Exposure to dangerous substances in the waste management sector

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Sirpa Laitinen, Tiina Rantio, Finnish Institute of Occupational Health, Finland

Contents

Introduction

The amount of waste generated in the EU has been growing and new was handling processes have emerged in the waste management sector. Workers in the waste management sector may be exposed to biological and chemical risks such as different vapours, smoke, fumes and dust as well and they may also need to handle chemical substances and infectious materials. According to interviews and follow-up studies workers in this sector have been found to experience more work-related symptoms and illnesses than other occupational groups [1], [2]. For example the work conducted in composting facilities of waste is associated with adverse acute and chronic respiratory health effects in the workers, such as mucosal membrane irritation, chronic bronchitis, conjunctivitis, and an accelerated decline of lung function. Workers may be exposed if they inhale hazardous substances, which may be present in complex mixtures of aerosols, bioaerosols and volatile organic compounds produced during the treatment of domestic, medical and industrial waste. They may also be exposed through direct contact (with skin or eyes or via the mouth) to hazardous chemicals, dust, and microorganisms present in the waste material. The following article provides information on the safe handling of dangerous waste, including how to avoid biological and chemical health risks.


Biological hazards and their health risks in the waste management sector

Occurrence of biological hazards

Waste materials contain nutrients and they often are moist, thus providing a favourable environment in which micro-organisms can thrive. The age and composition of waste together with storage temperature and humidity affect both the type and quantity of micro-organisms as well as their ability to live and multiply in the waste. Medical and clinical waste or the waste derived from animal origins may well contain pathogenic micro-organisms, i.e. these biological agents pose a risk of infection. Many of these pathogens have been categorized into four groups based on their relative risk in a European Directive 2000/54/EC for biological agents [3]. However, the greatest work-related hazard is usually attributed to irritation of the mucous membrane and to toxic or allergenic effects experienced after inhalation of a large number of micro-organisms and their fragments [4]. These are invisible and they do not necessarily even smell. Therefore, they can be considered ubiquitous.

Bacteria and their fragments

Biowastes, especially food scraps very often contain huge numbers of bacteria. Most of these bacteria are saprophytic bacteria, i.e. they feed and grow on decaying organic matter. However, some of these species particularly those present in animal waste, may be pathogens, and they can cause serious infections, such as brucellosis (Brucella spp.), campylobacteriosis (Campylobacter spp.), listeriosis (Listeria monocytogenes), salmonellosis (Salmonella spp.), shigellosis (Shigella spp.), and yersiniosis (Yersinia spp.).

All gram-negative bacteria in the waste contain components called endotoxins, which is a part of their cell walls. Endotoxins are pulmonary immunotoxicants [5]. They can cause acute systemic (fever, shivering, and joint pain) and respiratory symptoms (dry cough, shortness of breath), as well as acute lung function changes. One chronic effect of endotoxin exposure is an accelerated decline in lung function (COPD, chronic obstructive pulmonary disease). Additionally, endotoxin may exert adjuvant effects in the subject’s reactions to allergens since they may synergistically enhance the release of allergic mediators and increase the production of antibodies.

Gram-positive bacteria, such as Actinobacteria, Bacillus, and Clostridium genera, produce spores which are difficult to destroy. They can be resistant to heat, cold, desiccation and sunlight and hence, these types of bacteria may also survive in bioaerosols. In particular, “thermophilic Actinobacteria” can promote the development of extrinsic allergic alveolitis. Bacillus and Clostridium bacteria may be considered as pathogens, since, in some circumstances they can be the source of the anthrax (Bacillus anthracis), botulism (toxin of Clostridium botulinum), or tetanus (Clostridium tetani).

Fungi and their spores and mycotoxins

Fungi, such as moulds and yeasts, may trigger extrinsic allergic alveolitis, asthma and hypersensitivity, or organic dust toxic syndrome (ODTS) a property they share with bacteria [4]. Extrinsic allergic alveolitis (sometimes called hypersensitive pneumonitis) consists of a range of symptoms, including influenza-like symptoms, chills, fever, chest tightness, dry cough, malaise, weight loss, muscle and joint pains. Thea acute symptoms of allergic alveolitis appear 4 to 6 hours after exposure to the micro-organisms. ODTS is an acute condition; it is the body’s response to exposure to toxic levels of a hazard. The symptoms are similar than allergic alveolitis, but in general, ODTS does not lead to long term health effects and usually disappears on the next day after the exposure.

A fungus “Aspergillus fumigatus” can also cause infectious mycosis (broncho-pulmonary aspergillosis). Immuno-compromised individuals are at a particular risk suffering severe symptoms. Some fungal species, such as “Alternaria” and “Cladosporium”, are also known to be producers of type I allergens, which cause hypersensitivity reactions such as allergic rhinitis as an allergic reaction. Prolonged exposure to bioaerosols is likely to give rise to an increased risk of sensitisation to common fungi. Workers who have previously been sensitised to moulds may subsequently experience an exacerbation of symptoms at very low exposure levels.

Mycotoxins, secondary metabolites of fungi, are known to be potent carcinogens. However, very little is known about the respiratory health effects attributable to occupational airborne exposure to mycotoxins.

Viruses and prions

Medical and clinical laboratory waste may include extremely infectious agents, e.g. hepatitis, HIV and hemorrhagic viruses and prions. Workers’ exposure to these infectious viruses is mainly through accidental contact with a sharp object. However, little is known about the potential risks that workers encounter through exposure to viruses and prions present in the air or on surfaces of waste materials being processed. This is especially the case if the medical waste is present in normal domestic or industrial waste.

Parasites and vector-borne diseases

“Vector-borne disease” is the term commonly used to describe an illness caused by an infectious microbe that is transmitted to human being by blood-sucking arthropods. A vector may also be an animal, such as a rodent or a cat that is harbouring disease-causing micro-organisms allowing them to transfer from one host to another. These kinds of vector-borne diseases include leptospirosis (Leptospira spp.), Q fever (Coxiella burnetii) and toxoplasmosis (Toxoplasma gondii). [6] Waste can also include the eggs of parasitic worms (helminths e.g. Ascaris lumbricoides) and the cysts of parasites which can cause a gastrointestinal infections such as amoebiasis (Entamoeba histolytica), and giardiasis (Giardia lamblia).

Allergens

Contact with the organic components of animal or vegetable waste may have impacts on workers through allergenic routes. The allergic type I responses are generated by immunological sensitization towards a specific agent and they lead to the production of a specific immunoglobin E response. Some typical IgE-mediated allergies include asthma, allergic rhinitis and dermatitis caused by a skin contact with the allergen.

Routes of entry for biological agents

Biological hazards are derived from micro-organisms entering the host and then propagating within the body, resulting in disease. The most common routes of entry for biological hazards are through direct contact with waste or inhalation of airborne micro-organisms and their fragments. Direct contact can involve absorption through mucous membranes (eyes, nose and mouth) or damaged, burned or areas where skin is not intact. Ingestion during eating and smoking is also possible if the hands are contaminated with waste materials.

There is little data on the dose-response relationship between exposure and symptoms. The response due to a micro-organism depends on its virulence, infectivity, and the resistance of the body. Thus there may be great difficulty in determining limit values to which the health effects can be attributed. The general consensus is that exposure to high concentrations of micro-organisms should be avoided. Prolonged exposure to elevated levels significantly increases the risk of disease. Respiratory effects can be traced to the physical size and ability of the microorganisms and their fragments to be inhaled deep within the respiratory tract.

Chemical agents and their health risks in the waste management sector

Chemical agents in waste management sector may be inherent to the waste itself and/or produced during waste treatment. Workers may be exposed to dangerous chemical substances in waste treatment activities and different kind of health risks have been described [7].

Hazardous waste from industry and households may contain high amounts of all kinds of chemical substances. If they are not recognised and handled as hazardous waste, this could increase the hazardous properties of municipal solid waste in landfill, or during the incineration or composting plant processes [8].

Metals

Heavy metals are known to pose a considerable health risk in the waste management sector. Many industrial products (e.g. batteries, electrical equipment, stainless steel or plastic products) containing heavy metals still end up as waste and are unlikely to be recycled properly. Heavy metals might also be released during the waste processing. Currently it is still difficult to identify the actual sources of heavy metals detected in different waste types and products (e.g. lead in flue gas in incinerators may have originated from lead pigments in plastic or lead batteries)[9].

Waste management workers face health risks if they are exposed to metals during collecting and handling of toxic waste and during waste incineration processes. More than 30 different metals have been detected in the incinerated ash of unsorted urban waste, and most of these metals, such as arsenic, cadmium, chromium, lead, and mercury, are harmful to human health [10]. Workers may be exposed to metals by inhalation or ingestion or through skin contact. [11].

Arsenic

Arsenic in waste is typically originates from industrial products, such as wood preservatives, paints, dyes, and semiconductors. In addition, arsenic may be released during the burning of fossil fuels and wastes. One of the most dangerous sources of inorganic arsenic is the incorrect disposal of electronic waste [12], [13].

Arsenic is classified as being toxic if swallowed (H301) or inhaled (H331) [14]. It may exert detrimental effects on skin, mucous membranes and the nervous system. The effects may be delayed, and repeated or prolonged exposure of arsenic may cause damage to skin and the peripheral blood vessels. In addition, increased incidence of hypertension, cardiovascular disease and diabetes have been reported. Arsenic is carcinogenic to humans and possibly is dangerous toxicity for human reproduction or development [11], [15].

Cadmium

The use of cadmium has been restricted in electrical and electronic equipment in the EU countries since 2006. [16] However, cadmium found in waste incineration plants might originate from pigments and stabilisers in plastic or possibly from steel plating [9].

Cadmium is a heavy metal which is lethal if inhaled in sufficient quantities (H330) but it also damages organs if there is prolonged or repeated exposure (H372). It may cause cancer (H350) and it is suspected of causing generic defects (H341) as well as damaging fertility and the unborn child (H361fd) [14], [17]. Workers may exposed during waste treatment procedures. Cadmium fumes are irritating to the respiratory tract and may cause acute lung oedema and metal fume fever. The effects may be delayed and during repeated or prolonged exposure to dust particles, the lungs may be affected. Cadmium may have effects on the kidneys, such as causing kidney impairment. [11] [15]

Chromium

Chromium is used in tanning, wood preservation, and it can be present in pigments and dyes for plastics, paints, and textiles. Chromium alloys in stainless steel are an application. Today, most of chromium alloy products are collected for recycling. However, many types of stainless steel are not magnetic and they cannot be separated from waste streams by magnetic separation. Thus stainless steel may end up reaching solid waste incinerators or especially landfills, if collection for recycling is not carried out properly [9].

Chromium may cause irritation and corrosion of skin and mucous membranes tissue in nose and throat; it can also damage kidneys, blood, and liver. An allergic skin reaction (H317) may be caused by exposure to chromium (especially Cr(VI)) compounds in the working environment. Chromium compounds are also believed to cause cancer if they are inhaled (H350i). [11] [14] [15] [17]

Lead

Many different lead containing products end up in waste management systems and can contaminate incineration plants or landfills. Lead is still used in many products, such as plastics, lead crystal glass, cathode ray tubes, ceramics, solders, and pieces of lead flashing.

Lead can exert effects on the blood, bone marrow, central and peripheral nervous systems, gastrointestinal tract and kidney. In addition, lead and lead compounds may damage the unborn child and they are suspected of damaging fertility (H360Df). Lead is probably carcinogenic to humans. [11] [14] [15] [17] Lead compounds may damage many organs if there is prolonged or repeated exposure (H373) and they are harmful if swallowed (H302) and inhaled (H332). [14]

Mercury

The principal mercury sources in waste are dental amalgam, thermometers, batteries, backlights of computer screens, and fluorescent lights [9]. Volatile mercury which can react to form toxic organic compounds is one of the most harmful metals present in waste. Mercury is irritating to the skin and organic mercury compounds can be fatal if they come into contact with skin (H310) or if swallowed (H300). High levels of mercury vapour can cause pneumonitis and symptoms in the kidneys and central nervous system, even long after the actual exposure (H372, cause damage to organs through prolonged or repeated exposure). Mercury is suspected of being able to impair fertility and it may damage the unborn child (H360D). [11] [14] [15]


Gases

Ammonia

Ammonia is a colourless, pungent odour gas, which may be released into the environment during the natural breakdown of organic matter. Ammonia can be released from waste disposal sites. Where workers may become exposed to ammonia through inhalation or contact with the skin. Ammonia is irritating to eyes, skin, and respiratory tract (H314). Inhaling high concentrations of ammonia may cause lung oedema (H331) and frostbite. [11] [14] [15] [18]

Nitric oxide, nitrogen dioxide and nitrous oxide

Nitric oxide, nitrogen dioxide and nitrous oxide can be released during energy production process, including waste incineration. Workers may be exposed to these nitric compounds by inhalation. Nitrogen oxide may also exert effects if it comes into contact with the skin.

The effects of nitric oxide and nitrogen dioxide may be delayed. Nitric oxide is irritating to eyes and respiratory tract. Inhalation of nitric oxide may cause lung oedema and it has detrimental effects on blood. These effects may be delayed, repeated or prolonged exposure may affect the lungs. [11]

Nitrogen dioxide is corrosive if it comes into contact with the skin or respiratory tract (H314), and inhalation of the gas or the vapour may cause lung oedema (H330)[14]. Long-term or repeating exposure may have effects on immune system and pulmonary tissue resulting in decreased resistance to infection. In addition, nitrogen dioxide possibly exerts toxic effects upon human reproduction. [11]

Nitrous oxide may alter the activity of the central nervous system, and with prolonged or repeated exposure may have effects on bone marrow and the peripheral nervous system. This substance may also cause reproductive toxicity in humans. In a liquid form, nitrous oxide may cause frostbite. [11]

Sulphur dioxide

Sulphur dioxide is formed from fuel matter during incineration processes, such as energy and waste combustion. Sulphur dioxide is a colourless gas, which irritates the eyes and respiratory tract. It can cause severe superficial burns and eye damage (H314). Inhalation may cause asthma-like reactions and repeated or prolonged inhalation exposure may trigger asthmatic attacks (H331). [14] This substance may cause frostbite if a worker comes into contacted with its liquid form.

Reduced sulphuric compounds

Reduced sulphuric compounds, such as hydrogen sulphide, dimethyl sulphide, or methyl mercaptan can be formed, in waste dumps and composts which have been poorly ventilated. In addition to their unpleasant smell, inhalation of reduced sulphur-containing compounds causes serious health effects even of small concentrations. Exposure to sulphuric compounds prevents energy metabolism and thus is very harmful, especially to tissues which have large energy demands, e.g. brains, kidneys, and hearth.

Hydrogen sulphide can irritate the eyes and respiratory tract, and it may impare the activity of the nervous system. Inhalation of the gas can cause lung oedema (H330) and the liquid form may cause frostbite, though these effects may be delayed [14]. Dimethyl sulphide is irritating to eyes and skin and it can potentially to be neurotoxin. Methyl mercaptan is toxic if inhaled (H331) and it irritates eyes and respiratory tract and it may exert central nervous system effects. The effects may be delayed as well. [11] [14] [15]

Other gases in waste management

Methane gas and carbon dioxide have been identified as the primary health hazards present in landfill sites. High methane concentrations in the air cause permanent damage to health, because they prevent tissues obtaining oxygen. Carbon dioxide has actions on the respiratory tract and central nervous system. It can cause frostbite, and prolonged or repeated exposure may have metabolism consequences [15]. Carbon monoxide might be a problem in composting plants and, in addition, it can also be present in diesel exhaust [7]. It is toxic if inhaled (H331) and may exert effects on blood, and the cardiovascular and central nervous systems (H372). It is suspected of damaging fertility and it may damage the unborn child (H360D). [11] [14] [15]

Volatile organic compounds

In the waste management sector, volatile organic compounds (VOCs) can be released directly from waste materials or they are released due to metabolic activity of micro-organisms. The health effects of volatile organic compounds are typically evaluated by total amount of these compounds. Even low concentrations of VOCs may cause acute health effects most commonly to the eyes and respiratory tract. However, workers in waste management can be exposed to some VOCs also through skin contact. Many of the volatile organic compounds, e.g. benzene, toluene, dichloromethane, tetrachloroethylene, trichloroethylene, dichloroethane, phthalates, butadiene and dimethylacetamide found in waste are carcinogenic, mutagenic and reprotoxic chemicals (CMR chemicals). A mixture of VOCs has been found to cause irritation in the respiratory tract and inflammatory responses in the upper airways. [7]

Other chemical compounds

Polychlorinated dibenzo-p-dioxins (dioxins) and polychlorinated dibenzofurans (furans) are well known pollutants, and these are produced during waste incineration at temperatures below 800 °C, or when combustion is incomplete, or if polyvinyl chloride (PVC) plastics are incinerated. The health effects of dioxins and furans are, known to cause impairment of the immune system and the development of nervous system as well as reproductive functions. Dioxins are classified as a known human carcinogen. Furthermore, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can cause allergic dermatitis, chloracne and gastrointestinal disturbances. [7] [11] [17]

Polychlorinated biphenyls (PCB) can be considered as a problem in waste management for the same reasons as dioxins and furans, or when handling PCB containing waste [7]. It is known that PCB compounds may cause chloracne, liver damage, and reproductive effects, and they increase the risk for cancer. [11]

Polyaromatic hydrocarbons (PAH) are formed during all kinds of incomplete combustions. Most PAH compounds are carcinogenic and mutagenic. For example, naphthalene is a PAH compounds. Acute exposure to naphthalene by inhalation or by dermal contact has been reported to cause hemolytic anemia and to damage the liver. It may be a reproductive poison and possibly it is also carcinogenic. [11]

A wide range of exposure to chemical compounds can occur in hazardous waste management depending on the type of waste material being handled. Workers in this sector should be able to protect themselves against dangerous substances if the management of hazardous waste has been well organised and the workers have been trained about safe handling of hazardous materials.


Particles and aerosols in the waste management sector

General

Workers in waste management are also exposed to high levels of dust. Small particles are most harmful because they can penetrate deep into the respiratory tract, even as far as the alveolus. Elevated concentrations of particles might increase the likelihood of an asthmatic attack, imparing pulmanory capacity and increasing respiratory inflammation. [7]

Asbestos

Several naturally occurring fibrous silicate minerals are called asbestos. They are characterized by their separate advatageous thin, durable threads. Asbestos was once widely used because of its properties: it is heat resistant, withstands attacks from acids and other chemicals, is a good insulator, has a high strength and can be woven. Nowadays the use of asbestos is forbidden in many countries. In 1983, the European Union issued a Council Directive 83/477/EEC on the protection of workers from the risks related to exposure to asbestos at work. [19] In 2003 the EU banned the extraction of asbestos and the manufacture and processing of asbestos products (Directive 2003/18/EC)[20]. Furthermore, in 2005 all types of utilization of asbestos (Directive 1999/77/EC) were banned [21]. However, asbestos is still present in many buildings and other structures. Building maintenance workers and workers in the waste management sector (e.g. handling demolition waste) are at a high risk of coming into contact with the fibres [22].

Depending on the type of the fibres and the level and duration of exposure these health problems can lead to asbestosis, a chronic lung disease causing shortness of breath, coughing, and permanent lung damage and lung cancer. A smoker is 50 times more likely to develop lung cancer than a non-smoker if exposed to asbestos. There is no known safe level of exposure to asbestos. The time between exposure to asbestos and the first signs of disease can be as long as 30 years [23].

Other mineral dusts

Workers in the waste management sector may also be exposed to other mineral dusts. Crystalline silica is one such mineral dust and it is a basic component of soil, sand, granite, and many other minerals. Quartz is the most common form of crystalline silica. Crystalline silica has been classified as a human lung carcinogen. Additionally, breathing crystalline silica dust can cause silicosis. Smoking is known to cause lung damage and it adds to the damage caused by breathing silica dust [24], [25]. It is possible that workers in waste incinerator plants cannot be exposed to quartz.

Man-made mineral fibres

Man-made mineral fibres (MMMF) do not occur in nature. The significant commercial production of man-made mineral fibres began in the early twentieth century. MMMF products can release airborne respirable fibres during their production, use and removal. MMMF may irritate eyes, skin and the respiratory tract. Prolonged exposure to these fibres could lead to long-term effects, and some types of mineral wool are considered as possible carcinogenic to humans, in a similar manner to asbestos. This effect may depend upon the properties of the fibres, i.e. their diameter and length, chemical composition and persistence within the body [17], [26].

Wood dust

Airborne wood particles, wood dust from materials made from wood e.g. building materials in waste processes present a potential health problem. Inhalation of these particles may cause skin disorders, obstruction in the nose, and rhinitis, asthma and a rare type of nasal cancer. The extent of these risk and the associated wood types have not been clearly established [17], [27].

Nanomaterials

Nanomaterials possess unique chemical, physical and mechanical properties, and therefore they are incorporated into a wide variety of applications in different industrial branches, ranging from food and feed products to transport-related equipment. New sophisticated multicomponent or hybrid materials are being designed at an accelerated pace. Developing these innovative materials is an important driver for European competitiveness, but the increased use of nanomaterials also means that an increasing number of workers are potentially exposed at every stage of the material’s life cycle, from research and development through production to disposal and waste treatment. Nanomaterials, also called nanoparticles or ultrafine particles may have very different health hazards as the same substance present at a large size. The health effects of nanomaterials are mostly based on animal (in vivo and cells) laboratory studies, but some epidemiological and toxicological studies are also available. Exposure to ultrafine particles like diesel exhaust has been claimed to linked to higher mortality and aggravation of asthma and lung cancer. Metal oxide fumes may lead to so-called metal fume fever, which is an influenza-like disease. Nanomaterials have also been linked many other symptoms, e.g. cardiovascular effects, pulmonary effects, dermal toxicity as well as cytotoxicity and oxidative stress of cells [28], [29], [30], [31].


Exposure in the waste management sectors

Collection, sorting and recycling of waste, disposal to landfill

During collecting of waste and working in landfills workers are exposed to high levels of dust, which may contain bioaerosols, asbestos, crystalline silica, man-made mineral fibres, nanoparticles and metals. Bioaerosols, i.e. airborne particulate matter associated with micro-organisms and their fragments, are generated by physical handling of waste in a number of ways. Different processes, such as shredding and crushing of waste, may be significant sources of airborne particles and bioaerosols. Particularly high levels of bioaerosols may be emitted from the prolonged storage of waste. During handling operations, such as manual waste sorting and recycling facilities, workers can also be injured by materials contaminated by micro-organisms. Exposure to bioaerosols during waste collection and landfills depends on which micro-organisms are present in the waste, the type of container and truck, working methods and weather conditions.

Workers may be exposed to metals during collecting and handling of toxic waste. For instance, it is possible to be exposed to lead, mercury, and cadmium when recycling batteries. Exposure to chromium may take place when a worker handles materials during their recycling. Exposure to harmful chemicals may occur directly via recycling or in an indirect manner. For example, potential exposures to electronic waste (e-waste) involves the original constituents of the equipment, substances added (for example acids for chemical stripping of precious metals) during the recovery process, and substances formed as a result of the recycling process itself. The incorrect disposal of e-waste constitutes one of the most dangerous sources of inorganic arsenic entering the environment. The products made from recycled waste might also contain harmful chemicals. Volatile organic compounds include also some offensive smelling compounds, carbon dioxide, methane and aromatic and chlorinated hydrocarbons, which can released into the air during waste processing. Ammonia and reduced sulphuric compounds may be produced from waste in landfills. Up to 110 different volatile organic compounds (VOCs) have been detected during waste management processes. Dioxins, furans and PCBs might also be a problem [7].

Composting plants

It is difficult to control and prevent the spread of biological agents into air from the biomass present in a composting plant, and therefore high levels of biological agents are present in the ambient air. Different micro-organisms react differently to the conditions during composting. Enteric bacteria and viruses are likely to be killed by the temperature and low moisture, but some fungi can proliferate in the warm moist stage and then form spores once the composted waste dries out. Sporulating bacteria may also survive in the composting process as heat resistant spores. Prior treatment of waste, turning of compost piles and sieving of the final outcome of the compost are the most hazardous stages in processing, where compost workers handling the compost are often exposed to high levels of various aerosols and particles [7].

Elevated levels of gaseous substances, such as ammonia, VOCs, nitrogen dioxide, sulphur dioxide, hydrogen sulphide and other reduced sulphuric compounds, may also be detected inside of waste treatment plants. The gases are primarily derived from microbes in the decaying organic waste mass. Nitrogen dioxide may originate from the exhaust emissions of machinery.

Bioenergy producing facilities and incineration

Bioenergy is renewable energy produced from materials derived from biological sources (e.g. using anaerobic digestion). [32] As a fuel it may include biowaste consisting of wood, straw, manure, sugarcane, and many other byproducts from a variety of agricultural processes. The highest exposure to biological and chemical substances occurs during waste reception and handling before treatment. Elevated concentrations of hazardous substances may occur during the opening process, especially in the areas with enclosed tanks or lines. If gases are able to leak from the digester, ignition and explosion associated with methane and hydrogen are the main risks.

Workers may be exposed to smokes and gases in waste incineration process. Bioaerosols can be present in waste reception and storage. There may be significant exposure to heavy metals, quartz, dioxins, furans, PAH compounds and solvents is during the handling combustion ash and in cleaning and maintenance operations. These areosols can bind to solid particles. Nitric oxide, nitrogen dioxide and nitrous oxide can be released from energy production process and also from waste incineration. Dioxins and furans as well as PCBs and PAHs are well known pollutants, which might be produced as waste combustion by-products [7], [32].

Legal requirements and occupational exposure limits

Workers should be protected against risk of harmful substances since there are both national and [[Waste Management (Introductory article) | EU legislations]] regulating worker safety. Occupational exposure limits (OELs) represent an important tool for risk assessment and management. Some of the OELs of hazardous substances in waste management sector are presented in table 1. No legally binding limits for bioaerosols have been established. A health- based recommended OEL (8-hour TWA) for endotoxin could be 90 EU/m3 (9 ng/m3), because no adverse health effects are expected to occur after chronic occupational exposure below that level. [5]

Table 1. Some occupational exposure limits (mg/m3, if something else isn’t mentioned) of the most important hazardous substances in waste management sector.
Source: Adapted from Gestis Substance Database [11], NIOSH Pocket guide to chemical hazards [12] and EH40/2005 Workplace exposure limits [33]


Prevention and control of dangerous substances

At first an inventory of the chemical and biological substances in the waste management processes has to be made in the workplace. In addition, dangerous substances generated by the process, such as dusts, fumes and aerosols, have to be taken into account. Identifying dangerous substances in the waste management processes is very challenging because of the lack of labelling and the lack of safety data sheets on many of the substances present in the waste. Even though it presents a challenge, it is important to assess the potential exposure to the identified dangerous substances, examining the type of compounds and their potential hazardousness, intensity, length, frequency and occurrence of exposure to workers. Measurements can be carried out if needed to determine the level of exposure. The severity of the established risks has to be ranked. The ranking list can then be used to draw up an action plan to protect workers. If a hazardous chemical is known to be present in the waste collection, then one should refer to the material safety data sheet provided by the manufacturer of the chemical, and observe all relevant precautions related to the chemical.

Substitution and elimination

Exposure in waste management sector can be prevented if one is able to avoiding the dangerous substances in products which end up in the waste. If not possible, then the forming of hazardous waste should be eliminated. The use of certain hazardous substances in electrical and electronic equipment is restricted according to EU Directive 2002/95/EC [16]. In addition, in order to prevent the generation of hazardous waste, the Directive requires the substitution of various heavy metals (lead, mercury, cadmium and hexavalent chromium) and brominated flame retardants – polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE). Hazardous substances are also to be avoided when substituting hazardous products for safer ones, such as using water based paints instead of their solvent-based counterparts. Optimisation of the composting process, gas treatment with biofiltration can reduce VOC emission levels as well as the concentration of ammonia and other odourous compounds in composting plants.

The formation of dioxins and furans can be reduced by optimisation of the incineration process. [1] In the disposal of biological hazards such as medical and clinical waste, it is important to store them into spill-proof containers. The safe packaging, labeling and documentation requirements for infectious substances are described in the guidelines of the World Health Organization [34], [35]. Diseases-carrying vectors such as rodents have to be eliminated from waste be keeping it in closed bins. Avoiding long storage times of wastes and their storage in dry and cold circumstances prevent the multiplication of micro-organism in the waste. Waste management processes should also be developed in order to minimize the formation of harmful substances.

Isolation

Work processes in waste management should be designed in a way that when using adequate equipment and materials, then one can reduce workers’ exposure to dangerous substances. Avoiding the generation and release of bioaerosols, dust and gas into the air from waste is an effective prevention measure. [1] The risks are likely to be minimal in situations where processes are entirely automated and enclosed. Doors and windows of vehicles must be closed when they are involved in waste. However, maintenance and repair workers may have to enter enclosed spaces and therefore are still at a high risk. Specific measures have to be put into place for these operations.

Ventilation

Effective extraction ventilation of processes, a good supply of fresh air to the workspace, local and general ventilation and working inside a sealed cap with air filtration have a major impact on reducing exposure to hazard airborne substances. A high efficiency particulate air filtration is needed to remove most of the biological agents from the atmosphere in the ventilation systems. Particulate air filtration is also needed to avoid exposure to other dust particles and aerosols. Similar activated carbon filtration systems are available for gases. The regular maintenance of the ventilation systems is essential. [1]

Administrative controls

It is difficult to prevent exposure to these hazards completely by elimination and engineering controls. If the exposure is not avoidable, it should be kept to a minimum by limiting the number of exposed workers as well as the exposure time and frequency of the exposure.

Leak detection and preventive measures

The employer has to ensure that regular checks for chemical leaks and spills are conducted. In hazardous places, workers should use gas detectors, which can visibly and audibly alert them in times of danger. Gas detectors can be used to monitor oxygen, toxic and combustible gases and vapors. In combination with the external pump, a gas detector can be adopted to screen closed workspace before the worker goes there him/herself. In particular, this has to be done, if there is confined space entry into tanks and pipelines. Similarly a gas detector mounted on the wall is necessary to alert workers who are moving only temporarily into dangerous areas, such as reception areas of waste. The gas detectors have to be maintained on a regular basis in order to ensure that they are functional when needed. In areas where there is a significant risk of harmful gases being present in the air and an acute health risk, no one should be allowed to work alone without supervision.

Personal hygiene and housekeeping

Some infectious micro-organisms can survive on surfaces for extended periods of time. Therefore, regular housekeeping is very important in order to inhibit the growth and spread of micro-organisms. Surfaces on the workplaces in the waste management should be designed to be easy to clean and workers should have good facilities for washing. Workers must adhere to good personal hygiene, especially before eating, smoking, and when leaving the workplace, so that the micro-organisms and harmful chemicals are unable to be absorbed inside the body or transmitted to another environment on the clothes of contaminated workers. Thus, working clothes and footwear should be stored separately from private clothing.

Training

Information for workers is required to raise their awareness about the risks and importance to work safety. Workers have also to be trained for safe working practices. The training should ensure that workers should be aware of the risk of exposure and how they can control their exposure to the risk.

Medical surveillance

Waste workers should undergo pre-employment screening and regular health surveillance. Individuals with asthma who are sensitized to A. fumigatus or who have some other respiratory disease or who are immunosuppressed should avoid working with biological waste, unless their exposure to bioaerosols can be controlled [36]. Waste-handling workers can be vaccinated against some pathogens [37]. Vaccine-preventable diseases are hepatitis A and B or tetanus. The available vaccines should be given to those workers who are not already immune or have not been immunized against the biological agents to which they may be exposed.


Personal protective equipment

Harmful substances in waste products or their spread in waste management should be reduced by elimination, substitution, collection techniques or actions in working habits. If workers are still exposed this needs to be prevented by using personal protective equipments. In this case, the workers have to be trained in the appropriate use of personal protective equipment.

Respiratory protection

It is important to choose appropriate Respiratory protection equipment – requirements and selection respiratory protective equipment fitting well onto the face of the individual worker . The selection will be done carefully by fitting a person with a variety of options. The best option for waste management workers is a fan-assisted respiratory protection device system equipped with a combination of P3 particle and ABEK gas filters, with the protection class of TH3 or TM3. These systems will protect the workers’ face and eyes at the same time. Other safety categories are inadequate to protect the workers who are handling of biological agents including of those waste materials. The filtering face piece classified as FFP3 and marked with the letter R (reusable) is suitable if used in the short-term, up to a maximum of 2 hours’ duration of work.

Protective clothing

The use of protective coveralls and utilizing the services of a work wear laundry company can reduce workers’ exposure to biological and chemical agents in waste management. The leak thickness and the resistance to permeation and penetration by biological and chemical substances have to be considered in the selection of protective clothing. The mechanical strength of gloves is very important for manual operation conducted by waste workers to prevent infectious punctures through the skin. Similar protection is needed for the feet against hazardous substances.

Conclusions

It is very important to prevent and control of workers’ exposure in the waste management sector where they are confronted by many potential biological and chemical risks. The exposure to dangerous substances, such as micro-organisms, gases and metals, has been associated with a wide range of health effects: acute toxic effects, respiratory symptoms and diseases, infections, allergies and cancer. In particular, knowledge and research are needed about the occupational risks related to waste recycling technologies (e.g. landfill mining) and biowaste treatment (e.g. bioenergy producing facilities).


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Links for further reading

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Contributors

Deroiste, Sirpa Laitinen