Environmental features influencing the epidemiology of breast cancer

A recent study claimed that a larger proportion or breast cancer was due to environmental exposures than to hereditary factors. This controversial pub lication clearly indicates the essential importance of investigating the ge ne-environment interaction and having a clear idea of what are the essentia l environmental factors to investigate. Environmental exposures are a subje ct of current interest in breast cancer aetiology and two common issues are exposure to electromagnetic fields (EMFs) and certain pesticides, fungicid es and their residues. Overall. there does not appear to be an identifiable increased risk associated with domestic exposure to EMF, although there is a need for good studies with direct estimates of exposure. Oestrogens from a variety of sources. including chemical exposures, are determinant in bre ast cancer risk in women. Attention has recently increasingly focused on en vironmental exposures and environmental chemical pollutants as risk factors for breast cancer. The common nature of breast cancer in women., and such exposures, make such an association plausible, although far from proven as causal. Given also the resistant nature of concentrations in adipose tissue , it is important to attempt to identify any risk resulting from this expos ure. Based on current evidence, the risk of breast cancer associated with e xposure to organochlorine pesticides and their residues appears to be small , if it exists at all. However. one caveat is that the effect of individual or groups of PCBs as risk factors for breast cancer merits some further in vestigation. Indeed, a clear and powerful message which comes from recent w ork is that great care and attention must be given to any statistical analy sis of such chemical exposures given the potential for collinearity which e xists between the various chemical compounds and their congeners. (C) 2001 Harcourt Publishers Ltd.