C. Toothill

Hardness of domestic water and blood lead levels

1 The effect on the blood lead levels of residents in an area in which a soft plumbo-solvent water was hardened is examined. 2 Water lead levels fell after hardening was introduced whereas there was a small rise in water lead levels in a control area monitored over the same time. 3 The blood lead levels of residents fell after hardening and the fall was slightly greater than would have been predicted on the basis of the change in water lead levels. This suggests that lead is less well absorbed from hard water than from soft water. 4 Following hardening there was a significant fall in mean blood lead level of subjects living in houses which had initially had negligible amounts of lead in the water. This suggests that hard water may interfere with the absorption of lead from sources other than water.

Inorganic phosphate transport across the red blood cell membrane: the effect of exposure to hyperoxia

Red cell structure and function were examined in rats exposed to 80% oxygen: 20% nitrogen for five days and compared with red cells from air-breathing animals. Evidence of red cell destruction was noted in the animals exposed to hyperoxia. Osmotic fragility was found to be reduced in red cells from oxygen exposed rats (p less than 0.05), also, red cell haemolysis in hydrogen peroxide was noted to be greater (p less than 0.001) in these animals. Inorganic phosphate ion transport was significantly reduced (p less than 0.001) in the red cells from rats receiving oxygen for 5 days. The results demonstrate a decreased ability of the red cell to transport anions and suggest an impairment of the normal movement of water across the membrane following exposure to oxygen.

Further evidence of a fall in blood lead levels in Wales.

Random samples of residents in North Wales, some of whom had been seen in 1976 and others in 1981, were seen again in 1984. Blood lead estimations indicated that there had been a fall of about 5% per year. This is similar to the fall we estimated from two previous studies in Wales and is comparable to changes described in the USA and New Zealand.

Effects of blood storage on red cell antioxidative systems

The activities of the antioxidative enzymes superoxide dismutase, catalase and glutathione peroxidase and the concentration of reduced glutathione were determined in CPD-adenine blood stored at 4 degrees C for up to 20 days. Superoxide dismutase activity was found to be significantly reduced with storage beyond 10 days. The clinical significance of this finding is discussed.

Haem synthetase activity of human blood cells

Abstract Specimens of human blood were selected from patients with a wide variety of diseases, which contained an absolute enrichement of different cell types. Increased haem synthetase activity was associated with increases in white blood cells or nucleated red cell precursors but not with increases in reticulocytes. The cell sap obtained from specimens of blood containing increased numbers of nucleated red cell precursors shows haem synthetase activity and this is greatly stimulated by ether. The significance of these findings is discussed with respect to the cellular distribution of the enzyme in normal and pathological blood.

Heam synthetase in human blood

Abstract Heam synthetase (E.C. 4.99.1.1) activity has been demonstrated in a preparation from normal human blood; linear relationships are demonstrated between activity and enzyme concentration and time of incubation. The pH optimum is 8.2 with a second optimum at 9.3. Maximum enzymic activity is shown with concentrations of 4.10−5M of protoporphyrin and 10−5M iron. The enzyme was heat labile being totally inactivated at 100° for 1 min, and partially inactivated by storage at 37° for three hours. Other characteristics of the enzyme are described.

Evidence of a fall in cord blood lead levels in South Wales 1984-85.

A monitoring scheme for blood lead was based on cord blood samples and maternal blood samples taken in Swansea, South Wales. A fall of around 20% during 1984–85 is described. During this period there was virtually no change in petrol sales in the area and no overall change in air lead levels. Air lead showed large seasonal changes but these were not reflected in blood lead. Water lead levels gave no evidence of changes of any importance during the period of monitoring. These results suggest that petrol lead was at most a minor contributor to blood lead.

Air lead, blood lead and travel by car.

Evidence on the relevance of lead in petrol to lead in blood has come from two main sources. Cross sectional studies of blood lead levels in population samples and in the air to which they are exposed suggest that petrol makes only a very small contribution. However longitudinal studies in the USA in which changes in lead levels in petrol and changes in blood lead have been studied suggest that petrol makes a substantial contribution to blood lead. The possibility that this discrepancy might be explained by the exposure of subjects to very high levels of lead when travelling in motor vehicles is examined, and rejected.