Lead Poisoning in Children

LEADING ARTICLES

THE LANCET LONDON

18

APRIL

1964

Children THE diagnosis of lead poisoning in childhood is Lead

Poisoning in

The condition is apparently so uncomand its clinical features are often so vague that the diagnosis is not considered as often as it should be. Moreover, when the physician does suspect lead, he sometimes finds the results of laboratory investigations

doubly difficult.

mon

equivocal. The first difficulty-simply to think of lead poisoning possibility-can be overcome only by continuing awareness of the vital importance of early diagnosis. Untreated, the child may die (probably at least 25% of those presenting with encephalopathy do in fact die 1) or be left intellectually and emotionally abnormal.1 But the prompt use of sodium calciumedetate intravenously2 or intramuscularly3 can save lives and probably reduce the amount of cerebral damage. The diagnosis should therefore be considered in children with unexplained anxmia, convulsions, raised intracranial pressure, renal glycosuria and aminoaciduria,4 and abdominal pain, especially in the second and third years of life. Pica is a particularly valuable pointer to the diagnosis, although many children with catholic eating habits avoid lead poisoning, and the parents of as many as half the children with lead poisoning may deny the possibility.3 An inquiry about pica should nevertheless be a routine part of history-taking in young as a

children. The usual source of lead is painteither recently applied to the child’s cot by the father, using a preparation meant for outdoors, or many years ago to the interior woodwork or plasterwork of old houses, at a time when lead paint was commonly used for interior decoration.The immigrant children of Britain’s cities are in particular danger, for they often live crowded together in Victorian houses in a poor state of repair; flakes of paint are easily detached and, once the trick is learned, the child may eat a large amount of old lead paint out of boredom and lack of alternative amusement. Both parents may be out at work, and he is left with few or no toys and inadequate supervision. Less common sources are swallowed lead toys, which may be partially dissolved by gastric juice,7 the ingested products of burnt old lead batteries,8 and swallowed pieces of yellow crayon.44 When the possibility of lead poisoning is raised, certain investigations should be undertaken. The diagnosis is usually justified in the presence of two or more of the following findings 5 : microcytic anaemia 1. Smith, H. D. Arch. environm. Hlth, 1964, 8, 256. 2. Bessman, S. P., Rubin, M., Leikin, S. Pediatrics, 1954, 14, 201. 3. Chisolm,J. J., Jr., Harrison, H. E. ibid. 1957, 19, 2. 4. Roxburgh, R. C., Haas, L. Arch. Dis. Childh. 1959, 34, 70. 5. Byers, R. K. Pediatrics, 1959, 23, 585. 6. Griggs, R.C., Sunshine, I., Newill, V. A , Newton, B. W., Buchanan, Rasch, C.A. J. Amer.med. Ass. 1964, 187, 703. 7. Biehusen, F. C., Pulaski, E. J. New Engl.J. Med. 1956, 254, 1179. 8. Travers, E., Rendle-Short, J., Harvey, C. C. Lancet, 1956, ii, 113.

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with punctate basophilia; radio-opaque foreign bodies in the bowel lumen and lines of increased density at the growing ends of bone; coproporphyrinuria; renal glycosuria and aminoaciduria; and raised pressure and protein in the cerebrospinal fluid. Unfortunately, it is in the clinically puzzling case that these investigations may be unhelpful, although the estimation of urinary delta-aminolaevulic acidmay prove a more sensitive indicator. The measurement of lead excretion after a standard intramuscular dose of sodium calciumedetate, recently described by WHITAKER et all is another promising test: a clear-cut difference was found between normal children and children with definite or probable lead poisoning. Unfortunately the test requires the admission of the child to hospital, the giving of three intramuscular injections, and the collection of urine over the next 24 hours. A simpler procedure, such as the estimation of blood-lead, would obviously be preferable if only the results were as definite. In the past there has been some uncertainty about the upper limit of normal for blood-lead, which has usually been regarded as 50-60 g. per 100 m1.3 11; but an overlap has been noted between the values in normal children and in poisoned children.11 12 The value of blood-lead estimation has lately been reinvestigated by MONCRIEFF and his colleagues at Great Ormond Street.13 With 2 exceptions, the level in 80 normal children was found to be below 36 g. per 100 ml. Taking this figure as the upper limit of normal, they then investigated a group of 122 children with severe mental subnormality or behaviour disorders and made the surprising discovery that 45% had abnormal blood-lead values. Similarly, 30% of children with apparent encephalitis and 54% of children with abdominal pain, pica, vomiting, anaemia, or irritability gave abnormal results. Were all these patients suffering from lead poisoning ? This question is clearly of great importance, not only for doctors but also for parents of mentally abnormal children who have read about this work in the newspapers and are making the obvious deduction. It is hard to answer: even if the upper limit of normal is accepted, a blood-lead level of 40-50 p.g. per 100 ml. may mean no more than that the patient has pica because of mental abnormality due to a cause other than lead poisoning. Nevertheless, some cases of undoubted lead poisoning were diagnosed in this way, and MONCRIEFF et al. give details of 20 such patients. Coproporphyrinuria, punctate basophilia, and radiological signs were present only in the minority, so that diagnosis would have been difficult by the usual methods. The findings of a raised blood-pyruvate level after glucose administration gave confirmation in some instances. It would be interesting to know how blood-lead levels correlate with the results of the calciumedetate test of WHITAKER et al.10 A gratifving result of the widespread use of blood9. 10. 11.

S., 12. 13.

Haeger-Aronsen, B. Scand. J. clin. Lab. Invest. 1960, 12, suppl. 47. Whitaker, J. A., Austin, W., Nelson, J. D. Pediatrics, 1962, 29, 384. Bradley, J. E., Powell, A. E., Niermann, W., McGrady, K. R., Kaplan, E. J. Pediat. 1956, 49, 1. Tanis, A. L. Amer. J. Dis. Child. 1955, 89, 325. Moncrieff, A. A., Koumides, O. P., Clayton, B. E., Patrick, A. D., Renwick, A. G. C., Roberts, G. E. Arch. Dis. Childh. 1964, 39, 1.

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lead estimations at Great Ormond Street was the increased frequency of diagnosis after the introduction of the method. No doubt an increase in awareness of the possibility of the diagnosis in atypical cases was in

part responsible. But easy

access to a test

requiring

only single specimen of blood was also a factor. The provision of similar facilities in other centres and the encouragement to use them would doubtless pay similar dividends, even though the aetiological and therapeutic implications of borderline blood-lead levels might be matters for debate. a

Birds and Insecticides THE decision1 of the Minister of Agriculture, Fisheries, and Food to restrict the sale of aldrin and dieldrin, the chlorinated hydrocarbon insecticides, after this year is not likely to be the end of this story. As might be the further the inquiry into the poisonous effects of these compounds is pursued the more complicated the problem appears. The first effects to be noted were deaths in seed-eating birds which had fed on seed corn which had been dressed with one of these substances as an insecticide. The victims were mostly game birds and wood pigeons (and if the slaughter had been limited to the pigeons these poisons would probably have received a subsidy). It soon became clear, however, that the carnivorous birds and mammals which feasted on these corpses also suffered. Most of these substances are very stable and how far this train of damage may run no-one yet knows. A second serious effect is the infertility of the eggs laid by birds which have had a sublethal dose, and this may cause greater changes in the bird population than direct or indirect

expected,

poisoning. A recent paper2 from the staff of the Nature Conservancy reports some more observations on the residue of insecticides in the flesh of 85 birds of many species which have been found dead without obvious evidence of acute poisoning. Herons showed 13 parts per million, grebes nearly 6 p.p.m., sparrowhawks nearly 4 p.p.m., and owls (of three species) from 1 to 2 p.p.m. Vegetarians, such as wood pigeons and moorhens, contained hardly any insecticides. The analysis of eggs showed a similar picture. The highest figures were in fish eaters and peregrine falcons, with golden eagles some way behind. The figures for carrion crows were much lower. We should like to see these figures set out at greater length. The range of values for 12 eggs of peregrine falcons from an unstated number of nests was 3.0-36,0 p.m., which will prove more to the naturelover than to the statistician. There are several possible explanations of these interspecies differences. It has been shown that hens concentrate dieldrin from their food about twenty times as effectively as do fat lambs.3 It is unlikely but not impossible that there should be metabolic differences of this order between birds. Fish are susceptible to amounts of dicophane (D.D.T.) which do little harm to 1. See Lancet, April 4, 1964, p. 758. 2. Moore, N. W., Walker, C. H. Nature, Lond. 1964, 201, 1072. 3. Gannon, N., Link, R. P., Decker, G. C. J. Agric. Food Chem. 1959,

other creatures, and this may be due to an unusual capacity for concentrating the substance from waterwhich might explain the high figures in herons and grebes. Has anyone examined frogs which make up a good part of the diet of both ? One difficulty in coming to firm conclusions from this sort of evidence is our ignorance of the diet of many birds at different seasons: what is their bread-and-butter and what their caviare? Discussing the acute toxic effects of these poisons, we have more than once pointed to the absence of anything like controlled observations. Birds found dead from unknown causes may not be the best material for analysis. Indeed, we suspect that observation has probably told us as much as it can for the time being and the time is ripe for experiments. The difficulties are considerable, but work done in the U.S.A.4 (on species most of which are unknown here) has gone some way to establish the toxic dose of some of these compounds, As prosecuting counsel has often found, the mere presence of a poison in the human body is not enough to bring anyone to the gallows. The decision to restrict the sale of aldrin and dieldrin is justified until we know rather more than we do now, but we would not care to accept all the forecasts of future woe. Growing cabbages and carrots is a hard way of earning a living-and without an insecticide at least as good as aldrin and dieldrin it is going to be harder still.

Annotations THE NEW CURRICULUM AT EDINBURGH

A UNIVERSITY which appointed its first professor of medicine in 1685 is not likely to produce a revolutionary The changes announced at new medical curriculum. Edinburgh, although essentially conservative, are interesting in that they do show adaptation to recent trends that are becoming established. First, the time given to anatomy has been axed from 900 to 500 hours. This is an uneasy compromise. There are still, especially at the old who view this reduction traditionalists Edinburgh, with alarm, but most younger teachers probably consider 500 hours still far too long. Secondly, there is an inducement for the medical student to broaden his education by taking classes outside the medical faculty. This has arisen because of the realisation-after long students enter the university with very different scientific educations. Until recently all have had to take a common first-year course in chemistry, physics, and biology. Students with the appropriate school certificates will now be exempted from this course and can qualify in 5 years. Students with qualifications in one or two subjects only, which will include a large number of entrants from Scottish schools, where the teaching of biology is in general inadequate, will be partially exempt. In their first year, when not engaged in their remaining science subjects, they will be enabled to take courses in subjects such as psychology, social anthropology, and mathematics. Incentive for this will be the award of a B.sc. (Med. Sci.) after three years’ satisfactory study in the medical faculty. It remains

delay-that

4.

7, 826.

Bernard, R. F. Publications of the Museum, Michigan State University (Biological Science), 1963, vol. 2, p. 155.