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Current sun safety messages stress the importance of sun protection in avoiding the consequences of excessive exposure to ultraviolet radiation (UVR), such as skin cancers, cataracts and other eye diseases, and viral infections caused by UV-induced immunosuppression. However, adequate exposure to UVR has an important role in human health, primarily through UV-induced production of vitamin D, a hormone essential to bone health. Vitamin D insufficiency may be associated with increased risks of some cancers, autoimmune diseases and mental health disorders such as schizophrenia. Here, we review the evolution of current sun exposure practices and sun-safe messages and consider not only the benefits, but also the detrimental effects that such messages may have. UVR-induced vitamin D production can be inhibited by factors such as deep skin pigmentation, indoor lifestyles, older age, sun avoidance behaviours and clothing habits that limit skin exposure, with deleterious consequences for health. There is some early evidence that sun-safe messages are beginning to cause a decrease in skin cancer rates in young people. After the widespread promotion of sun safety, it may now be appropriate to refine public health messages to take better account of variations between groups and their susceptibility to the dangers and benefits of sun exposure.

Exposure to radiofrequency (RF) fields can occur in residential, occupational and medical settings. Since many technologies use RF fields, it is important to fully investigate their effects on the human body. Since the demonstrated effect of RF exposure is heating, it is important to critically evaluate studies of elevated temperature effects on the human body, from the cellular and tissue level to the whole body level, including potential effects on the susceptible groups such as the very young and the very old. WHO convened a Workshop in the Spring of 2002 on the subject of Adverse Temperature Levels in the Human. The goal of the workshop was to evaluate most recent data useful for the development of science-based RF exposure limits. This paper outlines radiation protection principles that underline such an evaluation. It discusses the quality of literature needed for sound scientific reviews, provides the hierarchy of scientific evidence used to establish effects, distinguish between biological effects and adverse health consequences and indicates how evidence is evaluated. In addition, criteria for determining the most sensitive effects, the value of an effect that has a dose-response and methods of extrapolation are also described. Finally, the need to account for scientific uncertainty in the formulation of guidance on exposure is discussed.

An international seminar on health effects of exposure to electromagnetic fields (EMF) in the frequency range from 300 Hz to 10 MHz (referred to as the Intermediate Frequency (IF) range) was held in Maastricht, Netherlands, on 7-8 June 1999. The seminar, organized under the International EMF Project, was sponsored jointly by the World Health Organization (WHO), the International Commission on Non-Ionizing Radiation Protection (ICNIRP), and the Government of the Netherlands. This report does not attempt to summarize all of the material presented at the conference, but focuses on sources of exposure, biophysical and dosimetric considerations pertinent to extrapolating biological data from other frequency ranges to IF and identifies potential health concerns and needs for developing exposure guidelines. This paper is based on presentations at the conference and reports of working groups consisting of the speakers and other experts. It concludes with recommendations for further research aimed at improving health risk assessments in this frequency range.

There has been considerable scientific effort to understand the potential link between exposures to power-frequency electric and magnetic fields (EMF) and the occurrence of cancer and other diseases. The combination of widespread exposures, established biological effects from acute, high-level exposures, and the possibility of leukemia in children from low-level, chronic exposures has made it both necessary and difficult to develop consistent public health policies. In this article we review the basis of both numeric standards and precautionary-based approaches. While we believe that policies regarding EMF should indeed be precautionary, this does not require or imply adoption of numeric exposure standards. We argue that cutpoints from epidemiologic studies, which are arbitrarily chosen, should not be used as the basis for making exposure limits due to a number of uncertainties. Establishment of arbitrary numeric exposure limits undermines the value of both the science-based numeric EMF exposure standards for acute exposures and precautionary approaches. The World Health Organization's draft Precautionary Framework provides guidance for establishing appropriate public health policies for power-frequency EMF.

While we welcome a scientific discourse on developing policy for electromagnetic fields (EMF) and on setting guideline limits, the letter by Kundi has a number of inaccuracies. The author appears not to understand the basis for the International Commission on Non-Ionizing Radiation Protection (ICNIRP, 1998), EMF guidelines, or the use of precautionary measures suggested by the World Health Organization (WHO). Two of our authors (MR and LK) were instrumental in the development of the draft WHO framework and our views are “not at odds,” but rather consistent, with it. First, the ICNIRP low-frequency EMF guideline limits are based on established adverse health consequences, namely, acute short-term effects on excitable tissues (nerve and muscle cells). The scientific evidence on the association between childhood leukemia and ELF magnetic fields is noted by ICNIRP, but is considered insufficient for guideline formulation. Second, the author’s assertion on relationships between EMF and “cardiovascular diseases, Alzheimer’s disease, amyotrophic lateral sclerosis, childhood and adult brain cancer, male and female breast cancer, and adverse pregnancy outcomes” is not supported by current scientific knowledge. A recent comprehensive health risk assessment by the WHO ELF Task Group (for publication as an Environmental Health Criteria monograph) forms the basis for our understanding of the scientific literature. It found, for example, that the evidence “does not support an association between ELF exposure and cardiovascular disease” (WHO, in press). The evidence