Erythrocyte ALAD Activity Research Articles

Different Behaviors of Erythrocyte δ-Aminolevulinic Acid Dehydratase

Different characteristics of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D1) between the workers with the history of occupational lead exposure and normals are described. In the blood of lead workers, when the hemolysates are heated at 60 C for five minutes, the activity of the erythrocytes ALA-D increases up to about 3.6-fold of an initial level, and as a result of heating the optimum in pH-activity curvee changes from pH 6.0 to pH 6.6, which is similar to the optimum pH of normal ALA-D. On the contrary, in normal blood, the optimum in the pH-activity curve is but little changed, even though the erythrocyte ALA-D activity is increased up to about 1.3-fold of the initial level by heating the hemolysates at 60 C for five minutes.

FACTOR-ANALYTICAL OBSERVATION ON DOSE-RESPONSE RELATIONSHIP OF LEAD IN THE OCCUPATIONALLY NON-EXPOSED

By the procedure of of factor analysis, the interrelationships of parameters relevant to lead exposure were statistically investigated. The parameters were clas-sified to three groups based on the results of these statistical analysis: the first group contained lead mobilized by CaEDTA and lead in blood, which were considered to be related to the body burden of lead; the second group, ALA-D in erythrocyte, δ-ALA in urine, coproporphyrin in urine and lead in urine, which should be the response to the body burden of lead; the third group, hemoglobin in blood.It was supported that there might be specific biological reactions to lead in people free from occupational or accidental exposure to lead, though the extent of the reac-tions was supposed to be much less than that of occupationally-exposed lead workers. The influence of lead to blood hemoglobin level was not found under usual urban environments.The biological significance seemed to be almost similar between lead in blood and lead mobilization test with the intravenous administration of CaEDTA from the view-point of dose-response relationship of lead. The regressions of urinary coproporphyrin and erythrocyte ALA-D activity on lead mobilized by CaEDTA or blood lead were supposed to be nearly linear in people free from occupational lead exposure.

Laboratory results of some biological measures in workers exposed to lead.

Erythrocyte ALA-dehydratase (ALAD) activity and blood lead levels were studied in different groups of subjects not occupationally exposed to lead, ie, male and female clerical workers, traffic policemen, motorway tollgate attendants, and chronic alcoholics in comparison with values obtained in workers in a lead- using industry. Among the subjects without occupational exposure to lead, the highest mean values of erythrocyte ALAD activity and the lowest mean values of lead in the blood were found in female clerical workers. Progressively lower mean values of ALAD activity and conversely higher mean values of lead in the blood were observed in the male clerical workers, traffic policemen, motorway tollgate attendants, and chronic alcoholics. In workers occupationally, exposed to lead, erythrocyte ALAD activity undergoes much greater reductions not only in the manifest phases of lead poisoning but even at the very beginning of exposure, and ALAD remains reduced even some time after exposure has ceased.

Delta-aminolevulinic acid dehydratase activity of erythrocytes and liver tissue in man: relationship to lead exposure.

The delta-aminolevulinic acid dehydratase (ALAD) activity of erythrocytes and of liver tissue was studied in subjects not occupationally exposed to lead. A considerable heterogeneity in the levels of ALAD activity of erythrocytes and of blood lead was confirmed in this group of subjects, an expression of the varying degree of absorption of lead that occurs in each individual who is exposed through pollution of the atmosphere and food. In the group of subjects studied, there was a correlation between the values of erythrocyte ALAD activity and the values of ALAD activity of liver tissue.

Biological quality guide for inorganic lead

1. If environmental exposure of the general public to a considerable extent takes place through various routes of entry, quality standards for one source of exposure (e.g. air, food, water) will not protect public health adequately. This is the case for inorganic lead. 2. Biologically available lead (lead in blood levels) and parameters of subclinical response may be expected to be feasible for indirect estimation of total environmental exposure; the feasibility has been studied. 3. Lead in blood levels (PbB) in target groups of the general population portray the total environmental exposure to Pb for this group. Such groups should include at least 50 subjects, of same sex, similar socio-cultural class, with narrow age range, and preferably at high risk (exposure or susceptibility). 4. Neither average levels nor one maximum level, but the distribution of levels in 98% of the target group should be taken as parameter of external exposure. 5. The maximum acceptable individual level for adults is PbB=40 Μg Pb/100ml; because of increased uncertainty in regard to pregnancy and developing neonate this level should be lowered to PbB=35 Μg Pb/100 ml. 6. Taking into account the maximum acceptable level of 35 Μg Pb/100 ml in 98% of subjects, and the normal variability of PbB levels as occurring in practice, the following distribution of PbB levels is proposed as biological quality guide: 98% ≦35 Μg Pb/100 ml, 90% ≦30 Μg Pb/100 ml, 50% ≦20 Μg Pb/100 ml. PbB levels in women should be corrected to male level on the basis of hematocrite. 7. If the general distribution of PbB levels in a target group exceeds the proposed guide, total exposure in the environment studied is too high; action should be undertaken directed at the total environment. If the distribution only exceeds the guide at high PbB levels, a point source of external lead exposure is probable; action should be directed at this source. 8. If in the environment total exposure to lead is too high, subsequent studies should determine contribution through various routes and sources: quality standards for air, food, water may have to be imposed; the same applies to emission standards. 9. Due attention to errors of measurement of Pb in blood is necessary. 10. It is not yet possible to propose a biological quality guide based upon Pb in urine or hair. 11. It is not possible to propose a biological quality guide based upon ALAD-activity in erythrocytes, neither on ALA-excretion in urine. 12. The proposed biological quality guide for lead in blood could enter governmental regulations, and so become a biological quality standard, if prevention of direct adverse effect on human health is aimed at.

EFFECT OF LOW LEAD CONCENTRATION ON HUMAN BODY

The concentration of lead in the whole blood of 203 traffic policemen, whose mean value and standard error of lead content in blood showed 9.60±0.22 (95% upper limit of 13.7) μg/100 ml of blood, differed from the large in scale of cities at low lead con-centration less than 10 μg/m3 of air.In comparison between traffic policemen and lead workers, the latter were signifi-cantly higher at the lead content and ALAD activity in erythrocytes than those of the former. The correlation between ALAD activity in erythrocytes and lead con-centration in blood was found in both workers, but among the samples under 15.0 μg pb/100 ml of blood in traffic policemen was not observed significant decrease of ALAD activity and any correlation.