Sorting and recycling of domestic waste. Review of occupational health problems and their possible causes

Abstract

In order to reduce the strain on the environment from the deposition of waste in landfills and combustion at incineration plants, several governments throughout the industrialized world have planned greatly increased recycling of domestic waste by the turn of the millennium. To implement the plans, new waste recycling facilities are to be built and the number of workers involved in waste sorting and recycling will increase steadily during the next decade. Several studies have reinforced the hypothesis that exposure to airborne microorganisms and the toxic products thereof are important factors causing a multitude of health problems among workers at waste sorting and recycling plants. Workers at transfer stations, landfills and incineration plants may experience an increased risk of pulmonary disorders and gastrointestinal problems. High concentrations of total airborne dust, bacteria, faecal coliform bacteria and fungal spores have been reported. The concentrations are considered to be sufficiently high to cause adverse health effects. In addition, a high incidence of lower back injuries, probably due to heavy lifting during work, has been reported among workers at landfills and incineration plants. Workers involved in manual sorting of unseparated domestic waste, as well as workers at compost plants experience more or less frequent symptoms of organic dust toxic syndrome (ODTS) (cough, chest-tightness, dyspnoea, influenza-like symptoms such as chills, fever, muscle ache, joint pain, fatigue and headache), gastrointestinal problems such as nausea and diarrhoea, irritation of the skin, eye and mucous membranes of the nose and upper airways, etc. In addition cases of severe occupational pulmonary diseases (asthma, alveolitis, bronchitis) have been reported. Manual sorting of unseparated domestic waste may be associated with exposures to large quantities of airborne bacteria and endotoxin. Several work functions in compost plants can result in very high exposure to airborne fungal spores and thermophilic actinomycetes. At plants sorting separated domestic waste, e.g. the combustable fraction of waste composed of paper, cardboard and plastics, the workers may have an increased risk of gastrointestinal symptoms and irritation of the eyes and skin. At such plants the bioaerosol exposure levels are in general low, but at some work tasks, e.g. manual sorting and work near the balers, exposure levels may occasionally be high enough to be potentially harmful. Workers handling the source-sorted paper or cardboard fraction do not appear to have an elevated risk of occupational health problems related to bioaerosol exposure, and the bioaerosol exposure is generally low. To our knowledge no studies have yet been published on occupational health problems and exposures in relation to recycling of glass or metal tins, or in relation to the production of biogas from biodegradable domestic waste. Limited information exists on the risk and causal factors of the occupational health problems, and analytical epidemiological studies and surveillance programmes need to be undertaken to elucidate causal links between exposures and work-related health problems. These programs can provide data which can be used for administrative regulations and recommendations, e.g. establishment of occupational exposure limits (OELs), to prevent occupational health problems at existing waste recycling plants as well as the large number of plants to be built throughout the industrialized world in the near future. When establishing such OELs attention should be paid to a series of technical problems which have not yet attracted sufficient attention: average versus peak airborne exposure, total versus inhalable aerosol exposure, microbial viriability, viable versus total microorgamsms and static area air sampling versus personal air sampling. In addition, synergistic interactions between the different components of the bioaerosol exposure as well as individual susceptibility may be of importance when OELs for exposures at waste sorting and recycling plants are to be established.