Interrelationship of biochemical responses to the absorption of inorganic lead

Effect of lead (Pb) exposure on the activity of superoxide dismutase and catalase in battery manufacturing workers (BMW) of Western Maharashtra (India) with reference to heme biosynthesis

The aim of this study was to estimate the activity of superoxide dismutase (SOD) and catalase in erythrocytes and malondialdehyde (MDA) in plasma of battery manufacturing workers (BMW) of Western Maharashtra (India) who were occupationally exposed to lead (Pb) over a long period of time (about 15 years). This study was also aimed to determine the Pb intoxication resulted in a disturbance of heme biosynthesis in BMW group. The blood Pb level of BMW group (n = 28) was found to be in the range of 25.8 - 78.0 microg/dL (mean + SD, 53.63 + 16.98) whereas in Pb unexposed control group (n = 35) the range was 2.8 - 22.0 microg/dL (mean + SD, 12.52 + 4.08). The blood level (Pb-B) and urinary lead level (Pb-U) were significantly increased in BMW group as compared to unexposed control. Though activated d- aminolevulinic acid dehydratase (ALAD) activities in BMW group did not show any significant change when compared to control group but activated / non activated erythrocyte - ALAD activities in BMW group showed a significant increase. Erythrocyte- zinc protoporphyrin (ZPP), urinary daminolevulinic acid (ALA-U) and porphobilinogen (PBG-U) of BMW groups elevated significantly as compared to control. A positive correlation (r = 0.66, p < 0.001) between Pb-B and ALA-U were found in BMW group but no such significant correlation (r = 0.02, p> 1.0) were observed in control group. Hematological study revealed a significant decrease of hemoglobin concentration, packed cell volume (%) and other blood indices and a significant increase of total leucocytes count in BMW group in comparison to control group. The serum MDA content was significantly increased (p < 0.001) and the activities of antioxidant enzymes such as erythrocyte- SOD (p < 0.001) and erythrocytecatalase (p < 0.001) were significantly reduced in BMW group as compared to control group. A positive correlation (r = 0.45, p < 0.02) between Pb-B and serum MDA level was observed in BMW group (Pb-B range 25.8 - 78.0 microg / dL) but such significant correlation did not notice in control group (Pb-B range 2.8 - 22.0 microg / dL). The study clearly showed an adverse effect of heme biosynthesis and imbalance of pro-oxidant / antioxidant status in lead exposed battery manufacturing workers resulting in increase in lipid peroxidation associated with decrease in erythrocyte-SOD and erythrocyte-catalase activities.

Avaliação da exposição ocupacional ao chumbo em uma metalúrgica um estudo transversal

OBJETIVO: Avaliar o nível de exposição ocupacional em uma metalúrgica de chumbo, através da determinação dos indicadores biológicos de exposição e efeito, com o objetivo de estabelecer um mapeamento das áreas de risco dentro da planta industrial. METODOLOGIA: Estudo transversal incluindo 195 trabalhadores de uma metalúrgica primária de chumbo, localizada no Estado da Bahia-Brasil, e um grupo de referência de 65 indivíduos. Nos grupos de expostos e controle foram realizadas as dosagens dos indicadores biológicos de exposição e efeito (IBE's) ao chumbo inorgânico, incluindo Pb-S, ALA-U, ZnPP e Hb.

Effects of cadmium and lead exposure on urinary N-acetyl-beta-D-glucosaminidase, beta 2-microglobulin and metallothionein of workers

Cadmium (Cd), lead (Pb), N-acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (BMG), metallothionein (MT) and creatinine (cre) in urine were measured in 36 male workers. Urinary Cd and Pb ranged from 0.2 to 9.7 and 0.1 to 4.8 micrograms/g cre with geometric means of 1.17 and 1.27 micrograms/g cre, respectively. Partial correlation coefficients between the logarithm of urinary Cd and that of NAG, BMG or MT controlling for pH and age were 0.460 (p < 0.01), 0.095 and 0.677 (p < 0.01), respectively. Partial correlation coefficients between the logarithm of Pb and that of NAG, BMG or MT controlling for pH and age were 0.040, 0.403 (p < 0.05) and -0.183, respectively. Multiple regression analysis was conducted on urinary NAG, BMG and MT using age, pH, log U-Cd and U-Pb. Log U-Cd was the only significant predictor variable of NAG (beta = 0.572; p < 0.01). Log U-Pb was the only predictor variable of BMG (beta = 0.386, p < 0.01). pH (beta = 0.286, p < 0.05) and Log U-Cd (beta = 0.839, p < 0.05) were significant predictor variables of MT.

[Physiopathology of inorganic lead poisoning]

This paper gives an overview of the hypotheses concerning the mechanisms of inorganic lead toxicity on cells and tissues, with emphasis on the effect of low-concentration lead. Inhibition of heme synthesis is responsible not only for lead-induced anaemia, but also for accumulation of delta-aminolaevulinic acid (ALA) and for lowering the concentration of cytochromes contained in the mitochondrial respiratory chain. Auto-oxidation of ALA is thought to result in the formation of free radicals. On the other hand, lead replaces ionic calcium in its role as second cell messenger. This mechanism would explain the abnormalities observed in synaptic transmission, arteriolar vasoreactivity and functioning of such cells as osteoclasts and osteoblasts. Nuclear toxicity, with abnormal expression of DNA genes and inhibition of certain enzymes such as membrane Na+/K+ ATPase, are also considered. The mechanisms of tissue toxicity are discussed.

The correspondence between U.K. 'action levels' for lead in blood and in water

This paper considers whether the Department of the Environment's water lead concentration criterion for lead pipe replacement and action in individual cases, i.e. 50 micrograms/l in any sample, is too high when set against the Department of Health's advisory action limit for blood lead concentration of 25 micrograms/100 ml. The relationships between blood lead and water lead concentrations found in the Glasgow and Ayr duplicate diet studies, together with unpublished data from Glasgow and Liverpool, indicate that over 10% of people exposed to an average water lead concentration of 100 micrograms/l (the earlier action level) would have blood lead concentrations above 25 micrograms/100 ml, as would about 4% of those exposed to 50 micrograms/l (the Maximum Admissible Concentration in an EEC Directive). For adults, average water lead concentrations should not exceed 30 micrograms/l to ensure compliance with the limit for blood lead, i.e. so that not more than 2% exceed 25 micrograms/100 ml. However, for one of the critical groups, bottle-fed infants (whose diet is 90% water), average water lead concentrations should not exceed 10-15 micrograms/l. The WHO's Provisional Tolerable Weekly Intake (PTWI) for children (25 micrograms/kg body weight) also implies that their water lead concentrations should not exceed 10-15 micrograms/l.

Urinary excretion of 5-hydroxyindoleacetic acid, delta-aminolevulinic acid and coproporphyrin isomers in rats and men exposed to lead

The urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA), delta-aminolevulinic acid (ALA) and coproporphyrin (CP) isomers (I and III) was investigated in rats and workers exposed to lead. Urinary excretion of 5-HIAA, which is the major metabolite of serotonin, was not influenced by the lead exposure. However, a significant increase in urinary ALA and CP was found in rats and workers exposed to lead. In particular, the urinary excretion of CP-III was markedly increased compared to that of CP-I in rats and workers exposed to lead.

Effects of exposure to lead among lead-acid battery factory workers in Sudan

Health effects of occupational exposure to lead were investigated among 92 exposed workers in lead-acid battery factory and 40 nonexposed workers serving as a control group from an oil mill in Khartoum North industrial area. The two groups were closely similar in age, stature, body weight, and socioeconomic conditions. A highly significant increase (P less than .01) was recorded in blood lead, urinary coproporphyrin, and basophilic stippled red blood cells of the exposed group in comparison to the control group. Central nervous system symptoms (insomnia, fatigue, weakness, and drowsiness) were reported by 50% and other symptoms such as abdominal colic and constipation were reported by 41% of the exposed group. Blue line on the gum was detected only on 2% of the exposed group. Strong associations between exposure to lead and the prevalence of central nervous system symptoms, abdominal colic, and constipation were recorded. Exposure to exceedingly high levels of lead in the working environment causes adverse health effects.

Lead and zinc concentrations in plasma, erythrocytes, and urine in relation to ALA-D activity after intravenous infusion of Ca-EDTA

Lead and zinc concentrations in plasma, erythrocytes, and urine, urinary ALA concentration, and ALA-D activity in blood were studied for four hours in two male lead workers during and after a one hour infusion of Ca-EDTA 2Na. Urinary and plasma lead concentrations increased as a result of administering Ca-EDTA 2Na, and the ratios of lead concentrations in plasma to those in urine were greatly increased. The increase of plasma lead concentration was not due to the haemolytic effect of Ca-EDTA 2Na but was mobilised lead, rapidly excreted in the urine. ALA-D activity in blood increased at the end of the experiment with a transient decrease during the infusion of Ca-EDTA 2Na. As zinc concentrations in erythrocytes and plasma did not decrease during the infusion despite an increase in the urinary excretion of zinc, the transient decrease of ALA-D activity was not due to a loss of zinc caused by Ca-EDTA 2Na. From the results of additional experiments in vitro, this transient decrease could be related neither to Ca-EDTA 2Na nor to lead in the blood.

Occupational lead exposure of storage battery workers in Korea

Two hundred and thirty-four lead workers employed in a storage battery factory in Korea were examined for lead in blood (PbB) and urine (PbU). delta-aminolaevulinic acid in urine (ALAU), coproporphyrin in urine (CPU), and haemoglobin. The dose-response relationship between PbB and ALAU suggested that a PbB below 50-60 micrograms/dl is a proper practical limit of biological monitoring for lead workers. The inter-relationship between PbB and ALAU or PbU was better explained by a segmental straight function than by a curvilinear function. Inclusion of data from workers whose PbB was below 30-40 micrograms/dl, if they comprise a relatively large proportion of the whole, seems to have a role as a dummy effect on the overall regression function causing the curvilinear trend. At a given blood lead concentration, the ALAU of lead workers increased with an increase in the duration of exposure. This could be explained by the chronic effect of lead on haem precursors. Semi-quantitative measurement of CPU still played an important part in the screening of lead workers due to its simplicity, showing high sensitivity (97.8%) in detecting lead workers with PbB of 60 micrograms/dl or over.

Arginase and kallikrein activities as biochemical indices of occupational exposure to lead

In a group of 60 workers occupationally exposed to lead the blood and urine lead concentrations, haematocrit, ALA-D and arginase activities, and urinary 5-aminolaevulinic acid (ALA) and coproporphyrin concentrations, and kallikrein activity were determined. Correlation coefficients of -0.78 and 0.77 for Pb-B/ALA and Pb-B/arginase were found respectively for lead concentrations above 40 microgram/dl blood, and 0.83, 0.76, 0.74, and -0.64 for Pb-U/ALA, Pb-U/Cp-U, Pb-U/kallikrein, and Pb.U/kallikrein, respectively. It seems that the increase in serum arginase activity may be indicative of liver damage while the decrease in kallikrein activity may indicate kidney damage in workers exposed to lead.

Increased ALA dehydratase activity and spleen weight in lead-intoxicated rats. A consequence of increased blood cell destruction

Lead was given in the diet (1%) to rats from birth and at different times the animals were studies for delta amino levulinic acid dehydratase (ALAD) activity, spleen weight, 59Fe incorporation in erythrocytes and 51Cr-labeled erythrocytes survival. The increased ALAD and spleen weight found after lead treatment is explained as a consequence of a shortened survival, which results in a younger age of circulating erythrocytes with higher ALAD activity.

Chromosomal aberrations in workers professionally exposed to lead

Chromosomes in cultured lymphocytes from the following groups were analyzed: 16 workers from a smelting plant for storage batteriers in Lyon, France; 7 workers from a factory where tin dishes are made at Nerem, Belgium; and 20 controls. The choice of the workers was made on the basis of either elevated blood lead (Lyon) or elevated urinary delta-aminolevulinic acid (Nerem). An increased number of severe aberrations--rings and dicentrics--were detected in the persons from Lyon, whereas no such aberrations but an increased number of fragments were seen in those from Nerem.

Lead effects among secondary lead smelter workers with blood lead levels below 80 microgram/100 ml

A subgroup of workers from a secondary lead smelter was defined to include those with blood lead levels not exceeding 80 microgram/100 ml and with no past history of elevated blood lead. Central nervous system symptoms (tiredness, sleeplessness, irritability, headache) were reported by 55% of the group and muscle and joint pain by 39%. Zinc protoporphyrin (ZPP) levels were elevated in 71% of cases. Low hemoglobin levels (less than 14 gm/100 ml) were found in more than a third of the workers. While BUN and creatinine were mostly in the normal range, there was nevertheless a correlation between ZPP and both BUN and creatinine. Reduced nerve-conduction velocities were present in 25% of the group; this was not significantly different from findings in a control group. The data indicate that a blood level of 80 microgram/100 ml is an inappropriate biological guide in the prevention of lead disease.

Relationship between lead concentration in blood and biological response for porphyrin metabolism in workers occupationally exposed to lead

The biological responses of the heme biosynthesis pathway in male workers moderately exposed to lead are discussed in relation to the concentration of lead in the blood. The level of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity in the group of lead-exposed workers was remarkably reduced while the level of erythrocyte protoporphyrin (Proto) in them was strikingly increased, compared to normal levels. On the other hand, the amounts of hemoglobin (Hb) and urinary delta-aminolevulinic acid (ALA) in the group of lead-exposed workers kept the normal levels. In the workers moderately exposed to lead, the log of erythrocyte Proto level was closely correlated to the blood lead level and the sensitivity of the Proto test was almost equal to that of erythrocyte ALA-D test. It was observed that the erythrocyte Proto was remarkably increased even in lead-exposed workers whose ALA excretion into the urine was in the range of normal level.

Reproductive ability of workmen occupationally exposed to lead

The reproductive ability of 150 men occupationally exposed to lead were studied by clinical and toxicological analysis. Subjects were divided into four groups: lead-poisoned workmen (23) and those showing a moderate (42), slight (35), or physiologic absorption (50). Findings show that (1) Lead poisoning as well as moderate increased absorption of lead decrease the fertile ability of men. An increased frequency of asthenospermia, hypospermia, and teratospermia have objectified the decrease. (2) Slight increased or physiologic absorption of lead do not significantly influence the fertile ability of workmen. (3) Hypofertility induced by lead is due, perhaps, to its direct toxic effect on the gonads, as no interference with the hypothalamopituitary axis were evidenced.

Parameters indicative of absorption and biological effect in new lead exposure: a prospective study

Tola, S., Hernberg, S., Asp, S., and Nikkanen, J. (1973).British Journal of Industrial Medicine,30, 134-141. Parameters indicative of absorption and biological effect in new lead exposure: a prospective study. Determinations have been made of the blood and urinary lead concentrations (Pb-B, Pb-U), haemoglobin concentrations (Hb), packed blood cell volumes (Hcr), urinary δ-aminolevulinic acid (ALA-U) and coproporphyrin concentrations (CP-U), as well as erythrocyte δ-aminolevulinic acid dehydratase activities (ALA-D), in respect of 33 workers entering occupational lead exposure for the first time in their lives. In a follow-up study lasting from one to four months samples were taken before exposure began, initially at intervals of two days and subsequently at intervals of one to two weeks. Nine control subjects were studied for Pb-B once, and for Hb, Hcr, and ALA-D weekly. The Pb-B rose and the ALA-D activity fell with no demonstrable time lag, while the latency periods of ALA-U, Pb-U, and CP-U were about two weeks. All of these laboratory tests reached a steady state during the follow-up. ALA-D showed the highest correlation to Pb-B and proved to be the most sensitive indicator of lead effect. Both CP-U and ALA-U were useful indicators of the effect of lead upon the organism, although a stepwise regression analysis, and their correlation coefficients with Pb-B, led to the conclusion that CP-U had better explaining power than ALA-U. The mean Hb and Hcr values were significantly lower at the end of the observation period than at the beginning, providing an indication that anaemia begins to develop early in the course of lead absorption.