Highlights of this issue

CMAJ 2001;164(4):457

"Should asbestos be banned worldwide?" is the question at the centre of this issue's controversy. Asbestos is known to cause lung fibrosis and cancer, but can the risks be controlled by technology or regulation of workplace practices? Do the health effects depend on the form of asbestos? Are substitutes satisfactory and safe, or do they carry their own risks? Will a country-by-country ban lead to the transfer of harm from developed to developing countries? Or is an international ban on asbestos a paternalistic action by the developed world that, like the ban on DDT, may have unforeseen consequences? These issues and arguments are debated by Joseph LaDou and colleagues from the Collegium Ramazzini, Michel Camus and Jack Siemiatycki.

Much of the asbestos debate hinges on disagreement about risks. In the final article of our Environment and Health series, John Bailar and John Bailer consider the science that underlies risk assessment. It is no single science but, rather, a multidisciplinary endeavour involving, among others, biologists, chemists, pathologists, toxicologists, epidemiologists, statisticians, hydrologists and meterologists. The data are complex and often incomplete; the outcomes are bounded by uncertainty and often controversial; risks are usually offset by benefits; and we do not know how best to weigh the one against the other. Nevertheless, decisions must still be made. The authors outline current strategies for deciding what is, and is not, acceptable risk.

The uptake of clinical practice guidelines has generally been limited, and physician, patient and practice barriers have been identified. In this issue, Finlay McAlister and colleagues review guidelines for the management of hypertension and consider their possible shortcomings. Possible barriers to uptake in this case include discordant recommendations, methodological deficiencies, overemphasis of blood pressure measurement without regard for other clinical risk factors, overly long and inaccessible formats, and a lack of local endorsement or applicability. In addition, current distribution strategies emphasize dissemination rather than implementation. The authors discuss methods for improving the latter.

Group B Streptococcus (GBS) is the most frequent cause of serious neonatal infection in North America. The effectiveness of intrapartum antibiotic prophylaxis is agreed upon; the best means of identifying patients in need less so. Several consensus statements were released between 1994 and 1997. Dele Davies and coworkers surveyed physicians' screening practices in 1994, 1995 and 1997. The proportion of physicians who screened at least 75% of pregnant women increased from 77% (754/981) in 1994 to 85% (693/812) in 1997, and the proportion who conformed completely with any of 3 consensus guidelines increased from 10% to 29%. Concurrently, the incidence of neonatal GBS disease decreased significantly.

Art Explosion Screening mammography has been shown to reduce breast cancer mortality among women aged 50–69 years. However, its appropriateness for younger women at average risk of breast cancer remains controversial. Jolie Ringash, with the Canadian Task Force on Preventive Health Care, has reviewed the evidence regarding the effectiveness of screening mammography that has accumulated since the task force's 1994 recommendation against the manoeuvre for women aged 40–49. The task force concludes that the current evidence does not support the manoeuvre's inclusion in, or its exclusion from, the periodic health examination of women under 50 years of age. It recommends that, upon reaching 40, women be told about the potential benefits and risks and assisted in deciding when they wish to initiate screening. In a related commentary Mary Barton underlines the relative paucity of information on harm and the uncertainties as to how best to counsel women about breast cancer screening.

Copyright 2001 Canadian Medical Association or its licensors