Chemistry International
Vol. 21, No.5, September 1999

1999, Vol. 21
No. 5 (September)
.. President's Report
.. News from IUPAC
.. Highlights from the Web
.. New Projects
.. Provisional Recommendations
.. New Books and Publications
.. Awards and Prizes
.. Conference Announcements
.. Conferences

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Chemistry International
Vol. 21, No. 5
September 1999

New Books and Publications


New Publications from the World Health Organization

Chrysotile Asbestos, Environmental Health Criteria No. 203

1998, xxi + 197 pages (English with summaries in French and Spanish), ISBN 92 4 157203 5, CHF 42./USD 37.80; In developing countries: CHF 29.40, Order no. 1160203. WHO distribution and sales, CH-1211 Geneva 27, Switzerland; E-mail: Publications@who.ch; Tel.: +41 22 791 24 76; Fax: +41 22 791 48 57.

This book evaluates the risks to human health and the environment posed by exposure to chrysotile asbestos. Also referred to as white asbestos, chrysotile is a naturally occurring fibrous hydrated magnesium silicate mineral having many commercial applications. Chrysotile is released to the environment from industrial sources. In addition, natural weathering of serpentine rock results in emissions to air and water.

Although the health risks associated with mixed exposures to the main commercial forms of asbestos (crocidolite, amosite, and chrysotile) are known, the evaluation was undertaken in response to the continuing widespread production and use of chrysotile following the International Labor Organization's recommendation to discontinue use of crocidolite asbestos, and taking into consideration that amosite is virtually no longer exploited. The asbestos cement industry is singled out as by far the largest current global user of chrysotile fibers. Main applications include production of corrugated sheets; flat sheets and building boards; slates; molded goods, including lowpressure pipes; and highpressure water pipes. Chrysotile is also used, in much smaller quantities, in the manufacturing of friction products, gaskets, and asbestos paper.

In assessing the health risks posed by chrysotile asbestos, the evaluation faced a number of methodological problems, including the industry-specific nature of exposure_response relationships, and difficulties with the interpretation of exposure data from older studies, which did not differentiate between exposures to amphiboles (crocidolite, amosite) and serpentine (chrysotile) fibers. Conclusions and recommendations reflect the consensus reached by a large group of scientists selected solely on the basis of their contribution to the open scientific literature. Some 500 references to the literature are included in this carefully documented assessment.

The report opens with a review of methods used for collecting and analyzing samples, followed by a discussion of sources of occupational and environmental exposure. Studies indicate that exposure may occur during mining and milling, processing of asbestos into products, construction and repair activities, and transportation and disposal of waste products containing chrysotile. Exposure to chrysotile fibers during construction, maintenance, or demolition of buildings is judged likely to entail high risks. Subsequent sections summarize levels of chrysotile detected in the environment and in various occupational settings, and review what is known about the uptake, clearance, retention, and translocation of inhaled or ingested fibers.

The most extensive sections review the results of toxicity studies conducted in laboratory mammals and in vitro test systems and of epidemiological studies in occupationally exposed workers. For humans, the report concludes that exposure to chrysotile asbestos poses increased risks for asbestosis, lung cancer, and mesothelioma in a dose-dependent manner, and confirms previous findings that asbestos exposure and cigarette smoking interact to increase the risk of lung cancer greatly. The report did not identify a threshold for carcinogenic risks. Evidence that exposure to chrysotile increases the risk of cancer at sites other than the lung was judged inconclusive.

To reduce the health risks posed by exposure, the report calls for the use of engineering and other control measures in workplace settings where occupational exposure continues to occur, and further concludes that, where safer substitute materials are available, these should be considered for use.

The Use of Essential Drugs, Eighth Report of the WHO Expert Committee (including the Revised Model List of Essential Drugs), Technical Report Series No. 882

1998, vi + 77 pages (available in English; French and Spanish in preparation), ISBN 92 4 120882 1, CHF 19./USD 17.10; In developing countries: CHF 13.30, Order no. 1100882.

This report presents and explains the tenth model list of essential drugs issued by WHO as part of its efforts to extend the benefits of modern drugs to the world's population. Intended to guide the selection of drugs in countries where the need is great and resources are small, the list identifies a core group of prophylactic and therapeutic substances judged capable of meeting the vast majority of health needs and thus deserving priority in purchasing decisions and procurement schemes. The model list also serves as an information and educational tool for health professionals and consumers, and facilitates the development of treatment guidelines, national formularies, information for patients, and other measures to improve drug use.

WHO model lists, the first of which was issued 20 years ago, are regularly updated to ensure that recommendations are in line with the latest data on the comparative safety, efficacy, and costs of specific drugs, as well as their relevance to priority health problems. Factors of stability, quality control, and international availability are also considered when validating and revising the lists.

The first part of the report provides updated information on several components of national drug policy necessary to ensure that essential drugs, corresponding to essential health needs, are available at all times in adequate amounts and in the proper dosage. Information includes selected requirements for quality assurance, advice on the compilation of shorter lists of essential drugs for use in primary health care, strategies for postmarketing surveillance and reporting of adverse drug reactions, and the role of relevant and reliable drug information in promoting the rational use of drugs. Also discussed is the growing problem of resistance to some of the widely available and relatively cheap antimicrobials included in the list, and the corresponding need for reserve antimicrobials.

The tenth WHO model list of essential drugs is presented in the second part, together with an explanation of changes made when revising the list. Organized according to therapeutic group, the list includes information on route of administration, dosage forms, and strengths for each of 306 drugs. To qualify for inclusion, a drug must be supported by sound data demonstrating safety, efficacy, and consistent performance in a variety of medical settings.

Among the most significant changes in the list are the inclusion of zidovudine for preventing the transmission of HIV from mothers to newborn infants, the addition of drugs for the treatment of opportunistic infections in immunocompromised patients, the replacement of several antiinfective drugs with safer and more effective preparations, and the addition of a new drug, triclabendazole, for the treatment of liver and lung flukes. The list also includes changes in line with the latest treatment regimens recommended in several WHO-sponsored programs for disease control.

 

 

 

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