This study was designed to assess the levels of some selected heavy metals and identify organic contaminants from soil collected from hospitals dumpsites and incinerator ash within Kaduna metropolis. Samples (soil and ash) were collected from three medical and one municipal dumpsite between the hours of 8am and 11am, when disposal activities are high. The mean concentrations of some heavy metals (Pb, Cu, Zn, Cd and Fe) were determined in both seasons by atomic absorption spectrophotometry while organic contaminants were identified by gas chromatography-mass spectrometry. Data of heavy metals collected were analyzed using ANOVA to conduct a test of significance; pollution index to assess environmental risk and Pearson’s correlation to determine relationship between parameters. The result showed the order of relative abundance as Fe>Zn>Cu>Pb>Cd. Saint Gerard catholic hospital dump soil contained more heavy metal concentration due to its high contents of sharps as waste while the municipal dump soil has the highest mean concentration of cadmium. The result also indicated a decreasing pattern in the mean concentrations of the heavy metals vertically down the soil depths. Seasonal variation shows high concentrations of heavy metals during the dry season than the wet season. Heavy metals were not destroyed by incineration and their concentrations depend on the amount of metals in the waste. The result from GC-MS showed some organic pollutants that have strong health implications. The pollution index showed that the municipal dump soil is severely polluted with cadmium and it is, therefore not recommended for agricultural activities. The pollution levels of the heavy metals decreased in the order Cd>Fe>Pb>Cu>Zn. Strong positive correlation (P>0.01) was recorded between Pb and Cu and between Fe and Zn. Cadmium has a positive correlation (P>0.05) with Cu and Pb. The studied physicochemical parameters in soil samples showed poorly sorted soil with sand fraction generally high in all samples. Alkaline pH,
ranging from 7.1 to 9.8 was observed while low soil organic matter was recorded (ranging from 0.28 to 2.25%) from sampling sites. The level of the studied metals in all the dump soils and ashes were within tolerable limit by WHO, FEPA and US EPA but could be of an environmental concern with continues dumping of medical wastes.
1.1 Hospital and Municipal Solid Waste
A modern hospital is a complex, multi-disciplinary system which consumes thousands of items for delivery of medical care and is a part of the physical environment (Chandra, 1999). It is place where patients’ health problems are diagnosed, analyzed and treated. During these activities, generation of solid waste is unavoidable.
The medical waste tracking act of United State defines medical waste as “any solid waste’’ that is generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biological and the animal waste from slaughter houses or any other establishment (US.EPA, 1988).
World health organization (WHO) defines hospital waste as the total waste stream from a health care or research facility that includes both potential risk wastes and non-risk waste materials. WHO (1999) states that 85% of hospital wastes are actually non-hazardous, whereas 10% are infectious and 5% are non- infectious but they are included in hazardous waste.
The world health organization has classified medical waste into seven categories:
i. General waste: This is largely composed of domestic or house hold type of waste. It is non-hazardous to human beings, e.g. kitchen waste, packaging material, wrappers and plastics.
ii. Pathological waste: This consists of tissue, organ, body part, human fetus, blood and body fluid. This constitutes hazardous waste.
iii. Infectious waste: The waste which contain pathogens in sufficient concentration or quantity that could cause diseases. It is also hazardous.
iv. Sharps: Waste materials which could cause the person handling it, a cut or puncture of skin, e.g. needles, broken glass, saws, nails, blades and scalpels.
v. Pharmaceutical waste: This includes pharmaceutical products, drugs and chemicals that have been returned from wards, have been spilled, are outdated, or contaminated.
vi. Chemical waste: This comprises discarded solid, liquid and gaseous chemicals, e.g. cleaning, housekeeping and disinfecting products.
vii. Radioactive waste: It includes solid, liquid and gaseous waste that is contaminated with radionuclide generated from in-vitro analysis of body tissue and fluid, in-vivo body organ imaging and tumor localization and therapeutic procedures (WHO, 2002).
Most medical waste constitutes a small fraction of municipal solid waste and if not properly handled could be hazardous. Municipal solid waste (MSW) normally termed as ‘‘garbage’’ or ‘‘trash’’ is an inevitable byproduct of human activity. It is usually generated from human settlements, small industries and commercial activities (Singh et al., 2011). An additional source of waste that finds its way to MSW is the waste from hospitals and clinics. When medical risk wastes are mixed with MSW, they pose a threat to human health and they may also have long term effect on environment (Pattnaik and Reddy, 2009). Municipal waste dumping sites are designated places set aside for waste disposal. Depending on a city’s level of waste management, such waste may be dumped in an uncontrolled manner, segregated for recycling purposes, or simply burnt.
The growth of the medical sector around the world combined with an increase in the use of disposable medical products has contributed to the large amount of medical waste generated. The
proper collection and disposal of this waste is of great importance as it can directly or indirectly have health risk impact on the public and environment (Babanyara et al., 2013).
It is ironic that the healthcare delivery system, which is established to provide treatment and safeguard the health of the people against illnesses, becomes a source of infection and means of spreading diseases in the process of medical treatment. Modern hospitals and research centers use a wide variety of drugs including antibiotics, cytotoxics, corrosive chemicals, radioactive substances, which ultimately become part of hospital waste. These generate different types of infectious and/or hazardous medical waste that poses enormous risk to patients, healthcare providers, waste pickers, and the community at large, if their disposal is not urgently and scientifically managed.
Most hospitals in Kaduna State, Nigeria are built close to residential areas and have their temporary dumpsites within their vicinity. This creates health challenges to the immediate communities via air, soil and water contamination. This research will create awareness amongst the hospital personnel in health-care units on the need to segregate medical wastes before disposing and the danger of improper disposal of hospital waste. This will further provide awareness on the need to always carryout research on the pollution level of medical dumpsite soil, plants and underground water within the vicinity.
1.3 Statement of Problem
Disposal of medical waste is of a growing environmental concern in the developing world. The problem is growing with an ever-increasing number of hospitals, clinics and diagnostics laboratories
universally. In developing countries such as Nigeria, where health concern is competing with limited resources, medical wastes have not received sufficient attention and the priority it deserves. The notion that disposal of waste is the responsibility of the government authorities has not enabled waste generators to appreciate the negative impact of improper waste disposal (Ngwuluka et al., 2009).
The main environmental problem associated with the disposal sites is the potential risk posed to the soil. Since the waste will be disposed directly on the surface of the soil, a number of contaminants including heavy metals readily penetrate and eventually contaminate the soil and percolate to the ground water.
1.4 Aim and Objectives
The aim of this research is to determine the levels of some heavy metals and organic contaminants at hospital and municipal dumpsites soil and incinerator ash within Kaduna metropolis, Nigeria. This aim was actualized via the following objectives:
i. Determination of physicochemical parameters such as pH, % organic carbon, electrical conductivity and particle size distribution of dumpsite soil.
ii. Determination of the concentration of some heavy metals, present in the soil and incinerator ash during wet and dry seasons.
iii. Identification of organic contaminants, present in the dumpsite soil and incinerator ash.
iv. Determination of pollution levels of the various hospitals dump soils for agricultural activity using pollution index analysis.
v. Determination of the relationship between the heavy metals and physicochemical parameters using Pearson’s correlation matrix.
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