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Seven advisers from a wide variety of health-related professions met with some 30 staff at WHO to discuss ethical issues currently arising in health and international cooperation. Far-reaching questions of responsibility and legitimacy were raised. The following observations are adapted from the final report on the meeting.

In the present investigation we purpose a simple, rapid and accurate method for the evaluation of sodium nitroprusside. In alkaline medium and on the presence of thiourea, a new complex is formed. The acidification of medium induced a blue solution (lambda m = 600 nm) that could be determined by spectrophotometry.

Reversed-phase high-performance liquid chromatography (HPLC) was adapted for the determination of trace concentrations of carbaryl and seven organophosphorus pesticides in drinking water. Between 100 and 300 ml of water sample is passed through a 1.5-cm precolumn, packed with C18-bonded silica or styrene-divinylbenzene copolymer (PRP-1) sorbent at a flow-rate of 3 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution programme. The analytes that have been concentrated on the precolumn are eluted and separated on a 15-cm C18 analytical column and are determined by measuring their UV absorption at 254 nm. This wavelength was selected as the optimum for the simultaneous determination of these pesticides. The preconcentration yields of the examined solutes obtained with the two types of precolumn are almost identical. Band broadening is avoided by a suitable choice of the C18 precolumn and the analytical column. With 200 ml of tap water, the recoveries for most of the examined pesticides were ca. 90%, except for carbaryl (54%). The detection limits are in the range 0.03-0.2 micrograms/l.

A study is performed on polychlorinated biphenyl (PCB) congener residues in samples of human blood and milk as well as in falcon and pigeon eggs. Most of the PCB congeners found in these biological samples were quantified by high-resolution gas chromatography (HRGC). A PCB technical mixture--namely, DP6 (Phenochlor)--was used for the calibration as its composition was previously determined by HRGC-mass spectrometry. The usefulness of such a congener analysis is outlined. It is the first time to the best of our knowledge that a Phenochlor mixture is used for standardization.

This paper provides preliminary findings on organochlorine residues in Tunisian foodstuffs, i.e.: butter, milk, cheese, fish, canned tuna and sardines, beef, egg yolk, chicken and beef liver. The techniques used are HPLC, MS-GC, ECD-GC.

This paper reports some preliminary results concerning hexachlorobenzene (HCB) contamination of Tunisian human milk, human cord and adult blood and foodstuffs (cows' milk, meat, eggs). The analyses were performed by gas chromatography with electron-capture detection.

A large collection of human milk samples and cord blood from various hospitals of Tunis is studied for organochlorine residues. Some results obtained by ECD-GC are given.