Changes In Blood Lead Research Articles

Blood lead as a cardiovascular risk factor.

Many epidemiologic and experimental animal studies support the hypothesis of there being a causal association between lead exposure and increased blood pressure/cardiovascular disease. This study includes 1,052 men and women from Copenhagen County, Denmark, who were examined in 1976 and 1981; in 1987, only the men were examined. Blood lead fell by approximately 40% for the men during the 11-year period and by approximately 30% for the women during the first 5-year period. There was a univariate association between systolic blood pressure and blood lead for both sexes in 1976, but it disappeared at the following examinations. For women, there was also a significant association with diastolic blood pressure, even after confounders were controlled for at the two examinations. Moreover, the authors found a significant univariate association between changes in blood lead and changes in systolic blood pressure from 1976 to 1987 in the males. All participants taking part in the study in 1976 were followed regarding hospital admissions and deaths throughout a follow-up period lasting for 14 years. There was a significant univariate association with total mortality, coronary heart disease, and cardiovascular disease. However, with regard to coronary heart disease and cardiovascular disease, the associations disappeared when confounders were controlled for. Blood lead was a significant predictor of total mortality after control for relevant confounders. This study supports the hypothesis of there being a weak causal association between blood lead and blood pressure, total mortality, coronary heart disease, and cardiovascular disease. The importance of this association is very modest for the individual, but the population attributable risk may be considerable.

First-Year Changes in Blood Lead and Zinc Protoporphyrin Levels within Two Groups of Occupational Lead Workers

First-Year Changes in Blood Lead and Zinc Protoporphyrin Levels within Two Groups of Occupational Lead Workers

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.

Relationship between lead concentration in the air and blood lead levels of people living and working in the centre of a city (Frankfurt blood lead study). II. Correlations and conclusions (author's transl)

The correlation analysis of the relationship between blood lead levels and lead-in-air concentrations measured in three winter periods showed a highly significant association despite a generally loose dependence of the variables. The regression equations clearly show that there would be a finite residual blood lead value even with completely lead-free air. In the case of the populations exposed to motor traffic in this study, this residual blood lead value is 80--90% of the initial value prior to the decrease in immission. The regression equations, statistically yield results which compare convincingly with ones obtained from model calculations based on studies of metabolism and respiratory physiology. The correlation between the observed changes in blood lead and the initial absolute values of blood lead concentration demonstrates with high statistical certainty that the higher the initial level, the greater was the observed change. This type of association also implies that there is a lower limit value of blood lead below which the decrease in blood lead changes to an increase despite reduction of lead-in-air.

Blood lead and zinc protoporphyrin in lead industry workers

A retrospective study was performed by evaluating the time course changes in blood lead and zinc protoporphyrin concentrations in 240 industrial lead workers. The data indicate that there is a considerable difference in rate of change and plateau state for each of the two parameters. The difference in time course in these parameters indicates that both should be monitored in workers in order to estimate the accumulation of lead and the metabolic response to the body burden.

Some factors affecting the utility of bovine blood as a control material in lead-screening programs.

Bovine blood is used frequently as control material in interlaboratory comparisons for blood-lead analysis, but an erythrocyte protoporphyrin control material is needed. We present data on the rate of changes in blood lead and erythrocyte protoporphyrin in steers fed lead acetate. We also show, by comparison of fluorescence spectra with those of known compounds, that most of the porphyrin in lead-burdened steers probably exists as free protoporphyrin IX along with some zinc-complexed protoporphyrin IX. Bovine blood is suitable as an erythrocyte protoporphyrin control material for laboratories using acid extraction procedures, but not for the proficiency testing of laboratories using hematofluorometers.

Kinetic analysis of lead metabolism in healthy humans.

The steady state kinetics of lead metabolism were studied in five healthy men with stable isotope tracers. Subjects lived in a metabolic unit and ate constant low lead diets. Their intake was supplemented each day with 79--204 mug of enriched lead-204 as nitrate which was ingested with meals for 1--124 days. The concentration and isotopic composition of lead was determined serially in blood, urine, feces, and diet and less commonly in hair, nails, sweat, bone, and alimentary tract secretions by isotopic dilution, mass spectrometric analysis. The data suggest a three compartmental model for lead metabolism. The first compartment encompasses blood and is 1.5--2.2 times larger than the blood mass. It contains approximately 1.7--2.0 mg of lead and has a mean life of 35 days. This pool is in direct communication with ingested lead, urinary lead, and pools two and three. The second compartment is largely composed of soft tissue, contains about 0.3--0.9 mg of lead, and has a mean life of approximately 40 days. This pool gives rise to lead in hair, nails, sweat, and salivary, gastric, pancreatic, and biliary secretions. Pool three resides primarily in the skeleton, contains the vast quantity of body lead, and has a very slow mean life. Bones appear to differ in their rates of lead turnover. Within the relatively small changes in blood lead observed in the present study, the transfer coefficients between the pools remained constant.

Longitudinal Observations of the Relationship Between Free Erythrocyte Porphyrins and Whole Blood Lead

Short- and long-term comparison of the variations with time of whole blood lead and free erythrocyte porphyrins (FEP) suggests that changes in FEP are slow and predictable whereas blood lead changes are quite unpredictable. However, when FEP suggests a different clinical category from blood lead, the blood lead is likely to change in the direction predicted by the FEP. Comparison of FEP to blood lead at first contact in 349 children with mild elevation of blood lead reliably predicted which children would still have elevated blood lead six weeks later and which would fall or be normal. The observation of long-term follow-up in four groups of children with various combinations of FEP and blood lead indicated that the follow-up blood lead could be predicted to change in the direction indicated by the FEP measurement. The implications for screening for lead poisoning are discussed.