This paper summarizes the published literature and current problems relating to possible cancerogenic effects of occupational and residential exposure to ELF electromagnetic fields at levels slightly above ambient background. There are several suggestions that such an exposure may increase the risk of cancer, but these studies failed to provide conclusive indications. The present state of uncertainty led to a variety of recommendations and statements being made concerning restrictions to the exposure of people to ELF electromagnetic fields. Attempts to detect direct chromosomal damage from ELF electromagnetic fields have proven negative, while results on cancer promotion have been controversial. On the basis of several epidemiological studies on occupational exposure, an increased risk of leukemia, brain cancer and male breast cancer is apparent; the literature on residential exposure provides some evidence of an effect on childhood cancer, especially leukemia; however, when interpreting these results some major methodological concerns should be kept in mind. In conclusion, the public concern and potential public health impact of this environmental agent argue strongly for addressing further research in order to identify mechanisms of action on biological systems, to define the proper assessment of exposure and to obtain good epidemiological evidence.

Adolescent↗

PubMedDate not supplied

[The use and utility of multistage models of carcinogenesis in cohort studies].

Multistage models have been widely employed in recent years and are thought to be useful for the interpretation of biological bases of epidemiological results. We have employed two general models, both interpretable under the multistage theory, using GLIM package for the simultaneous analysis of the effect on mortality of several factors, including age at first exposure, duration of exposure, time interval since exposure ended. In the multiplicative model (relative risk, RR) each variable is supposed to act multiplicatively on the number of expected cases. In the additive model (absolute risk, AR; excess of risk, ER) each variable is thought to act multiplicatively on the excess risk; the result is then added to the expected number of cases. These models were applied to data regarding exposure to aromatic amines and bladder cancer mortality. The results suggested that aromatic amines act on more than one stage of the carcinogenic process, most probably on both early and late stages. In addition, hints for prevention measures were obtained. In fact, the effect on late stages implies a decreasing risk after cessation of exposure, and in this case discontinuing exposure can be useful; an effect on early stages, instead, indicates the necessity of intensive medical surveillance even after cessation of exposure. However, it seems that the possibility of obtaining results interpretable under the multistage theory is at present confined to the rare cases in which there is a substantial excess mortality from specific cancers.

Age Factors↗