The chemical associations of Pb, Cd, Cu, and Zn in street dusts and roadside soils have been investigated by a sequential extraction procedure, which yields five fractions termed exchangeable, carbonate, Feoxide, organic, and residual.In the soils and dusts examined which covered a pH range of 6.9-8.4, only in the case of cadmium is there any appreciable proportion of total metal in the exchangeable fraction. Lead and zinc are predominantly associated with carbonates and Feoxides, whereas copper is largely in organic association.The results are interpreted in terms of the environmental mobility and bioavailability of the metals.

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Table I. Ion Chromatographic Conditions eluant: 1.5 mM Na2CO3/0.5 mM NaOH flow rate: 138 mL/h (30%) separator column: 3 x 150 mm anion precolumn plus 3 x 500 mm anion separator column suppressor column: 6 X 250 mm anion suppressor column meter full scale: 100 µ " '/cm (Model 10 detector only) injection volume: 100 mL acid than MBP, this dissociation effect is more pronounced for the DBP.In summary, the employment of a bipolar-pulse conductivity detector for ion chromatography, without the complications of a suppressor column, has produced encouraging data. Refinement of the electronics for thermal stability, noise immunity, and current output is in the development stage.Another application being considered for the bipolar-pulse detection technique is reverse-phase liquid chromatography, where the solution resistance may be too high for conventional bridge techniques. Also, the bipolar-pulse technique is being considered as a replacement for the conventional Wheatstone bridge electronics of a thermistor-based thermal conductivity gas chromatograph detector.

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The effect of blood-lead on children's behaviour was investigated in a sub-sample of 501 boys and girls aged 6-9 years from 18 primary schools within a defined area of central Edinburgh. Behaviour ratings of the children were made by teachers and parents using the Rutter behaviour scales. An extensive home interview with a parent was also carried out. Multiple regression analyses showed a significant relationship between log blood-lead and teachers' ratings on the total Rutter score and the aggressive/anti-social and hyperactive sub-scores, but not the neurotic sub-score when 30 possible confounding variables were taken into account. There was a dose-response relationship between blood-lead and behaviour ratings, with no evidence of a threshold.