Applying Nightingale charts to evaluate the heterogeneity of biomedical waste in a Hospital

OBJECTIVES: to evaluate the heterogeneity of biomedical waste (BW) using Nightingale charts. METHOD: cross-sectional study consisting of data collection on wastes (direct observation of receptacles, physical characterisation, and gravimetric composition), development of a Management Information System, and creation of statistical charts. RESULTS: the wastes with the greatest degree of heterogeneity are, in order, recyclable, infectious, and organic wastes; chemical waste had the most efficient segregation; Nightingale charts are useful for quick visualisation and systematisation of information on heterogeneity. CONCLUSION: the development of a management information system and the use of Nightingale charts allows for the identification and correction of errors in waste segregation, which increase health risks and contamination by infectious and chemical wastes and reduce the sale and profit from recyclables.


Introduction
Biomedical waste (BW) is defined as waste related to human or animal health services, including home care and fieldwork services; analytical laboratories for health products; morgues, funeral homes, and embalming services; drugstores and pharmacies; educational and health research facilities; zoonosis control centres; mobile health units; and acupuncture services (1)(2) .
According to the resolutions adopted in Brazil, (1)(2) BW is divided into five groups: Group A (infectious), Group B (chemical), Group C (radioactive), Group D (common), and Group E (piercing and cutting).
When BW is produced, the professionals who Several factors can contribute to errors in segregation. Among them is the lack of specific knowledge on BW by the professionals who generate and manipulate it and the minimal importance normally given to BW by these same professionals compared to other tasks they perform. There are also behaviour patterns derived from the similarity between household waste and biomedical waste that lead individuals (including health professionals) to dispose of BW generated at home together with common waste. Common examples are diabetic patients -who take injectable insulin daily -and injectable drug users, who generate piercing and cutting waste that is usually disposed of together with common household waste.
Household wastes and wastes inadequately disposed of in health facilities due to the poor management of BW in Brazil lead to several problems that can affect the health of the population and the health of workers who have direct contact with these wastes (3) . BW (6) .
The risks associated with improper handling of BW include inappropriate or even non-existent hazardous waste segregation and the mixing of such waste with common waste, which promotes contamination of the latter, increasing the amount of contaminated material and the related risks; inappropriate segregation of piercing and cutting waste without using mechanical protection, which is responsible for the largest number of occupational accidents in health facilities; and the disposal of BW in dumps, improper landfills, or together with household waste, which presents a serious risk of injury to waste collectors and of environmental contamination near the disposal site. This improper handling increases the risk of exposure, compromising the health of workers, patients, and the environment (7) .
In this context, the risks associated with BW management can be divided into three major areas: occupational, environmental, and contingency. Figure   1 presents the risks associated with the management process, showing the areas in which they occur, the type of risk, and which population is exposed to it.
Therefore, for safe management, it is essential that all individuals working in the health facility know the risks associated with their activities, have clear responsibilities, and are trained to perform the procedures related to waste management, as occupational accidents usually occur due to the combination of a number of factors or inadequacies (8) .  The objectives of this study were to assess the BW management system with emphasis on segregation efficiency (heterogeneity), which is the critical step in the waste management process, and to assess whether a Management Information System (MIS) and Nightingale charts are useful for analysing the efficiency of the management of these wastes.

Risks associated with BW management
Occupational Extra-hospital

Methods
This work is a cross-sectional study, the methods of which encompassed two distinct stages. The first stage consisted of data collection on the management of BW based on the direct observation, physical characterisation, and gravimetric composition of BW (9) .
The second stage consisted of implementing and maintaining a Management Information System (MIS) to record and process waste characterisation data, followed by systematisation and presentation in a Coxcomb chart format (10) , allowing the historical retrieval of a tool for data presentation in the field of nursing.
Data collection related to waste management was performed by:  (11) .
The system is being guided by a variation of the Unified Process (12) . Data are accessed through a web DBMS are a collection of programs to enable users to maintain a database and thus facilitate the process of defining, building, manipulating, and sharing data (13) . The Coxcomb chart was innovative in the collection, tabulation, interpretation, and graphical presentation of descriptive statistics. Figure 2 shows an adaptation of the original statistical chart (Coxcomb). This diagram shows the incidence and prevalence of death due to three main causes at the time: war wounds/injuries, diseases, or other causes. Based on Figure 3a, it is observed that the periods in which common waste had the highest heterogeneity are the months of May and February. In this category, a marked amount of recyclables incorrectly segregated as common waste is observed. It is also observed in Figure   3a that in February, a mixture of infectious waste with common waste was found (although in small amount).

Discussion
Given that the facility studied is a teaching hospital with a high turnover of students, when the months corresponding to the beginning of the semester are compared with the months corresponding to the end of the semester, differences in heterogeneity are observed. These values are smaller, for example, in July for common and recyclable waste (Figures 3a and 3b), which is the month in which student turnover is also smallest.
The mixture shown in Figures 3a and 3b reflects an increased amount of organic waste and reduction in the reuse of recyclables, as the latter is not sent to sorting or recycling centres (where it creates jobs and income) but taken instead to landfills or dumps, losing its commercial value.
Although the mixture of infectious with common waste (Figure 3a) is very small, it contaminates the entire sample, as once infectious waste comes into contact with other waste, the entire mass becomes infectious and must be treated as such. This contamination results in increased environmental and health risks, both inside the hospital (health professionals, patients and cleaning crew) and outside the hospital (workers involved with external waste collection, treatment and final disposal) (7) . Studies show that infectious wastes, especially piercing and cutting wastes, are the main categories responsible for occupational accidents (14) .
In May, more than 50% of the waste segregated as recyclable was, in fact, organic, which reduces the quality of recyclable waste destined for sorting centres, attracts vectors, and interferes in the work of waste collectors. It also increases the costs of recycling because it is necessary to re-categorize the waste for allocation to a landfill.
The presence of common and recyclable waste mixed with chemical and infectious waste (Figures   4a and 4b) increases the costs of the treatment of infectious waste and reduces the reuse of recyclables (15) , thus constituting a double loss. Chemical wastes, when segregated improperly, can result in human poisoning and injury in many ways. Injuries can be caused by contact with the product as well as by inhalation of gases or ingestion of contaminated food and water (16) .
Despite the possibility of accidents involving chemical and infectious waste, piercing and cutting waste causes the highest number of occupational accidents (17) .
It is worth noting that receptacles for infectious waste harbour biological fluids from several patients, and an accident involving one of these materials requires the worker to undergo a mandatory prophylaxis due to lack of knowledge of the source-patient, exposing the worker to strong side effects of medications and procedures that would not otherwise be necessary (18) .
The characterisation of BW is an essential tool in the assessment of waste generated, and it allows  The use of a MIS in health care facilities, aside from allowing the storage, access, and quick search of data, provides a temporal view of the phenomenon and tends to maintain the necessary behavioural changes to achieve 100% efficiency in the management process.
In other words: it is crucial to obtain a zero index of heterogeneity.
The generation of indexes and indicators is essential for self-monitoring of the management system and allows evaluation of the system's behaviour over time, supporting intervention and optimisation of the performance of the waste management process and of the continuing education programs. It also allows comparative analysis with other institutions. In this sense, it is emphasized that these performance evaluation tools can assist health care facilities, providing an overview of the situation of the procedures and practices adopted (19).
Nightingale charts are also suitable for this purpose due to allowing rapid visualization of the statistical data and influencing the BW decision-making process and the consequent reduction of risks to physical, environmental, and organisational health. As they allow for temporal data assessment, these charts indicate the months in which there were changes in the degree of heterogeneity of the waste categories evaluated, which can be confirmed by analysis of the standard deviation.