Abstract
The aim of this study was to characterize the profile of nonlethal victims of urban violence by firearms and to describe traumas suffered by victims, according to a medical–legal and forensic perspective. A cross-sectional and exploratory study was conducted at the Center of Forensic Medicine and Dentistry in northeastern Brazil. The sample consisted of 233 victims of urban violence by firearm who presented some type of trauma. Descriptive and multivariate statistics using cluster analysis (CA) were performed. The TwoStep Cluster method was chosen to characterize the profile of victims. The night shift (56.8%) and the period corresponding to Saturdays (20.0%) and Sundays (20.4%) concentrated the largest number of occurrences. Cases of trauma in more than one region of the body simultaneously prevailed (31.8%). Based on the CA results, the formation of two clusters with distinct victimization profiles was verified. Cluster 1 was mostly characterized by younger single victims who suffered violence by firearm in the urban area perpetrated by an unknown perpetrator, resulting in greater occurrence of isolated upper and lower limb traumas. In contrast, Cluster 2 consisted essentially of older, married, or stable-union victims who experienced firearm violence in the suburban area, perpetrated by a known aggressor, resulting in greater occurrence of multiple traumas, that is, affecting several regions of the body at the same time. These findings reveal different risk groups for urban violence by firearms and traumas, contributing to the planning of strategies with emphasis on health care, prevention, and promotion.
Introduction
Violence is a serious public health problem today, especially in developing and underdeveloped countries. According to the World Health Organization (WHO), more than 1.3 million deaths are registered annually due to violence. Of these, one in two deaths is perpetrated by firearms (WHO, 2014). Aggressions by this type of instrument have drawn the attention of the media and researchers from different areas of knowledge, given the high rates of assaults that can generate traumas, injuries, and deaths significantly affecting the quality of life and well-being of the population (Sanches, Duarte, & Pontes, 2009; Wakiuchi & Martins, 2011).
Gun-related violence comprises a violence perpetrated using a gun (firearm or small arm). In addition, gun-related violence may or may not be considered criminal. Criminal cases include homicides, assault using a deadly weapon, and suicide, or attempted suicide, depending on jurisdiction. However, noncriminal violence includes accidental or unintentional injury and death. Rates of this type of violence vary greatly among geographical regions, countries, and even subnationally. Regions with higher levels of economic inequality tend to have higher rates of death due to violence. Within countries, the highest death rates commonly occur among people living in the poorest communities (WHO, 2018).
Internationally, Brazil has one of the highest homicide rates (WHO, 2002). Firearm violence is more significant in capitals and large urban centers, affecting mainly young male adults living in suburban areas and with low schooling (Sanches et al., 2009; Waiselfisz, 2008, 2015; Wakiuchi & Martins, 2011). In 2012, almost 25,000 young adults died victims of this type of violence (Waiselfisz, 2015). Deaths from firearms injuries accounted for 27% of all deaths from external causes in the total population (Sanches et al., 2009).
In a survey conducted between 1980 and 2012, the death rate from these instruments increased 346.5% (Waiselfisz, 2015). Injuries associated with this type of violence can result in victims with irreversible injuries, unfit for work, or requiring health care through hospital admission, use of medications, and physical and mental rehabilitation, which lead to increased use of Health and Social Security System, raising health costs and hampering the development of the country (Rodrigues, Cerqueira, Lobão, & Carvalho, 2009).
The occurrence of violence is a multifaceted phenomenon because there are different forms, which are exhibited in a wide range of contexts. In addition, it is a leading cause of premature death. Social, cultural, and environmental factors seem to be related (d’Avila et al., 2019). Proven and promising violence prevention strategies that address societal factors include reducing alcohol availability; reducing access to lethal means, such as guns and knives; and promoting gender equality by, for instance, supporting the economic empowerment of women (WHO, 2018). Violence using a firearm deserves special attention due to its potential for permanent sequelae and death. Injuries caused by firearms cause irreversible damage, incapacity to work, and demands on the health sector to provide care at various levels of complexity, from prehospital to physical and mental rehabilitation of victims (Ribeiro, Souza, & Sousa, 2017).
In this sense, firearm-related violence points to the need to implement actions and public strategies aimed at preventing its propagation. The availability and use of these artifacts are modifiable risk factors that, if recognized and treated, may help to reduce the burden of serious injury and violent deaths (Nasrullah & Razzak, 2009). According to the WHO, the American Medical Association’s and the U.S. Centers for Disease Control and Prevention’s restricted access and safe storage are some ways to reduce the incidence of injuries and deaths by this type of violence (Gjertsen, Leenaars, & Vollrath, 2014).
Frequently, Brazilian individuals who suffer injury stemming from violence are referred from police stations to forensic services to carry out a physical examination called forensic medical examination, which has the main objective of evaluating and recording injury patterns. These examinations are carried out by two official technicians in forensic medicine and dentistry, and serve as a legal instrument that assists judges during the process of conviction or acquittal of the aggressor (Brazil, 1941).
After a critical literature review, it was verified that many studies have described injuries and lesions resulting from interpersonal violence among victims who attended hospital services (Gawryszewski & Rodrigues, 2006; Gawryszewski et al., 2008; Mascarenhas et al., 2009; Nasrullah & Razzak, 2009; Ogunlusi et al., 2006; Sanches et al., 2009; Waiselfisz, 2015). However, few have described the profile of victims and the characterization of traumas resulting from urban violence through the use of firearms in forensic services. Hospital-based data studies generally focus on investigating mortality rates and provide limited information on profile of violence victims.
Studies performed in forensic services are essentials to foster advancements in this field and to provide information related not only to injury but also to the violent events (such as violence context, aggressor’s sex, relationship between aggressor and victim, time of occurrence, and day of occurrence), providing valuable information for the decision-making process and establishment of public policies. Thus, the aim of this study was to characterize the profile of nonlethal victims of urban violence by firearms and to describe traumas suffered by victims, according to a medical–legal and forensic perspective, that is, analyzing data from violence victims treated at a Brazilian forensic service.
Materials and Method
Study Design and Setting
A cross-sectional and exploratory study was carried out based on the analysis of 6,129 medicolegal and social records of victims of urban violence treated at the Center of Forensic Medicine and Dentistry located in a metropolitan region during 4 years (January 2008 to December 2011). This center is a reference for 23 municipalities and provides care for victims of violence, covering an estimated population of approximately 690,000 inhabitants. The region studied represents a pole of economic development in northeastern Brazil, but social and economic disparities and the high rates of delinquency and crime are notorious. The authors used the Strengthening the Reporting of Observational Studies in Epidemiology checklist in this study.
The research was conducted using the database of the forensic institute to select records of urban violence cases by firearm against individuals of both sexes and at different stages of the life cycle that were observed during that period. National legislation provides that persons who are victims of violence, in reporting abuse to the police, must be referred for medical–legal examination at the Centers of Forensic Medicine and Dentistry. The main aim of these examinations is to assess the extent and severity of traumas, as well as to inform the judicial system, constituting a legal instrument that assists judges in the process of conviction or acquittal of perpetrators (Brazil, 1941).
After conducting a retrospective analysis of the forensic service database, 6,129 medicolegal and social records of victims of urban violence were identified during the period from January 2008 to December 2011. Of this total, 233 cases were related to gun violence and, therefore, were investigated in the present study. Patient’s records were selected consecutively because consecutive sampling is typically better than convenience sampling in controlling sampling bias.
The inclusion criteria were confirmed cases of patients with injuries resulting from violence using firearm, without restriction of gender or age group. Confirmation of violence cases was performed through forensic medical examination, which establishes the causal relationship between the pattern of injury presented by the victim and the episode of violence (Brazil, 1941). Records of violence with fatal outcome were excluded because the focus of the study was to analyze morbidity rather than mortality.
Sample size calculation was also performed a posteriori to ensure that the number of cases assessed was sufficient to extract relevant and accurate information, using Epidat software (version 4.1, Pan American Health Organization). The sample size calculation was performed considering the study design and the study objectives. The following parameters were considered: 95% confidence interval, 5% margin of error, and expected proportion of different types of trauma resulting from gun violence of 15%, resulting in a sample size of 196 cases. Then, the sample size of the study (233 cases) is appropriate and satisfies these requirements.
Prior to data collection, a pilot study was conducted to evaluate the proposed methodology and to standardize the interpretation of information available in the medical–legal and social records of victims. In the pilot study, three researchers underwent the training and calibration to perform data collection. The exercise was performed with 30 different reports and randomly selected from the year 2007 on two occasions, with an interval of 1 week. Because the institution does not yet have a digital information system, each record has been read and the information has been transcribed into a form. Intra- and interexaminer concordances were evaluated using the kappa test, and both obtained κ = .85 to .95, which is considered very good.
Methods of Measurement
The variables investigated included information related to the sociodemographic characteristics of victims, the circumstances of aggressions, the profile of aggressors, and the type of trauma suffered. All these data are collected routinely during the care of violence victims. The sociodemographic variables of victims were categorized as follows: age (≤19 years/20-29 years/30-59 years/≥60 years), sex (female/male), marital status (single, widowed, or separated/married or in a stable union), schooling (≤8 years of schooling/>8 years of schooling), occupation (not working/salaried/not salaried), and home region (urban/suburban area). Variables related to the characteristics of aggressions were violence context (victim’s residence/community environments), aggressor’s sex (female/male), relationship between aggressor and victim (known/strange, i.e., individuals identified by the police, but who had no personal or affective relationship with the victim), day of occurrence (Monday/Tuesday/Wednesday/Thursday/Friday/Saturday/Sunday), and time of occurrence (day shift, between 06:00 a.m. and 05:59 p.m./night shift, between 06:00 p.m. and 05:59 a.m.).
Traumas suffered by victims were assessed according to the anatomical location: affected body region (head/neck/upper limb/lower limb/thorax/abdomen/more than one body region), maxillofacial trauma (present/absent), type of trauma (soft tissue injury such as edema, bruising, lacerations, cuts, and abrasions/bone fracture/dentoalveolar fracture, i.e., lesions in teeth and supporting tissues).
Data Analysis
SPSS Statistics software version 20.0 was used for data analysis, and included descriptive and multivariate statistics using cluster analysis (CA). The TwoStep Cluster method was chosen to characterize the profile of victims of urban violence by firearm. This statistical technique has an exploratory character, and was designed to allocate individuals with similar characteristics to each other into the same group (cluster), to identify profiles or trends that could go unnoticed if using traditional data analysis techniques (Hair, Black, Babin, & Anderson, 2009). Its use in studies on interpersonal violence has increased because it allows to discover differential profiles of victimization that can be later approached through prevention strategies and actions of health promotion and social support (d’Avila et al., 2019). Traditional statistical methods are limited to test direct effects of one variable on another variable. One of the advantages of the TwoStep Cluster method is the ability to manipulate categorical and continuous variables simultaneously and to automatically identify the number of empirical clusters based on the Bayesian information criterion (BIC) and Akaike information criterion, which are used in a joint and comparative way to indicate the optimal empirical solution (Shih, Jheng, & Lai, 2010; Verma, 2013).
CA also allows the researcher to choose which and how many variables will be inserted into the software, which is very sensitive to the amount of missing data. Variables presenting percentage of missing data greater than 10% were not used in the multivariate analysis to avoid possible interferences (Shih et al., 2010). For the conformation of clusters, variables that were able to define clusters and that could later demarcate relevant victimization characteristics to guide the decision-making process and implementation of health prevention and assistance strategies were used. Thus, sociodemographic variables of victims were chosen, as well as those related to the circumstances of aggressions and the type of trauma (Figure 1).
Theoretical model used to characterize the profile of violence victims through CA.
To apply the method, all assumptions were fulfilled, namely variables with a low percentage of missing data and variables with theoretical relevance, being useful to characterize the profile of victims of violence (Shih et al., 2010). The criterion of choice for selecting the number of clusters was the BIC and the distance measure used was the log-likelihood. The clusters identified were compared using proportional difference analysis (Pearson’s χ2 test or Fisher’s exact test whenever appropriate) and Student’s t test for independent samples. The significance level was set at 5%. It is known that the delineation of clusters is a subjective process, but it was tried to standardize the choice of the name given to each formed cluster, in such a way that it represented the most outstanding characteristics in data and could guide the reader in the understanding of the main information demarcated by empirically obtained clusters (d’Avila et al., 2019; Freitas, Bonolo, Moraes, & Machado, 2015).
Ethical Considerations
This study was conducted in accordance with international standards (Declaration of Helsinki) and national legislation (Resolution CNS/National Health Council 196/96 and 466/12) governing ethics in studies involving human subjects and was evaluated by an independent ethics research committee (Protocol Number 0652.0.133.203-11).
Results
Table 1 shows the absolute and relative frequencies of variables related to the sociodemographic characteristics of victims. The majority of victims were male (88.4%), 20 to 29 years old (50.2%), without partner (67.8%), with up to 8 years of schooling (75.3%), not salaried (41.8%), and resident in the urban area (72.5%).
Distribution of Victims of Urban Violence by Firearm According to the Sociodemographic Characteristics.
Note. Differences in category totals due to missing data.
Table 2 shows the distribution of victims of urban violence by firearm according to the circumstances of assaults. The majority of cases occurred in community settings (95.3%). The aggressor was usually a stranger to the victim (61.8%) and male (100.0%). The night shift (56.8%) and the period corresponding to Saturdays (20.0%) and Sundays (20.4%) concentrated the largest number of occurrences.
Distribution of Victims of Urban Violence by Firearm According to the Circumstances of Assaults.
Note. Differences in category totals due to missing data.
Table 3 shows the distribution of victims of urban violence by firearm according to the characteristics of traumas. Cases of trauma in more than one body region simultaneously prevailed (31.8%). In 15.5% of cases, maxillofacial trauma was observed, mainly affecting soft tissues (66.7%), followed by cases of bone fracture (27.8%) and dentoalveolar fracture (5.6%).
Distribution of Victims of Urban Violence by Firearm According to the Characteristics of Traumas.
After performing CA, it was possible to identify two groups of individuals who exhibited different victimization characteristics. Table 4 shows the comparative analysis of clusters according to sociodemographic characteristics, event circumstances, and pattern of related traumas. Variables that most contributed to the external differentiation among clusters formed were victim’s age (p < .001), victim’s sex (p < .001), marital status (p < .001), region of residence (p < .001), relationship between aggressor and victim (p < .001), and affected body region (p < .001).
Comparative Analysis of Clusters According to Sociodemographic Characteristics, Event Circumstances, and Pattern of Related Traumas.
Note. C1 = Cluster 1; C2 = Cluster 2.
Student’s t test for independent samples.
Fisher’s exact test.
Pearson’s chi-square test.
Statistically significant at 5%.
Cluster 1 was characterized by younger single victims, who suffered violence by firearm in the urban area, perpetrated by an unknown perpetrator, resulting in greater occurrence of isolated upper and lower limb traumas. In contrast, Cluster 2 consisted essentially of older, married, or stable-union victims who experienced firearm violence in the suburban area, perpetrated by a known aggressor, resulting in a greater occurrence of multiple traumas, that is, those affecting various body regions at the same time (see Figure 2).
Victimization characteristics revealed by the CA.
Discussion
The significant increase in firearms violence primarily affects the younger population as a target and preferential instrument (Cardona & Agudelo, 2007; Gawryszewski, Kahn, & Mello-Jorge, 2005). In the present study, the prevalent age group is consistent with national and international literature, where the main victims of aggression by this artifact are young adults (Brito, Gugala, Tan, & Lindsey, 2013; Cardona & Agudelo, 2007; Gawryszewski et al., 2005; Nasrullah & Razzak, 2009; Ogunlusi et al., 2006; Sanches et al., 2009; Waiselfisz, 2015; Wakiuchi & Martins, 2011; WHO, 2002).
It is noteworthy that injuries and deaths of adolescents and young adults by this instrument affect these people at the beginning of their productive lives, forsaking their families, reducing their potential years of life, minimizing social and economic productivity, and imposing burdens on the country, affecting its economy and development (Carvalho, Cerqueira, Rodrigues, & Lobão, 2008). Regarding sex, the results of this research revealed that men were 7 times more likely to be victims of firearms than women, pointing out a relevant higher percentage of exposure among males and corroborating data found in other studies (Brito et al., 2013; Cardona & Agudelo, 2007; Gawryszewski et al., 2005; Nasrullah & Razzak, 2009; Ogunlusi et al., 2006; Waiselfisz, 2015; Wakiuchi & Martins, 2011; WHO, 2002).
In a forensic study conducted in Portugal, it was also found that males are the main victims of violence by this type of weapon (Caldas, Magalhães, Afonso, & Matos, 2010). Cases of assault involving a firearm should be interpreted as a clear attempt to cause the death of the victims. In addition, Brazilian men live, on average, 7 years less than women, and violence due to external causes, such as the use of firearms, is among the causes of premature death (Brazil, 2012).
In this study, as the multivariate CA technique was used to allocate individuals with similar characteristics to each other into the same group, it was identified that the majority of victims were single, especially those that composed Cluster 1. The fact that the perpetrator is known or unknown can often determine the circumstances in which events occur, and the region of the affected body can reveal the severity of the injury, as well as its potential for lethality. Marital status is not usually the focus of analysis in studies of this nature. Nonetheless, one of the current public health approaches related to violence addresses the need to cope with the problem by systematically collecting data aiming to characterize victimization profiles (Oliveira & Mello-Jorge, 2008).
In the present study, higher victimization was observed among individuals of low schooling, which is consistent with a previous study (Sanches et al., 2009). The association between low schooling and gun violence may be a consequence of poor educational policies and inefficient public services in the region studied (d’Avila et al., 2015).
The majority of victims were not salaried and urban residents. This is probably due to the fact that the risk of urban violence increases significantly in the presence of factors such as high levels of unemployment and urbanism. In addition, although widespread, violence mainly affects urban victims as target and preferential instrument (Cardona & Agudelo, 2007; Gawryszewski et al., 2005).
Regarding the aggressor’s sex, this study reported that men were the main aggressors. These have been also reported as the main aggressors and victims of firearm violence (Brito et al., 2013; Cardona & Agudelo, 2007; Gawryszewski et al., 2005; Nasrullah & Razzak, 2009; Ogunlusi et al., 2006; Sanches et al., 2009; Waiselfisz, 2015; Wakiuchi & Martins, 2011; WHO, 2002). In surveys carried out with medical hospital records, it was also determined that the aggressors of victims of injuries by this type of instrument were mostly male (Gawryszewski et al., 2008; Mascarenhas et al., 2009).
Aggressions were practiced mainly by an unknown person in a community environment, with the use of firearms, disagreeing from previous findings (Mascarenhas et al., 2009). In a study carried out in Nigeria (Ogunlusi et al., 2006), it was identified that most of the injuries caused by this instrument occurred during the act of robbery and theft, and it was caused by strangers in 15.9% of cases. This suggests that traumas are linked to aggressions or assaults, which culminated in a certain act of violence in the probable intention of injuring the victim. In addition, it is noteworthy that, in Brazil, there are approximately 17 million firearms in its territory, and 50% of these are under illegal possession and in the hands of citizens who support an informal private market or of criminals who are financed by drug trafficking (Drezfus & Nascimendo, 2005). However, it is important to highlight that the current data do not provide such information about context and that we can only speculate about these matters.
Identifying the regions of the body most affected after exposure to violence is also essential as it may reflect the severity and potential lethality of aggression (d’Avila et al., 2019). A study performed by Ribeiro et al. (2017), based on medical care given at Brazilian urgent and emergency health care services to people injured by firearms, concluded that the most common injuries were to arms and legs and to multiple organs. Regarding the type of trauma, although body injuries were the most common, there was a high prevalence of facial trauma from firearm violence in this study, in agreement with other national and international studies in literature that reported the facial region as the most affected (Abrahams, Jewkes, & Mathews, 2010; Davies, Kerins, & Glucksman, 2011; Hootman, Annest, Mercy, Ryan, & Hargarten, 2000). One hypothesis for this result is probably the fact that aggressors, who are eventually criminals and are in situations of violent robberies or disputes over drug trafficking, have the intention to destroy or cause extreme harm to the victim, because patients with head injuries are more likely to die or become extremely debilitated.
The time of occurrence is an extremely important variable to be analyzed from the point of view of public safety and intervention planning. The results of this study indicate that the occurrence of violence through the use of firearms predominated during the night and during the weekends, in agreement with other studies (Gawryszewski et al., 2005). High prevalence of occurrences throughout the weekdays was also observed; however, there is no description in literature regarding the period of the day and days of the week for occurrence of this type of violence.
When using segmentation analysis, two clusters with distinct victimization profiles were identified. Cluster 1 consisted essentially of younger single men who suffered firearm violence in the urban area, perpetrated by an unknown perpetrator, resulting in a greater occurrence of isolated upper and lower limb traumas. This situation is probably due to the fact that young adults participate more actively in social life in relation to other parts of society, becoming more exposed to violent events (Chrcanovic, Abreu, Freire-Maia, & Souza, 2011). In addition, robbery and physical assault are more likely to occur on the streets. This suggests that such occurrences are linked to assaults and aggressions, which resulted in violent act generating traumas (Nasrullah & Razzak, 2009)
However, Cluster 2 was predominantly composed of older men, married, or in a stable union, who suffered violence by firearm in the suburban area, perpetrated by a known aggressor, resulting in greater occurrence of multiple traumas, that is, affecting several body regions at the same time. These results are consistent with other studies found in literature (Gawryszewski et al., 2008; Mascarenhas et al., 2009). This fact may be due to socioeconomic factors peculiar to the region under study, where violence chronically occurring in suburban areas is the result of the lack of public policies toward this population. Initiatives to stop the availability of weapons were successful with the approval of the Disarmament Statute (Brazil, 2003). However, in the period between 1980 and 2012, although the population grew by around 61%, gunshot deaths rose by 387% (Waiselfisz, 2015), highlighting the need to develop new public policies to address gun violence.
In this sense, firearm violence represents a significant burden for Brazil, and reducing its morbidity and mortality is one of the main challenges for public health in the country (Gawryszewski et al., 2005). In fights and conflicts in which the outcome could have been less serious, when a firearm is present, the potential for a result involving injury and indeed even death is very high (Ribeiro et al., 2017). According to the Institute for Economics & Peace (IEP; 2014), the cost of violence in Brazil in 2012 was more than US$175 billion, equivalent to 7% of the country’s GDP in the period. Its confrontation involves obtaining quality information as a strategy for a deeper understanding of the problem.
Thus, representative population studies that also address the quality of life of victims of firearm violence need to be carried out with the aim of extending existing knowledge about violence by this type of instrument, to qualify health services for the care of these victims and to collaborate with the planning of intersectoral actions, to cope with this serious public health problem and violation of human rights.
Facing firearm violence goes beyond punishing the aggressor. An antiviolence culture must be strengthened at all levels of social organization. Public managers should create more efficient mechanisms to control the illegal sale of firearms, promote a culture of peace in schools and neighborhoods, improve social indicators, and allocate more resources to public safety. Victims of firearm violence need to receive special attention from health professionals.
Specialized care centers could be created, especially in geographical areas of greatest social vulnerability and greater records of violence. There is a need to think about a permanent program of confrontation that is not limited to action in large cities, but especially in medium and small municipalities where violence is becoming more evident.
Strengths and Limitations
One of the limitations of this study is the use of secondary data, which do not always have complete information. Factors such as alcohol availability and means restriction could not be investigated. Future studies should explore in greater depth the influence of these factors on the occurrence of violence. In addition, the results represent only a portion of the events, referring to the victims who sought police stations or who were notified in the hospitals and were referred to the legal medical examination service to seek a solution to their problems by legal means. Therefore, the results are valid only for victims of violence attended in forensic services. The CA algorithm also has limitations. One is the impossibility of making inferences for the entire population from the results obtained.
However, this study allowed the description of events and the characteristics of traumas of victims in a medium-sized municipality. It is hoped that the results obtained could guide the planning of actions to offer a better integration of the different systems of violence surveillance through the use of firearms to reduce the number of traumas resulting from these events.
Conclusion
The results revealed different risk groups for firearm violence and trauma: younger victims showing isolated upper and lower limb traumas and older victims who presented greater occurrence of multiple traumas, generating subsidies for the decision-making process and strategy planning with emphasis on health care, prevention, and promotion.
Footnotes
Acknowledgements
The authors are grateful to the Center of Forensic Medicine and Dentistry in the city of Campina Grande.
Author contributions
Alysson V. P. Ferreira, Ítalo M. Bernardino, and Luzia M. Santos participated in the acquisition and interpretation of data and in the preparation of the article, and approved the final article as submitted. Lorena M. Nóbrega and Kevan G. N. Barbosa participated in data acquisition and development of technical procedures for data formatting, and approved the final article as submitted. Sérgio d’Avila supervised the study and participated in the conception and design of the method and critical revision of the article for final approval.
Ethical approval
The study was carried out in compliance with international norms and national legislation governing ethics in studies involving human subjects and was authorized by the institution at which it was conducted. The study received also approval from an independent ethics committee (Process Number 0652.0.133.000-11).
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), MCT/CNPq no. 14/2010.