# Online Critical Debate Model: Deliberation for the Digital Age

Claudio Fuentes Bravo, Julián Goñi Jerez

### 1. Introduction

To argue is to build democracy (Fuentes 2019). The capacity to reach agreements among a diverse set of social and political actors is one of the key dimensions in the governability of complex societies (Gerring and Thacker 2008). Argumentation is precisely the origin of legitimacy and stability of national democracies. However, the nature and extension of argumentation in society is rapidly changing. Political scientists and public participation activists have systematically pushed for a greater empowerment and citizen control over political decisions. This is what is commonly known as the «deliberative turn». As Dryzek states:

The essence of democracy itself is now widely taken to be deliberation, as opposed to voting, interest aggregation, constitutional rights, or even selfgovernment. The deliberative turn represents a renewed concern with the authenticity of democracy: the degree to which democratic control is substantive rather than symbolic, and engaged by competent citizens (Dryzek 2002, 1).

The achievement of citizen control is not an easy task. It requires addressing major practical and conceptual challenges regarding the nature, objectives and methods of deliberation.

Claudio Fuentes Bravo, University of Chile, Chile<EMAIL_ADDRESS>Julián Goñi Jerez, Pontifical Catholic University of Chile, Chile<EMAIL_ADDRESS>FUP Best Practice in Scholarly Publishing (DOI 10.36253/fup\_best\_practice)

Claudio Fuentes Bravo, Julián Goñi Jerez, *Online Critical Debate Model: Deliberation for the Digital Age*, pp. 69-86, © 2021 Author(s), CC BY 4.0 International, DOI 10.36253/978-88-5518-329-1.08, in Adelino Cattani, Bruno Mastroianni (edited by), *Competing, cooperating, deciding: towards a model of deliberative debate*, © 2021 Author(s), content CC BY 4.0 International, metadata CC0 1.0 Universal, published by Firenze University Press (www.fupress.com), ISBN 978-88-5518-329-1 (PDF), DOI 10.36253/978-88- 5518-329-1

Regarding the nature of deliberation, Chambers (2003) asserts that the essence of democratic deliberation is talk-centric. Deliberation implies a series of communicative and linguistic procedures that allow for a certain *deliberative attitude* in which different actors are able to engage as peers in an exchange of reasons with the aim of reaching a shared practical judgement (Curato et al. 2017). According to Chilvers (2008), exercising deliberative democracy requires the development of *deliberative competencies* that allows for the orchestration of diversity, difference, antagonism and uncertainty. The emergence of dissent is a key dimension for a pluralist view of deliberation, as dissent is view as a marker of different voices being heard (Martí 2017). On the other hand, quality evidence and quality reasoning are nonetheless fundamental in order to assure that biased or factually wrong opinions may be discarded through the deliberation process (Landemore 2017).

Regarding the objectives of deliberation, Dryzek and Niemeyer (2006) argue that probably more important than reaching consensus in the results, it is reaching meta-consensus. A meta-consensus means that positions are not necessarily shared, but there is consensus regarding how a decision is made and what is the spectrum of legitimate options and evidence. Meta-consensus may be normative, epistemic or of preferences (Dryzek and Niemeyer 2007). Normative meta-consensus means that all involved values are considered legitimate. Epistemic meta-consensus means that all involved evidences and beliefs are considered trustworthy. Finally, preference meta-consensus means that there is agreement regarding the spectrum of legitimate outcomes and preferences of deliberation. For participants, reaching a meta-consensus means not only that they know what the other's positions are, but also that they know why they prefer them (Niemeyer 2011).

Regarding the methods of deliberation, and given the complexities of broadening deliberation in democracy, new ways of designing participation have arisen. The redesign initiatives are often referred to as «democratic innovations». According to Elstub and Escobar (2019), democratic innovations are defined as processes or institutions that are new to a particular governance or policy matter and that aim to re-imagine or deepen the role of citizens in governing through an extension of the opportunities of participation, deliberation and influence.

Most of these innovations are meant for competent adult citizens that are deemed ready for political engagement. However, there is a need to consider new innovations aimed at developing the necessary deliberative competencies (Curato et al. 2017) and attitudes (Chilvers 2008) that are required for this to happen. This educational democratic innovation should gain a bigger role, especially when considering the urgency of preparing the new generations for public engagement. Furthermore, there is a need to consider new innovations aimed at developing new analysis strategies that add representativeness (Schecter and Sullivan 2018) and meaningful discourse analysis and regulation (Niemeyer and Jennstal 2018) to existing deliberative initiatives.

This chapter presents our experience designing and analyzing deliberation initiatives during 2020. In particular, we seek to present how our experience with a large-scale online citizen engagement exercise called Tenemos Que Hablar de Chile [We have to talk about Chile] helped us to re-design and expand the Critical Debate Model (Fuentes 2011) for the context of online learning. In the first section, we will present a brief historical overview of the Critical Debate Model. In the second section, we will describe our experience with Tenemos Que Hablar de Chile highlighting our learnings. In the third section, we will describe our proposal for an online version of the Critical Debate Model. With our experience, we aim at illuminating new possibilities for the design and analyzing of deliberation in an online environment.

#### **2.** The Critical Debate Model

The traditional format of academic or school debate, especially the competitive version of debate is a widely popularized educational practice (Freeley and Steinberg 2009). However, the articulation of debate as an educational practice and debate as described by argumentation theory is still underdeveloped (Fuentes 2011).

A debate is an interrogation and defense process that aims at developing reasoned judgment about a proposition (Freeley and Steinberg 2009). Debate is also perceived as a practice that accentuates antagonism and force competition (Fuentes and Santibañez 2011). Finally, as participants of school debates are often forced to accept a fixed policy position without a possibility to change during the deliberation process, it can also lead to a lack of genuine epistemic commitment that should characterize democratic deliberations.

The Critical Debate Model (CDM) seeks to address these challenges by emphasizing the dialectical nature of debate over its competitive antagonism, while also allowing participants to change their initial point of view utilizing arguments presented by their counterparts. The CDM was created by Claudio Fuentes in 2008 based on his experience organizing the Chilean national debate tournament from 2002 to 2005. This tournament utilized the British Parliamentary Debate format. Because of the previously described challenges of this format, stakeholders expressed dissatisfaction. That lead to a re-interpretation of the tournament through the application of argumentation theory and emphasizing the educational dimension in 2008. Thus, the Critical Debate Model was created.

This format integrates the idea of two opposing teams (given from the traditional debate format) and adds a third team in charge of research. It is structured in three rounds of argumentation. In the last round, students are allowed to change their initial point of view and utilize evidence and arguments presented by the opposing team. Additionally, its evaluation and assessment methods are grounded in more contemporary approaches to argumentation as a dialogical process. The specific details of this model will be detailed later in this chapter.

Since its creation, the Critical Debate Model has been implemented as the basis for the Chilean national debate tournament from 2015 to 2018. Since 2011, it has also been implemented as part of the base curricula from the undergraduate program of psychology in the Universidade Federal de Pernambuco, Brazil and since 2019 in the Università di Padova, Italy as part of the Debate Tournaments for medical students.

Despite the fact that the Critical Debate Model addresses some of the major concerns raised about the traditional competitive debate formats, there are still some challenges left to face. On the one hand, this new format emphasizes the dialogical component of debate, but is still centered around competition. It is relevant to explore non-competitive deliberation designs to compare and define trade-offs between the two approaches. On the other hand, this new format emphasizes the educational dimension of debate, but the forms of assessment and feedback that is produced as part of this format is still underdeveloped. More audacious or comprehensive processing strategies can be explored, especially considering the recent advances in data sciences, particularly in the sub-field of natural language processing.

Finally, this format is designed for co-located interaction and thus is not necessarily suited for an online environment. An online version of the Critical Debate Model would allow for greater flexibility and more importantly, the utilization of distributed teams across countries and continents. This has become a much greater issue because of the COVID-19 crisis that has impossibilities all co-located team activities. In this context, and drawing from our experience designing and processing a massive citizen deliberation exercise (Tenemos Que Hablar de Chile) we seek to present an adjusted and improved version of the CDM for an online age.

#### 3. Analyzing Tenemos Que Hablar de Chile [We have to talk about Chile]

In 2020, our team was invited to participate in a large-scale public engagement exercise to talk about the future of Chile in the aftermath of the social crisis of October, 2019 that shook up the political climate of the country. The Tenemos Que Hablar de Chile project was developed through a partnership between the two most prestigious universities in Chile (*Pontificia Universidad Católica de Chile* and *Universidad de Chile*) with the funding of private citizens. The project aims at addressing the citizen's demands for a bigger, more inclusive and more transparent democratic space, in which it is possible to collaboratively construct a vision for the future of Chile. In particular, the project seeks to develop a citizen platform for public engagement. According to the organizers, the objectives of this initiative are threefold: (1) To impulse a massive social conversation about the challenges of the country. (2) To promote a way of dialoguing that showcases our differences and allows for our reunion around them. (3) To systematize, represent and respond to the vision of the future by the Chilean society in a rigorous manner.

Paralleling many of the concerns that have given form the «deliberative turn» in political science, Tenemos Que Hablar de Chile (TQHDC) defines its mission in terms of the following principles of citizen dialogues:

Of course, it is perhaps simpler to list a series of principles than to design an effective way to put them in practice. TQHDC canalizes all these attributes in three sub-initiatives. The «Citizen's consultations'» initiative coordinates individual responses through open-ended surveys into a series of predefined social topics, ranging from the environment, politics, science and technology to democracy and decentralization. The «Digital conversations» initiative organizes digital dialogue events (similarly to mini-publics actions) with purposely selected participants to ensure gender, regional, educational and age representativeness of the sample. The «Chile at scale» initiative is charged with the sampling process that will assure representativeness for the digital dialogues.

The digital conversations were designed by the Public Innovation Lab of the Pontificia Universidad Católica de Chile (LIPUC) and the Institute of Argumentation of the Universidad de Chile, represented by Claudio Fuentes. Each conversation was designed to follow a series of activities. These activities are:

### 4. A plan to analyze natural speech

As an interdisciplinary team, we were charged with the task to create a strategy for the systematization and analysis of the data produced as part of what is likely the largest private citizen dialogue initiative in the history of Chile. This is not an easy task, especially considering that it involved massive amounts of qualitative text expressed as natural speech (thus, not formalized or coded for analysis).

The strategy employed for the data analysis is based in Natural Language Processing (NLP). NLP is a sub-field of computer and data science that addresses the automatic processing and analysis of natural language (unstructured and spontaneous expressions of language). The analysis was carried out in the programming languages Python and R. Through a vast variety of techniques, such as tokenization, stemming, lemmatization, labeling, semantic analysis and dictionary analysis.

We assert that the application of NLP allows for a scalable and efficient analysis of qualitative data (compared to 'manual' qualitative inquiry) that maintains the naturalism of dialogue events (compared to surveys). In this sense we observe that recent advances in data science offer a new opportunity for an automatic, replicable and accountable analysis and systematization strategy in massive online deliberative initiatives. However, it must be stated that data science tools can only support and enable analysis decisions, but for an analysis plan to produce meaningful and substantive results, it must be founded on meaningful and substantive conceptual frameworks. In our case, we based our analysis in theoretical integration of argumentation studies, cognitive psychology and future studies.

Overall, our analysis plan was structured in three dimensions:

Overall, our strategy aimed at developing a series of automated analysis indicators that were the results of an operationalization of concepts deriving from cognitive psychology, argumentation theory and future studies. For instance, through verbal markers we were able to describe the degree of agency and perceived influence in the citizen's images of the future (Polak 1971; Taboli and Kapio 2018). We were able to develop indicators of semiotic distance (Zittoun and Gillespie 2018) through the analysis of syntactic complements and modal attitudes (Ballarin 2010) through verbal construction markers. The methods and results of this strategy plan will be published in detail once the project concludes. Beyond the potential discussions around the pertinence and reliability of each particular indicator, as a team we have already succeeded in the task of proving the feasibility of integrating different disciplinary traditions into natural language processing. We have observed during this process that there is much more that can be done when reporting deliberation results than just describing the expressed conclusions.

**5.** Learning from Tenemos Que Hablar de Chile

There were three main elements of the Critical Debate Model that we sought to reconsider based on our experience with Tenemos Que Hablar de Chile. These are: competition-driven format, analysis and processing strategies and the possibilities opened up by online deliberation.

TQHDC is a non-competitive and expressive instance of public engagement. These sort of approaches enable citizens to express their ideas, opinions and feelings regarding policy issues. In contrast to other democratic innovations, such as participatory budgeting (Elstub and Escobar 2019), TQHDC is not consequential in nature. This means that it doesn't produce a material result that is trazable and accountable. Beyond consequentiality, we observe that this experience lacked the form of controversiality and opposition that is required for people to change their minds (Leitão 2008). The lack of opposition or contrasting evidence that could be presented by policy makers or other actors can remove the epistemic conflict element that is present in the competitive debate models. In this sense, and contrasting to popular opinion, we concluded that the competitive element is a positive aspect that should be kept in an online CDM.

TQHDC was designed with the analysis plan in mind. This is one of the major victories of the project. The project involved trained facilitators that registered all key information that would later be used for automatic processing. In practice, this meant utilizing a SPOCA (Subject – Predicator – Object – Complement – Adverbial) grammatical structure. Ensuring a complete syntactic unit proved key for exploring non-traditional analysis ideas with Natural Language Processing. The CDM does not involve a strong registration process and does not require full SPOCA annotation. This is something that should be incorporated in order to open up new possibilities for analysis. The analytical ideas themselves could also be adapted from our TQHDC strategy and involve argumentative level and futurization level markers.

Finally, the TQHDC project was designed as an online experience. This decision was purely based on the health contingency of the COVID pandemic. However, we have been able to see how an online format allows for a level of social integration that could otherwise not be achieved. In particular, it allowed organizers to set quotas regarding gender, age, schooling experience and geographical location. Each participant could take part in the event without ever leaving their house and zone of comfort. In the context of CDM, it made us realize that digitalization is more of an opportunity than a challenge. We also learnt that the optimal setting for an inclusive online experience is using the least possible amount of external software. Just as face-to-face experiences can be innovatively arranged just through rules and structured actions, video call software is sufficient to support most of the debate experience. Requiring a single software makes the experience more accessible for more people and mitigates the effect of internet bandwidth issues. Additional software can be for information registration purposes, as used in TQHDC

In consideration of our experience with TQHDC we were able to question design decisions and propose an alternative to adjust and digitalize the Critical Debate Model. In the next section we present this proposal.

### **6.** Designing the Online Critical Debate Model

This proposal is based on argumentation learning studies and research on argumentation skills, development of thought and knowledge construction (Leitão 2000; Kuhn 1991; Billig 1996). In particular, it is based on the works of Selma Leitão (2000, 2008).

Leitão's (2008) analytical procedure was designed to capture beliefs revision processes during argumentation. Its analysis unit consists of three main components (1) the argument, (2) the counter-argument and (3) the response. Both general and specific cognitive operations depend on each of these components;

Firstly, *the argument* allows for the identification of a point of view that will frame the argumentation process and the ideas that ground the decision over the point of view selection. Cognitively speaking, *the argument* creates a point of reference in relation to which an evaluation (and potential transformation) of reasoned perspectives may, or may not, be installed in later phases of argumentation. Epistemically, *the argument* captures the momentary organization of knowledge by an individual in a particular topic, as well as his/her doxastic attitudes towards that knowledge.

Secondly, *the counter-argument* captures the existence of opposition voices in a knowledge discourse. This, in turn, introduces dialecticism that is inherent to argumentation. Cognitively, *the counter-argument* represents a discourse of alterity that allows the individual to evaluate his/her initial position in light of contraposition. Epistemically, *the counter-argument* unleashes the process of beliefs revisions.

Finally, *the response* is defined as the reaction –immediate or remote– to the opposition substantiated in the counter-argument. Cognitively, its presence in argumentation marks the metacognitive awareness by the individual of the contraposing positions and forces the individual to find ways of refuting them or to (partially or completely) accommodate his/her previous knowledge structures to fit the new evidence. Epistemically, it's the final deliberation instance in which all available evidence is laid out and the epistemic judgment is settled.

Based on these three dialectical components of argumentation, the Critical Debate Model encompasses three distinct rounds or moments:

3. Integration: The third round is based on the incorporation, construction, and argumentative collaboration. This process supports the epistemic function of argumentation, that is, the changing of participant's knowledge structures. During this stage, initial beliefs should be contrasted with the final remarks in order to find indications of change.

I must be noted that Leitão's (2008) analytical procedure was intended to mark the cognitive stages of knowledge transformation. The Critical Debate Model seeks, in turn, to transform those descriptive remarks into normative criteria to design successful argumentation learning experiences.

# 7. Overview of the Online Critical Debate Model

# Participants

Note: All participants are students in case of a school debate. One member of the judge's team is designated as the president of the jury and has an active role as a debate presenter.

# Team roles

Note: The team of judges is in charge of evaluating the debate, presenting and giving a verdict. Presenting involves framing the deliberation experience, explaining the format and participants, while also stating the relevance of the topic. Only in rounds 1 and 2 do teams have to comply with their role. After ending stage 2 and before the closing statements, teams have freedom to choose a role CONTRA or PRO the proposition. This means they can change their mind given the merit of the presented arguments.

# Team member roles

Note: The roles or arguers 1 and 2 are inverted in round two. We also emphasize the importance of having two separate judges for issues of legitimacy and reliability of the results.

Argumentation rounds

Arguer 2 (CONTRA) → Arguer 2 (PRO)

• Third round: Closing statement PRO → Closing statement CONTRA.

## Time usage

Main rules

# Debate proposition or theme

A debate proposition or theme is an open-ended problem that allows for both moral and technical examination (e.g. the Chilean healthcare system). Both teams are given the theme one week before the event. They are also notified about their role (CONTRA or for a proposition regarding the topic). For instance:

# Closing statements

In this stage, participants are free to choose whether to maintain or change their initial point of view. In any case, it is expected that this decision is made in consideration of meaningful reasons. A team may legitimately conclude that the opposing position is (fully or partially) right. However, this does not mean that the conceding team should not provide robust arguments for this decision. This is necessary for the judges to evaluate critical thinking and intellectual honesty.

Note: All information produced during the event will be registered and analyzed. In case of school debates, this report is sent to the institutions for learning purposes.

## Online platform

There are multiple channels fit to sustain an Online Critical Debate Model. We recommend the utilization of two separate channels for two different purposes. A video-call software (such as Zoom or Google Meet) allows for the open deliberation processes that occur in the first, second and third round (the latter being closing statements). A platform such as Zoom is ideal considering that the breakout rooms function allows students to meet privately while preparing during the timeout periods and judges to meet during the final evaluation period.

On the other hand, judges could work live on the material in a variety of platforms. Google Documents and Spreadsheet offers a more minimalist option, while other platforms such as Stormboard or Miró allows for a more designed and stylistic template to do all the registration, evaluation and preparation of the final documents. Such a platform could also be utilized by the team's Annotators. Figure 1 shows an example of a registration system that can be translated into a digital platform.

Figure 1. Example of a registration template.

### The importance of annotators

Annotators take note of the counterpart's arguments in the format determined by the rules of critical debate (point of view, justification, evidence). Annotation involves registering statements considering a SPOCA (Subject – Predicator – Object – Complement – Adverbial) grammatical structure that will facilitate processing with NLP tools. Furthermore, the annotators, taking advantage of the opportunity provided by online registration, can obtain the arguer's approval of the annotation and immediately validate the registration. This avoids having to carry out extra validation procedures.

The methodology used for the annotation of the arguments is based on an interactive visualization (that is, writing and grouping in a digital tool) of elements of the process and elements of the debate. This visualization is done through a registration software (such as Stormboard). Interactive visualization is a powerful tool for documenting options or agreements, and keeping jointly prepared or individual opinions tracked visibly, without 'losing' them in the dialogue (Ropers 2017). Additionally, applications such as Stormboard allow the use of templates to implement a «one idea, one card» display. This would permit a visual record of all opinions and keeps them visible throughout the argumentative interaction. Having visible information throughout the debate promotes conscious communication towards shared meaning within a group, and with the goal of understanding and solving problems.

# 8. Argument strength evaluation

As stated in the rules section, during a Critical Debate Model, two different forms of argument evaluation take place; at the individual level and at a group level. A group level evaluation is a comparison between the quality of a pair of arguments at the individual level. Through this evaluation, we declare if a particular argument is stronger or weaker (< or >) than another. To conduct this evaluation, a matrix with 7 columns must be prepared beforehand. Figure 2 represents an example Matrix in which the comparison is expressed by columns A, B and C.

Figure 2. Example of evaluation Matrix.

### Argument evaluation criteria

All judges compare a pair of arguments based on three criteria: (1) Argumentative structure, (2) logical coherence and (3) evidential weight.

The first criteria examined is argumentative structure. To be evaluated, all arguments must first demonstrate a point of view, justification and evidence (see «argumentative structure» in the rules section). If one of the arguments does meet any of these elements, it is automatically deemed weaker.

The second criteria examined is logical coherence. Logical coherence means that the point of view, justification and evidence must be meaningfully related amongst each other. Each justification must remain within the same thematic scope as the point of view and each evidence presented must directly support the interpretations made in the justification. If an argument is less coherent than another, then it is deemed weaker.

Finally, if all previous criteria are equally met, judges will evaluate the evidential weight of each argument. The argument that displays the more systematic, valid and reliable evidence is deemed stronger. Judges are encouraged to show how the evidential weight will be analyzing (using which markers) beforehand. Some examples or markers are the use of peer-reviewed articles, recent findings, findings made with larger populations or during large periods of time or so on.

In the example shown in Figure 1, we can observe that all arguments meet the argumentative structure criteria. However, if we consider the first argument pair, we observe that the evidence used in Argument (CONTRA) doesn't directly support the justification as it doesn't prove that the changes have made the healthcare system better. Because of this lack of logical coherence, the first argument is considered stronger. On the other hand, if we examine the last argument pair judges may conclude that the key difference lies in the evidential weight (if they predetermine that perception-based evidence is weaker than academically published external evaluations).

# *Closing statements*

Each team's closing statements are assessed in consideration of 4 requirements:

If teams meet all four requirements, they keep all accumulated points. If they only meet some of them, 25% are discounted, and if they don't meet any of them, they lose 50% of their accumulated points.

Note: It is important to keep in mind that students are allowed to change their initial position during the closing statements. However, it is still expected that all these elements are observable.

Final verdict

Debate organizers may decide to weigh each component of the debate differently. We recommend that the final decision is made considering each round independently. Each argument round can be decided in terms of the team that won the most arguments out of the three argument pairs (each winning argument is a point). Finally, the closing statement is decided based on the criteria mentioned in the previous section. Figure 3 shows a final verdict template.

Figure 3. Example of final verdict template.

### Ideas for the analysis of results

As showcased from our experience with TQHDC, having a structured and complete registration system allows for automatic analysis to take place. In turn, it permits the exploration of more audacious and creative forms of analysis through the operationalization of concepts from cognitive psychology and argumentation theory.

Some of the analysis ideas we are currently exploring are:

### 9. Discussion

Throughout this chapter, we have presented our experience designing and analysing online deliberation instances. We have presented our recent work with Tenemos Que Hablar de Chile (TQHDC) in order to extract insights that helped us re-design the Critical Debate Model for an online age. In particular, we reaffirmed the need for opposition in deliberation experiences and noticed how the lack of consequentiality hindered the impact of TQHDC. However, we did recognize how this project innovated regarding the role of annotation (anticipating automatic processing) and the exploration of new analysis options through the operationalization of argumentation theory and cognitive psychology. These learnings helped us to improve the Critical Debate Model and transform it to an online experience. Furthermore, we noticed how an online format allowed for more social integration and could possibilitate the use of distributed teams using participants from different cultural backgrounds and continental locations. This chapter then summarizes how an Online Critical Debate Model can be implemented in practice.

In Chile, debate events started out with a politically naive pedagogical pretension. However, as relevant stakeholders noticed how mobilizing debate is for adolescents' social consciousness and desires for a more open democracy, debate could no longer be perceived as just a traditional 'content' learning strategy. Debate and deliberation, especially when integrated into the curricula, can be a powerful tool to deepen political participation and to renew our compromise with democracy. In this context, having a more comprehensive and well-designed debate model was considered critical for following up on that promise. The Critical Debate Model seeks to do just that, through a thorough conceptualization based on critical and dialogical developments both in psychology and philosophy.

On the other hand, the consolidation of globalization and the unexpected digitalization produced by the 2020 pandemic, forced our team to think of ways to translate our advances into a digital format and new technologies. We have now started to grasp the new possibilities that emergent technologies open, both for design and analysis of deliberation experiences. The internet and new communication technologies allow students to interact with people they may otherwise never have met, through stylistic and pre-structured softwares that make the information registration process, time keeping, instant broadcasting and recording and many other aspects of a debate event much more user-friendly. Additionally, new advances in data science, particularly regarding natural language processing now allow debate organisers to create automated reports and to explore complex new ideas for analysis that are easily scalable, transparent and reliable. As we have asserted, we do believe that this is possible only if the analysis ideas are based on meaningful theoretical models.

Especially now, it seems vital to come up with new ways to promote online critical debates. Learning how to debate is learning how to argue, deliberate, reach agreements or at least to map our disagreements (meta-consensus). This ability is critical for a post-pandemic world that has already seen how western democracies and social cohesion are becoming weaker each year. Developing online debate models in developing regions is also crucial to bring about a more inclusive and critical globalization process.

Despite the relevance of designing an online critical debate experience, there are many challenges left to address. The CDM has to find better ways to increase the traceability of the arguments, that is, to register individual arguments and not only the overall conclusion of the debate. Individual arguments can be considered as the raw material of deliberation and the ultimate reference point to determine the presence of knowledge construction. We have made some advances in this line by including annotators, but there is still much to advance.

In terms of pedagogical design, we still need to find ways to promote better argumentative processes by allowing students to metacognitively pre-assess each contribution and by mitigating the incidence of ill-structured, imprecise, factically incorrect and disingenuous opinions. NLP could allow for the development of automated markers of poor quality arguments to let students train and become more aware of their own process. In this sense, the current design does not incorporate the sort of automated feedback and scaffolding needed for students to self-regulate and co-regulate their own argumentative practices and beliefs.

In terms of analysis and processing, we have to still look for better ways to validate registered information to assure a more reliable analysis. We propose that applications such as Stormboard could help in this direction to create interactive visualizations of the annotation process. Having immediate validation helps to increase trust in the process and to mitigate the impact of the annotator and judges bias. The current analysis plan also needs to be consolidated and empirically tested to determine which indicators help institutions to make better educational decisions after the event.

In terms of event organizing, we should find trustworthy and transparent mechanisms that help participants and judges to determine what are valid sources of information and how to avoid fake or unreliable news. This will likely become a sensitive topic considering how the notion of valid news is under political analysis and traditional sources of information lacking the legitimacy that they used to have. Regarding distributed teams, we still need to test the best way to cope with language barriers and time zone differences in order to make a fair and inclusive event in everyone's minds. Cultural and geographical differences can also problematize the idea of trustworthy information sources, as some participants and judges may attribute more epistemic or less confidence to certain social identities, leading up to epistemic injustice (Fricker 2008). In this sense, we notice that there is still a great challenge regarding how to promote epistemic justice during debates and what does that mean in this particular context.

#### References

Billig, M. 1996. *Arguing and thinking: A rhetorical approach to social psychology*. Cambridge: Cambridge University Press.


*3.1. SCB Fatigue Test Results*

The tensile strength of the SFP at different temperature values are shown in Figure 3, which is used as the basis for fatigue test. The variation trend of fatigue life with temperature and stress ratio is shown in Figure 4. Obviously, the properties of the SFP mixture are greatly affected by temperature and stress ratio: The flexural tensile strength decreases with the increase of temperature. When the stress ratio is low, the fatigue life decreases with the increase of temperature, and when the stress ratio is high, the fatigue life first decreases and then increases with the increase of temperature. The fatigue life decreases with the increase of stress ratio. The fitting results of the SFP fatigue prediction model are shown in Table 5. The fatigue prediction model R2 = 0.9937, and the fitting results are good. Compare the fatigue life prediction value calculated by the fatigue prediction model with the actual value obtained from the test, as shown in Figure 5. The analysis of Figure 5 shows that the predicted value of fatigue data is slightly larger than the actual value, but the change trend of the fatigue prediction model is the same. The expression can predict the times of material fatigue failure and judge the change trend of fatigue life under different conditions, which has reference significance in the design of semi-flexible pavement structure.

**Figure 3.** Flexural strength of the SFP.

(**b**) Variation trend of fatigue life with stress ratio.

**Figure 4.** Fatigue life of the SFP mixture.

**Table 5.** Fitting results of fatigue prediction model.

**Figure 5.** Comparison between estimated fatigue life and actual fatigue life.

#### *3.2. Discussion on Fatigue Performance of the SFP Mixture*

Taking the common asphalt mixture AC as the control group, the fatigue performance was measured by using the same test scheme as the above, which was used to evaluate the fatigue resistance of the SFP. Figure 6 shows the fatigue life comparison of the two materials under different environments. The fatigue properties of the two materials are significantly different, and the fatigue life of the SFP is much more sensitive to temperature and stress ratio. At low temperature and a low stress ratio, the fatigue life of the SFP is 4–5 times that of AC, which shows excellent fatigue resistance of the SFP. However, at a low temperature and high stress ratio, the fatigue life of the SFP decreases sharply, which has been significantly less than that of AC under the same conditions. At medium and high temperature, the fatigue life of the SFP is much less than that of AC regardless of the stress ratio. At the same stress ratio, from low temperature to medium temperature, the fatigue life of the SFP is greatly affected by temperature, while from medium temperature to high temperature is less affected by temperature.

(**a**) Variation trend of fatigue life with temperature. (**b**) Variation trend of fatigue life with stress ratio.

**Figure 6.** Fatigue life comparison of AC and SFP.

According to all conditions, the SFP mixture can only have better fatigue resistance under low temperature and low stress ratio, and the fatigue resistance under other conditions is worse than that of asphalt mixture, and the fatigue resistance under high temperature and high stress ratio is far worse than that of asphalt mixture. This is determined by the properties of its constituent materials. The asphalt aggregate ratio of the parent asphalt mixture of the SFP mixture is similar to that of AC mixture used for comparison (4.2% and 5% respectively), but the asphalt binder content of the SFP mixture decreases after grouting. Based on the preliminary analysis of the characteristics of the SFP mixture and the above results, it is considered that the poor fatigue resistance of the SFP mixture is due to the low strength and poor deformation capacity of grouting materials. In the process of fatigue loading, it can be considered that microcracks of different sizes and numbers will be produced in the three materials. The generation time of microcracks and the number and size of microcracks depend on the crack resistance of the material itself. Asphalt has the best deformation ability in the three materials and has self-healing ability. The aggregate has high strength and good crack resistance, it is difficult to produce microcracks, and the fracture energy required for crack propagation is large. The early strength cement used for grouting material has less strength than aggregate, high brittleness, less deformation resistance than asphalt binder, so its crack resistance is the worst. Based on the characteristics of the three materials, the grouting material is most prone to brittle failure during fatigue loading, resulting in stress concentration at the crack tip, which makes the crack expand rapidly in the specimen. In conclusion, the grouting material is easy to crack, resulting in a concentration of stress, which makes the anti-fatigue performance of the SFP poor.

#### *3.3. Digital Image Processing Results*

Count the area share of grouting material in the crack surface of the specimen and take the average value of three parallel specimens as the final result. The trend of the area share of grouting material in the fracture surface with temperature and stress ratio is plotted as shown in Figure 7. Determined by Archimedes method, the connected porosity of parent macroporous asphalt mixture of the SFP mixture in this study is about 18%. Therefore, in the section of the specimen, the area of grouting material should account for about 18%. If the area of grouting material in the fracture surface is relatively small, it can be considered that the crack tends to bypass the grouting material when it occurs and expands. If the area of grouting material accounts for a large proportion, it can be considered that cracks tend to pass through the grouting material when they occur and expand. The analysis of Figure 7 shows that the area of grouting material in the fracture surface of SCB fatigue test accounts for 10–25%.

(**a**) Area share of different stress ratio. (**b**) Area share at different temperature values.

**Figure 7.** Area share of grouting material in the fracture surface.

#### *3.4. Discussion on Cracking Mechanism of the SFP Mixture*

According to Figure 7a, when the stress ratio is less than 0.7, the area proportion of grouting material increases with the increase of stress ratio. Under a fatigue load, with the increase of stress ratio, the grouting material gradually becomes easier to crack than the asphalt phase. The strength of grouting material is higher than that of the asphalt phase. At a low stress ratio, the load has exceeded the fatigue failure stress of asphalt phase. Fatigue cracks begin from the asphalt phase and expand to the whole specimen with the asphalt phase as the main path. Early cracks will also appear in a few grouting materials at stress concentration positions. When the stress ratio increases gradually, the stress of grouting material gradually reaches and exceeds its fatigue failure stress. Due to the large brittleness and poor deformation capacity of the grouting material, the cracks occur earlier than the asphalt phase, and the propagation path of the cracks includes the asphalt phase and the grouting material. When the stress ratio is greater than 0.7, the area proportion of grouting material is close to 18%, which is due to less fatigue times under high stress ratio, and the failure form of material is more similar to single loading failure.

According to Figure 7b, the proportion of grouting material in the area of fracture surface first increases and then decreases with the increase of temperature, which may be due to the fact that the temperature sensitivity of cement grouting material is not as good as that of asphalt mixture. At low temperatures, the stiffness of the asphalt phase and the cement grouting material are both large, and close to brittle failure. However, because the strength of asphalt is lower than that of cement grouting material, its failure time is earlier when the temperature and stress are relatively low, so the area of grouting material in the fracture surface is relatively small. At medium temperature, the strength of asphalt phase and grouting material decreases. Asphalt has higher temperature sensitivity. With the increase of temperature, its deformation capacity improves, and the grouting material is still brittle failure. At the same time, due to the faster decline of modulus of asphalt phase, the grouting material shares a greater proportion of stress, and the cracking time of grouting material is earlier than that of asphalt phase, so the area proportion in the fracture surface increases. At a high temperature, the strength of asphalt decreases obviously, and the proportion of stress shared by grouting material continues to increase after asphalt softening. However, because the decrease of asphalt strength exceeds the increase of stress borne by grouting material, the area proportion of asphalt phase rises somewhat.

In actual use, due to the high strength of aggregate, the loading stress is difficult to cause damage. Asphalt has a self-healing ability.

During fatigue loading, the process of microcrack generation, incomplete self-healing, crack generation and propagation is repeated in the asphalt phase until the material is completely destroyed. The asphalt phase is the main factor controlling the fatigue resistance of asphalt mixture. The difference between the SFP mixture and asphalt mixtures lies in the role of grouting material in the destruction process. The strength of the grouting material is less than that of the aggregate. During the fatigue loading process, microcracks continue to occur in the grouting material, but the grouting material does not have the self-healing ability. At the same time, the stress concentration at the crack tip weakens the self-healing ability of the asphalt phase, and finally leads to the acceleration of the overall failure process of the specimen.

In conclusion, the difference of material properties and temperature sensitivity between the asphalt phase and the grouting material leads to the difference of fracture surface composition of specimens under different conditions. This phenomenon reveals that the poor fatigue resistance of the SFP mixture at medium and high temperature is caused by the brittleness of the grouting material, the difference of modulus between the grouting material and the asphalt, and stress concentration.

#### **4. Conclusions**

The fatigue resistance of the SFP mixture under different temperature values and stress ratio was evaluated by the SCB fatigue test, and the laboratory fatigue prediction model of the SFP mixture is established. The fatigue cracking mechanism of the SFP mixture is analyzed by a digital image processing technology. A fatigue prediction model for SFP structure calculation is derived. The conclusions are as follows:

1. At a low temperature and low stress ratio, the fatigue resistance of the SFP is 2–7 times that of AC. At a medium temperature or high stress, the fatigue resistance of the SFP suddenly drops to 15–45% of AC. Under the condition of high temperature and a high stress ratio, SFP almost loses its anti-fatigue ability.

This study points out that fatigue cracking is one of the main forms of the SFP structural cracking, and proposes a fatigue prediction model for SFP mixtures to provide a reference for structural design and life calculation, and provides research directions for improving the crack resistance of the SFP mixtures from the aspects of material composition and material modification.

There are two main limitations of this study. First, only one mix proportion of the SFP mixture is selected, and the fatigue prediction model has room for further optimization. Secondly, the cracking mechanism of the SFP mixture is analyzed from the surface after fracture, and the observation of fatigue cracking process is lack. In the later research, it is suggested to adjust the mix proportion of the SFP mixture to improve the fatigue prediction model of the SFP. It will be very effective to monitor and analyze the entire process of fatigue cracking of the SFP mixture with the help of real-time computer tomography and digital image correlation technology.

**Author Contributions:** Conceptualization, S.W., X.C and J.H.; methodology, S.W. and H.Z.; software, X.S.; formal analysis, S.W and M.G.; investigation, M.G.; resources, J.H.; data curation, S.W. and H.Z; writing—original draft preparation, S.W.; writing—review and editing, X.C.; visualization, S.W.; supervision, X.C.; project administration, X.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by The Open Fund Project of National Key Laboratory of High-Performance Civil Engineering Materials (2016CEM001), the National Natural Science Foundation of China (No. 51778136) and the China Scholarship Council.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article.

**Acknowledgments:** The authors gratefully acknowledge the financial support of Sobute New Materials Co. Ltd.

**Conflicts of Interest:** The authors declare no conflict of interest.


2.6.1. Conventional Pair-Wise Meta-Analysis

When there was adequate homogeneous data, quantitative synthesis was performed using RevMan 5.4 (The Cochrane Collaboration, London, England). Dichotomous data were presented as risk ratio (RR) with 95% confidence interval (CI), and continuous data were reported as mean difference (MD) with 95% CI. Heterogeneity between the studies in terms of effect measures was assessed using both the χ 2 test and the I2 statistic. I2 values of ≥50% and ≥75% were considered indicative of substantial and considerable heterogeneity, respectively. Due to the nature of non-pharmacological therapies, which are the interventions of interest in this review, it was difficult to guarantee the homogeneity of the implementation of the interventions, so we applied the random-effects model to meta-analyses [16]. When a sufficient number of studies (≥10) were included in each meta-analysis, publication bias was evaluated using a funnel plot.


**3. Results and discussion**

*Welding - Modern Topics*

brazing process.

Cu-Mn-Ni system.

**2. Experimental procedure**

cooling rate (40°C/min).

the working space of 1 × 10−3

brazing gap was 50 μm).

tation of several phases takes place.

stresses in brazed joints. The presence of solid solutions characterized alloys based

Proceeding from analysis of binary state diagrams of Cu-Ni, Cu-Mn, and Mn-Ni systems [13], Cu-Mn-Ni ternary system was selected as the base one [14, 15]. This system has a wide range of solid solutions. So, in the Cu-Mn-Ni alloy, additional alloying with silicon should improve the spreading of the surface of stainless steel, and alloying with iron should reduce erosion of stainless steel by brazing during the

This work aims to study the features of the formation of the microstructure of brazed joints, the relationship between the structure, the initial composition of the brazing filler metal, and the strength of dissimilar brazed joints Mo-stainless steel obtained by vacuum brazing using brazing filler metal of the

As the base metal, molybdenum, stainless steel 09Kh18N10, and brazing alloys based on copper-manganese system were applied. The brazing filler metal was applied in the cast form and was produced by melting in the laboratory installation in the shielding atmosphere of argon. The produced ingots were overturned and melted down (up to 5 times) in order to average the chemical composition and provide a uniform distribution of elements. The solidus and liquidus temperatures of cast brazing alloys were determined using the installation of high-temperature differential analysis in the shielding atmosphere of helium at constant heating and

Before brazing, the samples were machined and cleaned (degreased). The prepared samples were overlapped, and the brazing filler metal (**Table 1**) was placed on the surface of the base metal (near the gap) and loaded into a vacuum furnace with radiation heating to conduct capillary vacuum brazing with a rarefaction of

Brazing filler metal (**Table 2**) in the cast state was placed at the gap (size of fixed

**No. Base system of brazing filler metal alloying Brazing temperature, °C/time, min**

1 Cu-Mn-Ni-Fe-1.0Si 1050 /3 2 Cu-Mn-Ni-0.2 Si 1100 /5 3 Cu-Mn-Ni 1084 /3

For metallographic examinations the overlapped joints were brazed, and the specimens were cut out perpendicular to the brazing seam; the microsections were manufactured according to the standard procedure and examined using the scan-

Pa.

ning electron microscope TescanMira 3 LMU.

*Used brazing filler metals and brazing modes.*

The copper-manganese system has a minimum melting point (821°C) at a manganese concentration of 33.7 atom. %. With decreasing temperature, ordering processes occur in the alloys of this system, and the ordered phases Cu5Mn and Cu3Mn precipitate, increasing the strength of the solid solution. Analysis of nickelmanganese binary system is indicative of complete solubility of manganese in nickel in the liquid state at increased temperature but with temperature lowering precipi-

on copper-nickel and copper-manganese systems [13].

**106**

**Table 2.**


**Abstract**

Sequential analysis of metal speciation in geological samples has been demonstrated using mass spectrometry (MS). Various speciation for metal occurrences, such as water-soluble, exchangeable, oxidable, reducible, and crystalline, have been sequentially extracted from geological samples using a homemade device, followed by online ionized for MS analysis. The metal speciation in geological samples was not only useful for revealing the formation mechanism of geological samples but also beneficial for guiding the separation and exploitation of metals. Compared with the conventional methodology, the present approach takes the advantages of short analysis time (1 h), low sample consumption (1.0 mg), and high recovery (>95%), providing a useful platform for the efficient quantitative speciation analysis of metals in geological samples. This chapter introduces the mechanism and application of the MS approach for the analysis of rare earth minerals, dinosaur fossils, soil, etc.

**Keywords:** sequential analysis, direct analysis, metal speciation, mass spectrometry, geological samples

### **1. Introduction**

Geological samples include a wide range of substances, such as rocks, minerals, sediments, soil, coal, oil, fossil, atmosphere, and organisms. Chemical analysis of geological samples is one of the primary techniques in earth science, which generally involved to get information on major and trace elements, stable and radioactive isotopes, biomarkers, etc. The distribution coefficients of trace elements have been applied to deduce the diagenetic process [1], while the contents and associations of trace elements are usually employed to discriminate the tectonic environment [2]. Moreover, some trace elements can be regarded as geothermometers and geobarometers to estimate the physical-chemical conditions of diagenesis and mineralization [3]. The fractionation mechanisms of stable isotopes and the decay effects of radioactive isotopes have played an irreplaceable role in solving fundamental problems of earth science [4], by providing valuable information about geological time, terrestrial heat sources, atmosphere-ocean interaction, the evolution of crust and mantle, diagenesis, mineralization, tectonism, paleoclimate, and paleoenvironment. Besides,

the speciation of metals also shows great implications for guiding the exploitation of minerals [5]. Overall, chemical analysis of geological samples benefits the understanding of the earth from a microscopic perspective, with diversified application scenarios and broad application prospects.

To date, a great number of approaches have been proposed for the analysis of metal speciation in geological samples, including spectrometry, energy spectrometry, and mass spectrometry. For example, X-ray absorption spectroscopy (XAS) [6], X-ray diffraction (XRD) [7], and X-ray photoelectron spectroscopy (XPS) [8] were both applied to analyze the metal species. The advantages of these methods were that the sample pretreatment was simple and the analytical speed was fast. However, these methods always required a high concentration of metal species because of the relatively low detection sensitivity, and the quantitative performance of these methods was also deficient. On the other side, complex sample pretreatment, such as grinding, digestion, centrifugation, and filtration were used to extract the metal compounds from geological samples. Each process is time-consuming and labor-consuming, and maybe suffer from analytes losses [9]. After the sample pretreatment, the extracted compounds were then analyzed by chromatography methods (e.g., high-performance liquid chromatography, capillary electrophoresis chromatography, etc.) to identify the speciation by retention time, followed by coupling to inductively coupled plasma mass spectrometry (ICP-MS) [10] for quantitative analysis and electrospray ionization (ESI) MS for molecular structure analysis [11], which required expensive instruments and complex operation. Otherwise, a multistep offline sample pretreatment procedure was required for the sequential extraction of different heavy metal fractions according to the association form of metals in the samples [12, 13]. For example, in the Community Bureau of Reference protocol (BCR) method [12], 0.1 mol/L acetic acid (HAC), 0.1 mol/L NH2OH·HCl, 8.8 mol/L H2O2 and 1.0 mol/L NH4AC were used sequentially for extraction of different metal speciation from the soil, respectively. Each extraction step took more than 16 h. In the Tessier method [13], 1 mol/L NaAc solution (pH = 8.2), 1 mol/L NaAc/HAc (pH = 5.0), 0.3 mol/L Na2S2O4 + 0.2 mol/L Na-citrate +0.03 mol/L NH2OH·HCl in 25% HAC, 0.02 mol/L HNO3 + 30% H2O2 (pH = 2), HF-HClO4 were used to extract exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual fraction or speciation, respectively. The whole procedure would take more than 40 h. The extracted fraction or speciation was then analyzed by ICP-MS [14] or by inductively coupled plasma optical emission spectrometry (ICP-OES) [15]. Thus, a method that has the advantages of without tedious sample pretreatment, high analytical speed, high detection sensitivity, and high accuracy is necessitous for the analysis of the speciation of the metal.

Herein, a new strategy for sequential analysis of metals speciation in geological samples is proposed by regulating the interaction between reagents/energy and geological samples. Assisted by multiple energy forms such as ultrasound and heat, various element species in geological samples were sequentially extracted by chemical reagents with different physicochemical properties of polarity, acidity, and redox using a small amount of samples. The extracted analytes were then ionized online by different ionization techniques (e.g., ESI, ICP, etc.) for MS analysis. This strategy takes the advantages of avoiding sample pretreatment, high analysis speed, low sample consumption, and low labor and energy consumption, which has been used in various areas, such as environment monitoring [16, 17], material science [18, 19], food science [20, 21], life science [22, 23], and geology [24, 25]. In this chapter, we will focus on the application of this sequential speciation analytical strategy in geological samples, such as mineral samples, fossils samples, and soil samples.

*Sequential Speciation Analysis of Metals in Geological Samples by Mass Spectrometry DOI: http://dx.doi.org/10.5772/intechopen.110447*


**Author details**

Rajendra Sukhjadeorao Dongre1 \* and Dilip R. Peshwe2

1 Department of Chemistry, RTM Nagpur University, Campus, Nagpur, Maharashtra, India

2 Department of Metallurgy, VNIT, Nagpur, Maharashtra, India

\*Address all correspondence to<EMAIL_ADDRESS>
© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


**3. Major sources of increased iodine exposure: iodine supplementation, dietary iodine, iodine-containing contrast media, amiodarone, and the clinical forms of amiodarone-induced thyrotoxicosis**

#### **3.1 Iodine supplementation**

The assessment of iodine deficiency can be accomplished by assessing the prevalence and severity of goiter, by testing the excretion of iodine in urine, and by determining hormonal levels (e.g., TSH, FT4). When used alone, neither of these are sufficiently sensitive and specific to measure iodine deficiency of a population, but urinary iodine remains the index of choice in the monitoring of iodine supplementation programmes. The most successful method of intervention for iodine deficiency control is salt iodization, iodine being added to salt as potassium iodide (KI), potassium iodate (KIO3), or sodium iodide (NaI). Due to the high prevalence of hypertension and cardiovascular diseases, many countries proposed to promote the reduction of salt intake to 5 g/day (<2 g of sodium), so complementary measures are needed in order to tackle iodine deficiency [20]. But iodine also binds to fatty acids, so iodine oil can also be given orally or intravenously to severely iodine-deficient patients in the short term. Nascent iodine is like the precursor form of iodine, which converts into thyroid hormones. The human body can recognize and assimilate this form more easily than potassium salt. Lugol's solution is a widely used commercial iodine source, which contains elemental iodine and potassium iodide also. If someone consumes high quantities of iodine-rich foods (e.g., marine food, kelp), the use of iodized salt or iodinated water may increase iodine levels above the safe upper level as recommended by WHO. Individuals, who consume large amounts of seaweed regularly, are also exposed to the risk of iodine-induced hyperthyroidism [21, 22]. Several reports are available describing diet-induced thyrotoxicosis in patients consuming seaweed-containing foods or beverages [23]. Risk factors for iodineinduced hyperthyroidism include nontoxic or diffuse nodular goiter, latent Graves' disease, and long-standing iodine deficiency [24].

#### **3.2 Dietary supplements**

Most dietary supplements, as well as food and water, contains iodine as salts: sodium iodide, sodium iodate, potassium iodide, and potassium iodate. Different solid dosage forms of potassium iodide are available, but around 20% is assimilated from inorganic forms of iodine into the body [25]. Iodine is also present in most multivitamin/mineral supplements. Some case reports described that previously

#### **Table 1.**

*Commercially available nutritional supplements with iodine content exceeding the daily intake recommended by WHO (RDA—recommended daily allowances).*

euthyroid patients taking nutritional supplements developed iodine-induced hyperthyroidism [26–28]. The iodine content of dietary supplements shows high variability; some supplements may contain up to 160-fold of the recommended daily intake (**Table 1**). Short-term increase of basal and poststimulation TSH was described even in euthyroid patients administering dietary supplements with kelp [29, 30].

#### **3.3 Iodine-containing contrast media**

Iodinated contrast media (ICM) is given for computed tomography (CT), angiography, myelography, and arthrogram. The route of administration could be systemic as i.v, i.a., oral, rectal, and local. The pharmacokinetics of all currently available ICMs is similar. The half-life of ICM in normal renal function subjects is approximately 2 hours. Thus, approximately 20 hours are required for the total excretion of the administered ICM [31]. Referring to their iodine content and osmolarity, the contrast media are divided into ionic ICM with high osmolarity (1500–2000 mOsm/kg) or nonionic ICM with low and iso-osmolarity (600–1000 mOsm/kg). A list of iodinated contrast agents available in Romania and their molecular properties can be found in **Table 2**.

The safety profile of the systemic administered nonionic low- or iso-osmolar contrast currently in use is 5- to 10-fold better than the ionic high-osmolar agents [32, 33]. The ratio of iodine atoms to the number of contrast particles in lowosmolar solution is higher than compared with high osmolar ICM and hence have a greater concentration of iodine than the high osmolar [32]. In both low and high osmolar ICM, the iodine content is far greater than the recommended daily allowance. Patients generally are given 50 and 100 mL of contrast per CT scan; however, it is essential to know that not all CT scans require contrast media administration (see **Table 3**) [31, 33–35].

Higher doses of ICM may be required for invasive procedures such as cardiac catheterization. Typical doses for CT scans provide 2500–5000 μg of bioavailable free iodine and 15–37 g of total iodine [36]. Nonbioavailable iodine may be liberated to free iodide, particularly with increased half-times in the body (i.e., impaired kidney function) [35, 36]. After ICM administration, iodine deposits remain elevated for up to 4–8 weeks in patients with healthy thyroid. The urinary iodine excretion increased by 300–400% from baseline to peak levels after 1.1 week and normalized by 5.2 weeks following ICM administration [37].

After exposure to the iodine-containing contrast agent, the most rapid (hours to days) effect of pharmacologic doses of iodine is the Wolff-Chaikoff effect. The

**63**

**Table 3.**

*Prevention and Treatment of Iodine-Induced Thyrotoxicosis*

**Nonionic ICM Iodine content,**

Ethiodized oil 480

Head Neoplasm, meningitis, encephalitis, focal

angiography

Cervical Cervical mass or lymphadenopathy, suspected

Cardiothoracic Heart and thoracic vessels, trauma, staging primary thoracic neoplasms

gynecologic indications

Musculoskeletal Evaluation of soft tissue masses and suspected

CT angiography Evaluating the lumen of an artery, vein, or a

active bleeding

*Indications of contrast enhancement in CT imaging.*

Abdominopelvic Virtually all other gastrointestinal,

*The iodine content of nonionic iodinated contrast media (ICM) and their molecular properties.*

neurologic deficits, skull base disorders, orbital and vision disorders, pituitary imaging, complicated sinonasal disease, seizures, cerebral

tumor or infection, abnormalities of cranial nerves X, XI, and XII, brachial plexopathy

hepatopancreaticobiliary, genitourinary,

septic arthritis or infected prostheses

pseudoaneurysm and to assess for end-organ ischemia outside the brain or lung to detect

**CT type Contrast indicated Contrast not indicated**

Iobitridol 300, 350 Low Iodixanol 270, 320 Low Iohexol 240, 300, 350 Low Iomeprol 300, 350, 400 Low Iopamidol 300, 370 Low Iopromide 300, 370 Low Ioversol 240, 300, 320, 350 Low

**mg/mL**

**Osmolarity**

Head trauma, acute stroke, intracranial hemorrhage

Trauma unless arterial injury is a possibility or the mechanism of injury is

Coronary calcium scoring, pulmonary parenchymal evaluation lymph node

Colonography, renal stone evaluation, extraparenchymal

Extremities and spine

Monitoring a known aneurysm for growth or for detection of a hematoma

penetrating

evaluation

lymphoma

mechanism for this acute effect is partially explained by the generation of iodolactones, iodoaldehydes, and/or iodolipids, which inhibit thyroid peroxidase activity, necessary for thyroid hormone synthesis [37]. The decrease of thyroglobulin proteolysis resulting in reduced thyroid hormone secretion also may be contributing to the ICM-induced Wolff-Chaikoff effect. The diminished serum T4 and T3 concentrations temporarily increased the serum concentrations of TSH, in some cases above the normal range. The phenomenon is transient in euthyroid adult patients and does not typically determine permanent hypothyroidism [38].

*DOI: http://dx.doi.org/10.5772/intechopen.89615*

**Watersoluble, nephrotropic X-ray contrast media**

**Non-watersoluble**

**Table 2.**

#### *Prevention and Treatment of Iodine-Induced Thyrotoxicosis DOI: http://dx.doi.org/10.5772/intechopen.89615*

#### **Table 2.**

*Goiter - Causes and Treatment*

Survival shield X-2, Detoxadine®

(nascent iodine)

**Table 1.**

euthyroid patients taking nutritional supplements developed iodine-induced hyperthyroidism [26–28]. The iodine content of dietary supplements shows high variability; some supplements may contain up to 160-fold of the recommended daily intake (**Table 1**). Short-term increase of basal and poststimulation TSH was described even

*Commercially available nutritional supplements with iodine content exceeding the daily intake recommended*

**serving (μg)**

3000

1950 1300

**% RDA iodine per serving (%)**

16667, 8333, 4167, 2000

in euthyroid patients administering dietary supplements with kelp [29, 30].

**Nutritional supplement Iodine content per**

Terry Naturally® (Europharma) Tri-Iodine® 25000, 12500, 6250,

Natural Living Iodine Plus-2® 12500 8333

Oradix StemDetox™ 5000 3333

Dr. Mercola Iodine 1500, 500 1000, 333 Life Extension® sea iodine 1000 667

(1500–2000 mOsm/kg) or nonionic ICM with low and iso-osmolarity

their molecular properties can be found in **Table 2**.

by 5.2 weeks following ICM administration [37].

(see **Table 3**) [31, 33–35].

Iodinated contrast media (ICM) is given for computed tomography (CT), angiography, myelography, and arthrogram. The route of administration could be systemic as i.v, i.a., oral, rectal, and local. The pharmacokinetics of all currently available ICMs is similar. The half-life of ICM in normal renal function subjects is approximately 2 hours. Thus, approximately 20 hours are required for the total excretion of the administered ICM [31]. Referring to their iodine content and osmolarity, the contrast media are divided into ionic ICM with high osmolarity

(600–1000 mOsm/kg). A list of iodinated contrast agents available in Romania and

The safety profile of the systemic administered nonionic low- or iso-osmolar contrast currently in use is 5- to 10-fold better than the ionic high-osmolar agents [32, 33]. The ratio of iodine atoms to the number of contrast particles in lowosmolar solution is higher than compared with high osmolar ICM and hence have a greater concentration of iodine than the high osmolar [32]. In both low and high osmolar ICM, the iodine content is far greater than the recommended daily allowance. Patients generally are given 50 and 100 mL of contrast per CT scan; however, it is essential to know that not all CT scans require contrast media administration

Higher doses of ICM may be required for invasive procedures such as cardiac catheterization. Typical doses for CT scans provide 2500–5000 μg of bioavailable free iodine and 15–37 g of total iodine [36]. Nonbioavailable iodine may be liberated to free iodide, particularly with increased half-times in the body (i.e., impaired kidney function) [35, 36]. After ICM administration, iodine deposits remain elevated for up to 4–8 weeks in patients with healthy thyroid. The urinary iodine excretion increased by 300–400% from baseline to peak levels after 1.1 week and normalized

After exposure to the iodine-containing contrast agent, the most rapid (hours to days) effect of pharmacologic doses of iodine is the Wolff-Chaikoff effect. The

**3.3 Iodine-containing contrast media**

*by WHO (RDA—recommended daily allowances).*

**62**

*The iodine content of nonionic iodinated contrast media (ICM) and their molecular properties.*

#### **Table 3.**

*Indications of contrast enhancement in CT imaging.*

mechanism for this acute effect is partially explained by the generation of iodolactones, iodoaldehydes, and/or iodolipids, which inhibit thyroid peroxidase activity, necessary for thyroid hormone synthesis [37]. The decrease of thyroglobulin proteolysis resulting in reduced thyroid hormone secretion also may be contributing to the ICM-induced Wolff-Chaikoff effect. The diminished serum T4 and T3 concentrations temporarily increased the serum concentrations of TSH, in some cases above the normal range. The phenomenon is transient in euthyroid adult patients and does not typically determine permanent hypothyroidism [38].

ICM use could lead to thyroid dysfunction, namely to hypo- and hyperthyroidism. Iodine excess-induced hypothyroidism appears when the thyroid fails to escape from the acute Wolff-Chaikoff effect. It occurs in patients with a wide variety of underlying thyroid abnormalities, including Hashimoto's thyroiditis, previously treated Graves' disease, history of thyroid lobectomy, postpartum lymphocytic thyroiditis, interferon therapy, or type 2 amiodarone-induced thyrotoxicosis [12, 39, 40]. Not only the previous thyroid disorder but also the age of the patients is a contributing factor in hypothyroidism development. A systematic review evidenced that hospitalized neonates, especially premature infants exposed to iodinated contrast media, are at increased risk for development of hypothyroidism [41]. It could be hypothesized that hypothyroidism in this case to be partially secondary to an immature thyroid gland and an exaggerated Wolff-Chaikoff effect. Older age patients are also at high risk of developing hypothyroidism after ICM exposure, as reported in a study including the Asian population [42].

Patients with one exposure to ICM showed the highest risk of thyroid dysfunction compared with non-ICM exposure and a correlation was still found between the frequency of ICM exposure and the risk of hypothyroidism [42]. Conflicting data appear regarding to the time of onset of hypothyroidism after ICM administration: Rhee et al. [43] showed that the median time interval until the occurrence of hypothyroidism was 1 year, but Kornelius et al. [42] reported that hypothyroidism may develop 2.1 years after ICM exposure.

ICM-induced hyperthyroidism rarely occurs in individuals without prior thyroid dysfunction. Previously existent thyroid diseases, such as nodular goiter, Graves' disease, and long-standing iodine deficiency followed by thyroid autonomy, were reported to be associated with a higher risk of hyperthyroidism after ICM exposure [4, 13, 24, 36, 42]. The mechanism of ICM-induced hyperthyroidism involves impairment of the acute Wolff-Chaikoff effect due to rapid iodine excess and influx into the thyroid gland. Excess iodine intake will result in transient or permanent hyperthyroidism [13, 24, 42]. Kornelius et al. [42] found in their study a 22% increased risk of hyperthyroidism after ICM administration. Older patients (between 20 and 60 years) presented a more than twofold increased risk of hyperthyroidism compared with younger patients (less than 20 years old). The number of ICM exposures did not increase the risk of hyperthyroidism. It could be hypothesized that the "stunning effect" plays a certain role in hyperthyroidism, involving a diminished absorption of excess iodine in patients with repeated iodine exposure.

#### **3.4 Amiodarone**

#### *3.4.1 Amiodarone pharmacology*

Amiodarone is a class III antiarrhythmic agent, having short- and long-term actions on multiple molecular levels [44]. Its molecular structure resembles T3. However, amiodarone can alter thyroid function (inducing both hypo- and hyperthyroidism), which is due to amiodarone's high iodine content and its direct toxic effect on the thyroid follicle cells. Amiodarone is a benzofuran derivative with great lipophilicity, which is extensively distributed in adipose tissue, cardiac and skeletal muscle, liver, lung, and the thyroid. During its liver metabolization, approximately 6 mg of inorganic iodine per 200 mg of amiodarone ingested is released into the systemic circulation [45]. The average iodine content in Romanian diet is approximately 50–75 μg/day [3, 46, 47]. Thus, 6 mg of iodine markedly increases the daily iodine load. Amiodarone elimination from the body occurs with a half-life of approximately 55–100 days. The long half-life of both amiodarone and his active

**65**

peroxidase titer.

*3.4.3 Risk of thyrotoxicosis after amiodarone administration*

*Prevention and Treatment of Iodine-Induced Thyrotoxicosis*

correlate well with efficacy or with adverse effects [45, 48–50].

metabolite, DEA, contributes to his toxicity. For a therapeutic effect, a plasma concentration between 0.5 and 2.5 μg/mL is required; however, serum levels do not

that are due to iodine and those effects that are intrinsic properties of the drug.

The effects of amiodarone on thyroid function can be divided into those effects

After chronic amiodarone administration, the thyroid dysfunctions may occur in 5–22% of the patients. Risk factors for the development of thyroid disease include not only treatment duration and cumulative amiodarone dose but also age, gender, pre-existing thyroid pathology, and associated nonthyroid conditions [51–53]. The normal autoregulation process of thyroid prevents normal individuals from becoming hyperthyroid after exposure to the high iodine content substances. When intrathyroidal iodine concentrations reach a critically high level, iodine transport and thyroid hormone synthesis are transiently inhibited until intrathyroidal iodine stores return to physiological levels (see the Wolff-Chaikoff effect). Patients with underlying thyroid pathology, however, have defects in autoregulation of iodine: for example, in autoimmune thyroid disease exists a "fail to escape" from the Wolff-Chaikoff effect. The result is the development of goiter and hypothyroidism in Hashimoto's disease. Patients with areas of autonomous function within a nodular goiter do not autoregulate iodine and the addition of more substrate may result in excessive thyroid hormone synthesis and thyrotoxicosis (see Iod-Basedow) [13, 54, 55].

Amiodarone inhibits peripheral deiodinase (outer ring 5′-monodeiodination of T4), thus decreasing T3 production and increasing T4 level; reverse T3 (rT3) accumulates since it is not metabolized to T2 [4, 56, 57]; amiodarone and, particularly, the metabolite DEA block T3-receptor binding to nuclear receptors [58] and decrease the expression of some thyroid hormone-related genes [59]; amiodarone may have a direct cytotoxic effect on thyroid follicular structures, which results in a destructive thyroiditis [60]. Martino et al. described marked distortion of thyroid follicle architecture, necrosis, apoptosis, inclusion bodies, lipofuscinogenesis, markedly dilated endoplasmic reticulum, and macrophage infiltration after amiodarone [19]. The role of the pre-existing autoimmune process is widely debated, due to the conflicting results of the retrospective study data [17, 18, 55]. Even if amiodarone does not induce de novo autoimmune thyroid disease, by the direct cytotoxic effect, it may cause the release of pre-existing autoantibodies and thus worsen destructive thyroiditis. In a study [61], it was described that in women the prolonged amiodarone treatment (for over 2 years) increased the antithyroid

Predisposing factors for amiodarone-induced thyrotoxicosis include environmental factors such as dietary iodine (deficiency), as well as intrinsic factors such as pre-existing thyroid pathology. Depending on these factors, a great variability

*DOI: http://dx.doi.org/10.5772/intechopen.89615*

*3.4.2 Amiodarone and the thyroid*

*<IP_ADDRESS> Effects due to iodine*

*<IP_ADDRESS> Intrinsic drug effects*

metabolite, DEA, contributes to his toxicity. For a therapeutic effect, a plasma concentration between 0.5 and 2.5 μg/mL is required; however, serum levels do not correlate well with efficacy or with adverse effects [45, 48–50].