262

CLINICAL SYMPTOMS AND DAILY DOSE OF INSULIN IN NINE

PATIENTS CHRONICALLY OVERTREATED WITH INSULIN

*Glibenclamide 5 mg/day.

well’s3 estimate of 10%. Rosenbloom et al.4 gave a figure of70% in 101 insulin-treated pediatric patients. Our figure of20% may underestimate the frequency of chronic overtreat-ment in adults because nocturnal hypoglycaemia was not

sought systematically.II Medical Clinic,University of Munich,Klinikum Grosshadern,D-8000 Munich 70, West Germany

P. SCHWANDTW. RICHTER

J. WILKENING

3. Colwell AR. Med Clin N Am 1955; 39: 39.4. Rosenbloom AL, Giordano BP. Am J Dis Child 1977; 131: 881.

CORRELATION BETWEEN BLOOD-LEAD ANDCHROMOSOMAL ABERRATIONS

SIR,-We have been studying blood-lead concentrations andchromosome aberrations in Swedish bus-drivers.Two female and eight male bus-drivers aged 25-52 (mean 37), who

had been driving buses in a Swedish town with about 50 000 inhabi-tants for 3-29 years (mean 10 years) were studied. Five were smokers.Inquiry into their history regarding viral diseases, X-ray examinationsand radiotherapy, the use of drugs, and occupational exposure to lead,mercury, and styrene revealed nothing remarkable. Blood was takenby venepuncture and analysed for lead and chromosomal aberrations.All specimens were obtained and transported to the laboratory in thesame way. Lead was determined by atomic absorption after wet diges-tion and extraction in methylisobutylketone with dithizone. Peripherallymphocytes cultured for 72 h by standard. microculture technique

Relation between % of cells with chromosome aberrations andblood-lead.

were studied for chromosomal aberrations. 200 metaphases were ana-lysed from each subject. The chromosomal aberrations recorded in-cluded chromatid breaks, chromatid interchanges, acentric fragments,ring chromosomes, dicentric chromosomes, and pericentric inversions.The samples were coded and analysed by one observer.A positive correlation (Spearman’s rank correlation coeffi-

cient 0-74, 0-01<p<0-02, two tailed) was found between theblood-lead and percentage of chromosomal aberrations (seefigure).The five smokers had higher blood-lead values and higher

aberration-counts, but their lead values were normal for aSwedish population and the frequency of chromosomal aber-rations was in the normal range for our laboratory.

For 40 h a week bus-drivers, smokers and non-smokers, areexposed to city air polluted with dust, gases, and potentiallymutagenic substances, including lead, entering the vehiclethrough its ventilation system. Evidence that lead can causechromosomal damage in man3-6 is not clear-cut. Lead may justbe an indicator of exposure to other mutagens, such as tobaccosmoke and/or motor-car exhaust. Studies using Ames’ Sal-monella typhimurium assay system report mutagenic activityof particles in city air polluted with automobile exhaust.’2 Inone of these studies2 the mutagenic activity was positively cor-related with the lead content of the air samples.

Departments of Occupational Medicineand Clinical Genetics,

University Hospital of Lund,S-221 85 Lund, Sweden

BENKT H&Ouml;GSTEDTANNE-MARIE KOLNIGFELIX MITELMAN

ANDREJS SCH&Uuml;TZ

DR IMPERATO-MCGINLEY

S:R,&mdash;The editorial of July 7 onsexual behaviour and the sex hor-mones suggests that the esteemedEditor is not himself yet clear onthe issue of gender identity. Twiceyou assign the phrase "Imperato-McGinley and his colleagues" to

an unambiguously feminine ladynamed Julianne. The accompany-ing photograph, taken on the nightof our senior medical-school classdinner dance by the gentleman wholater contributed the hyphenatedportion to her name, should clarifyany lingering doubts.

Department of Pediatrics,School of Medicine,Yale University,New Haven, Connecticut 06510, U.S.A. DIANE M. KOMP

***To the many readers who have rejoiced in our discomfi-ture, our thanks-and to Dr Julianne Imperato-McGinley ourapologies.-ED.L. _

1. Pitts JN Jr, Grosjean D, Mischke TM, Simmon VF, Poole D. Mutagenic acti-vity of airborne particulate organic pollutants. Toxicol Letters 1977; 1:65-70.

2. Wang YY, Rappaport M, Sawyer RF, Talcott RE, Wei ET. Direct-actingmutagens in automobile exhaust. Cancer Letters 1978; 5: 39-47.

3. Bauchinger M, Schmid E, Einbrodt HJ, Dresp J. Chromosome aberrationsin lymphocytes after occupational exposure to lead and cadmium.Mutation Res 1976; 40: 57-62.

4. Forni A, Secchi GC. Chromosome changes in preclinical and clinical leadpoisoning and correlation with biochemical findings. In: Internationalsymposium on environmental health aspects of lead. Amsterdam, 1972.473-85.

5. Nordenson I, Beckman G, Beckman L, Nordstr&ouml;m S. Occupational and en-vironmental risks in and around a smelter in northern Sweden. IV. Chro-mosomal aberrations in workers exposed to lead. Hereditas 1978; 88:263-67.

6. Schwanitz G, Lehnert G, Gebhart E. Chromosomensch&auml;den bei beruflicherbleibelastung Dt Med Wochenschr 1970; 95: 1636-41.