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2.  "Clawbacks". 
PMCID: PMC1039264  PMID: 1386248
3.  One simple set of regulations. 
PMCID: PMC1007474  PMID: 3986139
4.  Short term prospective study of cognitive functioning in lead workers. 
In a short term prospective study 70 male lead workers performed a series of cognitive tasks on three occasions during an eight month period. Concurrently with the cognitive testing, the concentrations of blood lead, zinc protoporphyrin (ZPP) and urinary aminolaevulinic acid (ALA) were measured. Indicators of lead absorption were stable during the study and each subject was allocated to either a low (below 20 micrograms/dl), medium (21-40 micrograms/dl), or high (41-80 micrograms/dl) group on the basis of their average blood lead concentrations. Performance deficits tended to be restricted to the high lead group and, in general, neither practice nor continued exposure during the study altered the magnitude of these deficits. The main deficit was a slowing of sensory motor reaction time, which was seen most clearly when the cognitive demands of the task were low. In the cognitively simple five choice task, blood lead concentration correlated with impaired decision making, response execution, and "lapses in concentration." In the other cognitive tasks the high blood lead group tended also to be slower by a factor of about 1.08 but the dominance of cognitive over sensory motor demands attenuated the exposure-performance correlations. The high lead group also had difficulty in recalling nouns poorly related to the focus of an earlier semantic classification task. This difficulty increased over time and was one of the few findings that correlated with all measures of lead absorption. It is concluded that the primary psychological profile of lead impairment is one of sensory motor slowing coupled with difficulties in remembering incidental information.
PMCID: PMC1035449  PMID: 1954152
5.  Lead astray? 
PMCID: PMC1035379  PMID: 2064973
6.  Cognitive functioning in lead workers. 
In a cross sectional study of occupational exposure to inorganic lead 91 men performed a series of microcomputer based tasks assessing sensor motor reaction time, memory, attention, verbal reasoning, and spatial processing. Performance on the tasks was studied in relation to three ranges of blood lead concentration (low, less than 20 micrograms/dl; medium, 21-40 micrograms/dl; and high, 41-80 micrograms/dl) and exposure response correlations for blood lead concentration, zinc protoporphyrin (ZPP) (range 7-210 micrograms/dl), and urinary aminolaevulinic acid (ALA) (range 0.5-22.0 mg/l). The results show that the high group were impaired on most of the tasks used and, in general, the magnitude of the impairment correlated better with blood lead concentration than ZPP or urinary ALA. An examination of the patterns of task impairment indicated a general slowing of sensory motor reaction time which was relatively independent of the nature of the cognitive functions being tested. There was some evidence, however, suggesting mild impairment of attention, verbal memory, and linguistic processing. In general, workers with high blood lead concentrations showed clear impairment of sensory motor functions in the absence of correspondingly strong evidence for impaired processing and memory functions. It is argued that a general slowness in responding may underlie many previous reports of widespread cognitive impairment in lead workers.
PMCID: PMC1009851  PMID: 2818958
7.  High affinity of lead for fetal haemoglobin. 
In-vitro experiments using 203Pb were performed to identify lead-binding components in human haemoglobin. Sephadex A-50 ion-exchange chromatography of haemolysate showed that different types of haemoglobin had different affinities for lead. For the haemolysate from adults, lead was present in both Hb A (alpha 2 beta 2) and Hb A2 (alpha 2 delta 2), whereas, in the haemolysate from new-born infants, the haemoglobin of fetal origin, Hb F (alpha 2 gamma 2) showed a much greater affinity for 203Pb than the adult haemoglobin Hb A (alpha 2 beta 2), obtained from maternal blood. Analysis of the 203 Pb-labelled haemoglobin suggested that about 82% of 203Pb was in the globin polypeptide. Further analysis with carboxylmethyl (CM) cellulose chromatography indicated that the gamma globin of fetal origin had a higher affinity for 203Pb than the beta globin, whereas alpha globin appeared to be unimportant in lead binding. The results of the different affinities for lead of different Hb types are discussed with regard to the effect of lead upon haemoglobin synthesis.
PMCID: PMC1008710  PMID: 6158989
8.  Distribution of lead-203 in human peripheral blood in vitro. 
In-vitro experiments using 203Pb were performed to identify the lead binding components in human peripheral blood. The distribution of lead in plasma, in the red cell membrane, and within the red cell was also investigated. Studies of the distribution of 203Pb in whole blood showed that at a lead concentration of 2.45 mumol/l (50 micrograms/100 ml) about 94% of lead had been incorporated by the erythrocytes and 6% remained in the plasma. After extraction of lipid by a methanol/chloroform mixture, about 75% of the lead was found to be associated with the protein fraction. The lipid contained about 21% of the 203Pb, the remainder being in the aqueous plasma. SDS polyacrylamide gel electrophoresis of blood plasma showed that almost 90% of the 203Pb was present in the albumin fraction; the remainder was likely to be associated with high molecular weight globulins. Several binding sites were identified on the erythrocyte membrane. The high molecular weight component, about 130 000-230 000, was the most important 203Pb binding site. Chemical modification of membrane proteins suggested that the carboxyl groups are the major ligand responsible for most of the lead binding. SH groups of the membrane may have a minor role, but amino groups did not appear to affect the lead binding. The binding of lead to erythrocytes was not confined to membranes, over 80% of lead in blood penetrates into erythrocytes and binds to intracellular components. Gel chromatography of the haemolysate showed that over 90% of the 203Pb was attached to the haemoglobin molecule.
PMCID: PMC1008648  PMID: 7370196
9.  Interaction of calcium and lead in human erythrocytes. 
The interactions of calcium and lead on the human erythrocytes have been studied in vitro using 45Ca and 203Pb as tracers. The chemical groups binding calcium and lead on the erythrocytes were also investigated. Calcium ions in the plasma were shown to be capable of replacing the 203Pb on the red cells. More than 85% of the 203Pb in the erythrocyte was associated with the cytoplasmic components, and the rest was bound to the stromal membrane. About 90% of 45Ca was attached to erythrocyte membrane. Extraction of 45Ca and 203Pb-labelled erythrocyte membranes with chloroform/methanol mixture showed that the distribution patterns of these two nuclides are similar, with over 88% protein bound, less than 10% lipid bound, and traces in the aqueous phase. Chemical modification of erythrocyte membrane proteins with carbodi-imide, p-chloromercuribenzoate (PCMB), and maleic anhydride suggested that the carboxyl groups are responsible for binding lead and calcium to the red cell membrane. The SH groups may have a minor role in the binding for both cations. Amino groups did not appear to affect the binding of these cations. Gel chromatography of 45Ca-labelled erythrocyte membrane indicated that Ca++ bound to the same fraction of membrane proteins as 203Pb, corresponding to a molecular weight of about 130 000 to 230 000. A possible implication of these findings is that lead and calcium may compete for the same binding site(s) on the erythrocyte.
PMCID: PMC1008647  PMID: 7370195
10.  Oral and pharyngeal cancer in the North-west and West Yorkshire regions of England, and occupation. 
Patients with oral or pharyngeal cancer in the two main textile regions of England were matched for age and sex with patients having cancers not known to be associated with textile work. Data were recorded on age, sex, cancer site, and smoking, chewing and drinking habits together with dental and occupational history. There were 102 and 61 matched pairs of males and 52 and 60 matched pairs of females in the North-west and West Yorkshire regions respectively. There were significantly (P less than 0.05) more textile workers in the cases compared with their matched controls for only the females in the North-west. No particular type of textile work occurred more frequently for the cases than the controls in all four matched comparisons. Only for the males in the North-west were there significant differences (P less than 0.05) in the proportions of textile workers in the three cancer sites of the tongue, mouth and pharynx. These results do not confirm the association between textile work and oral or pharyngeal cancer found by the mortality study of Moss and Lee (1974). The results for the association between oral or pharyngeal cancer and smoking, drinking, chewing and wearing of dentures are discussed.
PMCID: PMC1008606  PMID: 508641

Results 1-11 (11)