Children’s participation, local policy and the digital environment: Visions and uses among Spanish municipalities


Children's policies at the local level stimulate initiatives in the municipalities to encourage child participation. In this article, we focus on the local political sphere as a space for the promotion of child participation and citizenship through digital mediation. It is in this immediate environment where the rights of children and adolescents are exercised and promoted. The study aims to analyse the contributions perceived by municipal leaders (elected officials and technical figures) of the digital environment and the uses they make of it to promote children’s participation in the municipality. This study is part of a national project that includes as collaborating entities the International Association of Educating Cities (IACE) and Child Friendly Cities (CAI-Unicef). 279 subjects (191 technical figures and 88 elected officials) from 179 Spanish municipalities associated members of IACE and/or CAI. Data were collected in 2020. Two ad hoc designed questionnaires were applied. Two of the most significant results of the study are: (a) the finding of the variable that establishes differences between those technical figures that mediate children’s participation with technological environments and those that do not; (b) the use made of the digital environment as an interactive space for informational purposes. It concludes on the need to rethink the digital environment as a participatory area and increasing the use of technology in support of children’s citizenship.


Participation, childhood, virtual environment, participatory culture, rights of the children, municipal government

Palabras clave

Participación, infancia, entorno virtual, cultura participativa, derechos del niño, gobierno municipal


Las políticas de infancia a nivel local dinamizan en los municipios iniciativas para impulsar la participación infantil. En este artículo nos centramos en la política local como espacio promotor de participación y ciudadanía infantil a través de la mediación digital ya que es, en ese entorno inmediato, donde los derechos de la infancia y la adolescencia se ejercitan y se promueven. El estudio persigue analizar qué aportaciones perciben los referentes municipales (cargos electos y figuras técnicas) del entorno digital y qué usos hacen de él para impulsar la participación infantil en el municipio. Este estudio forma parte de un proyecto nacional que cuenta como entidades colaboradoras a la Asociación Internacional de Ciudades Educadoras (AICE) y Ciudades Amigas de la Infancia (CAI-Unicef). Han participado en él 279 sujetos (191 figuras técnicas y 88 cargos electos) procedentes de 179 municipios españoles asociados a AICE y/o CAI. Los datos fueron recabados en 2020. Se aplicaron dos cuestionarios diseñados ad hoc. Dos de los resultados más significativos del estudio son: a) el hallazgo de la variable que establece diferencias entre aquellas figuras técnicas que median la participación infantil con entornos tecnológicos y con las que no lo hacen; b) el uso que se hace del entorno digital como espacio interactivo con fines informativos. Se concluye en la necesidad de repensar el entorno digital como un espacio participativo e incrementar el uso de la tecnología al servicio de la ciudadanía infantil.


Participation, childhood, virtual environment, participatory culture, rights of the children, municipal government

Palabras clave

Participación, infancia, entorno virtual, cultura participativa, derechos del niño, gobierno municipal


Citizen participation in public life plays an important role in democratic societies whose public policies seek to diminish the problems of citizen disaffection and governance, which characterize contemporary democracies (Díaz-Aldret, 2017; Innerarity, 2020). For the past three decades, child participation has been incorporated into international standards (Convention on the Rights of the Child, 1989 (Art.12); Council of Europe Recommendations on the participation of children under 18 (2012); goal 16.7 of the 2030 Agenda for Sustainable Development (UN General Assembly, 2015) and the UN Committee on the Rights of the Child (2016). This body of legislation has favoured various municipal initiatives to improve children’s participation (children’s participation bodies, participatory budgets, children’s groups, etc.); for example: “The Children’s City” (Tonucci, 1997), from which the initiative “My City with Children’s Eyes”, “Child Friendly Cities” (UNICEF) (, Save the Children, Global Kids and Eurochild programmes, through children’s councils targeting 8–17-year-old children.

Technologies have brought profound changes that affect the democratic culture and participatory practices of children and young people (De-la-Garza-Montemayor et al, 2019). What we do know is that children and adolescents use social media as a source of information on political and social issues, and that they perceive them as a quick and useful way to exercise their right to participation (give opinions, deliberate, make proposals, develop projects, support solidarity initiatives, and formulate protests) (Cho et al., 2020). Despite this, civic participation is scarce at this age and there is no clear awareness of digital media being seen as civic technology (Dias-Fonseca & Potter, 2016; Murden & Cadenasso, 2018).

Children’s participation and the digital environment

From an inclusive citizenship approach, children’s participation is understood as the process by which children, individually and/or collectively, express their opinions and decisions in matters that concern them directly on the basis of their age and maturity (Convention on the Rights of the Child, 1989). Unicef (2019) links child participation to a process of power transfer from adults to children, which transforms children from passive recipients to active, informed agents capable of influencing decisions that affect their lives.

Recent studies find that the digital environment can mobilise different levels and types of civic participation (Hart, 1992; White, 1996; Trilla & Novella, 2001; Tambouris et al., 2007; Guilló & Mancebo-Aracil, 2017; Unesco, 2019) and e-participation (Cáceres-Zapatero et al., 2015) which, as proposed by Lobera and Rubio (2015), ranges from information, communication, deliberation, and consultation/decision-making to creative action.

In relation to children’s participatory processes, one of the challenges faced by the political sphere is the need to provide this citizenry with offline and online scenarios for exercising citizenship, so that they can assume active roles, with responsibility and autonomy in the local, national, and global spheres (Livingstone et al., 2020; Kamruzzaman, 2020).

Digital technologies enable new forms of political and citizen participation based on horizontality and connectivity (Claro et al., 2020), including children’s participation (Council of Europe, 2016; UNICEF, 2016; Kaun & Uldam, 2017; Dennis, 2018; Boulianne, 2020). However, there is still a long way to go in terms of democratic innovation (Jenkins & Carpentier, 2013; Jennings et al., 2020), e-citizenship and children’s empowerment.

A digital environment for children’s participation

Recent studies have showcased the potential of technologies with children and young people in terms of citizen participation (Khalil, 2017; Roque et al., 2016). They are often thought of as socio-political innovations, rather than as consolidated realities in practice. As Save the Children Sweden (2020) demonstrates, the potential that policy makers see in technological devices to promote children’s participation is high, but in practice their use is residual. At a discursive level, institutional narratives on children’s e-participation oscillate between risk narratives (ICTs as potential threats) and empowering narratives (ICTs as transformative tools) (Livingstone et al., 2017). The EU Kids Online Network study (Smahel et al., 2020) reveals that digital practices among 9–16-year-olds are commonly recreational and relational, but not civic and political. It is known that the participatory potential of technology depends on the civic and political uses made of it and that the more participatory experiences children have in the offline world, the more likely they are to engage in participatory processes online and vice versa (Boulianne & Theocharis, 2018). This study analyses municipal initiatives in the Spanish context aimed at promoting children’s participation through digital environments. The research presented here is part of an emerging line of research on children’s participation in local politics through the digital environment. Specifically, it aims to analyse the contributions perceived by municipal leaders (elected officials and technical figures) of the digital environment and the uses they make of it to promote children’s participation in the municipality.

Materials and methods

In the research design ( a descriptive study (phase 1) was carried out on the state of children’s participation in Spanish municipalities that are members of the International Association of Educating Cities (IAEC) and Child Friendly Cities (CAI in Spanish). The study had an exploratory and diagnostic purpose covering the Spanish context and it integrated the design and application of a questionnaire in the framework of a self-administered online survey study (Díaz-de-Rada, 2021) to take a census of the forms of children’s participation present in the municipalities, to learn about the elements and practices that characterise the forms of participation identified and to describe the exercise of citizenship by children. One of the elements explored was the digital environment.


The sample consists of 279 subjects: 88 elected officials, councillors with political leadership functions and 191 technical figures, civil servants with programme coordination and dynamisation functions. They come from 179 Spanish municipalities belonging to the universe of 386 municipalities associated to IAEC and/or CAI. A two-stage cluster sampling was chosen, with selection of the primary sampling units (municipalities) by accessibility, and of the final units (individuals) by non-random routes and also by accessibility. The selected sample has a sampling error of ±5.4%, considering a confidence interval of 95% and a p-q of 0.5 (considering probability sampling).


Two questionnaires were designed: one for elected officials (EO) (; another for technical figures (TF) ( An initial design of the questionnaire was subject to a double validation process: logical, through judges, and empirical, applying it to 20 TFs and EOs in local administrations to assess the content of the questions (relevance and coherence) and their formulation (clarity and order). For both cases, three direct questions are asked to explore: whether or not participation is encouraged through digital environments; what digital tools they use; and what inputs they perceive. In the case of the TF questionnaire, it also seeks to explore the uses of digital environments in relation to three logics of citizen participation in the local sphere (Parés, 2017): 1) Representative; 2) Participatory; 3) Self-managed by children and adolescents. Specifically, we asked whether any digital environment was used; which digital environment; and how they use it.

The questionnaires received were filtered according to whether they had answered more than 50% of the questionnaire, eliminating 11 of the 99 EO questionnaires and 32 of the 223 TF questionnaires. The majority of respondents completed more than 80% of the questionnaire, which was validated with a Cronbach’s Alpha of 0.93.


The political and technical referents that both networks had as referents were invited to participate by e-mail. They were also informed about the issues of confidentiality and informed consent in accordance with the Organic Law on Data Protection, LOPD (Organic Law 3/2018, of 5 December), as well as the commitment of the research team as regards to the return of the data. This was followed by analysis and interpretation. At the end of October 2020, the research report was sent to the respondents (

Data analysis

Quantitative data were analysed using SPSS 25.0. Two databases were generated with labels and weighting factors for each record. The statistical analysis used was descriptive analysis, as well as inferential analyses. Specifically, the test used was the comparison of means Student Fisher’s t-test to determine whether there are significant differences between the averages of the group of technicians who say that children’s participation in the municipality is mediated by technological environments and of the group of technicians who do not use technological environments. The textual information was analysed by means of two types of analysis: one of a lexicometric-frequency nature for the identification of technological environments using the free software Iramuteq; the other, a thematic content analysis based on the constant comparison method (Corbin & Strauss, 1991; García, 2019) for understanding the contributions and uses of the environments. The content analysis took place in two phases. In the first, the inductive analysis aimed to find the emergent categories, based on which to generate the basic codes with which to code the content of the responses using the Atlas.ti 8 software. In the second, the deductive phase, the content of the responses was reduced to units of meaning (quotes) which were coded according to the codes developed in the previous phase as detailed in Table 1.

In order to reduce the content of the responses to units of meaning in the form of quotations, the general criterion was the search for the smallest unit of meaning that would allow unique coding, linking the quotation to a single code. Furthermore, when the same questionnaire response is separated into different quotations or units of meaning, these quotations are linked together. This makes it possible to make visible networks ( and between codes and quotations that show links of inclusion (the quotations of each code) and of relation (between the quotations of the same answer).


Contributions of digital environments and children’s participation: Elected officials and technical figures

Regarding the use of digital environments to mediate the participation of children and adolescents in the municipalities, 63.6% of the EOs and 64.9% of the TFs recognise their use.

Student’s T-test was used to identify the variables that differentiated between municipalities that promoted children’s participation with digital environments and those that did not. It was only significant in the group of TFs in relation to the variable reasons they claim to have for encouraging participation. In contrast, in the EO’s sample, no significant differences have been found between the variables studied and mediating the participation of children and adolescents with digital environments.

Table 2 shows the contrast results of the differences between averages for independent samples on the variable reasons for participation. TFs that mediate participation with digital environments give a higher value due to perceiving participation as a fundamental right in comparison to those who say they do not use digital environments (MPET =4.81 vs. Mp =4.52) with a standardisation of lower dispersion by the group of TFs who mediate participation with digital environments (SDPET =.488 vs. SDp =.948). The Student’s T-test confirms that there are differences between technicians who use digital environments and those who do not (t[179]=-2.751 and p<.05), with the former having placed greater value on participation as a right. Cronbach’s alpha was calculated for this item, obtaining an adequate internal consistency (α=0.787).

As for the other reasons why participation can be promoted in municipalities, no statistically significant relationship was found between the group of technicians who use technology to mediate participation and those who do not. Both groups give remarkably similar values to promoting participation as an improvement, as an enhancement of competence development and as a political exercise, regardless of whether they incorporate a technological environment to mediate children and adolescents’ civic participation.

Figure 1 represents the digital environments used in the municipalities to mediate children and adolescents’ participation according to EO and TF. The lexicometric analysis shows that local council websites and social media are the most widely used. In particular, the term web appears 31 times in EO contributions and 78 times in TF contributions. The term network appears 32 times for EOs and 37 times for TFs, and the adjective social appears 27 times for EOs and 35 times for TFs. Among digital media, Facebook (16 EO and 47 TF) and Instagram (15 EO and 38 TF) are the most used. Blogs are mentioned less frequently by the two respondents (11 EO and 23 TF), as well as Twitter which is mentioned more by technical figures (5 EO and 23 TF). The messaging application WhatsApp is referenced 5 times by EOs and 13 times by TFs.

In the content analysis of the EO and TF responses on what contributions they attribute to these digital environments in relation to children and adolescents’ participation, aspects related to seven cores have been gathered: they help to inform and disseminate (52 quotes); they open a space for expression (40 quotes); they facilitate participation (38 quotes); they generate proximity (33 quotes); they increase contact (31 quotes); greater speed (23 quotes); and they develop digital proficiency (7 quotes). The most referenced contribution by EO and FT is related to information. For the EOs (20 quotes), it is mainly valued as an environment to keep informed and facilitate access to certain information. The typical response was “a means of communication and dissemination” (EO,60). While, for the TFs (32 quotes), this information is mostly associated with giving visibility to the group and its actions, as well as disseminating its contributions to the rest of the children and adolescents, a typical response was “visibility in the campaigns and proposals for improving the city made by children” (TF,115).

From this point on, differences are already established between what is considered by one and the other group of respondents. The EOs cite proximity as often as information. Both categories are its main contributions. For them, digital environments provide proximity because they are a generation that relates more with these environments, they are tools that they handle and master, and they are attractive to them because they enable them to connect and bring them closer. This proximity is also associated with the augmentation/facilitation category, as well as with speed and immediacy. One response that exemplifies this category would be “reaching young people which we might not be able to reach in any other way. For them, digital environments sometimes provide comfort, a sense of security and confidence, and the agility they have developed in their generation” (EO,45). The next category mentioned by the EOs is to consider it as a space for expression, where they can express their ideas, proposals, complaints, and suggestions for improving the city. It is a medium through which they can make their contributions and where they can make it easier for other children and adolescents to do the same. Enabling immediacy is at this same level due to the fast and agile communication it provides. This contact becomes a channel for communicating, relating, and maintaining the relationship.

If we look into the categories that have emerged from the content analysis of TF contributions, after information at the same level we find providing a space for expression (27 quotes) and increasing participation (27 quotes). A space for expressing opinions that makes it possible to give children and adolescents a voice, present proposals or express their concerns. It increases and facilitates participation as it is more accessible from anywhere, more open, and it brings together a larger number of children and adolescents. An example would be the following contribution: “they facilitate the participation of children and adolescents, as they are part of their daily lives and they find it easy to use them, it is a way of adapting to the new social reality in which digital technologies are present in the personal, educational and social spheres of minors” (TF,74). TFs also see it as a contact, due to facilitating communication, convening and networking.

It is worth mentioning that a minority of EOs and TFs referred to the contribution of the digital environment to the development of digital skills. In both cases it is the contribution with the least amount of recurrence, but it is worth highlighting precisely for this reason.

Some of the TFs have revealed that during the pandemic period, digital environments have been a space that they have introduced for the first time, which they have tried out in order to be able to meet, stay connected, cohesive and communicate their concerns, as the following contribution states “we are still in an incipient process in such media... there is no clear project for children and adolescents to participate directly, but the lockdown period has helped us a lot to get children and adolescents to participate actively and allow us to keep in touch with them” (TF,64). It should also be noted that some respondents argued that digital environments are not usually used because they consider that they are not age-appropriate, as can be seen in the following response: “as I said before, we don’t usually use them much, as we consider that these media should not be used by children because of their age” (CO,39).

Forms of participation and uses of digital environments: Technical figures

Considering the three logics of citizen participation (representative, participatory and self-managed), significant differences were found in the value they assign to the reasons for encouraging participation among the TFs that accompany the participatory logic of citizen participation with the mediation of technology and those that do not. No significant differences were found in the other two logics of citizen participation. The results, as reflected in Table 3, indicate that the TFs that mediate participation with digital environments give a higher value due to their perception of participation as a fundamental right in comparison to those who say they do not use digital environments (MPET =4.92 vs. Mp =4.15) with a standardisation of lower dispersion by the group of TFs who mediate participation with digital environments (SDPET =.227 vs. SDp =.1.144). The Student’s T-test confirms that there are differences between technicians who use digital environments and those who do not (t[18]=-3.828 and p<.05), with the former having placed greater value on participation as a right.

In relation to the reason why participation is a citizen exercise, the TFs who mediate participatory practices with digital environments give it a higher value than those who do not (MPED =4.70 vs. Mp =4.08) with a standardisation of lower dispersion by the group of technicians who mediate these practices with digital environments (SDPET = vs. SDp =1.256). The Student’s T-test confirms that there are differences between the TFs who use digital environments and those who do not (t[48]=-2.353 and p<.05), with the former having placed greater value on participation as a political exercise. As regards the reasoning behind participation as an improvement, the results indicate a certain tendency towards statistical significance (p=.059), which we believe to be the case for participatory citizenship practices from a practical point of view. Finally, it should be noted that regarding the reason for participation as development of skills, it can be observed that there are no differences between TF of the two groups.

We will now move on to a content analysis of the TFs’ responses in relation to each of the logics of citizen participation: Representative (R), Participatory (P) and Self-managed (A), a first general analysis from the coding reports that the type of uses made of digital environments is smaller than the perception of possible utilities of digital environments. The main use focuses on external or internal communication and opinion gathering. There is a predominance of the use of digital media to disseminate information as opposed to other possible uses in terms of the number of quotes.

Looking at the meanings provided by the responses for each of these categories, there are strong similarities in the uses of digital environments in each of the practices, with little or no differences. Thus, when TFs talk about the use of digital environments for external communication, they refer to disseminating information. “Dissemination and information” (A_TF,77) are the most repeated words in all three practices. Communicating outwards is disseminating and providing information about what is being done. A typical response was “to disseminate the activities/projects that the adolescents have carried out” (P_TF,167).

Linked to this function of disseminating information about what is being done is the promotion and recruitment of new participants. The TFs talk about the use of digital environments as “informative and convening” (A_TF,49). It is interesting to mention that in participatory practice there is also talk of the use of registration, the example would be “dissemination of activities and registration in them” (P_TF,65), which can be explained by the nature of this practice, usually constituted by processes with a specific and limited duration in time. It can also be explained by the nature of the representative practice linked to the existence of stable bodies, that only in these bodies does the use of a repository arise, fulfilling a function of information transparency, as exemplified by this response, “all the minutes, photos, calendars, etc. are posted on the website” (R_TF,57) (R_TF,57).

The last use of digital environments mentioned by the TFs associated with external communication is that of awareness-raising or sensitisation; “informative, awareness-raising and recruitment” (P_TF,17). As this response illustrates, between conveying information and attracting new participants, the importance of the actions being undertaken needs to be explained and reassured. It is also interesting that only in the self-managed practice does a reporting function appear associated with awareness-raising; “social networks serve as a platform for this movement to disseminate, report, raise awareness and make calls” (A_TF,6), which can also be explained by the nature of this practice, which is associated with processes of citizen demands. From the analysis of the category of internal communication, it can be seen that the TFs make more use of digital environments to share information among the agents involved, pointing out the exchange of information between facilitators, families and children and adolescents, although in the latter case the communication may not be direct as can be seen in this example: “it is the means of communication between the secretary of the council and the children, although due to their age, most parents act as transmitters of the messages that are sent and not all of these parents share with their children what is communicated through these channels” (R_TF,172). This exchange of information serves, on the one hand, to facilitate the organisation of work, to remind people of responsibilities, to plan and coordinate; and, on the other hand, to generate spaces for meeting, identity and group feeling, to connect and be in contact among participants and with other related processes; “to be connected among council members, among other councils” (R_TF,96). It is noteworthy that the TFs report that the use of digital environments for internal communication has increased during this pandemic period both to stay in touch and to be able to work. This is illustrated in this response: “at this time, social networks have been of vital importance in order to be able to continue working” (R_TF,54).

Finally, the category with the fewest responses refers to the gathering of proposals, where a consultative use appears in the majority, to carry out “surveys to find out opinions” (R_TF,153). Only one response also reports the use of e-democracy platforms that allow for argumentation and voting between different proposals.

Comments and conclusions

The main objective of this study aims to explore what contributions are perceived by municipal leaders (EO and TF) in relation to the digital environment and what uses they make of this to promote children’s participation in the municipality. The most significant result of the study is the finding of the variable that establishes significant differences between those TFs that mediate children’s participation with technological environments and those that do not. This variable refers to the reasons why they encourage children’s participation. Those who claim that participation is a fundamental right or who understand it as a political exercise claim to use digital tools in their regular work with groups of children and adolescents as opposed to those who claim other reasons (e.g., as a process of improvement in the areas where it takes place, development of citizenship skills), who do not make use of these tools. It is likely that among the first group of professionals there is an affective commitment and, therefore, a higher level of involvement with participation as a civic value. This interpretation is plausible as it has been proven that those who work in social-educational projects guided by human rights and social justice values reflect a higher affective commitment to the goals and objectives of the organisation (Morilla-Luchena et al., 2019).

The results show that the digital environments most commonly used to mediate children’s participation are the websites of local councils, the social media sites Facebook and Instagram and the Whatsapp application. It is noteworthy that other online social media, whose popularity is widespread among 13–17-year-olds (e.g., YouTube or TikTok), or the use of blogs, virtual worlds, or online games, are not among the devices used. Similarly, there is no evidence of the use of civic technologies that are conducive to political participation with children and adolescents, similar to those used in the adult world, offering opportunities for debate (e.g., Loomio), decision-making (e.g., Agora voting, Democracia en red, Doodle) or other similar ones (Lobera & Rubio, 2015).

Another relevant finding is that local governments use digital environments essentially for informational and communicative purposes, but not for deliberative, decision-making, or creative functions. On the other hand, it should be noted that only a small number of responses link the use of digital environments to children’s skill development (e.g., digital, civic, or political, or global). The increased use of digital environments in the participation of children and adolescents in local politics would enhance their education as critical, active, supportive e-citizens, co-responsible for social change and would contribute to reducing political disaffection.

Two possible explanations that help to interpret the moderate percentage of municipal referents that make use of technologies to promote participatory processes with children are: firstly, historical-cultural reasons, since children are perceived as inferior and semi-citizens (Ramiro & Alemán-Bracho, 2016), which minimises their inclusion in participatory practices and reduces their involvement to the use of the digital environment to connect, inform and communicate; and secondly, reasons linked to the limited digital training of the technical figures who have traditionally been developing in-person children’s participation initiatives.

The results of this study are in line with the review of literature and other studies on digitisation as a mechanism for civic and political participation of citizens in general (Parés, 2017) and children’s citizenship (Unicef, 2019). So far, children’s participation in digital environments is reduced by the perceived threat and potential risks to which children under the age of eighteen may be exposed by inappropriate use of technological devices, either by the children and adolescents themselves or by adults (Pavez, 2014). In some ways, children’s citizenship rights are also at risk of being violated in the digital environment (Livingstone et al., 2017; Livingstone et al., 2020) by resistant and overprotective adult behaviours that limit children’s participation. However, the pandemic context has led to the proliferation of its use as a channel for citizen participation by children and adolescents. It has forced those responsible for local policies relating to children, education, and participation to overcome narratives of risk and distrust to make way for incipient innovative experiences through the digital environment aimed at deliberation, decision-making and the development of creative, participatory actions. This scenario opens up new possibilities and challenges for a more inclusive and meaningful children’s citizenship in the digital environment.

Finally, some limitations of the study should be noted. On the one hand, there is an absence of previous similar empirical studies on this subject and with these respondents. Existing studies are supported by analyses of good practices in child and youth participation (Gros & Schwartzman, 2020). As a non-probability sample, as is well known, there are limitations concerning generalisability. For this reason, the sampling error has been calculated as if the sample were probabilistic, making it possible to approximate the generalisability of the data obtained (risk of +-5.4%, confidence level of 95% and a pq of 0.50). It should also be noted that the study was conducted during the pandemic period, when the use of these digital environments proliferated. It is possible that this could lead to a bias in the results, but the results obtained show that it is still low. As a continuation of this line of research, the research project plans to ask children and adolescents about the use of digital environments in citizenship practices through a questionnaire and a participatory workshop. In short, digitally mediated children’s citizenship participation in the local policy space needs to foster an involved citizenship open to debate, deliberation, collaborative and creative democracy that is inclusive and meaningful.

Author Contribution

Idea, A.N.C., C.R.P.; Literature review (state of the art), A.N.C., C.R.P.; Methodology, A.N.C.; Data analysis, A.N.C., H.M.; Results, A.N.C., C.R.P., H.M., E.N.P.; Discussion and conclusions, A.N.C., C.R.P., H.M., E.N.P.; Writing (original draft), A.N.C., C.R.P.; Final revisions, C.R.P.; Project design and sponsorship, A.N.C. (1)