Few studies have investigated the occupational hazards of municipal solid waste workers, particularly in developing countries. Resultantly these workers are currently exposed to unknown and unabated occupational hazards that may endanger their health. We determined municipal solid waste workers’ work related hazards and associated adverse health endpoints. A multifaceted approach was utilised comprising bioaerosols sampling, occupational noise, thermal conditions measurement, and field based waste compositional analysis. Results from our current study showed highest exposure concentrations for Gram-negative bacteria (6.8 × 103 cfu/m3) and fungi (12.8 × 103 cfu/m3), in the truck cabins. Significant proportions of toxic, infectious, and surgical waste were observed. Conclusively, municipal solid waste workers are exposed to diverse work related risks requiring urgent sound interventions. A framework for assessing occupational risks of these workers must prioritize performance of exposure assessment with regard to the physical, biological, and chemical hazards of the job.
Municipal solid waste management is a vital activity in the context of protecting human health and environment [
Whilst over the past two decades valuable evidence has accumulated on the occupational dust and noise levels in the mining [
Additionally, most of these few studies primarily focused on waste recycling plants [
It is dust which is in the breathing zone or entering the respiratory system which may pose health risks to the employee and should therefore be assessed and monitored [
Additionally, assessments of workplace noise exposures are justified on the basis that noise hazards are globally ranked among the top five occupational stressors with grave repercussions on the worker and the organisation [
In both industrialized and developing countries, very little research is available on the thermal conditions in which waste workers work. More importantly, in tropical countries summer outdoor temperatures can be unbearably hot. Such high temperatures may render outdoor activities such as municipal solid waste collection, street sweeping, and landfilling operations a health hazard due to increased risk of excessive sweating, headaches, heat stress, offensive odours, and fly infestation from decomposition processes of organic waste fractions. Conversely, cold outdoor temperatures have been associated with frost bite [
Consequently this paper aims to determine the occupational dust, noise, and thermal exposures in the field of municipal solid waste management so as to build up the much needed evidence for developing a generic framework for assessing occupational health risks of municipal solid waste handlers.
Personal sampling was performed using two field monitors mounted in the breathing zone of workers, approximately 1.5 m above ground level. One monitor was for collecting of total dust and the other for bioaerosols (bacteria and fungi). Environmental samples were collected using similar equipment mounted at the breathing zone, from the active landfilling sites, truck cabins, and street cleaning sites. Total dust and bioaerosols samples were collected from various sites (Table
Total dust and bioaerosols exposures (mean and range) in different working areas.
Sampling site | Description | ( | Total dust mg/m3 | GNB 103 cfu/m3 | Fungi 103 cfu/m3 |
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Site A | Bin loaders | 12 | 8.2 (0.8–26) | 1.5 (0.16–6.8) | 66 (7.2–136) |
Drivers | 4 | 4.2 (0.8–12) | 1.6 (0.2–2.8) | 36 (6.4–68) | |
Skip bins | 4 | 3.2 (0.6–10) | 1.2 (0.1–6.4) | 28 (5.8–62) | |
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Site B | Truck cabin samples | 4 | 8.6 (0.9–26) | 1.6 (0.18–6.8) | 68 (6.4–12.8) |
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Site C | Site workers | 12 | 0.4 (0.2–0.8) | 6.8 (0.04–28) | 3.2 (0.4–8.2) |
Machine operators | 4 | 0.6 (1.4–2.2) | 22 (0.6–120) | 21 (0.3–100) | |
Site samples | 4 | 0.3 (0.1–0.8) | 6.2 (0.02–24) | 2.8 (0.2–7.4) | |
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Site D | Sweepers | 12 | 0.08 (0.04–0.3) | ND | 12 (14–24) |
Site samples | 4 | 0.04 (0.02–0.5) | ND | 8 (12–22) |
ND: none detected; GNB: Gram-negative bacteria; cfu: colony forming units; A: waste collectors; B: truck cabin; C: active landfilling site; D: street cleaning;
Our study found high mean exposure concentrations for total dust, Gram-negative bacteria (GNB), and fungi for personal samples collected from refuse bin loaders and truck cabin samples (Table
The high mean total dust, Gram-negative bacteria (GNB), and fungi exposure concentrations reported in our study for waste loaders and truck cabin may be attributed to the processes of manual offloading and loading of mixed waste streams without proper containment bags (Figure
Dust generation from loading mixed waste without proper containment bags.
Our study argues that transferring of waste from stationery bins to other bags (Figure
Process of transferring of waste from stationery bin to plastic bags.
Nonstationary bins that are directly emptied into the refuse collection truck could avert exposures encountered during the waste bin transferring process. Alternatively, all stationery bin containers may be fitted with removable bin liners that are directly emptied into the waste collection trucks.
Our study found high mean exposure concentrations for total dust, Gram-negative bacteria (GNB), and fungi for personal samples collected from refuse bin loaders and for truck cabin samples (Table
Park et al. [
The highest average noise levels (84.86 dBA) were recorded in the central waste collection points whilst the lowest (83 dBA) was in the cabin of waste collection truck. In all measured waste management sites (Table
Noise level measurements (dBA) in various working areas.
Site | Site description | Average noise value (dBA) | ISO standard (dBA) |
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A | Noise mainly generated by hydraulic waste collection trucks and passing traffic. | 84.86 | 85 |
B | Waste spreading in cells and soil cover application. Noise generated by waste compactors. | 84.32 | 85 |
C | Manual offloading of waste bins into waste collection vehicles. Noise mainly generated by hydraulic waste collection trucks and passing traffic. | 83.00 | 85 |
A: central collection points, B: active landfilling area, and C: offloading area into truck.
However, the major sources of noise were waste collection vehicles’ running engines, other traffic and landfilling vehicles. Constituents of municipal solid waste such as glass and metal tins also contributed to the occupational noise particularly during emptying of metal bins on the metal floor of waste collection vehicles. High working speed with regard to offloading of waste bins tended to produce a monotonous noise. Additionally, Jerie [
Our study findings are far below personal noise levels observed in glass waste collection operations (108 to 131 dB
In the present study we observed that none of the municipal solid waste workers wore any hearing protection devices though two workers in the waste collection crew complained of occasional temporary hearing loss. Whilst our study did not find mean noise levels above recommended levels we suggest that where hearing protection devices are considered as precautionary measures, there is need to consider the possibility of failure to hear warning sounds from other road users which may increase the risk of accidents and injury among waste workers.
Outdoor work is associated with greater exposure to hot and cold temperatures [
Summer thermal conditions measured in various waste sites.
Work site | Average | Waste workers’ concerns |
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Loading waste collection vehicles | 33.34 | Sweating, dehydration, heat syncope, and heat exhaustion. |
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Street and open areas sweeping | 33.28 | Loss of concentration. |
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Manning waste disposal sites | 33.29 | Offensive odours and high fly infestation from increased organic, sweating, heat stress, and headaches. |
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Driving waste collection vehicles | 26.25 | Sweating and occasional headache. |
Temperatures below and above those typically preferred by most people have a significantly detrimental effect on the safety related behavior of workers [
The current study found that on average the monthly total amount waste collected in the study area, in tones, was on average 566.08 of which 518.88 was from residential suburbs, 18.88 was from commercial enterprises, and 28.32 was from industries. Results from the physical waste compositional analysis revealed that residential waste on average constituted 24% food waste, metal containers 4%, glass and ceramics 2%, diapers 2%, toxic waste streams 1%, plastics and paper 13%, and 54% miscellaneous waste streams. The commercial waste stream was mainly dominated by food waste 42%, metal tins containers 24%, glass 1%, paper and plastics 7%, and other waste streams 24%. Evidently wastes from both the residential and commercial sources had significant proportions of biodegradable food waste. Biodegradation of such organic waste produces offensive odours and supports fly breeding and infestation particularly in summer when temperature is high. The presence of diapers, though in small proportions, in residential waste is a cause of concern since this poses risks of transmission of pathogenic organisms into waste workers’ hands. Waste from the industries was mainly scrap metals, rumble, glass, and food remains.
Results from the present study revealed that the major toxic waste streams in municipal solid waste included hair sprays, shampoos, expired medicines, pesticides and e-waste, shoe and floor polish, carpet and furniture cleaning agents, motor vehicle brake fluid, battery acid, and nail paints. Although available in small quantities (1%), toxic waste inevitably renders the entire municipal solid waste potentially toxic and can lead to various occupational health risks for waste collectors through inhalation, ingestion, and dermal exposure pathways. Pesticide residues such as organophosphates could affect the central nervous system through inhibition of the choline esterase enzyme. In the present study we observed discarded pesticide containers in household waste streams which could be a source of arsenic exposures for waste workers. The International Agency on Research on Cancer [
Arsenic can lead to cellular toxicity [
The major e-waste components found in the present study include fluorescent and nonfluorescent bulbs, circuit boards, lead and acid car batteries, printer inks and tonner, spark plugs, motherboards, keyboards, monitors, electrical switches, and thermostats. Fluorescent and nonfluorescent bulbs, circuit boards, and car batteries in municipal solid can be source of lead (Pb) and mercury (Mg). Similarly, inks and tonner for printers and NiCd rechargeable batteries can be a source of cadmium (Cd). Also, monitors and keyboards in municipal solid waste streams are a cause of concern since they can be primary sources of polyvinyl chlorides (PVC) which may emit harmful gaseous substances such as hydrogen chloride gas.
Previous literature has associated lead (Pb), cadmium (Cd), mercury (Mg), and polyvinyl chlorides from e-waste with various adverse mental health effects such as cognitive disturbances and reduced intelligence quotient (IQ) [
Household hazardous waste compositional analysis and associated hazards.
Waste type | Components | Potential hazards for waste handlers |
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Toxic (1%) | Hair sprays, lotions, shampoos, expired medicines, and pesticides | This can lead to systemic intoxication from inhalational exposures. This can also lead to severe burns from accidental or spontaneous ignition of flammable materials. |
E-waste (e.g., fluorescent bulbs, car batteries, printer ink, and tonner) | Toxic metals in e-waste may damage target organs leading to various toxicity effects. | |
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Infectious (2%) | Diapers and used tissue | Infectious waste can transmit bacteria responsible for spreading diarrhoeal diseases. Biodegradation of faecal matter in diapers generates offensive odours that can induce anorexia, nausea, and vomiting. |
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Mechanical hazards | Scrap metal, broken glass, razor blades, and needles | This can cause injuries through piecing and bruises and facilitate transmission of hepatitis B. |
Average % by weight calculated per weekly waste generation rates.
Results from the physical waste compositional analysis revealed considerable proportions of infectious materials in municipal solid waste (2%), such as diapers and used tissue (Table
Our study found relatively high levels of mechanical waste components such as scrap metal, broken glass, and razor blades (Table
Waste collector wearing nonpuncture-proof and worn out gloves.
Our paper presents the strength of the inclusion of occupational hygiene measurements related to several occupational hazards. Particularly, bioaerosols exposure determination, occupational noise, and thermal conditions measurement were done. However we did not measure exposures through other routes such as hand contact with contaminated materials. Thus our study is unable to estimate the microbiological risk through the ingestion route since we did not swab waste workers’ hands and nails to determine the remaining concentrations of
To the best of our knowledge, very limited studies have been conducted on the GNB and fungi exposure concentrations at municipal solid waste management sites such as active landfilling sites, refuse bin collection points, and truck cabins. Our study enriches and broadens the existing body of knowledge in this negated area (Table
Other shortcomings of our current study entail usage of relatively small samples sizes (Table
Our study found high mean exposure concentrations for total dust, Gram-negative bacteria (GNB), and fungi for personal samples collected from refuse bin loaders and for truck cabin samples. This suggests the priority for exposure assessment with regard to total dust and bioaerosols should be focused on waste loaders and the truck cabins. Also, we observed mean summer temperatures higher than 33°C in most waste management areas and workers complained of headaches, sunburn, heat stress, excessive sweating, dehydration, and difficulties in concentration in assigned tasks. Consequently our study argues that in tropical countries it is better to perform summer waste collection services in early morning hours or at night when temperatures are cooler. Waste workers should be encouraged to take regular breaks and rest in cooler shades where oral rehydration fluids can be given to refresh them. In light of the results from our physical waste compositional analysis, our study concludes that municipal solid waste workers are exposed to diverse toxic, mechanical, and infectious hazards requiring sound mitigation measures.
Approval of the University of Pretoria Faculty of Health Sciences’ Ethics Committee was obtained and the Ethics Reference Number is 343/2014. Approval from the study area’s town council was received in writing. A two-way dialogue was held with all the study participants where the purposes and procedures of the study were discussed and all participating workers voluntarily signed informed consent with the full rights to withdraw from the study without having to give any excuse. No samples of blood or body fluids were collected from participants in this study. Where images of workers were used deliberate attempts are taken to hide the facial appearance of workers and all data collected was treated with utmost confidentiality and the anonymity of respondents was greatly respected.
The paper was presented at the Public Health Practitioners Association (PHASA) Conference of South Africa, held in the period 19–22 September 2016, but is not under consideration for publication in any journal.
The authors declare that there is no conflict of interests regarding the publication of this paper.