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of which two are special reports, and two book reviews . Four of them may be of interestto readers of Waste Management & Research .

A study of rotating disk eddy current separators for non-ferrous metals contains boththeoretical, treatment and experimental laboratory data . Better performance is predictedfor the next generation of eddy current separators .

A special report from the Warren Spring Laboratory at Stevenage in England dealswith "Cryogenic Comminution in Scrap Recycling". Despite the clear mechanical advan-tages, the cost of the liquid nitrogen required makes most applications uneconomical .

The other Special Report from Bilthoven describes "Research Results RegardingBiological Soil Treatment Techniques in the Netherlands" . Biological degredation candestroy a large number of pollutants . In-situ treatment of oils, aromatics and chlorinatedcompounds is often the methods of choice after a spill . Land farming has also been usedfor intentional destruction of petroleum refinery wastes . The present report is a goodintroduction to experimental work on this subject in the Netherlands .

One Book Review deals with "The Value and Use of Scrap Tyres", largely from aEuropean point of view. The emphasis is on recovery of energy or material values andthe reviewer did not mention any discussion of disposal options .

The hybrid journal is well prepared and should continue to represent the high stan-dards of its ancestors .

BOOK REVIEW :NORDIC EVALUATION OF DIOXIN RISKS. By U. G . Ahlborg et alL reviewed byan expert group from Sweden, Norway, Finland and Denmark . (Nordisk Dioxinrisk-bedomning), published in Swedish by Nordisk Ministerrad, Copenhagen 1988, 141 pp.,No charge, ISBN 87 7303 100 2. Reviewed by R . B. Dean.

This work contains a nine page English summary and over 200 references through 1987The only sources of dioxin-like compounds considered to be significant in the Nordic

countries are pulp and paper mill wastes and accidental fires involving polychlorinatedbiphenyls (PCBs) . The principal route is consumption of fish from certain waters .

Although mother's milk may have dioxin levels above the recommended level ofintake the advantages of breast feeding far outweighs the risk. An as yet unpublishedpaper by K . Noren shows that the levels of Dioxins and other chlorinated phenolics inmother's milk have decreased markedly in the Stockholm area between 1972 and 1985 .

When setting limits an arbitrary safety factor of 1/200 of the no effect level (NOEL)in animals has been used . WHO [EURO] Environmental Health Series 17 (1987) ondioxins and furans from municipal incinerators and 23 (1988) on PCBs, PCDDs andPCDFs are relied upon extensively .

A revised table of toxicity equivalents is presented and is reproduced here togetherwith the Eadon factors from 1983 (Table 1) . Applications of the various publishedequivalents to analyses of chlorinated dioxins and furans show agreement withinfactor of 2 in almost all cases .

Professor Ahlborg pointed out in discussions at a recent conference that neitherrubbish incineration, according to Swedish rules, nor household fireplaces emit enoughdioxins to cause a risk from inhalation . However since dioxin levels in some fish exceedrecommended levels of intake, efforts to reduce emissions of dioxins to the environmentshould continue .

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Report and reviews

TABLE IProposed nordic model for TCDD-equivalents

Weighing factors

Ahlborg & Victorin (1987) Impact on health of chlorinated dioxins and other trace organic emissions .Waste Management and Research, 5, 203-224.

PCDD/PDCF Nordic 1988 Eadon 1983

2,3,7,8-TCDD 1 .0 1 .01,2,3,7,8-PeCDD 0 .5 1 .01,2,3,7,8-substituted HxCDDs 0 .1 0 .0331,2,3,4,7,8-HpCDD 0.01OCDD 0.001 -

2,3,7,8-TCDF 0 .1 0 .331,2,3,7,8-PeCDF 0.01 0.332,3,4,7,8-PeCDF 0 .52,3,7,8-substituted HxCDFs 0 .1 0 .012,3,7,8-substituted HxCDFs 0.01 0 .0OCDF 0.001 0 .0