People, Planet, and Profit: A Bibliometric Analysis of Triple Bottom Line Theory

Scientific production on Triple Bottom Line Theory is, recently, attracting attention in the literature. A series of factors are related to this interest, among them: (i) the scarcity of productive resources; and, (ii) the need to optimize processes not only in economic terms, but especially in their environmental and social aspects. These factors have fostered the study of sustainability models. Therefore, the present study aims to conduct a bibliometric investigation into Triple Bottom Line Theory. To this end, an analysis of 1386 publications, published between 1999 and 2020, indexed in the Web of Science database, was developed. Additionally, the present article describes in detail the main contributors to the academic debate on this topic. Furthermore, it highlights the relevant areas of research at the present time. It was found that the search for models to assess environmental, economic and social performance is highly relevant today. It was also found that, among the main models used for this purpose, the class of Data Envelopment Analysis models stands out.


Introduction
The scarcity of natural and environmental resources, characterized by the growing demand for raw materials from global supply chains, has led countries to intensify the design of sustainable policies. In this context, both public entities and private organizations are being encouraged to rethink their practices to increase the environmental, economic and social efficiency of their processes. Given this scarcity of resources, sustainability assumes a prominent place and can even differentiate the increase of competitiveness in the international market (Matopoulos et al., 2015;De Carvalho et al., 2020;He et al., 2020;Lowitt, 2011).
The concept of sustainability comes from ecology and describes a natural, regenerative system: that is, one that maintains its basic properties over time to satisfy a given population, replenishing itself continuously (Zhou et al., 2018). Sustainability can be defined as the degree of resilience of systems and processes (Chofreh et al., 2015). The main theoretical framework of sustainability is the concept of sustainable development, coined by the World Commission on Environment and Development (WCED) and defined as: a process that meets the needs of the present without compromising the ability of future generations to meet their needs (Brundtland et al., 1987).
Since sustainable development deals with progress that does not compromise resources for the future, this concept can be understood from three perspectives, namely: (i) a type of growth that is environmentally friendly, (ii) a form of development that must be economically viable, and finally, (iii) a type of development that must advocate for social responsibility. Inspired by the tripartite character of sustainable development, in 1994 John Elkington defined a new theoretical framework called the Triple Bottom Line Theory (TBL or 3BL). This concept gained relevance in that it allowed the insertion of sustainability principles within business organizations (Elkington, 2001). concept in its internal processes was the oil company Shell, in 1997 (Elkington, 1997).
Among the attributes that make TBL stand out, it is noteworthy that, by encompassing the environmental, economic and social elements, this theory manages to address several elements of the same organization within a single, theoretical model (Janjua, Sarker, & Biswas, 2020). Since 1997, several initiatives have been taken at the local, national and international levels, with the aim of addressing the different aspects of sustainability and the respective challenges that they present (Mebratu, 1998;Michelsen et al., 2016).
Beginning in the early 2000s, a strong global movement has put pressure on companies feel pressured to direct efforts towards the principles of the Triple Bottom Line Theory (Elkington, 2002). According to Zhou et al. (2018), this trend is explained by the mismatch between the growing demand for natural resources and the scarcity of several of these raw materials. This problem becomes even more evident when considering recent changes in the consumption profile of a portion of consumers, who have started to demand environmental certifications, products and/or services of the Cruelty-free type, for example, opposing unethical bodily production practices (Tang & Zhou, 2012). In addition, the recent development of emerging markets, such as China and India, has put further pressure on the sustainability of organizations, as they impact the arrangement of production chains globally (Burki, Ersoy, & Dahlstrom, 2018).
It is in this context of the scarcity of raw materials that the need to study the sustainability of organizations gains relevance. Thus, the success of organizational sustainability management processes depends on well-defined assessment models. Joseph Juran's famous phrase illustrates this issue: "whoever does not measure does not manage, whoever does not manage does not improve" (Conti et al., 2017). Therefore, measuring the performance of organizations regarding the use of productive resources is a topic that arouses the interest of local governments, the business sector and society in general (Stubbs & Cocklin, 2008;Rehman et al., 2019).

Objectives
The general objective of the present article is to analyze the scientific production on the Triple Bottom Line Theory (TBL or 3BL). To this end, a bibliometric survey was carried out regarding 1386 publications, published between 1999 and 2020 and indexed in the Web of Science (WoS) database. Specifically, it is intended to: (i) develop a descriptive study, showing the main sources of publication, authors, articles and countries that have publications on TBL; (ii) present the evolution of academic production on this topic; (iii) highlight the hot and cold areas of the academic debate about TBL; and, (iv) establish a research agenda on the theme.

Method
The Web of Science (WoS) database (Reuters, 2019) was used to develop the present article. The choice is justified by two facts: (i) WoS has interfaces with the main bibliometric software, which allows the extraction of a significant set of bibliographic metadata, namely: abstracts, authors, cited references, countries, institutions and times cited; and, (ii) WoS is the main global repository for scientific research (Saadat & Shaban, 2012). Following the choice of the database, the search parameters were established. The search parameters included the descriptor "Triple Bottom Line"; that is, all publications containing the expression "Triple Bottom Line" in their titles, abstracts or keywords were extracted.
All scientific papers indexed in the WoS database which satisfied the established criteria were selected. They totaled a sample universe of 1386 publications. Articles from conferences, journals and books, as well as technical reports, were analyzed. Metadata of work published between 1999 (first publication on the subject, based on the WoS) and 2020 (this is the last, most recent year) was extracted. Data collection took place on August 7, 2020.
Finally, the general aspect of these publications, including the evolution of research on TBL as well as a network of the keywords used most frequently in the selected articles, was verified. Metadata was analyzed using the VOSviewer ® software (www.vosviewer.com) and the Bibliometrix ® package, available for free in the R software (https://www.bibliometrix.org). It is noteworthy that VOSviewer ® allows the creation of clusters and maps that aggregate the content of publications from various perspectives, such as keyword clouds (Van Eck & Waltman, 2017).

Results
As stated above, the search for publications on Triple Bottom Line Theory, published between 1999 and 2020  Following the descriptive analysis of these publications, it becomes necessary to study each of the main publications on Triple Bottom Line Theory in greater depth. Table 3 presents an initial synthesis of these publications, indicating which was the pioneer work, which was the work with the highest number of citations and, finally, which was the most recent work to be published on that topic. Table 3 also presents the title of each of these works and a summary of their theoretical contributions.  Elkington (1999) 13

Petroleum in the 21st century: The triple bottom line: implications for the oil industry
This work, focused on the oil sector, introduces the concept of the Triple Bottom Line. The objective of the research was to present the idea that companies and organizations should extend their agenda beyond the objectives of economic prosperity, adopting a three-dimensional approach to business, adding social justice and environmental quality as new objectives in their agenda.

Carter e Rogers (2008) 1257
A framework of sustainable supply chain management: moving toward new theory The authors conduct a large-scale literature review and to introduce the concept of sustainability. Specifically, they investigated the field of supply chain management and demonstrated the relationships between environmental, social and economic management.

Modelling environmental and economic sustainability of logistics
The objective of this work is to explore the factors that affect investment in technology to balance the environmental and economic sustainability of logistics. Source: authors. Table 1 lists the top ten publications in terms of the number of citations, presenting each of the authors as well as the titles and objectives of the studies. It is noticed again that the results in Table 4 are indirectly related to Lotka's Law, since a limited number of authors have significant influence on the research on Triple Bottom Line Theory. This influence is seen not only in the number of published works but also, and especially, in the number of citations obtained by these publications.  Through a literature review, the authors verified the evolution of research related to the theme of sustainability. The research focused on a thorough analysis of all the journals that published on this subject.

Sustainable supply chain management: evolution and future directions
Carter e Easton (2011) 583 The objective of this article is to carry out a systematic review of the sustainable supply chain management (SSCM) literature in the main magazines of logistics and supply chain management, over a period of 20 years.

Landscape sustainability science: ecosystem services and human well-being in changing landscapes
Wu (2013) 502 This article aims to: (1) elucidate the main definitions and concepts of sustainability; (2) to examine the main definitions and concepts of landscape sustainability, and (3) to propose a framework for the development of a science of landscape sustainability.

Conceptualising sustainability assessment
Pope, Annandale e Morrison-Saunders (2004) 466 This article seeks to provide some clarifications, reflecting on the different approaches described in the literature as ways of assessing sustainability and evaluating them in terms of their potential contributions to sustainability.

A fuzzy multi criteria approach for measuring sustainability performance of a supplier based on triple bottom line approach
Govindan, Khodaverdi e Jafarian (2013) 408 This article explores sustainable supply chain initiatives and examines the problem of identifying an effective model based on the TBL approach for supply chain supplier selection operations, presenting a diffuse multicriteria approach.

Getting to the bottom of "triple bottom line"
Norman e Macdonald (2004) 341 In this article, the authors critically examine the notion of "Triple Bottom Line" and its measurement systems.

Sustainability-oriented innovation of SMES: a systematic review
Klewitz e Hansen (2014) 334 This article provides a systematic review of the literature on sustainability-oriented innovations (SOIs) for small and medium-sized enterprises (SMEs). Balancing priorities: decision-making in sustainable supply chain management Wu e Pagell (2011) 329 In this study, the authors attempt to answer the question: how do organizations balance short-term profitability and long-term environmental sustainability when making decisions about the supply chain under conditions of uncertainty?
To present the evolution of academic interest in research related to Triple Bottom Line Theory, Figure 4 shows the number of publications on TBL according to the years of publication. There is an exponential increase in the number of publications as a function of the years. In addition, as shown in the upper right portion of Figure 3, it appears that 96.29% of the variations in the number of materials published on TBL can be explained by temporal variation. Given the above, the "quantitative presentation" of the relevance of TBL today is significant.  Vol. 11, No. 1;2021 from global supply chains, has led countries to intensify the design of sustainable public policies. In this context, to understand how to balance organizational responsibilities effectively in this "new era", the Triple Bottom Line sustainability theory emerges.
The present article contributes to the incipient debate about Triple Bottom Line Theory. It presents, in a pioneering way, a bibliometric study containing a comprehensive investigation of the main publications already carried out in the area. It is hoped that the present study will serve as a basis for researchers interested in the subject, as well as provide a roadmap for organizations working in the TBL context.
Due to their environmental, economic and social relevance, scientific publications on TBL have increased exponentially during the 21st century, which indicates that it is an important area of research. In addition, the present article also looks at the hot and cold areas related to the TBL debate. It was found that topics such as the preparation of global sustainability reports, the development of performance measurement models (through the TBL pillars) and the construction of decision-making models are topics of current relevance in the literature. It should be noted that Data Envelopment Analysis (DEA) models have been used repeatedly for this purpose.
Finally, as a research agenda, a detailed study of decision-making models, aimed at measuring the environmental, economic and social performance of organizations, is recommended. It is suggested that the classic DEA models, especially their positive points as well as their main theoretical limitations, be analyzed. Therefore, it is believed that this research area, as it is still in its early stages, needs a more solid theoretical foundation. This will allow the adoption of assertive models for the management of organizations in the future, thus contributing to the rational use of scarce resources.