SORTING AND RECYCLING OF DOMESTIC WASTE - REVIEW OF OCCUPATIONAL-HEALTH PROBLEMS AND THEIR POSSIBLE CAUSES

In order to reduce the strain on the environment from the deposition o f waste in landfills and combustion at incineration plants, several go vernments throughout the industrialized world have planned greatly inc reased recycling of domestic waste by the turn of the millennium. To i mplement the plans, new waste recycling facilities are to be built and the number of workers involved in waste sorting and recycling will in crease steadily during the next decade. Several studies have reinforce d the hypothesis that exposure to airborne microorganisms and the toxi c 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 experienc e an increased risk of pulmonary disorders and gastrointestinal proble ms. High concentrations of total airborne dust, bacteria, faecal colif orm 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 landfil ls and incineration plants. Workers involved in manual sorting of unse parated domestic waste, as well as workers at compost plants experienc e more or less frequent symptoms of organic dust toxic syndrome (ODTS) (cough, chest-tightness, dyspnoea, influenza-like symptoms such as ch ills, fever, muscle ache, joint pain, fatigue and headache), gastroint estinal problems such as nausea and diarrhoea, irritation of the skin, eye and mucous membranes of the nose and upper airways, etc. In addit ion cases of severe occupational pulmonary diseases (asthma, alveoliti s, bronchitis) have been reported. Manual sorting of unseparated domes tic waste may be associated with exposures to large quantities of airb orne bacteria and endotoxin. Several work functions in compost plants can result in very high exposure to airborne fungal spores and thermop hilic actinomycetes. At plants sorting separated domestic waste, e.g. the combustable fraction of waste composed of paper, cardboard and pla stics, the workers may have an increased risk of gastrointestinal symp toms and irritation of the eyes and skin. At such plants the bioaeroso l exposure levels are in general low, but at some work tasks, e.g. man ual 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, a nd the bioaerosol exposure is generally low. To our knowledge no studi es have yet been published on occupational health problems and exposur es in relation to recycling of glass or metal tins, or in relation to the production of biogas from biodegradable domestic waste. Limited in formation exists on the risk and causal factors of the occupational he alth problems, and analytical epidemiological studies and surveillance programmes need to be undertaken to elucidate causal links between ex posures and work-related health problems. These programs can provide d ata which can be used for administrative regulations and recommendatio ns, e.g. establishment of occupational exposure limits (OELs), to prev ent occupational health problems at existing waste recycling plants as well as the large number of plants to be built throughout the industr ialized world in the near future. When establishing such OELs attentio n 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, viabl e versus total microorgamsms and static area air sampling versus perso nal air sampling. In addition, synergistic interactions between the di fferent components of the bioaerosol exposure as well as individual su sceptibility may be of importance when OELs for exposures at waste sor ting and recycling plants are to be established.