact behaviour to some extent such as whether or not to carry the handset close to reproductive organs (8). Men who kept their mobile phone away from body-parts while it was not in use were half as likely to perceive health risks from the specific behaviour. If one carries his mobile phone close to body parts, he might be prompted by being inquired about possible negative effects and may rate higher levels of risk perception.”

Discussion:

Page 13, first paragraph: “For example, up to 64% of men…” Can you add a reference for this study?

AR: We have now cited a reference

In general, I would recommend that in the first paragraph you highlight the most important findings of your study (including those on risk perception levels) and then start with the comparison to other studies in the second paragraph.

AR: We have revised this and divided the paragraph accordingly. We have added the following to the discussion (parag 1), “Men who carried their handset in close contact with their body, perceived higher risks from RF-EMF exposure compared to those who kept it away from the body. However, they were less likely to perceive health risks from their mobile phone handset carrying behaviour.”

Page 15, first paragraph: I think the potential of selection bias is a more important aspect here then the question of the generalisability of your study to other parts of Australia. As mentioned above, the use of a convenience sample and the potential of selection bias, e.g. with respect to attraction to use of technical devices in general and mobile phones in particular, and potential implications for the interpretation of your numbers, should receive some attention. If I am not mistaken, there is some evidence from other studies on mobile phone use that individuals with higher levels of usage tend to have a higher interest to participate in such studies than non-regular users. On the other hand, it may also seem plausible that people with higher levels of concern regarding health effects are more prone to join such as study as yours (which may lead to an overestimation of the true level of risk perception in the general population). To make a long story short, it would be great if you could add your thoughts on those aspects to the discussion part.

AR: We have now added this to the limitation section and it reads as, “Participants were recruited via advertisements and may be pre-selected based on their access to the invitations and voluntary expression of their interest for participation and hence may not be representative of the source population.”

Minor comments:

Abstract, second sentence: “… and to assess relationship…” should read “… and to assess its/the relationship…” (add “its” or “the”)

AR: Thank you. We added “the”

In the second part of the abstract, some percentages are provided with decimal places and some without. I would recommend to harmonise this.

AR: Corrected

Introduction, third sentence: “enabled” should read “enable” as all other sentences in this paragraph are framed in present tense.

AR: Corrected

Results, first sentence: The information that 356 men participated is redundant since the sample size is already mentioned in the methods section. I would thus recommend to remove the first sentence and add the age range to the sentence describing the mean (SD) age of participants.

AR: We have now deleted the sentence describing the mean (SD) age of participants as it is already presented in the table. Sample sized also removed from results section.

Page 14, last sentence: Add a comma after “body”

AR: Corrected

Page 15, first paragraph: “eg winter” should read “e.g., winter”

AR: Corrected

Reviewer #4:

I do think that the manuscript merits to be published on PlosOne. In my opinion, Authors correctly addessed the comments of Reviewer 1. Moreover, I agree with Authors on their answer to the comment of Reviewer 2.

I have only a minor point to raise:

Table 1, Education: what does it means TAFE? On the Internet you can find some clues, e.g. :Australian Technical and Further Education (TAFE) institutes are government-owned providers of VET courses (Vocational Education and Training). Authors have to be more explicit, also with the use of a footnote that permits to the readers to understand the meaning of that acronym (without surfing the Internet!)

AR: We have now replaced TAFE with Vocational training (diploma).

Submitted filename: PONE-D-21-18441R1_Authors_response_R2.docx

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23 May 2022

Mobile phone carrying locations and risk perception of men: a cross-sectional study

PONE-D-21-18441R2

Dear Dr. ZELEKE,

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Reviewer #3: All comments have been addressed

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Reviewer #3: Yes

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Reviewer #3: Yes

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Reviewer #3: Yes: Tobias Weinmann

30 May 2022

PONE-D-21-18441R2

Mobile phone carrying locations and risk perception of men: a cross-sectional study

Dear Dr. Zeleke:

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