Exposure to lead and cadmium of children living in different areas of North-West Germany: results of biological monitoring studies 1982–1986

Summary Between 1982 and 1986 several surveys were carried out to determine the levels of lead and cadmium in blood, urine, and shed deciduous teeth (incisors only) of children living in rural, suburban, urban, and industrial areas of North-West Germany. Blood lead (PbB) and blood cadmium (CdB) were measured in about 4000 children. In rural, suburban and urban areas the median PbB levels vary between 5.5 and 7 g/dl, with 98th percentiles varying between 10 and 13 g/dl. The median CdB levels are between 0.1 and 0.2 g/dl, with 95th percentiles between 0.3 and 0.4 g/l. Children from urban areas have significantly higher PbB levels than children from rural and suburban areas. Regarding CdB no differences could be detected. Children living in areas around lead and zinc smelters, particularly those living very close to the smelters, have substantially increased PbB and CdB levels. Children from lead worker families also have substantially increased PbB and CdB levels. The lead levels in shed milk teeth (PbT) were determined in about 3000 children. In rural, suburban and urban areas the median PbT levels are between 2 and 3 g/g, with 95th percentiles between 4 and 7 g/g. Children from urban areas have significantly higher PbT levels than children from rural and suburban areas. The highest PbT levels (on a group basis) are in children from nonferrous smelter areas. The median levels of lead in urine (PbU) are between 6 and 10 g/g creatinine, with 95th percentiles between 20 and 30 g/g creatinine. Children from polluted areas have higher PbU levels than children from less polluted areas. The median levels of cadmium in urine (CdU) are in the order of 0.1 g/g creatinine, with 95th percentiles being in the range of 0.5 and 1.0 g/g creatinine. Girls have higher CdU levels than boys. There are no differences between groups of children from different areas. Children from lead worker families have higher PbU and CdU levels than otherwise comparable children. The results of the present studies indicate a further decrease of PbB in children from North-West Germany since the CEC blood lead campaigns carried out in 1979 and 1981. The decrease of lead exposure also seems to be reflected by a decrease of tooth lead levels.The studies presented in this communication were supported by the Ministry of Work, Health and Social Affairs and the Ministry of Environment and Agriculture of Nordrhein-West-falen, FRG     

Lead in deciduous teeth of children living in a non-ferrous smelter area and a rural area of the FRG

Summary Lead concentrations were measured in the deciduous teeth (incisors) of 302 children living in a lead-smelter area in the FRG (Stolberg, Rheinland) and of 86 children living in a nonpolluted rural area (Gummersbach, Bergisches Land). Blood lead levels were determined in 83 of the children living in the lead smelter area. On average, tooth lead levels of children living in the smelter area (mean: 6.0 g/g; range: 1.49–38.5 g/g) were significantly higher than those of children living in the rural area (mean: 3.9 g/g; range: 1.6–9.4 g/g). Blood lead levels were 6.8–33.8 g/100 ml (mean: 14.3 g/100 ml). Children of lead workers had on average higher tooth lead and blood lead levels than children of people who were not lead-workers. Tooth lead levels increased with increasing duration of residence in the lead-smelter area and with the degree of local environmental pollution by lead, as indicated by the lead content of the atmospheric dust fall-out around the children's homes. The correlation coefficient of tooth lead vs blood lead was 0.47. The intra-individual variability of tooth lead levels was low (r=0.86), and tooth lead levels of brothers and sisters were similar (r=0.75), suggesting that tooth lead may be used as a representative and reliable indicator of long-term lead exposure.This study was carried out at the request and with support of the Ministerium für Arbeit, Gesundheit und Soziales NW, Düsseldorf     

Reasons for Testing and Exposure Sources Among Women of Childbearing Age with Moderate Blood Lead Levels

The purpose of this study was to examine the circumstances under which women receive blood lead tests in New York State and to characterize the sources of lead exposure among women of childbearing age with moderate blood lead levels. Telephone interviews were conducted with 135 women between the ages of 18 and 45, with blood lead levels from 10 through 25 g/dl, were used to collect information on the reason for their blood lead test and possible sources of lead exposure. It was found that the two most common reasons to be tested for blood lead were workplace screening (47%) and pregnancy (27%). Occupational exposure was the primary source of lead exposure in this population (46%). Another common source of lead exposure was home renovation (24%). A significant proportion (31%) of women with blood lead levels from 10 through 25 g/dl had no known current source of lead exposure. Based on New York's sample, there are a significant number of women of reproductive age with potentially fetotoxic blood lead levels.     

Increase in the amount of erythrocyte δ-aminolevulinic acid dehydratase in workers with moderate lead exposure

Summary The amount of ALA-D in human erythrocytes was determined directly by radioimmunoassay or calculated from the restored activity assayed in the presence of zinc and dithiothreitol, and a good correlation was observed between the RIA-based and the restored activity-based amounts.The RIA-based amount of ALA-D in the blood of 10 normal individuals (blood lead levels of 5.6 ± 2.3 g/100 ml: mean ± SD) and 19 lead-exposed workers (blood lead levels of 41.2 ± 10.2 g/100 ml) was 54.1 ± 11.8 g/ml blood and 92.3 ± 20.6 g/ml blood, respectively, indicating an apparent increase of the enzyme amount in lead-exposed workers.A significant increase in the amount of erythrocyte ALA-D calculated from the restored activity in lead-exposed workers was observed even in the low blood lead level of 10–20 g/100 ml, resulting in the range of blood lead level 20–40 g/100 ml. No significant difference was observed in hematocrit and hemoglobin content between lead-exposed and non-exposed groups. These observations suggested that the increase of erythrocyte ALA-D in lead exposure was not due to anemia, which might result in the increase of young erythrocytes in peripheral blood.This increase in the amount of ALA-D in human erythrocytes might be a result of the function to overcome the inhibition of the enzyme in bone marrow cells during lead exposure, and these findings may throw light on the danger to human health of low-level lead toxicity.Abbreviations ALA-D -Aminolevulinic acid dehydratase or 5-Amnoevulinic acid hydro-lyase, EC 4.2.1.24 - ALA -Aminolevulinic acid - Rc Reticulocyte - RIA Radioimmunoassay - DTT Dithiothreitol Supported in parts by Science Research Fund of the Ministry of Education, Science and Culture of Japan and by Research Grant of Fujiwara Foundation of Kyoto University     

Blood lead levels in the general population of Taiwan,Republic of China

The purpose of this study was to investigate the environmental lead exposure of the general population in Taiwan. A total of 2919 residents of Taiwan were selected by multistage sampling methods. The participants were characterized by questionnaires and 10 ml venous blood was collected for blood lead measurement. A quality assurance/quality control program was designed during the analysis of blood lead levels. The mean blood lead level of 2719 residents without occupational lead exposure was 8.29 ± 5.92 g/dl. After adjustment for age and sex distribution to the Taiwan general population, the mean blood lead level was 8.10 g/dl. Adjusted for an 11% underestimation of blood lead levels among the six laboratories, the mean blood lead level was estimated to be 8.99 g/dl. This study also found that blood lead levels were associated with personal characteristics, i.e., gender, ethnic group, education level; lifestyle factors, i.e., smoking, alcohol consumption, sources of drinking water; and residential location, i.e., levels of urbanization, distance of house from the road. However, age, floor of residence, milk consumption, betel nut consumption, and Chinese herbal drug consumption were not found to be associated with blood lead levels. These results show that blood lead levels in Taiwan residents were not higher than in most developed and developing countries. Environmental lead pollution does not seem to be a serious problem in Taiwan.     

Chronic toxicity of the bromoxynil formulation Buctril® to Daphnia magna exposed continuously and intermittently

Two chronic toxicity tests were conducted in which Daphnia magna were either continuously or intermittently exposed to bromoxynil octanoate (BO; as Buctril^®) for 28 d. In the intermittent exposure test, daphnids were exposed to daily pulses of BO with 24-h mean concentrations equal to those in the continuous exposure test, and the peak concentrations were three times the 24-h mean values. After 28 d of continuous exposure to BO, survival of daphnids was reduced at 80 g/L, whereas mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults were all reduced at 40 g/L. Intermittent exposures to daily pulses of BO for 28 d caused reduced survival of daphnids at 24-h mean concentrations 40 g/L and reduced mean number of young per adult, intrinsic rate of natural increase, and mean weight of adults at 24-h mean concentrations 20 g/L. The estimated geometric mean-maximum acceptable toxicant concentrations of BO based on 24-h mean nominal values were 28 g/L for continuous exposures and 14 g/L for intermittent exposures. These results demonstrated that continuous-exposure studies may not be adequate in assessing herbicide toxicity to aquatic biota when concentrations fluctuate temporally.     

Determination of pentachlorophenol and chlorobiphenylols in biological samples

Conclusion Pentachlorophenol is detectable in samples of aquatic fauna from relatively clean areas. The levels are probably not significant toxicologically.The described procedure for the determination of chlorobiphenylols may be used to detect these compounds in the g/g range in biological samples. All samples contained some unidentified compounds in the chlorobiphenylol fraction.     

Effects of lead on red blood cell membrane proteins

Summary The effects of lead on red blood cell (RBC) membrane proteins were studied in two groups of workers with different lead exposure levels: Group 1 (6 subjects employed in a battery plant) with a mean blood lead of 40.1 (SD = 3.7) g/100 ml; Group II(5 workers employed in different industries) with a mean blood lead of 60.6 (SD = 8.0) g/100 ml, compared with a control group with mean blood lead of 15.6 (SD = 9.3) g/100 ml. The analysis of RBC membrane polypeptides was carried out by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and by using a densitometer for percentage measurement of the bands corresponding to protein fractions. The results show a very significant decrease in Band 3 (anion channel) and 4.1 in more exposed workers (Group II) only. The effects of lead on RBC membrane proteins seem to be evident at blood-lead levels higher (> 50 g/100 ml) than those previously reported in literature. These results confirm the effects of lead on membrane proteins, even if the exact mechanism, particularly the influence of proteolysis and the meaning of the interference, still needs to be investigated thoroughly.     

Assessment of thyroid,testes, kidney and autonomic nervous system function in lead-exposed workers

Summary The objective of the study was to assess whether moderate occupational exposure to lead may be associated with early changes in potential target organs (thyroid, testes, kidney, autonomic nervous system). Workers exposed to lead in a lead acid battery factory (n = 98; mean blood lead 51 g/dl, range 40–75 g/dl) and 85 control workers were examined. None of the indicators of kidney function (in urine: retinol-binding protein, ₂-microglobulin, albumin,N-acetyl--d-glucosaminidase; in serum: creatinine, ₂-microglobulin), endocrine function (follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, thyroxine, triiodothyronine) and autonomic nervous system (R-R interval variations on the electrocardiogram) were correlated with lead exposure (blood lead or duration of exposure) or showed significantly different mean values between the exposed group and controls. These results and an assessment of the published data suggest that compliance with the Directive of the Council of the European Communities on lead exposure (health surveillance in workers whose lead in blood exceeds 40 g/dl and removal from exposure when blood lead exceeds 70–80 g/dl) would prevent the occurrence of significant biological changes in the majority of lead-exposed workers.     

Investigations on neurotoxicity of chemical substances at the workplace

Summary A cross-sectional study was performed in order to investigate the influence of chronic lead-exposure on the peripheral nervous system. We examined 148 male workers of a storage battery manufacturing plant, who had been exposed to lead metal and inorganic lead compounds for 1 to 28 years (mean 11 years). Fifteen workers with non-occupational risks of peripheral neuropathy (former diseases, alcohol abuse, medication) were excluded from the study. The investigation program comprised: case history, physical examination, analyses of blood- and urine-samples and determination of maximal motor, mixed and sensory conduction velocity (NCV) of the ulnar and median nerve of the right forearm. Objectively no worker showed any signs of health effects related to lead exposure. The Biological Monitoring included the determination of (1) Blood-lead level (Pb-B), (2) Free erythrocyte porphyrins (FEP), (3) -Aminolevulinic acid dehydratase (ALA-D) and (4) -Aminolevulinic acid in urine (ALA-U). Further time-weighted-average (TWA)-values of Pb-B were calculated on the basis of several determinations over the period 1975–1981. The following actual (TWA) median values resulted: Pb-B 53 g/dl (54 g/dl), ALA-U 5.6 mg/l (8.4 mg/l), FEP 2.0 mg/l (2.0 mg/l). The Biologischer Arbeitsstoff Toleranz Wert (BAT) of 70 g//dl for Pb-B was exceeded in 15 workers (11%), and of 15 mg/l for ALA-U in 30 cases (23%). In comparison with age-matched controls, the lead workers showed a mild slowing of NCV with mean values between 0.8 and 2.0 m/s. Multiple stepwise regression analyses revealed statistically significant correlations between the four NCV and age as well as Pb-B. There were better correlations by using TWA than actual data of Pb-B. Consideration of the results of the regression analyses, together with an evaluation of the individual neurophysiological status as a function of internal lead exposure, a dose-effect-relationship was found only in the case of Pb-B exceeding 70 g/dl. From our study it is concluded that chronic lead exposure resulting in blood-lead levels of below 70 g/dl is no occupational risk causing a functionally significant slowing of nerve conduction velocities.With Grants from the Deutsche Forschungsgemeinschaft, Bonn (Project no. Va 23/19-1)     

A pilot study of lead and cadmium exposure in young children in Stockholm,Sweden: Methodological considerations using capillary blood microsampling

A capillary blood microsampling technique was tested among urban young children in Stockholm. Blood lead (BPb) and hemoglobin (Hb) concentrations were determined in capillary blood obtained by fingerstick from 41 children, 13–20 months old, and the accompanying parent. The quality control included control for lead (Pb) and cadmium (Cd) contamination of material and equipment used for blood sampling, washing procedures for the hands and fingers to be punctured, comparisons of Pb and Cd concentrations in blood obtained by fingerstick and by brachial vein puncture from the same individuals, analysis of external quality control samples for Pb and Cd in blood together with the collected samples, and evaluation of the analytical performance using linear regression analysis.The results showed that blood sampling material may contaminate the blood samples with amounts of Pb and Cd that would seriously influence the monitoring results in the low concentration range (<100 g Pb/L and <1 g Cd/L). However, it is possible to obtain reliable BPb concentrations (>10 g Pb/L), but not BCd concentrations (<1 g Cd/L), with the capillary blood microsampling technique tested provided that a strict quality control is applied. The sampling procedure tested was well accepted by the children and their parents. The children's median BPb concentration (27 g/L; range 9–73 g/L) was similar to the median BPb concentration of their parents (27 g/L; range 7–74 g/L). However, the correlation between child and parent BPb concentrations was poor (R²=0.20), which may indicate different sources to Pb exposure in children and parents.     

Three-year survey of blood lead levels in 8828 Taiwanese adults

The purpose of this study was to investigate environmental lead exposure in the general Taiwanese population. A total of 8828 Taiwanese adults selected by a multistage sampling method were investigated. Characteristics of the participants were ascertained by questionnaire and 10 ml venous blood was drawn by public health nurses. The blood specimens were distributed to six laboratories for blood lead level (BLL) measurement. A quality control program was applied during the analysis of the BLLs in order to improve precision and accuracy. The arithmetic mean BLL of the 8828 Taiwanese adults was 7.70 ± 5.23 g/dl, with a maximal level of 69.1 /dl. The median was 6.5 /dl and the 90th percentile was 14.0 g/dl. After logarithmic transformation, the geometric mean was 1.84 ± 0.67 g/dl. This study also found that elevated BLLs were associated with certain personal characteristics, i.e., gender, ethnic group, and education level; life-style factors, such as smoking, alcohol consumption, Chinese herbal drug consumption, milk consumption, and sources of drinking water; residential location, i.e., level of urbanization; and occupational history of lead exposure. However, age, floor level of residence, distance from house to road, and betel nut consumption were not associated with elevated BLLs. These results showed that BLLs in the Taiwanese population were not higher than those in developed and developing countries. Most of the influencing factors were also found in other studies; however, local factors such as ethnic group, Chinese herbal drug consumption, and sources of drinking water are important considerations in Taiwan when examining ways to prevent overexposure to lead in the general population.     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination on mink. II: Reproduction and kit development

Adult ranch-bred mink (Mustela vison) were fed diets containing either 0, 1.0 g/g polychlorinated biphenyls (PCB) (Aroclor^® 1254), 1.0 g/g methylmercury (MeHg), a combination of 1.0 g/g PCB plus 1.0 g/g MeHg, or 0.5 g/g PCB plus 0.5 g/g MeHg. Fertility of adult male mink, percentage of females whelped or number of kits born per female were not affected by the treatments. However, growth rate of kits nursed by mothers exposed to 1.0 g/g PCB was significantly reduced. There was a synergistic effect of PCB and MeHg which reduced kit survival in groups receiving both chemicals simultaneously. Kit survival to weaning in the control, 0.5 g/g PCB/MeHg, and 1.0 g/g PCB/MeHg groups was 72.0%, 62.7% and 35.8%, respectively. The results suggest that growth and survival of mink kits are adversely affected at dietary levels of PCB and MeHg currently present in some environments.     

Evaluation of studies of the relationship between blood lead and air lead

Summary An evaluation of the major studies of the effects of airborne lead on blood lead levels of male and female adult and child populations is presented. Analysis of these studies shows that the blood lead-air lead slope for adults is approximately 1.0 for both men and women. This implies that an exposure to an additional 1 g Pb/m³ of air can result in an increase of approximately 1 g Pb/100 ml of blood. The precision of the slope for adults is rarely better than ±0.5 to ±0.7 and can be as large as ±1.0. A large portion of this uncertainty in the calculated slope is due to blood lead measurement error. The slope of the blood lead-air lead response for children ranges from 0.7 to 1.4 and is approximately the same as that for adults. The accuracy of this number is less clear for children than adults due to the small data base. Many of the studies of children have been on populations living in the vicinity of smelters. It is questioned whether these data are representative of the air lead exposure of children living in urban and suburban communities.     

Internal lead and cadmium exposure in 6-year-old children from western and eastern Germany

Lead and cadmium levels in blood and deciduous teeth (shed incisors only) of 6-year-old German children were determined in 1991 in a large epidemiological study carried out in rural and urban areas of western Germany (Duisburg, Essen, Gelsenkirchen, Dortmund, Borken) and eastern Germany (Leipzig, Halle, Magdeburg, Osterburg, Gardelegen, Salzwedel). In total, blood lead and cadmium levels of 2311 German children and tooth lead and cadmium levels of 790 German children were analyzed. Blood lead levels were generally low in all study areas with geometric means between 39.3 g/1 and 50.8 g/l in the western German and between 42.3 g/1 and 68.1 g/l in the eastern German study areas. The mean blood lead level of Turkish children (n = 213) living in the western German study areas was 50.1 g/l and thus 5.6 g/1 higher than the overall geometric mean of the western German children. The higher exposure may be explained by a higher oral uptake from food and different living conditions. These children were excluded from multiple regression analysis because they were all living in the western study areas. The mean tooth lead levels ranged between 1.50 and 1.74 g/g in the western and between 1.51 g/g and 2.72 g/g in the eastern study areas. Thus, they show a distribution pattern similar to blood. Blood and tooth lead levels were higher in urban than in rural areas and higher in the eastern German than in the western German study areas. With regard to the blood and tooth cadmium concentrations, no significant differences between the study areas could be found. The mean cadmium levels in blood ranged between 0.12 g/1 and 0.14 g/l and the mean tooth cadmium concentrations between 20.8 ng/g and 27.8 ng/g. Blood and tooth lead and cadmium levels of the eastern and western German children were thus mainly at a relatively low level in all rural and urban study areas. The study demonstrates and confirms that blood and tooth lead levels are influenced by several demographic, social, and environmental variables. The results indicate that there has been a further significant decrease of lead and cadmium exposure in western German children since our last epidemiological study carried out in the same study areas in 1985/1986.     

Internal exposure to organic substances in a municipal waste incinerator

Summary Fifty-three persons occupied in a municipal waste incinerator were examined with respect to their internal exposure to organic substances which may be produced during pyrolysis of organic matter. For this purpose the levels of benzene in blood, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in plasma, and mono- (MCPs), di- (DCPs), tri- (TCPs), tetra-(TECPs) and pentachlorophenol (PCP) and hydroxypyrene in urine were determined. For control purposes, 431 men and women were examined. Significantly higher values for the workers were found for the excretion of hydroxypyrene [median (m): 0.24vs 0.11 g/l; non-smokers], 2,4/2,5-DCP (m: 10.5 vs 3.9 g/l) and 2,4,5-TCP (m: 1.2 vs 0.8 g/l) and for the HCB level in plasma (m: 4.4 vs 2.8 g/l). For the concentrations of 4-MCP and 2,3,4,6/2,3,5,6-TECP, the controls had significantly higher concentrations in urine than did the workers in the incineration plant (m: 4-MCP 1.7 vs 1.2; 2,3,4,6/2,3,5,6-TECP: 1.2 vs 0.3 g/l). No significant differences between workers and controls were detected with respect to benzene in blood (m: 0.20 vs 0.28 g/l; non-smokers), 2,4,6-TCP and PCPs in urine (m: 0.85 vs 0.60 and 2.2 vs 2.2 g/l) or the levels of PCB congeners in plasma (m: 138, 153, 180: 5.6 vs 4.1 g/l). The elevated levels of hydroxypyrene, 2,4/2,5-DCP, 2,4,5-TCP and HCB in biological material may be related to the incineration of the waste. These elevations, however, are very small and are of interest more from the environmental than from the occupational point of view.     

Chronic toxicity and bioaccumulation of 2,5,2′,5′- and 3,4,3′,4′-tetrachlorobiphenyl and Aroclor® 1242 in the amphipodHyalella azteca

The addition of 100 (g/L of Aroclor^® 1242 (A1242) or 2,5,2,5-tetrachlorobiphenyl (TeCB) during 10 week chronic toxicity tests withHyalella azteca resulted in complete mortality. There were no effects on survival, growth, or reproduction after addition of 30 g/L. Toxic effects were observed at tissue levels of between 30 and 180 g/g on a wet weight basis, and tissue levels appear to be a better indicator of toxicity than levels in water. No toxic effects were observed after additions of up to 2,700 g/L of the coplanar congener 3,4,3,4-TeCB.H. azteca has the ability to avoid accumulating in excess of 140 g/g 3,4,3,4-TeCB. The amount taken up was proportional to the amount added in water up to 100 g/L, but was constant at higher additions, possibly accounting for its relatively low toxicity. The low toxicity of the coplanar congener, as compared to the non-coplanar 2,5,2,5-TeCB, is in direct contrast to the high toxicity of coplanar PCB congeners to mammals and may be associated with slower rates of aromatic hydrocarbon metabolism in amphipods. Polychlorinated biphenyl levels measured in amphipods from Lake Ontario are approximately 100-fold below levels associated with toxicity inH. azteca, but are above levels which, through biomagnification up the food chain, lead to salmonid residues in excess of 2 g/g, a tolerance limit for human consumption.     

Assessment of exposure to lead of the general population in the French community through biological monitoring

Summary The aim of the council directive of 29 March 1977 of the European Community (1) is the screening for non-work-related lead exposure levels in the general populations of European (member) countries. In France, such testing was carried out in eight metropolitan areas (having more than 500000 inhabitants), another eight critical areas surrounding industrial emission sources and one area (Vosges) having a high level of lead contamination in the water. In view of the reference values (maximum 35 g/ dl in an individual blood sample) adopted by the directive, the situation is most serious in the area where the exposure is due to the lead contamination in the water. Individuals here run a seven times greater risk of exceeding the 35 g/dl blood-lead limit relative to urban populations where the lead comes mostly from vehicle emissions into the atmosphere (i.e. 9.3% of the blood-lead values of the Vosgian sample exceed 35 pg/dl; 3.5% for the industrial complexes which deal with lead and 1.4% for the urban zone). While these vehicle exhausts are the subject of much current concern, in perspective, the problem of lead pipe contaminated drinking water appears to be of far greater importance.     

Placental transfer of lead,mercury and cadmium in women living in a rural area

Summary The influence of the lead content of drinking water on the transplacental transfer of lead was investigated in 70 pregnant women living in a rural area of Belgium. The mothers were divided into 2 groups: group A: morning water lead below 50 g/liter; group B: morning water lead above this value. In group A, the mean lead content of water was 11.8 g/liter and in group B it amounted to 247.4 g/liter.The difference in the mean lead concentration between the two groups were for maternal blood: 3.2 g/100 ml, for umbilical cord blood: 3.3 g/100 ml, and for placenta: 3.6 g/100 g. These differences are statistically significant.There were significant correlations between water lead and lead concentration in blood (mother, newborn) or placenta. An increment of water lead concentration from 50 to 500 g/liter increases blood lead concentration in mother and in newborn by about 3 g/100 ml and in placenta by about 2.5 g/100 g (wet weight).     

A new HPLC fluorimetric method to monitor urinary delta-aminolevulinic acid (ALA-U) levels in workers exposed to lead

Summary A new sensitive HPLC method for the determination of urinary delta-aminolevulinic acid (ALA-U) was used to evaluate the relationship between blood-lead (Pb-B) and ALA-U levels in male workers exposed to lead. The differences between the ALA-U levels determined by this method (ALAU-HP) and by a colorimetric method (ALA-U-CL) are discussed. The HPLC method gave values similar to the ALA-U-CL values at high ALA-U level. However, at low blood-lead levels (58 ± 22 g/l, n = 23), the mean ALA-U-HP level corrected by urinary creatinine level was one-third of the corrected ALA-UCL level (0.83 ± 0.14 and 2.4 ± 0.5 mg/g creatinine, respectively). A significant increase of the mean corrected ALA-U-HP level was observed at 162 ± 22 g/l Pb-B (P < 0.05, n = 26), while that of ALA-UCL was observed at 245 ± 30 g/l Pb-B (P < 0.01, n = 37). The regression equation based on the logistic model fitted well to the relationship data between the Pb-B level and the percentage of the subjects with corrected ALA-U-HP above the cut-off point (1.12 mg/g creatinine) and the expected Pb-B level for 50% response was 270 g/l Pb-B, while it did not fit well to the relationship data between Pb-B level and the percentage of the subjects with corrected ALAU-CL above the cut-off point (3.5 mg/g creatinine). The maximum responses for the two sets of corrected ALA-U levels were both observed at 625 ± 25 g/l. The corrected ALA-U level by HPLC method seems to be a useful indicator for biological monitoring of exposure to lead at low levels (< 400 g/l Pb-B = health-based biological limit, WHO) as well as high ones.