Blood lead concentration and biological effects in workers exposed to very low lead levels

A longitudinal study was carried out on two groups of workers engaged in tin/lead alloy welding in the telecommunication sector. The risk of exposure was evaluated by measuring levels of airborne lead (PbA) and the amount of lead absorbed (PbB). The-correlated effects were assessed by determining zinc protoporphyrin (ZPP) and hemoglobin levels (Hb) and red blood cell (RBC) count. We also recorded subjective symptoms reported by workers. One group of welders composed of 365 subjects underwent two monitoring sessions performed in 1991 and 1995, respectively (Group A). A second group of welders (whose number fluctuated between 148 and 247 subjects) underwent yearly testing for 7 consecutive years (1988-1994; Group B). Results indicated a very low risk of lead exposure during microwelding operations (PbA range, 1.5-24 micrograms/m3). In fact, blood concentrations of Pb (range, 5-55, micrograms/dL) among both groups of welders were significantly higher than those in the general population in Rome (PbB range, 5-16 micrograms/dL); nevertheless, they were significantly lower than the Occupational Safety and Health Administration's permissible exposure limits ZPP determined only in Group B of welders ranged from 5 to 16 micrograms/dL (median, 22 micrograms/dL). No variation was found in the other biological parameters investigated, and no health effects were observed. During the study period, the introduction of some technological innovations led to a further reduction in Pb exposure and, subsequently, to its total elimination. PbB concentrations gradually declined to lower values (6-36 micrograms/dL), and it was interesting to note that ZPP concentrations also decreased to normal levels (range, 2-47 micrograms/dL; median, 11 micrograms/dL), demonstrating that the effect of lead on heme synthesis may occur even at very low levels of Pb exposure.     

Lead in the blood and protoporphyrin levels in erythrocytes in glass workers exposed to lead]

The craniofacial cephalometric dimensions, angles and dimensional ratios of five Finnish individuals with complete testicular feminization (CTF) were compared with their first-degree relatives and population female and male controls. The linear and angular measurements were made from standardized lateral cephalograms of patients and normal population controls from the 'Kvantti Study' series. The women with CTF tended to have cranial base and maxillary complex dimensions between those of the normal control females and males. Their mandibular corpus was found to be longer than in normal control females, while their ramus was shorter compared with that of normal males. They also showed a smaller sagittal length ratio of the maxilla to the mandible, a smaller ANB angle and a more acute gonial angle than in both normal control females and males. Comparison of the women CTF with their first-degree female relatives showed basically the same trends as when comparing them with normal female controls. As the phenotype in these females with CTF is due to insensitivity to, or lack of androgens, it is suggested that the presence of the Y chromosome in these females leads to craniofacial dimensions between those of normal females and males which influences the growth of the mandibular corpus. This follows the same general metric pattern that is observed in many of their adult head and body dimensions as well as in their dental arches.     

The influence of bone and blood lead on plasma lead levels in environmentally exposed adults

There is concern that previously accumulated bone lead stores may constitute an internal source of exposure, particularly during periods of increased bone mineral loss (e.g., pregnancy, lactation, and menopause). Furthermore, the contribution of lead mobilized from bone to plasma may not be adequately reflected by whole-blood lead levels. This possibility is especially alarming because plasma is the main circulatory compartment of lead that is available to cross cell membranes and deposit in soft tissues. We studied 26 residents of Mexico City who had no history of occupational lead exposure. Two samples of venous blood were collected from each individual. One sample was analyzed by inductively coupled plasma-magnetic sector mass spectrometry for whole-blood lead levels. The other sample was centrifuged to separate plasma, which was then isolated and analyzed for lead content by the same analytical technique. Bone lead levels in the tibia and patella were determined with a spot-source 109Cd K-X-ray fluorescence instrument. Mean lead concentrations were 0.54 microg/l in plasma, 119 microg/l in whole blood, and 23.27 and 11.71 microg/g bone mineral in the patella and tibia, respectively. The plasma-to-whole-blood lead concentration ratios ranged from 0.27% to 0.70%. Whole-blood lead level was highly correlated with plasma lead level and accounted for 95% of the variability of plasma lead concentrations. Patella and tibia lead levels were also highly correlated with plasma lead levels. The bivariate regression coefficients of patella and tibia on plasma lead were 0.034 (p<0. 001) and 0.053 (p<0.001), respectively. In a multivariate regression model of plasma lead levels that included whole-blood lead, patella lead level remained an independent predictor of plasma lead level (ss = 0.007, p<0.001). Our data suggest that although whole-blood lead levels are highly correlated with plasma lead levels, lead levels in bone (particularly trabecular bone) exert an additional independent influence on plasma lead levels. It will be important to determine whether the degree of this influence increases during times of heightened bone turnover (e.g., pregnancy and lactation).     

Effect of dietary calcium on blood lead concentrations in occupationally exposed and nonexposed workers

PURPOSE: Evaluation of night glare after excimer laser in situ keratomileusis (LASIK) using two different ablation zone diameters. METHODS: One hundred and twenty eyes of 60 consecutive myopic patients received LASIK with the Nidek EC-5000 excimer laser. Eyes were randomized so that every patient had a single ablation zone of 5.5 mm on one eye and an ablation zone of 5.5 mm with a transition zone of 1.0 mm diameter larger on the other eye. Night glare was measured by two methods; a spot light test and a subjective questionnaire. RESULTS: At 6 months, 54 patients (90%) were examined; results of the spot light test showed that 40 patients (74.1%) perceived more glare with the eye with the single ablation zone; the subjective questionnaire indicated that 22 patients (40.7%) had more night glare with the eye with a single ablation zone compared to the other eye. The use of the transition zone increased the required total ablation depth by 20%. CONCLUSION: The use of a peripheral transition 1.0 mm diameter larger than the ablation zone significantly decreased night glare after LASIK with slight increase in the required central ablation depth.     

Relationship between lead mining and blood lead levels in children

The authors studied blood lead levels of 226 randomly selected children, aged 6-92 mo, who lived in either a lead-mining area or a nonmining area, and 69 controls. The authors sought to determine to what extent mining activities contributed to blood lead levels in the children. The mean blood lead levels in the study and control groups were 6.52 microg/dl and 3.43 microg/dl, respectively. The corresponding proportions of children with elevated blood lead levels were 17% and 3%. Soil and dust lead levels were up to 10 times higher in the study than the control group. Elevated blood lead levels appeared to result from exposure to both lead-mining waste and lead-based paint. Mining waste was the cause of the higher prevalence of elevated blood lead levels in these children.     

Biological effect monitoring in industrial workers from the Czech Republic exposed to low levels of butadiene

Blood samples were collected twice (in 1993 and 1994) from 19 workers exposed to 1,3-butadiene and 19 matched controls. Three exposed and three control subjects were the same in 1993 and 1994. Personal passive dosimetry was performed in 1993 and twice in 1994 on the day preceding blood sampling. Mean exposure level in 1994 was 1.76 +/- 4.20 ppm (S.D.) and individual exposure levels ranged between 0.012 ppm (detection limit) and 19.77 ppm. Using the clonal assay, geometric mean of hprt mutant frequencies adjusted for cloning efficiency, age and smoking were, respectively, 7.85 (+/- 7.09) x 10(-6) and 10.14 (+/- 9.16) x 10(-6) in pooled (1993 plus 1994) exposed and control subjects. The difference was not statistically significant indicating that 1,3-butadiene did not induce a detectable increase in mutations at the hprt locus. A similar result was obtained for the 1994 subjects alone. There was no difference between adjusted geometric mean mutant frequencies of exposed and unexposed non-smokers or between exposed and unexposed smokers. Analysis of chromosomal aberrations in lymphocytes from 1994 subjects indicated that the percentage of aberrant cells was significantly enhanced in exposed subjects. In 1993 (data not shown), it was impossible to demonstrate a significant increase of aberrant cells in subjects exposed to 1,3-butadiene. Frequencies of micronuclei in cytochalasin-B blocked binucleate lymphocytes in exposed and unexposed 1994 subjects were not significantly different. This was also the case for earlier samples analyzed in the same plant. Using the comet assay for 1994 subjects, no statistically significant difference was found between the whole group of exposed and unexposed subjects. This was true for both the comet tail length and the percentage of DNA in the tail. In exposed smokers, however, the comet tail length was significantly longer than in unexposed smokers. Unexpectedly, in unexposed smokers the tail length was significantly shorter than in unexposed non-smokers. It was also unexpected that the percentage of DNA in the comet tail was significantly lower in exposed non-smokers than in unexposed non-smokers.     

Effect of personal hygiene on blood lead levels of workers at a lead processing facility

The relationship between personal hygiene and blood lead levels was tested at a lead processing facility. During the workers' semiannual respirator fit test, when they were confident their hands were clean, the amount of lead on their right hands was measured. Samples were obtained by cleaning one entire hand with a wiping towel treated with a proprietary mixture of alcohol, surfactants, and ethylenediaminetetraacetic acid. Wipe samples were analyzed for total lead and then compared with the worker's blood lead level. Each worker's personal habits at rest were also observed. Workers with more than 1 year's experience had a significantly positive correlation between lead on the hand tested and their blood level. The study strongly suggests that lead on the skin ultimately enters the bloodstream. The route of entry was not investigated. Personal habits of the workers with high blood lead levels were observed to include actions that would quickly contaminate their hands shortly after washing.     

The relationship of blood lead and dietary calcium to blood pressure in the normative aging study

BACKGROUND: Previous studies have demonstrated a positive relationship between elevated blood lead (BPb) and blood pressure (BP), but few have additionally examined the role of dietary calcium. METHODS: The cross-sectional relationship between BPb and BP and the possible protective influence of increased dietary calcium on that relationship was examined among 798 male participants in the Normative Aging Study (NAS), a cohort of older men with relatively low BPb levels. RESULTS: The age range of these subjects was 43-93 years (mean = 66.1, SD = 7.4 years) and blood lead concentrations ranged form 0.5 to 35 mcg/dl (median = 5.6 mcg/dl). For the cohort overall, neither ln blood lead nor dietary calcium were significantly correlated with BP. In multivariate linear regression analyses that adjusted for age, body mass index, dietary calcium intake (adjusted for total calorie intake), alcohol intake, sitting heart rate, kilocalories/week expended in exercise, haematocrit, and smoking status, a unit increase in ln BPb predicted an increase on 1.2 mmHg diastolic blood pressure (DBP) (95% CI : 0.11, 2.2; P = 0.03). Adjusted calcium intake of 800 mg/day predicted a decrease of 3.2 mmHg systolic blood pressure (SBP) (95% CI : -5.6, -0.24, P = 0.03). There was no evidence of an interaction between dietary calcium intake and blood lead on BP. When the analyses were restricted to those men <=74 years old, a unit increase in ln BPb predicted an increase of 1.6 mmHg DBP (n = 681; 95% CI : 0.42, 2.7; P = 0.007). However, when men on antihypertensive medication (AHM) were excluded from the analyses, ln BPb was not significantly associated with increased DBP nor was adjusted calcium significantly associated with SBP. CONCLUSIONS: The study did support the hypothesis that increased BPb was associated with increased DBP in a cohort of older men with low blood lead, but there was no evidence of interaction between BPb and dietary calcium on BP. However, the relationship between increased BPb and DBP did not hold when those on anti-hypertensive medications were excluded.     

Effect of anemia on blood and tissue lead in rats

The effect of anemia on the lead content of blood, red cells, and tissue was studied in rats given oral lead, 54 mg/kg-day for 6 days. The 16 rats made anemic (hematocrit, 26%) by bleeding on days 1, 3, and 5 had significantly higher concentrations of lead in the kidney, liver, red cells, blood, and brain (but not in the bone marrow). Increases in blood lead in anemic subjects were correlated with the concentrations in red cells, kidney, and liver. The greater increase in the lead content of all tissues of the anemic rats is consistent with increased lead absorption in anemia and is considered relevant to the clinical coexistence of anemia and lead poisoning.     

The effect of the OSHA lead exposure in construction standard on blood lead levels among iron workers employed in bridge rehabilitation

The symptomatology sometimes due to a giant styloid process can be very troublesome and at the same time unspecific, raising differential diagnosis problems with a large group of pathologies. We report a clinical case of elongated styloid syndrome, stylalgia or Eagle's syndrome, that forced our team to the exeresis of the anomalous process. We emphasizes the relative simplicity of the diagnosis and its treatment as well, especially when the intrabucal approach is followed.     

Medical surveillance studies of workers exposed to low level benzene

The paper presents th results of an investigation of haematotoxicity in workers exposed to low benzene concentrations. Forty-seven female workers in the shoemaking industry, exposed to solvent mixture and twenty-seven non-exposed controls were examined. Benzene concentrations in the working atmosphere ranged from 1.9 to 14.8 ppm. Significant differences in the levels of benzene in blood and phenols in pre- and post-shift urine between the exposed and control groups confirmed benzene exposure. Haemoglobin level and mean corpuscular haemoglobin concentration were significantly lower, and mean corpuscular volume was higher in the shoemaking workers than in controls. In the subgroup of shoemaking workers exposed to benzene concentrations of 5 ppm or lower, no differences in haematological parameters were found. In conclusion, exposure to a benzene concentration lower than 5 ppm does not appear to produce an increased level of abnormal haematological outcomes detectable in routine medical surveillance. The results of the study corroborate the present maximum permissible concentrations (5 ppm) as a protective limit preventing the onset of haematotoxic non-leukemogenic effects of chronic benzene exposure.     

Measurement of vitamin D3 metabolites in smelter workers exposed to lead and cadmium

OBJECTIVES: To investigate the effects of lead and cadmium on the metabolic pathway of vitamin D3. METHODS: Blood and urinary cadmium and urinary total proteins were measured in 59 smelter workers occupationally exposed to lead and cadmium. In 19 of these workers, the plasma vitamin D3 metabolites, (25-hydroxycholecalciferol (25 OHD3), 24R, 25-dihydroxycholecalciferol (24R,25(OH)2D3) and 1 alpha,25-dihydroxycholecalciferol (1 alpha, 25(OH)2D3)) were measured together with blood lead. Vitamin D3 metabolites were measured by radioimmunoassay, (RIA), lead and cadmium by atomic absorption spectrophotometry, and total proteins with a test kit. RESULTS: Ranges for plasma 25(OH)D3, 24R,25(OH)2D3 and 1 alpha,25(OH)2D3 were 1.0-51.9 ng/ml, 0.6-5.8 ng/ml, and 0.1-75.7 pg/ml, respectively. Ranges for blood lead were 1-3.7 mumol/l, (21-76 micrograms/dl), blood cadmium 6-145 nmol/l, and urinary cadmium 3-161 nmol/l. Total proteins in random urine samples were 2.1-32.6 mg/dl. Concentrations of lead and cadmium in blood showed no correlation (correlation coefficient -0.265) but there was a highly significant correlation between blood and urinary cadmium. Concentrations for 24R,25(OH)2D3 were depressed below the normal range as blood and urinary cadmium increased, irrespective of lead concentrations. High cadmium concentrations were associated with decreased plasma 1 alpha,25(OH)2D3 when lead concentrations were < 1.9 mumol/l and with above normal plasma 1 alpha,25(OH)2D3 when lead concentrations were > 1.9 mumol/l, Kruskal-Wallis analysis of variance (K-W ANOVA) chi 2 = 10.3, p = 0.006. Plasma 25(OH)D3 was negatively correlated with both urinary total proteins and urinary cadmium, but showed no correlation with plasma 24R,25(OH)2D3, 1 alpha,25(OH)2D3, blood lead, or blood cadmium. CONCLUSION: Continuous long term exposure to cadmium may result in a state of equilibrium between blood and urinary cadmium. Cadmium concentrations in blood could be predicted from the cadmium concentration of the urine, (regression coefficient +0.35 SE 0.077). Exposure to cadmium alone decreased the concentrations of 1 alpha,25(OH)2D3 and 24R,25(OH)2D3, whereas exposure to both cadmium and lead increased the concentrations of 1 alpha,25(OH)2D3. It has been suggested that cadmium and lead interact with renal mitochondrial hydroxylases of the vitamin D3 endocrine complex. Perturbation of the vitamin D metabolic pathway by cadmium may result in health effect, such as osteoporosis or osteomalacia, risks which are possibly increased in the presence of lead.     

A survey of blood lead levels in dogs and cats

The blood of 206 dogs and 26 cats was analyzed for lead by non-flame atomic absorption giving mean levels of 6.4 mug/100 ml for dogs and 5.2 mug/100 ml for cats. Statistical treatment of the results using a paired Students' t-test showed significant differences by age for dogs but not for cats. Urban dogs had significantly higher blood lead levels than country dogs (P less than 0.05) thus indicating that dogs can be regarded as useful environmental monitors for lead pollution.     

Screening children exposed to lead: an assessment of the capillary blood lead fingerstick test

We describe results of a 3-year study in which 499 paired venous and capillary blood specimens, collected by fingerstick on the same day, were analyzed for lead (BPb) and erythrocyte protoporphyrin (EP). False-positive rates (FPRs) and the proportion of false positives were calculated at four BPb thresholds. At the 100 microg/L threshold, the FPR for all data was 13%, but the proportion of false positives was only 5%. The log ratios of capillary-to-venous BPb data indicate that, with the exception of eight outliers, two subpopulations exist that follow a log-normal distribution. These two subpopulations, the "core" (n = 303) and "shifted" (n = 188) groups, on average generated a positive bias at 100 microg/L BPb of 8.6% and 30.3%, respectively. The log ratios of capillary-to-venous EP data followed a normal distribution, indicating that capillary EP is not statistically different from venous EP.     

The relationship of lead in soil to lead in blood and implications for standard setting

As part of a soil lead regulation process, this review was conducted to determine the association between lead in soil and established human health effects of lead or validated biomarkers of lead exposure. We reviewed only studies where soil exposure could be distinguished from other sources of lead and whose design could reasonably be used to infer a causal relationship between soil lead and either biomarkers or health effects. No such studies of health effects were found. Studies describing a quantitative relationship between soil lead and blood lead did meet our criteria: 22 cross-sectional studies in areas with polluted soil; and three prospective studies of soil lead pollution abatement trials. The cross-sectional studies indicated that, compared to children exposed to soil lead levels of 100 ppm, those exposed to levels of 1000 ppm had mean blood lead concentrations 1.10-1.86 times higher and those exposed to soil lead levels of 2000 ppm had blood lead concentrations 1.13-2.25 times higher. The prospective studies showed effects within the ranges predicted by the cross-sectional studies. Differences in results between studies were surprisingly modest and likely explainable by random sampling error, different explanatory variables included in data analyses and differences in methods of measuring lead in environmental specimens.     

关于我国废铅实得率低下的原因的研究

通过分析铅的生命周期流动过程,找出了影响废铅实得率的因素。它们是:铅品的国内消费率、可回收性铅消费率、折旧废铅回收率等。在中国铅业调研的基础上,估算了近年来这些影响因素的实际数值。讨论了废铅实得率低下的原因:一是铅品的大量出口;二是铅的消费结构中耗散性消费太多;三是废铅回收状况太差。提出了改善中国废铅实得率的对策。     

Antioxidant supplementation and respiratory functions among workers exposed to high levels of ozone

Ozone exposure has been related to adverse respiratory effects, in particular to lung function decrements. Antioxidant vitamins are free-radical scavengers and could have a protective effect against photo-oxidant exposure. To evaluate whether acute effects of ozone on lung functions could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blind crossover design. Street workers (n = 47) of Mexico City were randomly assigned to take daily a supplement (75 mg vitamin E, 650 mg vitamin C, 15 mg beta carotene) or a placebo and were followed from March to August 1996. Pulmonary function tests were done twice a week at the end of the workday. During the follow-up, the mean 1-h maximum ozone level was 123 ppb (SD = 40). During the first phase, ozone levels were inversely associated with FVC (beta = -1.60 ml/ppb), FEV1 (beta = -2.11 ml/ppb), and FEF25-75 (beta = -4.92 ml/ppb) (p < 0.05) in the placebo group but not in the supplement group. The difference between the two groups was significant for FVC, FEV1, and FEF25-75 (p < 0.01). During the second phase, similar results were observed, but the lung function decrements in the placebo group were smaller, suggesting that the supplementation may have had a residual protective effect on the lung. These results need to be confirmed in larger supplementation studies.     

The risk of lead and health conditions of exposed workers in the Siena region]

With careful selection of patients, complete resection of pulmonary metastases from breast carcinoma may be a useful therapeutic option. Such a treatment appears to offer a significant survival benefit when compared with medical treatment alone, or with incomplete resection.