Applying the UASB reactor to treat sewage sludge containing sulphides

About 50 epidemiological reports about possible associations between cancer morbidity and exposure to electromagnetic fields (EMFs) were published between 1979 and 1994. The majority of them (60‐75 per cent) documented a slight (1.5 to twofold) but significant increase in the incidence of certain rare forms of neoplasms (leukaemia, lymphoma, brain tumours). A limited support for carcinogenic potencies of EMFs is provided from cellular studies, but the effects appear to be generally weak, transient and difficult to replicate. Concludes that the available evidence associating cancer and EMF exposure is too tenuous to be convincing but too consistent to be ignored. Further progress needs better quantification of exposure levels and conditions, evaluation of dose‐effect relationships and liability to confounding carcinogenic factors that may influence morbidity rates in the investigated populations.