REVIEW OF HEALTH-RELATED ASPECTS OF BIOSOLIDS LAND APPLICATION

Under direction of Ottawa City Council (Ontario, Canada), the Medical Officer of Health (MOH) retained a consultant team to review health-aspects of land application of anaerobically digested, dewatered biosolids. At the time, in response to public concern, Council had suspended the land application program pending the outcome of the MOH's recommendation. The team had three months to complete the review before the next spreading season.The investigation focused on three groups of contaminants which had been identified by an earlier Water Environment Association of Ontario study as “not having sufficient, credible evidence to demonstrate they are not of concern in sewage biosolids”, namely:PathogensUnregulated MetalsEstrogenic hormones and pharmaceutically active compoundsAlso the “emerging issues” of polybrominated diphenyl ethers (PBDEs) and odour-related health effects were identified. The review included both a literature search and interviews with specialists reflecting the spectrum of views on these topics. A review of health studies was added to provide an overall perspective on the information collected. The lack of rigorous case reports and epidemiological investigations relevant to the particular product and application methods in use was noted.The paper summarizes the findings in each of these areas which lead the MOH to recommend the resumption of land application with the implementation of proposed Best Management Practices and ongoing monitoring of both application processes and the scientific literature. Nevertheless, Ottawa City Council elected to end land application of anaerobically digested, dewatered biosolids based on odour-related symptom experiences of residents near to application sites.