Chemistry International
Vol. 22, No.2, March 2000

2000, Vol. 22
No. 2 (March)
..News from IUPAC
..West Africa Chemical Society
..Reports from Symposia

..Awards and Prizes
..New Books
..Reports from Commissions
..Conference Announcements

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Chemistry International
Vol. 22, No. 2
March 2000

New Books and Publications


New Publication from the World Health Organization

Polybrominated Dibenzo-p-dioxins and Dibenzofurans, Environmental Health Criteria No. 205

1998, xxi + 303 pages (English with summaries in French and Spanish), ISBN 92-4-157205-1, CHF 66.-/USD 59.40; In developing countries: CHF 46.20, Order No. 1160205.

This book evaluates the risks to human health and the environment posed by exposure to polybrominated dibenzo-p-dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs). Of no commercial use, these compounds are generated as unwanted by-products of various industrial and combustion processes and have been detected as contaminants in a number of brominated organic chemicals, many of which are used as flame retardants.

Thermolysis of brominated flame retardants is an important source of emissions, as is the incineration of products containing these flame retardants, most notably scrap computers and business machines. PBDDs and PBDFs have also been detected in emissions of motors using both leaded petrol and unleaded petrol, with and without catalytic converters, and in emissions of diesel engines.

In view of the complexity of these compounds, the problems with analytical procedures, and substantial gaps in the experimental database, the report makes a special effort to determine the extent to which the environmental behavior and toxic effects of PBDDs and PBDFs resemble those of their better characterized chlorinated analogs, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). An effort is also made to determine the extent to which PBDDs and PBDFs contribute to the overall hazard posed by environmental ìdioxins'.

The opening sections consider currently available analytical methods for detection and analysis, and discuss the principal sources of human and environmental exposure. Although data are limited, the available evidence confirms formation of PBDDs and PBDFs during fire accidents, especially when electrical appliances are involved, during the use of flame retardants and fire extinguishers, during waste disposal and treatment, and during combustion processes in engines. Current environmental levels are judged to be much lower than those for the ubiquitous PCDDs and PCDFs. Evidence suggests that occupational exposure may occur in a variety of workplaces. Workers at greatest risk are those employed in the plastic and recycling industry, where brominated flame retardants or products containing them are used; fire fighters; and cleanup personnel associated with fires. Some monitoring results are also available for exposures in workplaces equipped with a number of electrical appliances continually in use, such as displays and computer monitors.

A section on environmental behavior cites evidence that these compounds are similar to their chlorinated analogs, with preferential distribution to carbon- or fat-rich compartments and long persistence. Data on kinetics and metabolism are assessed in the next section, which concludes that these compounds are distributed throughout the body, with major deposits found in liver and adipose tissue, followed by skin and muscle.

Data from experimental studies of toxicity support the conclusion that the thymus, lymphatic tissue, and liver are the principal targets of toxic action. Thymus atrophy and other signs of immunotoxicity were the effects most consistently seen in laboratory animals. Data on human exposures and health effects were judged inadequate to support an assessment of hazards for the general population or a recommended safe level of exposure.

In view of the growing worldwide production and use of brominated flame retardants as additives to a series of polymers, the report concludes that the amount of bromine-containing waste will be increasing in the future, and that electronic scrap from casings and printed circuit boards of computers, flame-retarded with brominated compounds, will reach the waste streams as a potentially major source of release to the environment. As the potential for toxic action of these compounds is judged similar to that of their chlorinated analogs, the report recommends that every effort should be made to prevent environmental pollution with PBDDs and PBDFs. To avoid release in the environment, the report further concludes that brominated flame retardants should be phased out and that all products flame-retarded with bromine compounds should be labeled and disposed of only in properly constituted waste incinerators designed to minimize emissions.



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