Medical Laboratory Liquid Waste Management in Togo: State of the ART from a Cross-Sectional Study

Introduction

Medical laboratories play a crucial role in disease diagnosis, patient health monitoring, and medical research [1]. However, these facilities generate substantial amounts of liquid waste, including chemical reagents, biological fluids, and disinfectants. Improper handling and disposal of such waste pose significant risks to human health and ecosystems [2]. The global challenge of medical waste management has profound implications, as inadequate disposal can directly or indirectly impact healthcare workers, patients, waste collectors, and the public at large [3].

Medical laboratory liquid waste is produced daily in healthcare settings, and its proper management is essential to prevent environmental contamination [4]. The components of this waste can infiltrate soil, water bodies, and air, leading to pollution and public health hazards. Substances such as heavy metals, solvents, disinfectants, and pharmaceutical residues, even at low concentrations, can be highly toxic and persistent in the environment [5]. Consequently, efficient waste management is vital to mitigating ecological disruptions and minimizing adverse effects on human health [6].

Globally, an estimated 2 million healthcare workers are exposed to infections due to inadequate biomedical waste management. Infectious healthcare waste can transmit more than 30 bloodborne pathogens, including hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) [7-9]. Therefore, proper handling of hazardous biomedical waste should not be optional but mandatory. Effective healthcare waste management requires a structured approach encompassing waste generation control, segregation, collection, storage, transport, treatment, and disposal, following best practices in public health, environmental conservation, and economic sustainability [10,11]. In Togo, recent efforts have been made to enhance the quality of medical laboratories and solid waste management. However, data on compliance with international regulations for hospital liquid waste management remains scarce. This study aims to assess the composition of liquid waste generated by a selected medical laboratory in Togo and evaluate its potential environmental impact. Understanding the nature of this waste will support the development of sustainable waste management practices within the healthcare sector, ensuring both environmental protection and public health safety.

Material and methods

Study design

A cross-sectional descriptive and analytical study was conducted in 6 public healthcare facility laboratories from June to September 2022. This study included clinical laboratories from six public district health facilities of Togo using a random sampling method. For confidentiality reasons, the participating laboratories were anonymised and are hereafter referred to as Laboratory A, Laboratory B, Laboratory C, and Laboratory D. These laboratories comprised district and regional health facilities located in central health facilities. The study participants included all medical laboratory professionals, waste management officers, plumbing officers, and waste handlers in the selected facilities. A structural questionnaire was used to identify the medical lab activities and assess the associated risks. This questionnaire was developed based on the recommendations of the following standards and guidelines: i. ISO 14001:2004–Environmental Management Systems: General Guidelines on Principles, Systems, and Implementation Techniques, which provide a framework for identifying and mitigating environmental risks in laboratory settings; ii. International Committee of the Red Cross iii. (ICRC), 2011: Waste Management, outlining best practices for the safe handling, treatment, and disposal of hazardous and non-hazardous laboratory waste. IV. SLIP-TA Checklist / V. Strengthening Laboratory Management Toward Accreditation (SLMTA): A structured assessment tool for evaluating laboratory quality management systems and biosafety compliance. VI. Biosafety/Biosecurity Improvement Checklists: Practical tools designed to enhance laboratory biosafety and biosecurity measures by ensuring compliance with best practices and international guidelines. The environmental impact of the laboratory liquid waste was assessed through a comprehensive analysis encompassing both microbiological and physicochemical parameters. Lastly, the impact on soil and environment was estimated (Figure 1).

Study parameters

To decipher the environmental impact of the selected medical laboratories' activities, the quality of the liquid wastes produced by these medical laboratories was assessed. Two main families of parameters were included namely microbiology and physico-chemical parameters. The microbiology assessment included total coliforms, thermotolerant coliforms, faecal streptococci, Escherichia coli, and anaerobic sulfite-reducing bacteria (ASR). The Physicochemical parameters included temperature, conductivity, biochemical oxygen demand (BOD) as well as Trace Metal Elements (TMEs) such as Cr, Cu, Zn, Ni, Pb, and Hg.

Sampling, transport, and Pre-processing

The main sample used in this study consists of wastewater effluent from the activities of medical laboratories from selected health facilities. Samples were collected from two different manholes at each facility: wastewater effluent from medical laboratory activities and office building activities. The samples were collected from all facilities on the same day. A depth-integrated sampling technique was employed to collect the wastewater samples for all physicochemical analyses using 600 mL plastic bottles [12]. The bottles were thoroughly washed with distilled water and rinsed repeatedly with water to be sampled. Triplicate water samples were collected from each sampling site. One in a sterile 250mL flask for microbiology inspection, the second in a clean 2000 mL bottle without preservatives for analysis of conductivity, BOD as well as COD, and the last but not least 200 mL of wastewater to which a drop of acetic acid is added as a preservative for the analysis of Trace Metal Elements (TMEs) such as Cr, Cu, Zn, Ni, Pb, and Hg. Each laboratory was assigned a pre-coded numerical value. For safety, the samples were handled using appropriate uniforms and protective equipment. All bottled water samples were capped immediately, stored in an icebox containing accumulators at 4-8°C, and transported immediately to the laboratory within 24 hours.

Physico-chemical characterization

In situ analysis

To ascertain the temperature and pH of the wastewater effluent, the thermometer and pH meter were respectively introduced directly into the wastewater before sampling [13].

Ex vivo analysis

To access the level of DBO5 of the wastewater effluent, the mercury-free differential pressure detection method was used as described previously [14]. Briefly, the wastewater was incubated for 5 days at 20°C in the dark, and the level of oxygen consumed, expressed as BOD5, was measured using the LH-TB100 BOD meter. The conductivity was measured by evaluating the electrical conductance of the water effluent between two metallic electrodes of the conductometer (SANXIN Model SX736: pH/mV/Conductivity/DO) [15]. Trace metal analysis, including Chromium (Cr), Zinc (Zn), Copper (Cu), Lead (Pb), Nickel (Ni), and Mercury (Hg), was performed using atomic absorption spectroscopy (AAS) as described previously [16]. Briefly, Standard solutions for each element were prepared to establish calibration curves, which were subsequently used to determine the concentrations of these metals in the water effluents. Quantification was carried out using an atomic absorption spectrophotometer (AAS, iCE 3000 SERIES, Thermo Fisher). The measurement of trace metal concentrations was conducted under specific experimental conditions (Table 1).

Microbiological profiling

To assess the microbiological quality of wastewater from hospitals included in this study, the pour plate method was used [17]. Following serial dilutions of the water effluents, the water samples were homogenized, and appropriate dilution volumes were collected. A volume of 1 mL was dispensed into Petri dishes, while 0.5 mL was transferred into tubes for the TSN medium with the corresponding dilution. Then, Molten agar was poured into the plates and homogenized using a figure-eight motion. After solidification, the inoculated plates were incubated under the following conditions: 30°C for 24 hours for the VRBL medium, 37°C for 48 hours for Slanetz and Bartley media, 44°C for 24 hours for VRBL and Brilliance E. coli media, while the TSN medium was incubated at 44°C for 48 hours. Characteristic colonies, categorized as S (smooth) or F (filamentous), were manually enumerated on each plate using a fine-point marker [18]. The results were expressed as colony-forming units per milliliter (CFU/mL).

Statistical analysis

Data were digitally recorded using Microsoft Excel 2019 and exported to IBM SPSS Statistics (version 21; IBM Corp., Armonk, NY, USA) for analysis. Descriptive statistics were used to summarize the data. Categorical variables, including personnel categories, laboratory activities, environmental aspects, and compliance status, were presented as frequencies and percentages. Continuous variables from physicochemical and microbiological analyses (Temperature, pH, conductivity, heavy metals, BOD₅, and bacterial counts) were summarized using minimum and maximum values (ranges). Measured parameters were compared with established regulatory standards to determine compliance. Environmental risk levels were classified based on predefined criteria, including extent, frequency, severity, and reversibility, and categorized as low, moderate, or high risk.

Results

Profile of laboratory personnel in Healthcare medical laboratories

The distribution of laboratory personnel across the five healthcare medical laboratories varies significantly, with a total of 41 staff members. The majority of the personnel responsible for activities hold a university-level education, representing 51% (21 out of 41) of the total personnel. CHR-Sokodé has the highest number (17 personnel), including the only medical doctor (biologist) and the highest count of senior laboratory engineers (3), medical laboratory technicians (4), and laboratory technicians (4). In contrast, CHP-Tchamba and CHP-Sotouboua have the lowest numbers, with 8 and 5 personnel, respectively. Medical laboratory technicians (14) and laboratory assistants (12) constitute the majority of the personnel, while biosafety officers (3) and an occupational exposure officer (1) are present in select facilities. Administrative staff are limited, with only two administrative secretaries (Table 2).

Main activities recorded in the medical laboratories

A comprehensive assessment was conducted to gather the core activities performed in medical biology laboratories evaluated across the Central Region. The activities recorded were categorized into five main domains: facility maintenance and sanitation, administrative and logistical operations, sample handling and diagnostic analysis, specialized laboratory techniques, and biosafety and waste management. The laboratory performs a broad spectrum of essential activities categorized into facility maintenance, administrative operations, diagnostic procedures, and biosafety management. Facility maintenance and sanitation involve the cleaning and disinfection of laboratory spaces and equipment, as well as general building upkeep, including plumbing, electrical work, and renovations. Administrative and logistical operations encompass patient registration, scheduling, and record management. Phlebotomy and sample handling include sample collection and initial processing to ensure proper diagnostic workflow. The laboratory conducts diverse diagnostic analyses, including haematological testing (complete blood count, coagulation tests), biochemical assessments (liver function, glucose monitoring), immuno-serological analyses (infectious disease and autoimmune diagnostics), parasitological investigations (malaria and intestinal parasite detection), and bacteriological evaluations (microbial culture and antibiotic susceptibility testing). Additionally, specialized techniques such as microscopic slide preparation and staining, reagent and culture media preparation, centrifugation, and autoclave sterilization of biohazardous materials are performed to enhance diagnostic accuracy and quality control. Biosafety and waste management protocols are strictly adhered to, encompassing the segregation, collection, transport, and treatment of hazardous and non-hazardous solid waste, as well as the management of liquid waste and septic sludge. These activities reflect the laboratory’s critical role in ensuring diagnostic precision, operational efficiency, and compliance with biosafety regulations (Table 3).

Direct environmental aspects of medical biology laboratories activities

The assessment of the direct environmental aspects of laboratory activities identified multiple potential impacts. Atmospheric emissions were observed, and Wastewater discharge was noted. The laboratory generated both hazardous and non-hazardous waste, necessitating appropriate segregation, treatment, and disposal measures. Resource consumption, including water, energy, and raw materials, was significant. Additionally, the risk of soil contamination and Transport- related emissions were recorded, likely due to improper disposal or accidental spills (Table 4).

Physicochemical analysis of laboratory wastewater effluents

The Physicochemical assessment from various healthcare facilities reveals a mixed compliance with regulatory standards. The results indicate that Temperature and pH levels fall within acceptable ranges of 20-30°C and 6.0-9.0, respectively, with observed values ranging from 20 to 22°C and 7.04 to 8.03. However, significant variability is noted in conductivity, spanning from 0.1686 to 13.09 mS/cm, which may indicate diverse contamination sources. Heavy metal concentrations generally adhere to limits, except for Mercury, which exceeds the regulatory threshold of 0.01 µg/L, with levels reaching up to 24.151 µg/L. Notably, Biological Oxygen Demand (BOD₅) is substantially elevated, ranging from 14.9 to 912 mg/L, far surpassing the limit of 30 mg/L (Table 5).

Microbiological contamination of wastewater effluents

The microbiological analysis of the waste water samples from various healthcare biological laboratory facilities shows significant contamination. Total coliforms are present in concentrations ranging from less than 1 to 500,000,000 CFU/100 mL, which far exceeds the regulatory limit of less than 10,000 CFU/100 mL. Thermotolerant coliforms, an indicator of fecal contamination, reach up to 10,000,000 CFU/100 mL, also surpassing the limit of less than 10,000 CFU/100 mL. Escherichia coli, a specific indicator of fecal contamination, is generally undetectable except at one site with 1,600 CFU/100 mL, still exceeding the limit of less than 1 CFU/100 mL. Fecal streptococci levels are high, up to 3,400,000 CFU/100 mL, exceeding the limit of less than 10,000 CFU/100 mL. In contrast, sulfite-reducing anaerobes are mostly undetectable, meeting the regulatory standard. Overall, these findings highlight severe microbiological contamination (Table 6).

Assessment of environmental aspects and their impact

We next evaluated the impact of medical laboratory activities on soil and the environment. This assessment was based on the extent, frequency, number, and reversibility of environmental aspects. The analysis revealed that most activities pose a high risk of soil pollution, which could lead to significant environmental degradation. Activities such as medical biology analyses and centrifuge usage generate hazardous biological waste, posing severe environmental risks due to improper disposal practices. Wastewater management is inadequate, with effluents often discharged into soak pits or non-functional treatment plants, leading to harmful environmental impacts at the laboratory facilities A, B, and C. High electricity and water consumption are noted at several facilities, contributing to resource depletion in laboratory A and D. Pest control treatments emit hazardous chemicals, though with varying frequencies and impacts. Noise emission is considered a minor issue (Table 7). Overall, these activities are categorized as high- risk due to their potential for significant environmental harm, necessitating improvements in wastewater treatment, hazardous waste management, and resource efficiency to mitigate these risks.

Discussion

The distribution of 41 laboratory personnel across five healthcare medical laboratories reveals significant disparities, with 51% holding university-level education. Laboratory A has the highest staffing level (17/41), including the only medical doctor and leading numbers of senior laboratory engineers, medical laboratory technicians, and laboratory technicians. In contrast, Laboratory C and E have the fewest personnel (8 and 5, respectively). Medical laboratory technicians (14/41) and laboratory assistants (12/41) form the majority, while biosafety officers (3/41) and an occupational exposure officer (1/41) are scarce, and administrative support is minimal, with only two secretaries. This distribution could lead to disparities in service quality and workload management, potentially impacting diagnostic accuracy and turnaround times in understaffed facilities [19]. The concentration of specialized personnel, such as the medical doctor and senior engineers, in laboratory A suggests a hierarchical structure where more complex analyses are centralized. The limited number of biosafety officers and occupational exposure officers raises concerns about adherence to safety protocols and the potential for occupational hazards within the laboratories [20].

Furthermore, to assess the impact of these laboratory activities, we first evaluated the direct significant environmental aspects related to soil and the broader ecosystem. The analysis revealed that the majority of activities (18 out of 22) carried out in the surveyed laboratories posed a high risk of pollution, which could contribute to the degradation of soil microfauna and microflora. Consequently, this pollution could contaminate surface water and rapidly reach groundwater sources. Regarding the overall environmental impact, most activities (12 out of 18), accounting for 66.7%, were classified as high-risk for environmental pollution. This finding differs from the study by Fatemi et al., that reported a lower frequency of high-risk activities (35.2%) [21]. This discrepancy may be due to the broader scope of our assessment, which considered all laboratory activities, whereas their study focused solely on the use of volatile chemical products in laboratories and facilities.

To assess the actual impact of the surveyed laboratories activities, we measured selected physico-chemical and microbiological parameters in wastewater effluents from these facilities. The results revealed that certain physico-chemical parameters (conductivity, BOD5, copper, lead, and mercury) and microbiological indicators (total coliforms, thermotolerant coliforms, Escherichia coli, and faecal streptococci) posed a risk of contamination to receiving environments, including soil and surface water. These findings align with others risk assessment studies. For example, mercury concentrations in sludge were alarmingly high, posing ecological risks, while BOD₅ levels in wastewater samples reached up to 2,400 mg/L, far exceeding regulatory standards [22]. In addition, elevated conductivity levels in wastewater, indicating dissolved ion concentrations, have been linked to pollution from industrial activities. For example, a study on industrial effluent found conductivity values of 266.10 µS/cm, highlighting its role as an indicator of dissolved inorganic pollutants [23].

Our results showed that the same physico-chemical and microbiological parameters posed a risk of contamination to receiving environments. The trace metals Cu, Cr, Zn, Ni, Pb, and Hg are among the most commonly studied elements in surface waters. Even at low concentrations, these metals can have significant ecological and health impacts [24]. The wastewater from the surveyed laboratories contained trace elements at much higher levels compared to wastewater from office buildings. This suggests that these elements pose a significant environmental risk and are a major source of surface water pollution in the Central Region. Environmental pollution caused by laboratory activities poses a potential risk not only to laboratory personnel but also to other departments and the surrounding population [25]. Furthermore, without corrective measures, the accumulation of laboratory waste could contribute to ozone layer depletion and global warming [26,27]. Understanding the impact of these environmental factors is essential for assessing the level of risk associated with laboratory activities. Therefore, we evaluated the impact of significant environmental aspects. The findings revealed that the majority of activities in these medical biology laboratories (40 out of 58) posed a high risk to personnel, primarily due to biological and chemical hazards. These findings align with previous studies highlighting similar concerns [20,28]. For instance, a study conducted in Moroccan medical biology laboratories assessed chemical risks in accordance with the CLP Regulation. Researchers identified 144 substances and reagents that could affect the health of analytical technicians. They found that 17% of these chemicals were associated with low-priority risk scores, 55% with average-priority risk scores, and 28% with high-priority risk scores. This underscores the significant chemical hazards present in such laboratory settings [29]. Similarly, the Centers for Disease Control and Prevention (CDC) emphasizes the importance of biological risk assessments in laboratories. They note that many laboratory activities have been linked to undesirable events, including laboratory-acquired infections. Furthermore, an evaluation of exposures in molecular biology laboratory environments highlighted that laboratory workers are frequently exposed to a wide range of hazardous substances. The study found that chemicals such as ethanol and ethidium bromide were commonly used, and workers were occasionally exposed to known human carcinogens. This diversity and frequency of exposure necessitate robust risk assessments and safety protocols to protect laboratory personnel [30].

Collectively, these studies emphasize the critical need for comprehensive risk assessments in medical biology laboratories. Identifying and understanding environmental factors, particularly biological and chemical hazards, are essential steps toward implementing effective preventive measures and ensuring the health and safety of laboratory personnel.

Conclusion

This study demonstrates that clinical laboratory activities in the selected public healthcare facilities in Togo generate effluents and waste that pose significant environmental and public health risks. Despite acceptable pH and temperature levels, elevated concentrations of heavy metals, high organic load, and excessive microbiological contamination indicate inadequate wastewater treatment and waste management practices. The predominance of high-risk activities underscores the urgent need to strengthen environmental governance in clinical laboratories through improved waste segregation, treatment infrastructure, staff training, and adherence to international environmental management standards. Implementing these measures is essential to mitigate environmental pollution and protect community health. Furthermore, ongoing research and innovation are necessary to develop more environmentally friendly laboratory practices and technologies in the future.

Conclusion: Clinical laboratories in public healthcare facilities in Togo generate inadequately treated effluents with high microbial and chemical contamination, highlighting significant environmental risks and the urgent need for improved laboratory waste and wastewater management systems.

Declarations

Author Contributions

Gnatoulma Katawa conceptualized and designed the study, supervised the research activities, ensured methodological rigor, and critically revised the manuscript. Eya Hélène Kamassa supervised the experiments, contributed to data analysis and interpretation, and drafted the original manuscript. Tambli Sankarlernga performed experiments, data collection, provided technical and logistical support, and participated in manuscript revision. All authors read and approved the final version of the manuscript.

Ethical approval and consent to participate

Ethical approval for this study was obtained from the Togo Bioethics Committee for Health Research (Comité Bioéthique de Recherche en Santé, CBRS; approval number 049/2022/CBRS, issued on 06 April 2022). Written informed consent was obtained from all participants before enrolment in the study.

Funding

The authors received no specific funding for this work.

Acknowledgements

The authors express their sincere gratitude to all participating laboratories for their valuable contribution to this research. We also acknowledge the support of the laboratory and field staff involved in sample collection and processing.

Competing interests

The authors declare that they have no competing interests.