PbB Levels Research Articles

Dietary and Inhalation Intake of Lead and Estimation of Blood Lead Levels in Adults and Children in Kanpur, India

This research was initiated to study lead levels in various food items in the city of Kanpur, India, to assess the dietary intake of lead and to estimate blood lead (PbB) levels, a biomarker of lead toxicity. For this purpose, sampling of food products, laboratory analysis, and computational exercises were undertaken. Specifically, six food groups (leafy vegetables, nonleafy vegetables, fruits, pulses, cereals, and milk), drinking water, and lead air concentration were considered for estimating lead intake. Results indicated highest lead content in leafy vegetables followed by pulses. Fruits showed low lead content and drinking water lead levels were always within tolerable limits. It was estimated that average daily lead intake through diet was about 114 microg/day for adults and 50 microg/day in children; tolerable limit is 250 microg/day for adults and 90 microg/day for children. The estimated lead intakes were translated into the resultant PbB concentrations for children and adults using a physiologically-based pharmacokinetic (PBPK) model. Monte Carlo simulation of PbB level variations for adults showed that probability of exceeding the tolerable limit of PbB (i.e.,10 microg/dL) was 0.062 for the pre-unleaded and 0.000328 for the post-unleaded gasoline period. The probability of exceeding tolerable limits in PbB level was reduced by a factor of 189 in the post-unleaded scenario. The study also suggested that in spite of the introduction of unleaded gasoline, children continue to be at a high risk (probability of exceeding 10 microg/dL = 0.39) because of a high intake of lead per unit body weight.

Renal and Neurologic Effects of Cadmium, Lead, Mercury, and Arsenic in Children: Evidence of Early Effects and Multiple Interactions at Environmental Exposure Levels

Lead, cadmium, mercury, and arsenic are common environmental pollutants in industrialized countries, but their combined impact on children’s health is little known. We studied their effects on two main targets, the renal and dopaminergic systems, in > 800 children during a cross-sectional European survey. Control and exposed children were recruited from those living around historical nonferrous smelters in France, the Czech Republic, and Poland. Children provided blood and urine samples for the determination of the metals and sensitive renal or neurologic biomarkers. Serum concentrations of creatinine, cystatin C, and β2-microglobulin were negatively correlated with blood lead levels (PbB), suggesting an early renal hyperfiltration that averaged 7% in the upper quartile of PbB levels (> 55 μg/L; mean, 78.4 μg/L). The urinary excretion of retinol-binding protein, Clara cell protein, and N-acetyl-β-d-glucosaminidase was associated mainly with cadmium levels in blood or urine and with urinary mercury. All four metals influenced the dopaminergic markers serum prolactin and urinary homovanillic acid, with complex interactions brought to light. Heavy metals polluting the environment can cause subtle effects on children’s renal and dopaminergic systems without clear evidence of a threshold, which reinforces the need to control and regulate potential sources of contamination by heavy metals.

Assessing Lead Risks at Non-Residential Hazardous Waste Sites

ABSTRACT In 1996, the U.S. Environmental Protection Agency (USEPA) developed the Adult Lead Methodology (ALM) to provide an interim approach to assessing risks from non-residential exposures to lead. Because such exposures often involve occupational activities of adults, the ALM was directed at assessing soil-related lead risks to adults. Consistent with other approaches used in Superfund risk assessment, the ALM was designed to predict quasi-steady state blood lead concentrations (PbB) that might result from soil exposure. These predictions are converted to a risk estimate, expressed as the probability of exceeding a PbB level of concern. To examine the assumptions and variables in the ALM that have become available since 1996, a comparison was made of the attributes of seven alternative research models for which adequate documentation is available to understand and implement each approach. Several of these models have been used in regulatory decision-making; however, the USEPA has officially embraced none for general use. This analysis suggests that the ALM can continue to serve as a reasonable tool for assessing risks associated with non-residential exposures to soil. Under certain circumstances other models may be more applicable (i.e., for assessing acute or intensive exposures); however, the ALM is recommended for the majority of risk assessment applications.

Neurocognitive Impairment in Lead-Exposed Children of Andean Lead-Glazing Workers

The level of lead (Pb) exposure necessary to induce intellectual impairment has not been firmly established. Some studies using conventional language-based intelligence tests have reported that pediatric blood lead (PbB) levels lower than 10 microg/dL (0.483 micromol/L) are associated with neurocognitive impairment. However, these tests may introduce cultural biases in the assessment of intellectual functioning. The objective of this study was to assess the effects of PbB concentration on nonverbal intelligence in Andean children with chronic environmental Pb exposure using a nonlanguage-based test of cognitive functioning. Using Raven Colored Progressive Matrices (RCPM) as a measure of nonverbal intelligence, this study investigated the effects of Pb exposure (biomarker: PbB levels) on intellectual functioning in 188 chronically Pb-exposed children (age range: 5.33-11.67 years) of Ecuadorian Andean Pb-glazing workers. The mean PbB level of the 188 children was 29.3 microg/dL (range: 3.5-94.3 microg/dL). Forty-seven children had PbB levels <10 microg/dL (Centers for Disease Control and Prevention [CDC] I classification), of which 30 had abnormal (ie, < or =25th percentile) RCPM standard scores. Of the 141 children with PbB levels > or =10 microg/dL, 97 had abnormal RCPM scores. A regression analysis revealed a statistically significant negative association (r = -0.331, P < 0.0001) between PbB level and RCPM standard score. Conversion of RCPM standard scores to estimated IQ scores showed an approximate two-point decrease in IQ for each 10-microg/dL increment in PbB level from 10 to >70 microg/dL. Performance on a test of nonverbal intelligence was inversely associated with chronic Pb exposure in Andean children with PbB levels below and above the CDC risk management level of 10 microg/dL, with the decline in test scores suggesting a dose-response relationship.

Comparison of Colorimetric and HPLC Methods for Determination of .DELTA.-Aminolevulinic Acid in Urine with Reference to Dose-Response Relationship in Occupational Exposure to Lead

Both traditional colorimetry and recently developed HPLC-fluorometry have been in use for determination of delta-aminolevulinic acid in urine (ALA-U), an effect marker of occupational exposure to lead (Pb). The present study was initiated to compare the values by the two methods on an epidemiology basis among workers occupationally exposed to lead (Pb), to estimate quantitatively the colorimetry-associated increment over the values by the HPLC method, to evaluate ALA-U determination in occupational health service for Pb-exposed workers, and to identify a critical Pb-B to induce an elevation in ALA-U. For this purpose, blood and urine samples were collected from three groups of Pb-exposed workers (both men and women in combination, including smokers) and analyzed for Pb in blood (Pb-B; measured in all subjects) and ALA-U (by colorimetry or HPLC), i.e., Group 1 (164 subjects with urinalysis by the two methods), Group 2 (2,923 subjects by colorimetry), and Group 3 (2,540 subjects by HPLC). ALA-U when measured by colorimetry was higher than the values by HPLC, and that the mean difference on a group basis was 1.4 mg/l (in a range of 1.1 to 1.8 mg/l), irrespective of Pb-B levels. It was also found that the increase in ALA-U was small when Pb-B was relatively low (e.g., < or = 40 microg/100 ml), and that the increase on a group basis in response to an increase in Pb-B from 5 to 40 microg/100 ml was as small as < or = 0.6 mg/l. Thus, ALA-U appeared to be not a sensitive marker of Pb effects at low Pb-B levels. ALA-U however increased substantially with a point of inflection at the Pb-B level of about 17-34 microg/100 ml. Thus it was concluded that ALA-U as measured by colorimetry is greater than ALA-U by HPLC by 1.4 mg/l on average irrespective of intensity of Pb-exposure, which may induce bias in evaluation of health effect, and that ALA-U levels will increase when Pb-B is in excess of 17-34 microg/100 ml.

Current pediatric and maternal lead levels in blood and breast milk in Andean inhabitants of a lead-glazing enclave.

Prenatal and postnatal lead (Pb) exposure may induce neurodevelopmental disabilities in children. As part of an ongoing health-monitoring study, blood lead (PbB) levels were compared in 90 children tested in 2003 (current group) and 166 children tested between 1996 and 2000 (reference group) in Ecuadorian Andean villages with high Pb contamination. The mean PbB level for children in the reference group was 40 microg/dL (range, 6.2-119.1), and significantly higher than the mean PbB level of 25.5 microg/dL (range, 2.1-94.3) for the current group (t test, P = 0.0001). An analysis of variance revealed no significant main effects for age and gender and no significant interaction between age and gender for the current group but a significant age by gender interaction for the reference group (F = 5.96, P = 0.01). Regression analysis revealed a significant correlation (r = 0.258, P = 0.01) between PbB level and age for males but not for females in the reference group. The Pb levels in breast milk from nursing mothers ranged from 0.4-20.5 microg/L (mean, 4.6), and the PbB levels in the breastfeeding mothers ranged from 4.5-35.2 microg/dL (mean, 17.1). The PbB levels of mother-infant pairs ranged from 4.6-27.4 microg/dL for mothers and 3.9-33.5 microg/dL for infants. The results showed significantly reduced PbB levels in children in the study area and suggest that a Pb education and prevention program contributed to the current reduction in Pb intoxication.

The behavior and routes of lead exposure in pregrasping infants.

Understanding the routes of lead exposure in a very young infant is an essential precursor to identifying effective strategies for minimizing blood-lead (PbB) levels throughout infancy. The present study integrated observational data, lead-loading data, and household airborne particulate levels <10 microm (PM(10)) to understand the broad patterns of lead exposure in infants from Port Pirie, South Australia. Seven, 2-19-week-old infants were observed between three and six times, for 3-9 h per visit, at intervals of 1-9 weeks. Household lead-loading and PM(10) data were collected for five of the families. Eight objects were observed in an infant's mouth, but only the infant's fingers, pacifier, and nipple of the mother's breast or teat of a bottle were observed in an infant's mouth for an average of more than 1% of an observation day. The objects most frequently put in an infant's mouth were their own fingers or their pacifier. Synthesizing our data on behavioral frequency, lead loading, and the surface area of contact, and using estimates of dose response, and sampling, transfer, and absorption efficiencies, the results suggest that a 4-month-old infant could absorb up to 4 microg of lead a day (equivalent to a PbB level of up to about 2.4 microg/dl) by mouthing their fingers, about two-thirds of all exposure routes identified in this study. Estimates also suggest that lead uptake via inhalation accounts for about 0.5-3% of an infant's PbB at 5 microg/dl. If our estimates reflect real routes and values, the majority of the average PbB level of 6-month-old infants in Port Pirie during 2002 could potentially be accounted for by the normal infant and family behaviors observed in this study. While the current level of concern is 10 microg/dl, recent studies indicate no safe threshold for Pb exposure, and so interventions for reducing chronic low-level exposure are useful. We suggest that home-based interventions for reducing Pb exposure should focus on maintaining low Pb loadings on objects that are directly associated with an infant, and outside objects that have few transfer steps to the infant.

Lead and Methylene Chloride Exposures Among Automotive Repair Technicians

Potential exposures among repair technicians engaged in vehicle resurfacing operations prior to spray painting have not been thoroughly characterized. Environmental and personal air monitoring conducted in the State of Rhode Island have shown that automotive repair technicians may be exposed to metal particulates in sanding dust and methylene chloride vapors during vehicle paint removal operations. Hand wipe samples demonstrated that metals in sanding dust adhered to the hands of workers throughout the duration of the work day and were available for incidental ingestion from the handling of food/nonfood items and hand-to-mouth contact. A blood lead (PbB) screening effort among 21 workers at 2 facilities showed that 4 non-/less-exposed workers had mean PbB levels at the U.S. geometric mean of 2.8 μg/dL, while 2 out of 9 (22%) dedicated vehicle repair technicians had PbB levels at or above 30 μg Pb/dL whole blood—the level for potential adverse reproductive effects. Methylene chloride exposures were also found to exceed the Occupational Safety and Health Administrations (OSHA) 8-hr time-weighted average (TWA) action level and permissible exposure limit (PEL) in a limited number of samples (120 and 26 ppm, integrated work shift samples). Our findings suggest that thousands of professional technicians and vocational high school students may be at increased risk of adverse reproductive and/or other systemic effects.

Controlling Lead Concentrations in Human Blood by Regulating the Use of Lead in Gasoline

After having been emitted at maximum rates in the 1960s and 1970s, lead has become less ubiquitous in industrialized countries as a result of increasingly stringent policies to limit the use of this heavy metal as an anti-knock additive in gasoline. Using a detailed reconstruction of lead emissions in Europe (PbE), of the air concentration of lead in Europe (PbC) and repeated measurements of lead concentrations in human blood (PbB) in Germany since about 1980, we have constructed an empirical model that estimates PbB given PbE. This model is used for 2 purposes: i)To estimate PbB levels for the 1960s and 1970s in Germany, when emissions were maximum and monitoring blood levels had not yet begun. It turns out that PbB peak emissions were reaching a mean level, which health officials considered potentially harmful for fetuses and small children. ii) To estimate how PbB levels may have developed if regulations of the use of lead in gasoline had been implemented differently. In case of no or delayed regulations, the model estimates that PbB levels well beyond the critical level would have emerged. Thus, the regulation instituted in Germany since the 1970s has reduced significant health hazards.

Blood lead levels in Egyptian children: influence of social and environmental factors.

The wide spectrum of damage to the health of children from environmental lead (Pb) is a matter of global concern. The neurotoxicity of long-term low-level exposure to lead has a special relevance in children.1,2 Although the consumption of paint chips or proximity to a lead-emitting smelter has been associated with PbB (blood lead) levels > 40 μg/dL, these 2 factors are not considered contributors to moderately elevated levels (> 10 μg/dL). Therefore, activities that contribute to lower levels of Pb exposure should be identified. The aim of this pilot study was to establish the social variables predictive of higher lead levels in young Egyptian children.

Activity of Glutathione Peroxidase, Glutathione Reductase, and Lipid Peroxidation in Erythrocytes in Workers Exposed to Lead

The aim of this study was to estimate the activity of glutathione peroxidase (GPx), glutathione reductase (GR), and malondialdehyde (MDA) in erythrocytes in healthy male employees of zinc and lead steelworks who were occupationally exposed to lead over a long period of time (about 15 yr). Workers were divided into two subgroups: the first included employees with low exposure to lead (LL) (n=75) with blood lead level PbB=25-40 microg/dL and the second with high exposure to lead (HL) (n=62) with PbB over 40 microg/dL. Administration workers (n=35) with normal levels of PbB and zinc protoporphyrin in blood (ZPP) in blood were the control group. The activity of GPx significantly increased in LL when compared to the control group (p<0.001) and decreased when compared to the HL group (p=0.036). There were no significant changes in activity of GR in the study population. MDA erythrocyte concentration significantly increased in the HL group compared to the control (p=0.014) and to the LL group (p=0.024). For the people with low exposure to lead (PbB=25-40 microg/dL), the increase of activity of GPx by about 79% in erythrocytes prevented lipid peroxidation and it appears to be the adaptive mechanism against the toxic effect of lead. People with high exposure to lead (with PbB over 40 microg/dL) have shown an increase in MDA concentration in erythrocytes by about 91%, which seems to have resulted from reduced activity of GPx and the lack of increase in activity of GR in blood red cells.

Succimer (meso-2,3-dimercaptosuccinic acid (DMSA)) treatment of Andean children with environmental lead exposure.

The authors studied children in Andean villages contaminated by a lead-glazing cottage industry. Mean blood lead (PbB) level in 35 exposed children, aged 3-14 years, a year before treatment, at the time of initiation of a comprehensive lead education and prevention program, was 53.4 microg/dL. PbB levels immediately before and three weeks after a ten-day regimen of succimer treatment of the 35 children were 43.4 microg/dL and 34.3 microg/dL, respectively, showing a 21% reduction and a significant difference between means (t = 5.09, p = 0.0001). PbB levels of the same children a year before treatment and immediately pre-treatment were also significantly different (t = 10.59, p = 0.0001). Thus, a ten-day course of succimer chelation effectively reduced PbB in children with moderate to severe Pb intoxication, and the education and prevention program, initiated with parents, health care providers, and educators, also contributed significantly to reducing PbB.

Biomarkers of Renal Effects in Children and Adults with Low Environmental Exposure to Heavy Metals

The health effects of chronic exposure to heavy metals such as lead, cadmium, and mercury are widely documented, yet few data exist about the renal impact of low environmental exposure to these metals, particularly in children. The aim of this study was to assess renal parameters in children and adults living in an environment known for its past heavy metal contamination around two nonferrous smelters in northern France (Noyelles-Godault and Auby) and to compare their results with age and gender-matched controls living in neighboring municipalities with unpolluted soil (total: 400 children, 600 adults, sex ratio = 1). The integrity of renal function was assessed by measuring the urinary excretion levels of total protein, albumin, transferrin, g 2 -microglobulin, retinol-binding protein, brush border antigen, and the enzyme N-acetyl- g -D-glucosaminidase (NAG). The mean blood concentrations of lead (Pb-B, children h 42.2 w /L, adults h 71.3. w /L) and of cadmium (Cd-B, children h 0.52 w g/L, adults 0.86 w g/L) were all relatively low, indicating a low uptake of these heavy metals from the environment despite relatively high levels in soil (between 100 and 1700 ppm for lead and 0.7 to 233 ppm for cadmium). Pb-B levels were, however, significantly increased in boys, girls, and women--but not men--living in the polluted area. Boys, men, and women living in the polluted area had also on average higher Cd-B levels. The concentrations of mercury in urine (Hg-U) were by contrast similar in control and exposed groups. None of the renal parameters studied showed a significant difference between control and exposed groups. The influence of heavy metals on renal parameters was further assessed by stepwise multiple regression, testing Pb-B, Cd-B, Hg-U, age, gender, body mass index (BMI), urinary creatinine levels, and area of residence as predictors in both children and adults, including first-order metal interaction terms, smoking habits, and alcohol consumption in adults. The only positive correlation was found between the urinary excretion of NAG activity (standardized for BMI and urinary creatinine) and Cd-B levels when taking the whole children population, indicating that even low cadmium burdens may produce subtle effects on the proximal tubule in children, although deleterious consequences are unlikely should exposure not increase. However, in the absence of other positive findings even after studying the smaller subgroups with higher levels of heavy metals, these results are clearly indicative of the minimal renal impact of living around nonferrous smelters that are currently complying with pollution regulations, even when soil contamination is still high.

Health risk for children from lead and cadmium near a non-ferrous smelter in Bulgaria

In an interdisciplinary approach the exposure to lead and cadmium of the population living in the vicinity of a Bulgarian non-ferrous metallurgical plant was studied to determine the routes of exposure. Two exposed villages situated 4 and 6 km SW and W, respectively, – in the plume of the plant's emissions – and a village for comparison situated 14 km SE of the plant were selected for the study. The blood of children aged 3 – 13 years from the exposed villages (n=111) and the village for comparison (n=18) was analyzed for lead (PbB) and cadmium (CdB) as well as for free erythrocyte protoporphyrin (FEP) and haematological parameters. A personal questionnaire concerning nutrition habits and life-style was filled in by interviewers of the children's parents.The cadmium levels in blood were within the variation range stated for Bulgaria. The exposed children had a mean CdB of 0.38±0.18 μg/l (range 0.10 – 0.90 μg/l) and the comparison group 0.31±0.35 μg/l (0.06 – 1.42 μg/l). The mean PbB value measured in the exposed children was 240±96 μg/l (77 – 631 μg/l), while the mean value of PbB for the reference group was 149±57 μg/l (63 – 285 μg/l). Individual PbB levels >150 and >200 μg/l were found in 85% and 62%, respectively, of the exposed children and FEP >80 μg/dl erythrocytes was detected in 21%. There was a concentration-response and a concentration-effect relationship (r=0.51, D>0.001) between PbB and FEP.According to the questionnaire only 10.3% of the interviewed families in the two exposed villages buy all food from the market, the others produce a significant part of their food themselves. The PbB levels of children who consume certain foods of local production (cabbage, cereals, poultry, and beef) were significantly higher compared to the PbB values of children whose families purchase these foods from the market. No significant relationship between lead in children's blood and the use of tin and ceramic utensils, drinking and irrigation water, hygiene habits, family tobacco smoking habits, playgrounds and traffic intensity were revealed. There was a significantly higher incidence of prematurely born babies in the exposed population.The proven relationship between lead intake via the food chain and existing significant health risks is the basis for risk communication. Measures aimed at healthier nutrition and life-style intend to contribute to decreasing the risk of the population living in the smelter region.

Adult:Child Differences in the Intraspecies Uncertainty Factor: A Case Study Using Lead

Adults and children differ in their susceptibility to the toxic effects of lead. Lead was therefore used as a case study to evaluate intraspecies differences by comparing the adult and child minimal Lowest Observed Adverse Effect Level (LOAEL) or the No Observed Adverse Effect Level (NOAEL), allowing an evaluation of the ten-fold intraspecies uncertainty factor (UF). The lead intakes (in µg/kg/d) necessary to achieve target blood lead (PbB) levels reflecting the minimal LOAEL or NOAEL were determined using biokinetic slope factors (BKSFs), which relate lead uptake to PbB levels. The analyses assumed chronic, low-level oral exposure to lead, and the response of a typical adult and child. Child analyses used a target geometric mean (GM) PbB of 4.6 µg/dL (95% of population <10 µg/dL), resulting in lead intakes of 1.9 µg/kg/day (assuming 100% soluble lead) and 4.9 µg/kg/day (assuming 25% soluble lead and 75 % soil lead). Adult analyses assumed intake of 100 % soluble lead, and used target GM PbB levels of 4.2 µg/dL (95% of population <11.1 µg/dL) and 11.4 µg/dL (95% of population <30 µg/dL), resulting in lead intakes of 1.9 µg/kg/day and 5.1 µg/kg/day, respectively. The results indicate that despite the greater vulnerability of young children to the effects of lead as compared to adults, the minimal LOAEL or NOAEL for lead is remarkably similar between children and adults. In this case, the application of a tenfold intraspecies uncertainty factor to adjust the adult minimal LOAEL or NOAEL for a child would be unnecessary, despite the well-established vulnerability of children to lead.

Lead-based paint health risk assessment in dependent children living in military housing.

In children, lead can cause serious permanent damage as a neurotoxicant. The objectives of the study were to evaluate potential exposure to lead-based paint in family housing units at a typical U.S. military installation and determine blood lead (PbB) levels in children ages 6 years or younger residing in these housing units. The authors conducted a risk assessment of 1,723 housing units and occupants at Fort Devens in Massachusetts. Data from the military dependent cohort was compared to estimates for the U.S. national population as reported from Phase 1 of the Third National Health and Nutrition Examination Survey (NHANES III). A total of 1992 individuals (1,009 males and 983 females) were screened for PbB, stratified into age groups, and separated into racial/ethnic categories. Four (0.3%) dust samples and 59 (11.6%) internal and 298 (77.8%) external paint chip samples contained hazardous levels of lead. The geometric mean PbB concentration for people ages 1 year and older reported by NHANES III was 2.8 micro g/dL, compared with 1.5 microg/dL for the military installation cohort (p<0.0001). PbB levels were higher for males than for females and higher for blacks than whites 6 years of age and older. Hispanics had lower PbB concentrations for all age groups except for those ages 1-2.9 years. Prevalence of PbB levels >10 microg/dL for all age groups was 1.6% in the military cohort, compared with 4.5% for the general population. For ages 1-2.9 years, no blacks or Hispanics and 0.6% of whites had PbB levels >10 micro g/dL, compared with 21.6% of blacks, 10.1% of Hispanics, and 8.5% of whites for the general population. For ages 3-5.99 years, 0.15% of blacks, 0% of Hispanics, and 0.3% of whites had PbB levels > or = 10 microg/dL, compared with 20.0% of blacks, 6.8% of Hispanics, and 3.7% of whites for the general population. Lead exposure for occupants of on-post military housing is much less than for those residing in the civilian sector.

The relationship between blood lead levels and periodontal bone loss in the United States, 1988-1994.

An association between bone disease and bone lead has been reported. Studies have suggested that lead stored in bone may adversely affect bone mineral metabolism and blood lead (PbB) levels. However, the relationship between PbB levels and bone loss attributed to periodontal disease has never been reported. In this study we examined the relationship between clinical parameters that characterize bone loss due to periodontal disease and PbB levels in the U.S. population. We used data from the Third National Health and Nutritional Examination Survey (NHANES III), 1988-1994, for the analyses. A total of 10,033 participants 20-69 years of age who completed a periodontal examination and had whole blood tested for lead were examined. Four types of periodontal disease measures were used to indicate oral bone loss: periodontal pocket depth, attachment loss extent, attachment loss severity, and the presence of dental furcations. We found that dental furcations were the best periodontal bone loss indicator for PbB levels (p = 0.005) in a multivariate linear regression model adjusting for sex, age, race/ethnicity, educational attainment, poverty status, smoking, and age of home. Furthermore, after additional modeling, we found a smoking and dental furcation interaction (p = 0.034). Subsequent stratified analyses indicated that current and past smoking is an effect modifier for dental furcations on PbB levels. These findings indicate that increased PbB levels may be associated with advanced periodontal bone loss, particularly among people with a history of smoking.

Specific relationship between blood lead and air lead in the crystal industry.

The main objective of the study was to establish the consequences of exposure to crystal dust on blood lead level in workers employed in hand-finishing and grinding crystal pieces. The second objective was to research a relationship between ambient air lead and blood lead. A study conducted in eastern France on 131 subjects occupationally exposed to an aerosol containing crystal particles involved personal measurements of atmospheric exposure to lead, determination of blood lead and, by questionnaire, collection of personal data on exposure characteristics, state of health and level of hygiene of survey volunteers. Initial analysis showed that differences in exposure at the workplace corresponded to differences in blood lead in the operators. There was definitely a potential risk of overexposure to lead, but the existence of this risk was not confirmed by level of blood lead concentrations and, moreover, no clinical signs of lead poisoning in the employees exposed were revealed. The existence of a relationship between personal air (PbA) and blood lead (PbB) levels in grinders and polishers was demonstrated. This relationship, of the form log PbB=2.064+0.181 x log PbA, turns out to be different from those provided by previously published models, which were developed from studies conducted in lead-acid battery manufacturing plants and form the basis of national regulations. Thus, chronic exposure at 100 microg/m(3) of lead at a crystal-grinding workshop corresponds to a mean PbB level of 270 microg/l, whereas the recognized models estimate 350 to 500 microg/l. This study revealed a specific risk for these categories of exposed individuals. The origin of the descriptive model obtained for the lead exposure/ PbB level relationship raises, through the example of lead, the more general problem of the need to take into account differentiation of chemical substances containing the same element in biological monitoring.

Effect on blood lead of airborne lead particles characterized by size.

Worker exposure to airborne lead particles was evaluated for a total of 117 workers in 12 work-places of four different industrial types in Korea. The particle sizes were measured using 8-stage cascade impactors worn by the workers. Mass median aerodynamic diameters (MMAD) were determined by type of industry and percentage of lead particles as a fraction of airborne lead (PbA) concentration was determined by particle size. Blood lead (PbB) levels of workers who matched airborne lead samples were also examined. A Scheffé's pairwise comparison test showed that MMAD and the fractions of each of respirable particles and lead particles < or =1 microm relative to PbA varied greatly by the type of industry. The concentrations of lead particles < or =1 microm, which the Center for Policy Alternatives model assumes is relatively constant at 12.5 microg/m3, increased with increasing PbA concentration. In addition, a better correlation was detected between concentrations of particles < or =1 microm and concentrations of respirable lead particles (r = 0.82) than that between concentrations of small particles and PbA (r = 0.61). A simple linear regression indicated that PbB correlated better with respirable lead concentration (r2 = 0.35, P = 0.0001) than with PbA concentration and had a higher slope coefficient. Controlling for respirable lead concentration reduced the partial correlation coefficient between PbA concentration and PbB level from 0.56 to 0.20 (P = 0.053). The results indicate that the contribution of respirable lead particles to lead absorption would be greater than that of PbA. This study concludes that the measurement of PbA only may not properly reflect a worker's exposure to lead particles with diverse characteristics. For the evaluation of a worker's exposure to various types of lead particles, it is recommended that respirable lead particles as well as PbA be measured.

Urinary homovanillic acid and serum prolactin levels in children with low environmental exposure to lead

Current evidence suggests that the neurotoxic effects of lead may partially be mediated through interference with the dopaminergic system. The aim of this study was to assess the levels of two peripheral dopaminergic markers- serum prolactin (Pro-S) and urinary homovanillic acid (HVA-U) - in children living around two lead smelters, who are presumed to be exposed to high environmental lead pollution (n = 200), and compare their results with 200 age- and sex-matched controls living in an area unpolluted by heavy metals, giving a total of 400 children (200 boys and 200 girls). The influence of lead exposure on HVA-U and Pro-S was assessed by stepwise multiple regression, testing lead concentrations in blood (Pb-B), age, sex and area of residence as predictors. Though lead levels were significantly higher in boys and in the lead-polluted environment, mean Pb-B values were relatively low, indicating a low uptake of lead in the contaminated environment (39.5 μg l-1, range 4.6-165μgl-1, n = 200), and no significant correlation could be found with either Pro-S or HVA-U. However, when the subgroup of 121 children with Pb-B levels above 50 μg l-1 were considered, a weak positive correlation was found between Pb-B and HVA-U (r2 = 0.04, p = 0.03), whilst in the even smaller subgroup of 15 children with Pb-B levels above 100 μg l-1, Pro-S appeared to be positively correlated with Pb-B, though the numbers of children were too small for the correlation to reach statistical significance (p = 0.095). These weak associations, probably not important in biological terms, indicate that Pro-S and HVA-U are not useful biomarkers at present exposure levels to lead in the environment. Nevertheless, the finding of subtle biochemical alterations in the dopaminergic system at Pb-B levels of around 100μgl-1 supports the recommended setting of the action level at this value.