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: [email protected];
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.