Sickness absence of lead workers and controls

Certificated sickness rates and levels of lead exposure of 955 men who worked in a lead accumulator factory during a period of seven years (1965-72) were examined. The men were divided by department into four exposure groups; a second division into three groups was made, based on the mean of each man's blood lead measurements during the study period. Absences showed no age pattern, but men who left during the seven years of observation (ex-workers) had had a higher absence rate (842 spells/1000 man years) than those still employed in 1972 (535 spells/1000 man years). There was no significant difference in absence rates or lengths of absences between differently exposed departments either for all causes or for a selected group of potentially lead-induced causes. However, the proportion of potentially lead-induced absences was significantly higher in ex-workers (12-2%) than in current workers (7-4%). Similar analysis showed no significant differences in absence rates of men with different blood lead levels. It was concluded that higher levels of lead exposure did not seem to be associated with higher rates of absence or longer absences either for all causes of absence combined or for those causes which might be attributable to lead.

Establishment of erythropoiesis following bone marrow transplantation in a patient with congenital hypoplastic anemia (Diamond-Blackfan syndrome)

Marrow transplantation was attempted in a 13-yr-old boy with congenital hypoplastic anemia who had never responded to corticosteroid therapy. Prior to the transplant, he had received 238 transfusions, at least 12 of which were from his father. He was prepared for grafting with antilymphocyte globulin, procarbazine, and total body irradiation (1000 rads). The patient, whose red cells were Group B, then received marrow cells from his Group O, histocompatible, sister. Thereafter, reticulocytes, Group O erythrocytes, and female leukocytes appeared in the peripheral blood. Erythroid precursors were seen in the patient's marrow for the first time in his life, and all lacked fluorescent Y chromosomes. Dividing cells were all female. After initially progressing well, the patient developed interstitial pneumonia and died 55 days after the transplant. The successful erythroid graft suggested that this patient's failure to produce red blood cells was due to a defective stem cell rather than to a humoral defect, plasma inhibitor, or abnormal marrow microenvironment. It suggested further that sibling marrow may be engrafted in patients who have received multiple transfusions, even from a parent.

Blood lead and erythrocyte delta-aminolevulinic acid dehydratase levels in Manchester taxi drivers

Among 40 Manchester taxi drivers the mean blood lead was 1.10 mumol/1 (22.8 mug per 100 ml). The mean erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity among 34 of them was 30.1 units. No significant association was found between the blood lead levels and erythrocyte ALAD activity in these 34 men. No significant association was found between either blood lead elvels or erythrocyte ALAD activity and duration of service or weekly mileage as a taxi driver or with drinking or smoking habits, or age. The mean blood lead of those with homes in the north east quadrant of the city was higher than of those living elsewhere but the difference was not statistically significant. Although there was no correlation between blood lead levels and the source of domestic water, the mean blood lead of those with lead domestic plumbing was appreciably higher than the level of those with copper plumbing. There was no indication that, by virtue of their occupation, the taxi drivers were liable to greater lead absorption than their fellow-citizens.

Pair comparison and ascending series NaCl threshold: criterion and residual effects

Ascending series detection and recognition thresholds, both with and without interstimulus water rinses, and pair comparison thresholds, with varied presentation order, were measured for NaCl. Thresholds were measured in situ against a normal salivary background and also after rinses with 60 mM and 1 M NaCl. Predicted changes in the level of adaptation of the taste receptors, due to NaCl concentration changes in the mouth, were seen to vary the measured thresholds. Ascending series thresholds without interstimulus rinses were highest of all, although they were reduced by rinsing. The order of presentation in pair comparison tests was seen to vary thresholds in a manner predicted by proposed adaptation levels. Effects were also noted which were due to criterion definition and language. The trends found in the present experiments were also found in the literature.

The effect of portacaval anastomosis on oral carbohydrate tolerance and on plasma insulin levels

In patients with portal hypertension, plasma insulin levels were raised both fasting and after oral glucose or intravenous tolbutamide. This supports previous suggestions that resistance to endogenous insulin plays a major role in producing the impaired glucose tolerance found in chronic hepatic dysfunction. The operation of portacaval anastomosis was followed by impaired oral fructose tolerance, but did not significantly change oral glucose tolerance. Plasma insulin levels were unchanged by the operation, either fasting or following the stimulus of an oral glucose load or intravenous tolbutamide. The insulin response after operation was only higher after intensive pancreatic beta cell stimulation by a combination of glucose, tolbutamide, and glucagon. These results indicate that, in patients with hepatic dysfunction, little insulin is being removed by the liver from the portal blood except when the insulin secretory rate is unusually high.

Pathogenesis of experimental pulmonary alveolar proteinosis

Rats exposed to various airborne dusts developed a condition identical to pulmonary alveolar proteinosis as seen in man. The experimental condition developed through a stage of endogenous lipid pneumonia, characterized by numerous large foamy macrophages widely distributed throughout the lung. These cells broke down to release a finely granular material which finally condensed to reproduce the appearances of alveolar proteinosis. Electron microscopy indicated that the alveolar material was produced by type II pneumocytes and may therefore represent pulmonary surfactant. A study of the dust-handling mechanism showed that in affected animals macrophage mobility was seriously impaired.

On the use of a polyelectrolyte in a thermocell

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An investigation of lead absorption in an electric accumulator factory with the use of personal samplers

Williams, M. K., King, E., and Walford, Joan (1969).Brit. J. industr. Med.,26, 202-216. An investigation of lead absorption in an electric accumulator factory with the use of personal samplers. Thirty-nine lead workers and controls, in stable conditions of exposure, each wore personal lead-in-air samplers daily for two weeks. During the second week samples for blood lead, urinary lead, urinary coproporphyrin, urinary δ-aminolevulinic acid (ALA), the punctate basophil count, and haemoglobin were taken daily. Duplicate estimations were made on one day. The lead exposures of men doing almost identical jobs differed by ratios of up to four to one. This could be attributed only to personal differences in working habits. The correlation coefficients and regression equations of the biochemical tests with lead-in-air and with each other were determined. The mean values and 95% confidence limits of single determinations of some of the biochemical tests corresponding to the two commonly accepted TLVs of lead-in-air (0·20 and 0·15 mg./m.³) were calculated from the regression equations. For each biochemical test the variation due to analytical error, the variation from day to day within subjects and the residual variation due to analytical error, and the residual variation about the regression on lead-in-air were calculated. Previous estimates of the latter are not known. Excessive confidence may be placed in an index of exposure due to its low coefficient of variation within subjects unless the coefficient of variation between subjects about regression is taken into account. This correction for specific gravity of estimations of lead and ALA in spot samples of urine was found to reduce slightly the residual variation between subjects about the regression on lead-in-air and to increase the correlations with lead-in-air and with the other biochemical tests, but these changes were not statistically significant. The modified method used for estimating blood lead and urinary lead is described and validated.

A trial of Terylene overalls for lead-acid electric accumulator pasters

A comparison of Terylene and cotton overalls has been made in the lead-acid electric accumulator industry. Six hand pasters wore personal lead-in-air samplers for two weeks. Three of the men wore cotton overalls the first week and Terylene overalls the second; the other three men wore Terylene overalls the first week and cotton overalls the second. The mean lead-in-air concentration in the breathing zone when the men wore Terylene overalls was slightly greater than when they wore cotton overalls but the difference was not statistically significant. Significant differences of lead-in-air concentrations were found between men and between the two weeks but not between days within the weeks. The lead-in-air concentration did not increase during the week. Neither a change to Terylene overalls nor more frequent laundering of overalls should be recommended for pasters in this factory on the basis of this study.

Lead absorption in children

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