<P> Harrison and Oakes suggest that, in particular, "until investigations are carried out that answer these questions (... about the safety of Class B sludge ...), land application of Class B sludges should be viewed as a practice that subjects neighbors and workers to substantial risk of disease ." They further suggest that even Class A treated sludge may have chemical contaminants (including heavy metals, such as lead) or endotoxins present, and a precautionary approach may be justified on this basis, though the vast majority of incidents reported by Lewis, et al. have been correlated with exposure to Class B untreated sludge and not Class A treated sludge . </P> <P> A 2005 report by the state of North Carolina concluded that "a surveillance program of humans living near application sites should be developed to determine if there are adverse health effects in humans and animals as a result of biosolids application ." </P> <P> After treatment, and dependent upon the quality of sludge produced (for example with regards to heavy metal content), sewage sludge is most commonly either disposed of in landfills, dumped in the ocean or applied to land for its fertilizing properties, as pioneered by the product Milorganite . </P> <Table> <Tr> <Td> </Td> <Td> This section needs expansion . You can help by adding to it . (June 2018) </Td> </Tr> </Table>

What happens to sludge from a sewage treatment plant
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