As a growing number of countries focus on reducing waste quantities through landfill diversion projects, occupational health concerns arise.
In Sealand, Denmark, eye and skin irritation, nausea, vomiting and diarrhea are some symptoms reported by workers who collected the organic waste fraction for a composting plant during the summers of 1990 to 1992. In addition, they experienced other flu-like symptoms caused by organic dust toxic syndrome (ODTS).
The problems began to occur after the collection schedule was changed from a weekly to a biweekly pickup. Substituting bins, which control leakage but must be opened for emptying, for sacks also contributed.
Hot weather and moisture in source-separated kitchen waste, combined with the less frequent collection, added to microorganism growth, according to Per Malmros of the Danish Working Environmental Service (DWES).
"Recent studies have indicated that implementation of some new waste collection systems may result in an increased risk of occupational health problems," reported Malmros, Otto Poulsen of the National Institute of Occupational Health and other Danish experts in The Science of the Total Environment.
"The few data available on exposure to bio-aerosols and volatile compounds have indicated that these waste collectors may be simultaneously exposed to multiple agents such as dust containing bacteria, endotoxin, mold spores, glucans, volatile organic compounds and diesel exhaust," they continued. Bio-aerosols contain biologically active agents such as microorganisms and their toxins.
Likewise, Malmros stated that workers at compost facilities experience relatively frequent ODTS symptoms including coughing, chest tightness, chills, fever, muscle ache and joint pain, fatigue and headache, as well as eye inflammation, weakness and gastrointestinal problems.
"In addition, cases of severe occupational pulmonary diseases (asthma, alveolitis and bronchitis) have been reported. Several work functions in compost plants can result in very high exposure to airborne fungal spores and thermophilic actinomycetes," Malmros continued.
Despite a growing number of experiments and studies in recent years, current knowledge about the risk and causal factors of occupational health problems is limited. To fill this gap, DWES is conducting a five-year research program, ending in 1997.
The program's goals are to develop new, standardized methods for measuring and evaluating the most important exposures; to determine dose-response relationships; to intensify educational programs; and to help develop guidelines, rules and regulations for safe collection and treatment.
This information will be critical as Denmark, among other European nations, strives to reduce household waste quantities and subsequent environmental impacts to the extent possible. One way Denmark can meet its 50 percent recycling goal by the turn of the century is to increase the diversion of organic waste through composting and biogas generation.
Considering the hefty investments required, Danish occupational health authorities consider it "of paramount importance to ensure a healthy work environment when such new systems and plants are implemented."
A European country with comparable waste policies, priorities and technology level is Germany, where controversy has been mounting over the need for measures to protect waste management facilities' employees. Approximately 1,500 people are employed at German compost plants and 11,000 at material recovery facilities.
In a study completed in 1995, Franz Daschner and associates at the Institute for Environmental Medicine and Hospital Hygiene, Freiburg, compiled, analyzed and interpreted all available scientific data on airborne spores in waste recovery facilities.
The researchers found that the existing literature on the topic lacks standardized measuring procedures, resulting in wide fluctuations in data; frequently fails to differentiate among the various spores; and leaves threshold values for health problems undetermined.
The study revealed that composting facilities' spore concentrations fell within ranges similar to or lower than those in other environments (see chart). According to the study, intended as a basis for informed discussion, there is insufficient evidence to support the hypothesis that the health of workers in existing composting plants and materials recovery facilities is particularly endangered by exposure to micro-organisms.
Meanwhile, the Danish experts also are calling for detailed analytical studies and monitoring programs. They see a major research challenge in describing "the causal relationship between a matrix of occupational, potentially dangerous exposures occurring simultaneously and a multitude of adverse health outcomes."