CHARACTERISTICS OF MEDICAL SOLID WASTE AND ASSESSMENT OF THE MANAGEMENT PRACTICES OF ITS INFECTION COMPONENTS IN SELECTED GENERAL HOSPITALS IN LAGOS STATE

Abstract

Infectious waste account for a fraction of the total solid waste generated in any city, but has a high potential for infection and injury than any other kind of waste. Mixed with the ordinary waste, infectious waste could make the entire municipal solid waste stream a public health hazard. In Nigeria, there is a gap in knowledge on the profile of medical waste composition and characterisitics. This study was designed to characterise medical solid waste and assess the management practices of its infectious components in selected general hospitals in Lagos State. A descriptive cross-sectional survey involving four hospitals selected from the twenty-three general hospitals using table of random numbers was carried out. Solid waste generated daily were weighed for one month, and physically characterised into paper/carton, kitchen waste/grasses/plant cuttings, cotton, plastics, metals and glass. Grab samples of organic fraction of waste was chemically analysed for pH, carbon, nitrogen,lead, cadmium and nickel using 1992 American Public Health Association (APHA) standard methods. Infectious waste samples were microbiologically assessed for predominant infectious bacterial and microbial load using APHA (1992) standard methods. Knowledge and practice of infectious waste management for 207 waste handlers and generators randomly selected from 415 hospital staff were assessed using a validated questionnaire with a 10-point knowledge scale. A knowledge score ≤5 points was considered as poor. A ten-item observational checklist was used to obtain information on infectious waste segregation practices, waste treatment and disposal methods and use of personal protective equipment. Descriptive statistics, Chi-square test and ANOVA were used for data analysis. A total of 84.2±39.4kg waste was generated daily in the selected hospitals. Daily output of infectious and non-infectious waste were 23.5±13.5kg and 60.7±26.0 kg respectively. Weight of characterised waste components were: 34.0±9.3 kg (paper), 20.6±7.5 (kitchen waste/grasses/plant cuttings), 15.5 ±6.9 (plastics), 2.7±1.3 kg (metal) and 1.6±0.5 kg(glass). Chemical characterisation of the waste showed the following components: pH-6-7, carbon-48.1%, nitrogen-1.6%, lead-11.9 mg/kg, cadmium-1.3 mg/kg and nickel-21.6 mg/kg. The predominant organisms isolated in infectious waste were Klebsiella pneumoniae (35.9%), Staphylococcus aureus (29.7%) and Proteus mirabilis (14.1%) with mean counts of 2.0x10>12 ±7.0x10>1 cfu/100g, 17.0x10>12±cfu/100g, and 0.2x10>12±2.1x10>1 cfu/100g respectively. Among the respondents, 35.7% were handlers and 63.3% were waste generators. Knowledge score of respondents was 5.4±1.5; knowledge score of waste handlers (5.9±1.5) was significantly higher than that of waste generators (5.1±1.4) (p<0.05). Majority (60.4%) of the respondents had poor knowledge and 32.6% practised infectious waste segregation. In all the hospitals, infectious waste was not treated before disposal. Personal protective equipment (PPE) utilised by majority (87.4%) of the respondents was latex gloves and inappropriate use of PPE was common among waste handlers (85.6%). Management of infectious waste was poor among health workers. Hospital management should engage in continuous training of its members of staff on proper handling of medical waste.