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ing treatment. We conclude from these figures that the regimen used in this study cannot be accepted as safe and nontoxic. Several other groups are developing potentially safer and less toxic regimens which may well prove to be as effective, and they regard this objective as a main aim of such trials rather than the production of increasingly toxic combinations of drugs. Is it wise, therefore, to accept this group’s proposal to give a quadruple regimen, in even higher dosage, to patients with "earlv" disease? King’s College Hospital

D. J. LEAPER D. P. LEIBERMAN J. MACINTYRE

Medical School,

London SE5 8RX

First Draw Water Lead

CONTRIBUTION OF LEAD IN DRINKING WATER TO BLOOD-LEAD

SiR,-The contribution drinking-water lead makes to the body burden of lead is controversial. In normal circumstances the bulk of ingested lead is acquired from food, but when lead in drinking water is increased this source can contribute significantly to the quantity of ingested lead;’ such increases stem from lead used in plumbing, including the lead solder in joints of copper pipes. A Government survey2 estimated that 9% of households in Britain (29% in Scotland) have first-flush drinking-water lead concentrations in excess of the W.H.O. limit of 048 mol/1 (100 ug/l or 0-1 parts per million). The European Economic Community is recommending a lowering of the acceptable limit to 0.24 ,mol/1 (50 g/1), though it is uncertain for which type of water sample this limit should apply. Our measurements of lead in water and lead in blood challenge the need to lower the acceptable limit of water lead.

Samples were accumulated over the past four years from studies done on different sectors of the Scottish population. The findings3-6 indicate a consistent pattern of results, suggesting that the heterogeneity of these samples is not important. Some of these surveys have concentrated on housing with lead pipes and high water-lead concentrations. All blood-samples were taken from an arm vein into 10 ml heparinised plastic vials. Anyone working with lead or in a lead-related industry was

(fmoll1)

2-Mean blood-lead values for nine groups at intervals of first-flush water lead.

Fig.

excluded. Water samples (250 ml) were taken into acid-washed (lead-free) polyethylene bottles at first flush in the morning from the cold tap used for food preparation and after the same tap had run at full flush for at least 5 min. Lead was analysed by flameless atomic-absorption spectrophotometry (Perkin Elmer 306/HGA 72) with deuterium background correction. Monthly checks for accuracy of blood-lead were carried out by participation in the National Quality Control Scheme. Water leads were checked by polarography (Shandon Southern ’

A1660). Fig. 1 shows the blood-lead and first-flush water lead for 949 samples. There is considerable variation in blood-lead, but there is an underlying positive relationship between the two (r=0.52,P

[Contribution of lead in drinking water to blood-lead].

661 ing treatment. We conclude from these figures that the regimen used in this study cannot be accepted as safe and nontoxic. Several other groups a...
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